Thermoplastic

Thermoplastic

Thermoplastic Materials

BASIC INTRODUCTION:

The word “plastics” refers to products produced from polymers by various processes.

Processes such as injection moulding, extrusion, blow moulding, vacuum moulding, thermoforming, injection blow moulding, rotational moulding, etc. A provided polymer can be used in many other types of goods, such as Adhesives, coatings, fabrics, elastomers, etc. In the plastics industry, polymers are referred to as plastic resins. Big molecular weight polymers are “Compounds or products composed of monomer repeated units.

The Constituents of thermoplastics:

Thermoplastics are referred to as simple homopolymers. Many products are copolymers, where the base polymer has been modified to optimize manufacturing characteristics and improve moulded material properties. Polymer molecular weights affect material properties and melt flow properties are determined by molecular weight distributions.

Broad softening temperature range, strong resilience, and low shrinkage define amorphous polymers. Polymer crystallinity gives higher melting temperatures, higher shrinkage, and increased rigidity. To develop a combination of properties from two compatible polymers, alloying and blending are commonly used. Elastomeric additions enhance toughness. Lower additions give toughened thermoplastics, whilst higher amounts produce thermoplastic elastomers.

Groups of Thermoplastics:

The structure of their prime polymer groups. In their basic form, very few thermoplastics are used and can be modified in several ways. To obtain improved properties, copolymers polymerize two monomers to obtain desired properties, often to assist impact resistance or processing. Blends and alloys, of which PC/ABS is the most prevalent combination available from several sources. However, there are other industrially provided combinations of thermoplastics. Thermoplastic elastomers can be widely classified as olefin, styrene, polyurethane (ester or ether), polyester, or polyamide.

Groups of thermoplastics
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Two major types of plastics are available, namely thermoplastics and thermosets.

  • The amorphous and semicrystalline forms consist of thermoplastic polymers. It is considered that all amorphous and semicrystalline thermoplastics are identical and are commonly referred to as thermoplastics. In comparison to semicrystalline thermoplastics, amorphous thermoplastics have 0% crystallinity and are defined by varying degrees of “semicrystalline.” Thermoplastics are referred to as semicrystalline though they cannot reach 100% crystallinity.
  • The naturally translucent amorphous thermoplastics include polystyrene, polymethyl methacrylate (PMMA), polycarbonate, polysulfides, polyimides, etc. Both amorphous and semicrystalline thermoplastics are considered to be characterized by crystallinity, whereas their thermoset counterparts are categorized by cross-linking.

Thermoplastics can be categorized into two main bases:

  1. Functional usage or categories
  2. Families

The functional usage of thermoplastics itself has five classifications under it. They are:

  • General-purpose (commodity) thermoplastics:
    This group comprises primarily polyethylene (PE), polypropylene (PE), and (PP), Polyvinyl Chloride (PVC), polystyrene (PS), and some of their monomer-based copolymers. More than 50 per cent of thermoplastic materials comprise these four thermoplastics. Usually, material thermoplastics have average mechanical properties and demand low prices as such. Since they are cost-effective, they are used in vast amounts.
  • Quasi-commodity thermoplastics:
    The quasi-commodity thermoplastics have mechanical property values that are typically above commodity thermoplastics but are not high enough to be comparable to those of engineering thermoplastics. The higher-than-average mechanical values make the quasi-commodity thermoplastics such as Acrylonitrile–butadiene–styrene (ABS), Polymethylmethacrylate (PMMA), Polyethylene terephthalate (PET), Styrene-acrylonitrile (SAN), K-resin, etc., to command prices in the range that are above those of the typical commodity thermoplastic.

In addition, there are other aspects of the quasi-commodity thermoplastic material that are more improved than those of the commodity thermoplastic material. For pop-bottle and other packaging uses, PET’s gas permeability and ECSR (environmental stress cracking resistance) characteristics make it the reference material.

The higher costs of quasi-thermoplastic resins result in smaller consumption volumes than those of thermoplastic commodities.

  • Engineering thermoplastics:
    The thermoplastic materials classified as engineering thermoplastics have Mechanical and exceptional properties above average and these allow them to regulate higher prices than commodities and quasi-commodities thermoplastics.

Owing to their high costs, engineering thermoplastics have poor consumption capacities; the polyamide family’s nylons are the most commonly used engineering thermoplastic materials to replace silk. They are very fashionable and in-demand textiles which are also used as under-the-hood automotive materials. PCs are widely used to make helmets and in high-impact glass applications. In addition to PPS’s high mechanical properties, it is insoluble in solvents below 200°C.

LCPs have ease of processing despite their high strength standards, and their self-reinforcing characteristics make them excellent choices in blends.

  • Speciality thermoplastics:
    One or more special properties of speciality thermoplastic materials compensate for their lack of outstanding mechanical characteristics. Owing to their unusual and specific features, they are high-priced and have meagre consumption rates. The non-stick properties of PTFE make it perfect for the material of choice in cooking pots and other coating applications. It can be used as desirable heat and an electric oven due to its high thermal stability combined with low thermal conductivity and low dissipation.

The strong intensity and features of openness make them suitable materials for the protective glass application of Polyimides (PI), Polysulfone (PSu), and Polyphenylene oxide (PPO). Liquid crystalline polymers (LCPs) have been included as speciality thermoplastics because of their high costs.

  • New and emerging thermoplastic materials:
    This is a new category that includes materials such as functionalized thermoplastics (FTPs), nanocomposites of thermoplastics (TPNCs) and others.
  • Thermoplastic Nanocomposites:
    The advent of nanoparticle fillers allows the properties of thermoplastic materials and other matrices to be modified. Research in the field indicates that small amounts of nanoparticle fillers can increase the mechanical and other thermoplastic properties with careful processing. A new category of materials considered as TPNCs can yield matrices.

There are multifunctional characteristics of TPNCs; characteristics such as modulus, strength, durability, chemical resistance, resistance to gas permeability, thermal stability, and dimensional stability are strengthened.

  • Functionalized Thermoplastics:
    FTPs include functional classes that make it possible for them to be interactive and form intermolecular bonds and intramolecular bonds. Typically, FTPs have linear backbones, and chain-ends add functionalization. In the chain, functionalization can also be achieved via block and graft copolymerization. FTPs are emerging products with varied and creative uses. The functionalization of polymeric matrices and nanoparticles allows new materials such as nanocomposites and the materials such as to be produced and formed. Electricity conducting thermoplastics, blends, biodegradables, high-temperature thermoplastics, etc.

Groups of Thermoplastics


The various materials can be roughly classified to differentiate between engineering thermoplastics and commodity materials; However, a few thermoplastics can be a part of both categories-

Thermoplastics for high-performance manufacturing: liquid crystal polymers (LCP), polyphenylene oxides, aromatic polyketones (PEEK, PAEK), fluoropolymers (PTFE, FEP, PVDF) or ethers (PPO, PPE), polyimides (TPI), polyphenylene sulfides (PPS), polysulfones (PSU), polyether sulfones (PES), polyamide imides (PAl), polyetherimides (PAl) (PEI).

Engineering thermoplastics: Polyacetals (POM), polyamides (PA, nylons), polyphthalamide (PPA), polycarbonates (PC), polybutylene terephthalates (PST).

Engineering (and commodity) thermoplastics: thermoplastic elastomers (TPE), polymethylmethacrylate (PMMA), Acrylonitrile-butadiene-styrene (ASS), polyethylene terephthalates (PET).

Choosing the right thermoplastic
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Commodity (and engineering) thermoplastics:
High-density polyethylene (HOPE), ethylene-vinyl acetate (EVA), polyvinyl chloride (PP), ionomers, polypropylene (PP) (PVC). O Material thermoplastics: polyethylene low density (LOPE), polystyrene (PS), cellulose acetate (CA) (CA).

APPLICATIONS OF THERMOPLASTICS:

The development and use of thermoplastics are associated with different commercial sectors. The major ones are:

Automobile: Used under the bonnet (radiators, hoses, electrical components, housings, etc.), external bodywork (bumpers, lights, trim, spoilers, fuel tanks, etc.), and interior furnishing (dashboards, fixtures, trim, etc.).

Electrical and electronic products: domestic appliances (refrigerators, microwave ovens, coffee makers, kettles, etc.), office equipment (telecommunications, computers, fax machines, etc.) and entertainment (televisions, hi-fi, personal stereos, computer games, etc.).

Health care: Surgical implements, catheters, implants, syringes, sterilized components, tubing.

Construction and civil engineering work: Pipelines and fittings (gas, water, drainage, etc.), sheeting, panelling, electrical cabling and ducting, windows frames, storage containers, bulk handling, geotextiles, tools.

Packaging: films, shrink-films, plastic bags, blister packs, containers.

Consumer goods: Furnishing, toys, cosmetics, household furniture, leisure, and sports.

Thermoplastics in consumer goods

METHODS OF PROCESSING:

To maximize product production, thermoplastics can be treated in a variety of ways:

  • Injection Moulding (multiple cavities, a large cavity, reaction, and foaming).
  • For gradual moulding.
  • Rotational Moulding
  • Moulding for compression and transfer.
  • Extrusion and extrusion coating Co-extrusion.
  • Filaments are drawn, and fibres are woven.
  • Hot-dip, bed covering, electrostatic, and fluidized.
  • Plastisol

Thermoforming, welding, calendaring, embossing, metalizing, shrinking, and bonding will secondarily process the resulting product type. Therefore, thermoplastics must have both the desired manufacturing characteristics and the moulded properties needed. To attain the optimal overall efficiency, the base virgin resin is usually compounded with other constituents, including reinforcements and fillers, other polymers and elastomers, antioxidants, UV stabilizers, fire retardants, dyes, and lubricants.

Reinforcements and Fillers required to obtain thermoplastic:

 

  • Particulates (e.g., talc, glass, mica) boost stiffness and rigidity but reduce the efficiency of performance.
  • As a colorant or for screening against ultra-violet (UV) radiation, carbon black is a common additive.
  • The stiffness, rigidity, and resilience of the base polymer are greatly increased by fibre reinforcement (e.g., glass, carbon, and aramid).
  • Usage of Additives to protect polymers:
  • Antioxidant additions stabilize polymers during the processing phase.
  • UV stabilizers must ensure an adequate life for several polymers (mainly for thin sections), especially outdoors.
  • Fire retardants are needed if the application is meant to deter the spread of flames, such as cars, public transport (aircraft), office equipment, household goods, and construction materials.
  • Lubricants aid in the manufacture of moulded products or decrease the surface coefficient of friction.

Processing Characteristics of thermoplastics:

 

Melt flow properties are important for both polymers and the optimal process line. High melt flow indices are suitable for injection moulding, although extrusion demands lower values. Some polymers absorb atmospheric moisture to maintain moulding consistency, and raw materials need to be dried before processing, such as polyamides.

 

Many polymers are susceptible to contraction, which are harmful to dimensional stability or optical appearance. By adding fillers and strengthening, it prevents shrinkage. With melt flow directions and reinforcing orientation, the grade of shrinkage in the polymer varies.

Moulded Material Properties of thermoplastics:

Engineering applications:

Stiffness (modulus), strength and elongation (tension, bend, and possibly compression and shear), properties of impact (notched and unnotched), temperature distortion and softening of heat, absorption of moisture and water, flammability, thermal expansion coefficient, and electrical properties. Also, basic application criteria can include fatigue (tension and flexural) properties, creep tolerance, and relaxation of stress over various temperatures. It isn’t easy to present these above properties by grade, manufacturers are consulted directly.

 

Commodity applications:

Appearance (colour, transparency, shine, surface texture), strength, elongation, modulus, impact properties, hardness, and tear resistance. Safety approvals for certain categories (food contact, toys) are to be considered.

Environmental and Chemical Performance:

Thermoplastics can be compared by Stability to aqueous salts, alkalis, and acids. Chemical resistance to concentrated acids and alkalis. Resistance to tenderness or attack by organic materials, including petrol, oils, fats, and solvents.

 

Environmental stability:

Resistance to oxidation, degradation to weather, Ultraviolet resistance, and environmental stress cracking resistance (ESCR). Temperature resistance, including effects of fire. Temperature resistance, including effects of fire.

 

Tolerance to the constituents of foodstuffs (like dairy products and fruit juices) so that the packaging is not compromised by the substance found in the packaging or, most specifically, the packaging does not damage the product.

Body-fluid resistance and sterilization processes for medical instruments and equipment. Similarly, any documented toxicological effects on inserted products. Thermoplastic medical grades usually signify short-term needs, such as body cavity drains and catheters.

POLYOLEFINS: POLYETHYLENE, POLYPROPYLENE, AND THEIR COPOLYMERS

 

The Polyolefin Family

 

Polyethylene and polypropylene are two of the four thermoplastics for general usage that account for 90% of the overall thermoplastic use. They are ethylene and propylene polymers, respectively. For certain other monomers, ethylene and propylene are the least costly raw materials for polymers’ processing and production.

 

The characteristics of the polyolefin family vary from high crystallinity at the high melting point of linear polymers to pure amorphous (or nil crystallinity) materials such as ethylene-propylene monomer (EPM) and ethylene propylene diene monomer (EPDM) rubbers, branched, or cross-linked. The polyolefin family consists of polypropylene, polyethylene, ethylene-vinyl acetate (EVA), polyallomer, ionomers, EPM, EPDM rubbers, ethylene ethyl acrylate (EEA), chlorinated polyethylene, chlorosulfonated polyethylene, and others.

POLYETHYLENE

The polymer formed by the polymerization of ethylene is polyethylene. Ethylene (CH2=CH2) is an unsaturated olefin gas derived from petroleum distillation (oil and gas). Of all the alkenes, ethylene is a light gas and the simplest. Owing to the presence of the carbon-carbon double bond in its chain, it is known to be unsaturated. Its unsaturated form makes it eligible to form a polymer or polyethylene as a monomer capable of being polymerized. The standard raw material stock for ethylene’s manufacture is naphtha.

The naphtha, derived from the distillation of petroleum and other ingredients, is made into ethylene by steam cracking. The largest outlet of ethylene monomer is polyethylene in the form of LDPE and high-density polyethylene (HDPE). In packaging applications, the complete use of ethylene and linear LDPE (LLDPE) as a replacement for other polyethylenes is used.

 

The two main applications of ethylene are ethylene dichloride (17.5 percent) and ethylene oxide (12 percent) as they act as precursors for the polymers, polyethylene terephthalate (PET), and polyvinyl chloride (PVC).

Polyethylene
Image Credits Cesare Gargioli

Unique Properties of Polyethylene

Polyethylene is a thermoplastic for general purposes or commodities, which has the largest annual production rate of all plastics Because of its low cost per kilogram-volume and its low specific gravity. It also has exceptional properties.

 The production rate is huge for polyethylene. Polyethylene is a class of materials ranging from LDPE and polyethylene of medium density (MDPE) to HDPE. Polyethylene has a negative 120°C low glass-transition temperature (Tg). The glass-transition temperature of polyethylene is lower than for other industrial rubbers.

However, because of its characteristic high crystallinity of around 40 per cent – 65 per cent in LDPE and 70 per cent – 95 per cent in HDPE, polyethylene is not rubberlike or elastomeric at room temperature. The high crystallinity of polyethylene accounts for its comparatively high melting time of 110°C for LDPE and 138°C for HDPE. This is also responsible for increased translucency.

Polyethylene is incredibly versatile and does not require plasticizers to be applied. This property offers ease of processing and makes it easy to process. Polyethylene is a suitable and cost-effective commodity for various manufacturing processes. Various Products such as tubes, films, and sheets that pinch is produced using polyethylene.

This polyethylene elastomeric-like feature gives it strong durability and impact properties. Under strain, very high polyethylene exhibits Stretch, which has high values of elongation. UHMWPE fibre is advertised as having similar properties to those with stainless steel and fibres of polyamide. The UHMWPE fibre is the latest version of polyamide fibre in bulletproof and shrapnel penetration resistance (SPR) applications.

 

Polyethylene has good chemical resistance acids, alkali, and salts and therefore it accounts for its usage in household detergent bottles and is susceptible to strong oxidizing agents. Susceptibility of polyethylene to chemicals increases as the level of crystallinity and LDPE is probably to be more susceptible than HDPE.

Polyethylene possesses low moisture absorptivity which does not require to be dried before processing improves polyethylene’s electrical insulation properties as the absence of moisture demotes electrical conductivity. Polyethylene holds electrical insulation properties. This is an important area of concern regarding the use of polyethylene for medical, industrial, and automobile goods such as labware, seals, implant parts, air ducts, fuel tanks, etc.

Polyethylene granules

Limitations to the use Polyethylene

Polyethylene is a commonly used plastic, and its use is limited due to its relatively low tensile strength. LDPE and HDPE are popular in consumer and packaging goods like toys, bottles, fruit crates, garbage cans, recreational and recreational equipment for outdoor use. Polyethylene has to be modified and reinforced in these and other applications to be able to survive outdoor UV light and heat penetration.

 

Materials used for Polyethylene collection

The choice of polyethylene resin for their use in applications is based on three major and important properties:

  • The Density: they are three density groups of polyethylene
  1. 0.91–0.925 (LDPE)
  2. 0.926∼0.940 (MDPE)
  3. 0.941–0.95 (HDPE)

 

  • Index Melt (MI the Melt Index is defined as the volume of polyethylene melt-extruded by a fixed orifice at 190 ° C and the prescribed pressure within 10 minutes. The most often used parameter to apply to the average molecular weight is MI. High molecular weight, melt viscosity, increased impact tolerance, and stress-cracking resistance properties contribute to lower MI values. Higher molecular polyolefins: polyethylene, polypropylene, and their copolymers’ weight mean less simplicity of manufacturing. Strong MI values indicate a reduction in tensile power, temperature reduction, and hardness properties.

In conjunction, these three properties apply and cover much of the Key polyethylene properties.

Polyethylene uses

The general-purpose, ease of manufacturing, the cost-effectiveness of polyethylene make it ideal for different applications to be created. Polyethylene’s ease of production and flexibility ensures that, with multiple processing processes, it can be processed into goods.

 

Blown-Film Polyethylene Products:

application include:

  • General-purpose packaging
  • Laminations
  • Frozen-food films
  • Ice bags
  • Hole liners
  • Trash bags

 

Cast-Film Polyethylene Products:

application areas include:

  • Bread bags
  • Frozen foods
  • Ice bags
  • General-purpose packaging
  • Diaper linings
  • Construction films
  • Trash/garbage bags
  • Box liners
  • Enclosable zipper bags
  • Biohazard bags
  • Mattress bag
General purpose food packaging

Extrusion Coating and Laminated Polyethylene Products:

application areas include:

  • Milk and food carton stock (maximum consumption area)
  • Kraft paper
  • Foil and polymeric films
  • Spiral wound cans for packaged motor oil and fruit juices
  • Adhesive layer in snack food packages, etc.

 

Blow-Moulded Polyethylene Products:

application areas include products with hollow interiors:

Bottles Cartons (milk, bleach, detergent, personal care products such as eye drop bottles, etc. [mostly LDPE for low stiffness and squeezability]

  • Toys
  • Ice chests
  • Automotive air conditioning and heating ducts
  • Under-the-hood reservoirs

Injection-moulded Polyethylene thermoplastic Products:

The variety of injection-moulded parts illustrates the wide range of resin properties available.

 

LDPE: thermoplastics that hold good in High ductility, excellent resistance to alcohols, bases, and acids. Lab equipment—tubing, small tanks, wash bottles, pipette washing equipment, trays and containers, bags, food storage—trays and containers, bags, etc.

 

LLDPE: thermoplastics that hold good in Flexibility and toughness, good transparency and higher tensile strength than LDPE.  cable insulation coating, Industrial grade packaging, food packaging, pipe, toys, buckets, etc.

HDPE: thermoplastics that hold good in Excellent durability, high specific strength, excellent chemical and corrosion resistance, low moisture absorptivity and compliance with FDA. Medical—prosthetics, orthotics; industrial—material handling components, tanks, water storage, water pipes, chain guides; consumer—garbage containers, food containers, etc

           

Pipes and Profile-Extruded Polyethylene Products:

Both LDPE and HDPE are used, but HDPE is dominant because of its superiority of pipes and profile-extruded goods

  • Toughness
  • Tolerance to abrasion
  • Strong tolerance to creep

 

Typical application areas for “pipes and profiles” in which thermoplastics used are:

  • Drinking water pipes
  • Corrosive chemicals
  • Irrigation
  • Sewer lines
  • Gas distribution
  • Flexible tubing for medical purposes

 • Oil and gas gathering lines

Wire and Cable Coating thermoplastics:

All polyethylene, LDPE, LLDPE, MDPE, HDPE, and XLPE are used as electrical wire and cable insulation and jacketing materials. In low voltage electrical insulation applications, Polyethylene’s strong dielectric and mechanical properties support it well. In high thermal resistance standards, cross-linkable polyethylene (XLPE) is used to insulate power cables.

Typical application areas include:

  • Electrical power cables
  • Communication cables
Pipes
https://plastrading.com/wp-content/uploads/2018/01/newpipe.jpg

Extruded Sheet/Vacuum Forming:

Polyethylene is extruded into sheets, and then the desired product is vacuum-formed. Due to the quasi-structural nature of thermoplastic products, HDPE is the preferred polyethylene type. In thermoplastic products, the benefits of HDPE include flexibility, low-temperature properties, and durability. The chemical resistance of polyethylene and the ability to withstand Steam sterilisation for thermoplastic goods is a beneficial trait.

 

Typical application areas of thermoplastic polyethylene are –

  • Truck bed liners
  • Miniature swimming pools
  • Food containers
  • Shipping containers

Rotational Moulding of thermoplastics:

The most favoured type is polyethylene in soil, sugar-like, sugar-size for strong heat transfer in rotational moulding thermoplastic applications.

Typical application areas of rotational moulding thermoplastic are

  • Chemical tanks
  • Water tanks (portable and non-portable)
  • Trash containers
  • Fuel tanks
  • Biofuel stations
  • Marine and kayaks
  • Automotive parts
  • Heating oil tanks
  • Insulated containers
Chemical tanks

Coextruded PE thermoplastic Products:

These are specifically used in cases of flexible packaging. This is mostly due to the presence of specific features present in these types of thermoplastic

  • Good moisture barrier properties
  • Sealing properties
  • Ease of co extrusion with other materials in blow moulding, chill casting, and coating

application areas are

  • Cosmetic packaging
  • Pharmaceutical packaging
  • Cheese packaging
  • Jelly packaging
  • Dairy products packaging

Ultra High-Molecular-Weight Polyethylene thermoplastics:

UHMWPE is touted as one of the extraordinary thermoplastics widely used in the current trend. The unusual and unique properties of UHMWPE include anti-friction properties, toughness, impact strength, abrasion resistance, and resistance to corrosion and chemical attack to produce make it perfect for water-related applications, such as nets, tow lines, mooring lines, fishing lines. UHMWPE’s incomparable adaptability, flexibility and durability make this thermoplastic a choice material for scientists, engineers and designers globally. This thermoplastic with extremely large molecular chains gives extraordinary features:

Excellent sliding properties regardless of the low friction coefficient.

  • Self-lubricating (non-caking and sticking)
  • Sound dampening properties
  • Good chemical and stress-cracking resistance
  • Ease of machining
  • FDA and USDA approval

POLYPROPYLENE:

 

The three major kinds of polypropylene are

  1. Homopolymers
  2. Random copolymers
  3. Heterophasic copolymers

The production of polypropylene (PP), currently the second most common plastic material, was also stimulated by the invention of the Ziegler-Natta catalysts. The free radical method that generates LDPE does not manufacture polypropylene. A new development in polypropylene processing technologies is the use of metallocene catalysts. Another current trend is Spherizone from Bassell, a fluid bed, multi-zone circulating reactor (MZCR) reactor technology with two interconnected zones that can create distinct materials and expand the range of properties of polypropylene.

Polypropylene
Credits: https://upload.wikimedia.org/wikipedia/commons/9/99/Polypropylene_isotactic_mini_trp.png

Raw materials used for polypropylene

The polymer formed by the polymerization of propylene is polypropylene. Propylene (CH2=CHCH3) is an unsaturated olefin gas derived from petroleum distillation in a process identical to ethylene. Due to the carbon-carbon double bond in its chain, it is known to be unsaturated. Its unsaturated state makes it eligible to form a polymer as a monomer capable of being polymerized. The standard raw material supply for propylene production is naphtha.

Unique Properties of Polypropylene:

Polypropylene is durable and easy to produce, making polyethylene a suitable and cost-effective commodity for the manufacture of various items, such as films and sheets. As it can melt and resolve, polypropylene is recyclable. It is designated in the resin recognition coding (RIC) scheme of the Society of the Plastics Industry (SPI) as number 5.

The higher temperature tolerance of polypropylene makes it ideal for trays, funnels, pails, bottles, carboys, and instrument jars that need to be sterilized regularly for use in clinical and medical environments. Polypropylene is very resistant to dilution and accumulation of acids, alcohols, bases, and mineral oils. For plating and chemical tanks and laboratory cabinetry, and semiconductor benchtops, polypropylene’s chemical resistance allows it to be a popular product.

Polypropylene is also used in washers and gaskets because of its chemical tolerance and temperature tolerance. Polypropylene has low moisture absorptivity which enhances polypropylene’s ease of processing. polypropylene is most appropriate for low voltage electrical insulation.

Limitations of polypropylene:

To be able to endure outdoor ultraviolet (UV) light exposure and humidity, polypropylene must be adjusted and reinforced.

  • Application areas of polypropylene:
  • Appliances and consumer products
  • Automotive
  • Agriculture
  • Building and construction
  • Leisure, outdoors, and sports
  • Medical and healthcare
  • Packaging
  • Fibres
HDPE Bags

Resins from polypropylene in appliances and consumer goods:

The availability of polypropylene varieties capable of withstanding long-term, prolonged exposure to heat and detergents allows polypropylene to be used to manufacture appliances that offer products of quality, comfort, and efficiency. appliances applications include Dishwashers, Washers and Dryers, Refrigerators, Floorcare, Food and freezer ware, Trigger sprayers, Totes, pails, and buckets, Trash cans, Lawn furniture.

The applications for automobile interiors include Dashboards, Dashboard carriers, Pillar claddings, Door pockets, Door panels, Consoles, Chairs. Polypropylene’s under-the-hood vehicle applications include Heating, ventilation, and air conditioning (HVAC), Batteries, Battery covers, Electronic housings, Air ducts, Splash shields, Pressure vessels, Reservoirs, Engine covers and others.

Polypropylene Agricultural Products:

Polypropylene has very poor humidity absorptivity. Products designed for agricultural applications allow air and water flow while providing wind and cold protection by creating a microclimate around the crop. This influence on the microclimate serves as an important Climate barrier, which removes extreme conditions of temperature.

Roofing, doors, screens, piping, decks, fences, rails, and wraps are fields of use. In plastic matrix wood composites, polypropylene is found to be commonly used. Composites of plastic matrix wood outlast typical materials and need less upkeep. They are immune to peeling, splintering, splitting, and fading.

Yarn for carpet backing, ropes, cordage, twine and thread, textiles such as thermal underwear, geotextiles, and others are applications of polypropylene thermoplastic fibres. The demand for fibre is a potential field for polypropylene globally.

Monofilament, bicomponent staple, multifilament, staple, slit film yarns, spun bonds, upholstery fabrics, melt-blown nonwovens, plastic pulps, and extruded nets, ropes and cordage, carpet backing, carpet face yarns, geotextiles, filtration products, horticulture/agricultural materials, automobile interior fabrics, spill-cleaning fabrics, spill-cleaning fabrics include fibrous types of polypropylene.

Yarn on loom

THE VINYL FAMILY: PVC AND COPOLYMERS:

 

Polyvinyl chloride (PVC)— [CH C 2− − HCL] n

Polyvinyl acetate (PVA) [ — CH2 3 − − OH O C− − =O (CH)] n

Polyvinylidene chloride (PVDC) [ — CH2 2 − − CCL] n

Copolymer of PVC and chlorine → + (CL P 2 VC) or chlorinated PVC

The best attribute of vinyl is its affinity for plasticizers; They build stable, dry, versatile solutions in recognized non-volatile, inert liquids known to be called plasticizers.

Polyvinyl Chloride

—CH2—CH — Cl –[CH2–CHCL] n–

The Vinyl Family

  • Polyvinyl chloride (PVC)— [CH C 2− − HCL] n
  • Polyvinyl acetate (PVA) [ — CH2 3 − − OH O C− − =O (CH)] n
  • Polyvinylidene chloride (PVDC) [ — CH2 2 − − CCL] n
  • Copolymer of PVC and chlorine → + (CL P 2 VC) or chlorinated PVC

POLYVINYL CHLORIDE:

Polyvinyl chloride (PVC) is a polymer manufactured from vinyl chloride monomer (VCM). PVC plasticization makes it more compact and simpler to use. It has a linear structure similar to polyethylene, but with a chlorine structure. An atom that substitutes an atom of hydrogen for alternative atoms of carbon. By volume consumption, it is the third-largest multipurpose thermoplastic. The chlorine atom is bulkier on the vinyl backbone than the hydrogen atom counter, which gives the PVC polymer chain a highly polar appearance. In the PVC polymer chain, the repeating mer unit contributes to a small crystallinity degree and a high level of amorphousness. This contributes to Transparency and better mechanical properties.

Of the four main product thermoplastics, PVC is the least expensive:

Polyethylene, polypropylene, and polystyrene polyvinyl chloride. This has a greater advantage in marketing the product. This is chiefly attributed to the

  1. PVC composition
  2. Energy specifications for PVC fabrication

PVC- Unique Properties

PVC is the only general-purpose thermoplastic that adds plasticizers, additives, and modifiers, including unlimited, wide, and effortless adaptation of the required physical properties of products, such as flexibility, elasticity, and impact resistance. Although the physical properties of end products can be modified by additive compounding, only a few forms of resin are needed to cover all applications (fibre, rigid and flexible plastic, rubber, paint, and adhesive).

In recycling, this controllability is also highly helpful. The ease of PVC alteration means that only a few PVC resin types are needed for various areas of use, such as rigid and flexible plastics, adhesives, coatings and paints, elastomers, fibres, etc. In a few readily modifiable ways, the existence of PVC is highly desirable in global recycling and sustainability initiatives. PVC is resistant to fire (self-extinguishing). The inclusion of chlorine in the construction of PVC strengthens this property.

The high dielectric strength of PVC ensures that it can be used for high voltage electrical insulation Applications. PVC has poor absorption of moisture and intrinsic tolerance to the growth of fungi/algae. In domestic water-related applications such as shower curtains, bathroom wall covers, swimming pool linings, etc., this accounts for PVC’s high use. PVC has ease of adhesion, painting, and printing. This is due to the chlorine presence and the resulting polarity in the PVC row.

PVC Polymer chain
Credit: Odile Madden

Problems associated with PVC and their remedies:

PVC is sensitive to UV light (sunlight) and switches colour from transparent to yellow or orange with UV-light penetration. This can lead to deterioration of Properties of mechanical and other types. It has been recognized that garden-hose products with non-fortified PVC have tasty water. This condition can be remedied using UV stabilizers such as black carbon, titanium dioxide, and others. Uncompounded PVC has a meagre resistance to fire. This heat resistance problem of PVC can be solved during compounding by adding heat stabilizers, lubricants, and plasticizers.

Applications of PVC:

In today’s society, rigid PVC pipes are ubiquitous. The benefits of extruded PVC pipes include ease of installing, lightweight, Rigidity, cost-effectiveness, resistance to degradation, non-toxicity, maintenance convenience, among others. Windmill blades provide a new novel use of extruded PVC products. In this application, lightweight, corrosion-resistant resistance, and decreased noise are attractive qualities. Typical areas of application include:

  • Cold water plumbing services
  • Fire ring mains
  • Water mains and potable water services
  • Sewage main—pumped and gravity fed
  • Drainage installations—domestic and industrial
  • Factory supply lines
  • Slurry lines
  • Effluent lines
  • Corrosive fluid pipelines—dyehouses, chrome, and zinc plating plants, etc.
  • Fume extraction ducts chilled water lines for refrigeration and air conditioning plant
  • Saltwater pipes used in small boat engines cooling and ballast tanks
  • Irrigation farm and ranch-irrigation system and sprinkler systems

PVC is most suitable for high volume production of film and sheet for

  • Vinyl upholstery
  • Pool linings and flooring
  • Shower curtains
  • Tablecloths
  • Rainwear
  • Geosynthetic membranes
  • Shoe soles
  • Appliance wire plugs
  • Automotive parts (armrests, vinyl upholstery)
PVC Pipes
https://www.worldconstructiontoday.com/wp-content/uploads/building-products/12043/pvc.jpg

New polymerization technologies allow PVC resins of higher molecular weight to be produced. Due to the higher polymerization cycle times, the new UHMW PVC resins cost more. UHMWPVC, though, has attributes that are much greater than PVC ones.

Increased compression collection, higher tensile strength, elongation, tear strength, module, chlorinated PVC (CPVC) developed primarily for corrosive and high-temperature environments include these attributes. CPVC can be machined and welded. CPVC is a fire retardant; its ability to stretch, mould, and weld allows it to be used in various applications, including tanks, plumbing, scrubbers, and ventilation systems, Resistance to abrasion, thermal resistance and lower brittleness.

Applications of UHMWPVC are:

  • Kink-resistant tubing
  • Peristaltic medical pumps that need transparent tubes which can be subject to constant cycling stresses
  • Weatherable automotive glazing beads
  • Hazardous material boots for environmental-clean-up
  • Bulbs for handheld resuscitators used by paramedics in sub-zero weather
  • Power cords for snowblowers
  • Low-flame/low-smoke cable compounds
PVC Foot mat

POLYSTYRENE AND COPOLYMERS:

Polystyrene and copolymers of styrene family are:

  • ABS—acrylonitrile, butadiene, styrene
  • SAN—styrene, acrylonitrile
  • SBR—styrene–butadiene rubber
  • K-resin—styrene–butadiene
  • Acrylonitrile-styrene-acrylate (ASA)

Polystyrene – By volume product or general-purpose thermoplastic, PS is the fourth highest. The thermal processing of styrene produces polystyrene, which produces high polymers similar to rubber. The raw material for producing PS is Styrene (HCH=CHC6H5) or vinyl benzene. Styrene is manufactured from ethylbenzene.

PS is a thermoplastic that is extremely flexible and usable as high-impact, high-speed, and highly specialized resins. The addition of styrene monomer polymerization generates it. In an oxygen-free environment, styrene polymerizes spontaneously when heated, but catalysts are required to allow complete polymerization at lower temperatures.

Clear PVC
https://www.plasticpipeshop.co.uk/assets/images/Clear-PVC-Category-Image-290x220.jpg

For PS output, the four main polymerization processes, bulk, solution, emulsion, and suspension, may be used. Often due to its purity advantage and high conversion efficiency, bulk polymerization is the most used method for producing crystal clear PS.

Properties and Characteristics of Polystyrene (PS):

This thermoplastic is expensive. PS (zero crystallinity) is amorphous or non-crystalline and is a very simple (crystal clear) substance with good optical properties. The benzene molecule on the PS vinyl backbone makes it bulky and prevents the structure from being ordered or packed. That makes it amorphous for PS.

PS quickly softens, but since it is amorphous, it does not exhibit a sharp melting point. PS has poor optical dispersion. PS’s low optical dispersion ensures that PS can be used in applications that require optical clarity (lenses, optical piping, etc.). PS and plastics have very low thermal conductivity and good water absorption resistance by good heat insulators.

PS has good chemical resistance to acid, alkali, and salt additions. PS has high hardness and gloss but is easily scratched. PS has exceptional artistic principles. It has no flavour, scent, or toxicity. Most    Industrially available PS qualifies for food communication clearance by the FDA Applications.

The packaging is the main PS use field, which involves packaging for fruit and milk, closures, lids, trays, and baskets for manufacturing, vending cups, and fast-food containers. Appliances are second with 19%; household electronics have 12%; furniture and furnishings have 9%, and others have 24%. Others include housewares, games, tools for leisure, etc. PS can process the acceptable methods used in the processing.

Thermoplastics, but most PS products are mostly generated by injection. Extrusion, moulding, and thermoforming. The uses of PS vary from basic household products like toys to the electronics industry’s engineering applications. Injection-moulded PS products encounter competition from lower-cost thermoplastics such as HDPE and polypropylene. The suitability of PS for injection moulding would enable it to retain its market share in electrical and electronic components and consumer goods in particular.

Polystyrene chain
https://upload.wikimedia.org/wikipedia/commons/4/41/Isotactic-polystyrene-chain-from-xtal-3D-balls.png

Thermoplastics, but most PS products are mostly generated by injection. Extrusion, moulding, and thermoforming. The uses of PS vary from basic household products like toys to the electronics industry’s engineering applications. Injection-moulded PS products encounter competition from lower-cost thermoplastics such as HDPE and polypropylene. The suitability of PS for injection moulding would enable it to retain its market share in electrical and electronic components and consumer goods in particular.

PS packaging is more eco-friendly and requires fewer energy and processing costs than equivalent paper or coated paperboard products. The use of PS foam in cups and other packaging applications, since PS foam weighs less than equivalent paper packaging items, means lower emissions during transport. Recycling of PS is an emerging trend in the market.

STYRENE–ACRYLONITRILE:

Styrene-acrylonitrile (SAN) is a styrene copolymer (HCH=CHC6H5) or Acrylonitrile and vinyl benzene (CH2=CH−C- N). Styrene is made from ethylbenzene; ethylbenzene, in the presence of aluminium chloride, is produced from the chemical reaction between ethylene and benzene. Acrylonitrile is a solvent that is synthetic, colourless, explosive, and flammable with a strong, pungent odour. It is relatively soluble in water and miscible with most organic solvents. In the processing of the acrylic fabric, acrylonitrile is mostly used.

Seventy-five percent of SAN is used to manufacture ABS, ASA, and AES copolymers as a raw material; this accounts for the highest end-use of SAN. Some SAN main applications include:

  1. Container part of juice mixer
  2. Disposable cigarette lighter
  3. Brush and toothbrush handle
  4. Vacuum cleaner and humidifier parts
  5. Medical syringes, blood handling equipment
  6. Electric fan propeller
  7. Artificial kidney parts
  8. VTR tape parts
  9. Food utensils, mixer bowls, etc.
  10. Bicycle reflector
  11. Transparent Stationary battery cases (OPzS battery)
  12. Water meter housing
  13. Cosmetics container
  14. Printer components
  15. Refrigerator compartments
  16. Computer reels
  17. Chair shells
  18. Dishwasher-safe houseware products
  19. Optical fibres, lenses
  20. Packaging (cosmetics, food, medical, and others)
  21. Appliance knobs, fixtures, drawers, and shelving
  22. Colour and additives concentrate carriers for engineering thermoplastics
  23. Water filtration housing, drinking tumblers, water jugs, kitchen and picnic ware (hot and hot-water resistance)
  24. Radio dials, TV screens, etc.
Thermoplastic transparent SAN container battery
Credit: https://microtexindia.com/battery-products/opzs-battery/
Styrene Acrylonitrile chain
Credits: https://3.imimg.com/data3/OE/NJ/MY-3468186/styrene-acrylonitrile-500x500.png

Acrylonitrile–Butadiene–Styrene Terpolymer Resin (ABS): ABS is acrylonitrile (HCH=CH−C ⁇ N), butadiene (H2C=CH−HC=CH2), and styrene (HCH=CHC6H5) or vinyl benzene copolymer (terpolymer). This thermoplastic plastic is colourless, toxic, and flammable liquid with a distinctive pungent odour is acrylonitrile or vinyl cyanide.

The key cause for the popular use of ABS is its distinctive blend of Characteristics, such as strength and hardness. It is scarce for a thermoplastic material to have high durability and impact resistance properties combined with stiffness and rigidity. ABS has this property mix. It derives from acrylonitrile the chemical resistance and high strength properties; from butadiene the durability, impact resistance, and low-temperature properties; and from styrene, the stiffness, polish, and increased processability.

Based on the monomeric constituents’ ratio and molecular level connectivity, ABS polymers can be designed and formulated to provide various physical properties; translucent types of ABS can also be produced. ABS can be recycled, but with intensive recycling, colour properties would be lost.

ABS Polymer Chain
Credits: https://www.injectionmould.org/wp-content/uploads/2019/04/ABSAcrylonitrile-Butadiene-Styrene-.png

Applications:

 

Non-Toxicity is a desirable property of ABS resins and they are used in food grade applications. Their applications also include bathtubs, containers, pipes, refrigerator liners, and suitcases. ABS earns the global market to a greater extent. ABS’s use in applications of pipes and fittings; cost-effectiveness, lightweight, rust-resistant, seamless interior finish due to superior flow characteristics, and the ability to endure earth loads, mechanical loss, and low temperatures make ABS pipes and fittings more desirable than metal piping.

components made of ABS resins include Business machines, computers, and telephone housings constitute a considerable portion of ABS resin’s appliances market.

  • Vacuum cleaner housing
  • Refrigerator door liners
  • Radio and TV cases
  • Instrument panels
  • Decorative light trims, etc.
ABS Applications in Cars panels

A very fast-developing ABS resin industry is the transport-automotive market. The properties that make ABS and other plastics the products of choice in automotive applications are lightweight, corrosion resistance, fuel economy, cost-effectiveness, environmental friendliness, ease of manufacturing, styling freedom due to a decreased degree of design constraints.

Exterior automotive parts of ABS include-

  • Headlight housings
  • Mirror housing
  • Fuel filler door
  • Tail Light housings
  • Wheel trims
  • Grilles, etc

Interior automotive parts of ABS include-

  • Door and tank liners
  • Interior trim panels
  • Air register and vents
  • Knobs and grips
  • Consoles
  • Instrument panel retainers (ABS and ABS/PC blends)
  • Bumpers (blends)

The medical industry is an emerging one for ABS resins. The advantageous mixture of properties such as rigidity, dimensionality, ABS resins, blends Stability, impact strength, the stability of colour, thermal stability, processing ease, and processability.

Biocompatibility and sterilizability tests make them ideal for the manufacture of opaque parts of medical equipment, such as components for surgical instruments, testing devices, drug delivery systems, and IV systems. Due to their cost-effectiveness, high resistance, impact efficiency, low temperature, corrosion resistance and toughness properties, ABS resins are ideal candidates for power tool housings.

Other uses of ABS:

  • Luggage
  • Furniture
  • Camper tops
  • Golf carts
  • Trays & Computer Keyboards
  • Toys
  • Coffee maker parts
  • Thermos flask housing
  • Boats
ABS Applications Computer Keyboards

THE NYLON (POLYAMIDE) FAMILY:

Nylons are thermoplastic resins that are engineered processes. Nylons are semicrystalline, thermoplastic polymers that are engineered. Hydrogen bonding between polyamide chains is given by the amide group (-CO-NH-) and is responsible for high strength, high stiffness, durability, and other properties of nylon. Such properties have made nylon one of the best of all available synthetic fibres. Nylon 6/6 and 6 are the most widely used in the textile and carpet industries. Nylon has a normal temperature of glass transfer and is distinguished by-

 

  • High strength
  • High stiffness (modulus); high specific stiffness
  • High impact strength
  • Low coefficient of friction
  • Chemical resistance
  • High heat resistance
Nylon 6 & Nylon 66 Polymer chains
Image credits: https://upload.wikimedia.org/wikipedia/commons/thumb/4/4d/Nylon6_and_Nylon_66.png/320px-Nylon6_and_Nylon_66.png

Unique features of Nylon:

Nylon is a thermoplastic semi crystalline engineering material. It is a linear aliphatic polyamide that can crystallize primarily due to the amide groups (-CO-NH-) strong intermolecular hydrogen bonds found consistently along the polymer chain and the powers of van der Waals between the methylene chains. Diamine and dibasic acid nylons such as nylon 6/6 have greater crystallinity than amino acids such as nylon 12 due to their higher methylene-carbonamide (CH2/CONH-groups) ratio.

Normally, relatively high glass transition temperature and relatively high melting temperatures define nylons as a family. This is due to the inclusion of polar groups in nylons, which are used for their strength rather than flexibility characteristics. Polar groups in nylons enable hydrogen bonding between adjacent fibres that increases the strength and rigidity.

Temperature determines the mechanical properties of nylon. The addition of heat stabilizers to nylon mitigates this heat sensitivity issue and can be used for long-term output at elevated temperatures. Moisture has the same effect on nylon as humidity. nylon needs to be dried before processing. Nylon possesses good chemical resistance.

Sterilizing is a great feature of nylon.

The degree of sterilizing depends on the grade. Sterilization is a critical condition in the medical and healthcare industry for applications. Both removable and multiple-use machines are subject to this condition. The numerous producers of plastics make unique types of nylon grades. Nylon has a very high resistance to abrasion and wear.

 

This is due to the low friction coefficient. Another characteristic of nylon is that it is Self-extinguishing and is also considered. Nylons are primarily semi-crystalline resins (there are amorphous types), and as they cool to room temperature, the melt solidifies into crystalline and amorphous areas.

The casting method of in-mould polymerization creates components and products with higher molecular weight, higher crystallinity, increased dimensional stability, ease of machining, and higher compressive and tensile capabilities than those of injection moulding and extrusion. The casting process may also develop nylon products. Rollers, bushings, gears, sheaves, sprockets, wear mats, star wheels, etc., are examples of cast nylon products.

Nylon raincoat

Applications of Nylon:

The major uses of nylon fibres include

  • Apparel such as blouses, dresses, foundation garments, hosiery, lingerie, underwear, raincoats, ski apparel, windbreakers, swimwear, zippers, and cycle wear
  • Home decor and furnishings such as tablecloths, bedspreads, carpets, curtains, mats, etc.
  • Tyre cables, hoses, conveyor belts and seat belts, parachutes, racket belts, cords and nets, sleeping bags, tarpaulins, tents, fishing line, dental floss, etc.
  • Extruded monofilaments; surgical suture monofilament, brush tufting, wigs, etc.
  • Garment interlinings and wipes (supplies strength and resilience)
  • Nylon separators for Ni/H and Ni/Cd batteries
  • Thermal Insulators, speciality high-quality papers, Split table-pie fibres in high-performance wipes, 
  • Automotive
  • Consumer products
  • Electrical/electronics
  • Packaging
  • Industrial/mechanical
  • Fuel connectors
  • Bumpers
  • Hydraulic clutch lines
  • Engine cooling fans
  • Car brake lines
  • Battery cases
  • Fuel and emission control lines
  • Gears, bearings, bushings
  • Odometer frames
  • Windshield wiper bearings
  • Gasoline filter housing
  • Mirror housing
  • Dipstick
  • Motorcycle crankcases etc

The high durability, toughness and strength of nylon fibre makes it a material of choice in the use of automobile air bags. Nylon materials have an exceptional combination of mechanical properties, including rigidity, strength of force, durability, outstanding chemical resistance to oils and fuel, and can endure high-temperature exposure. When added over PVC in building wire, nylon jackets benefit since they shield the insulation during conduit pull-through and reduce the force used to pull the wires through the conduit (nylons have a low coefficient of friction).

Some nylon wire and cable electrical/electronic uses include fibre optics, telecommunications, electromechanical wires, wire insulation for switchboards, electronic connectors, etc. Use of nylon in plumbing fixtures include water taps, water meter frames, gaskets, mixing and control valves, etc. applications of nylons in Sports equipment include, but are not limited to, shoe soles (injection moulded), tennis racquet parts (strings, frames), protective shoe caps, ski shoes and bindings, etc.

 Industrial tubing and nylon sections include, but are not limited to, dispensers of beverages, brewery pipes, seals and valves, gaskets, Lines for pneumatic power and supply, water hose. Nylons have excellent resistance to abrasion and excellent friction characteristics that make them ideal for bearings, gears, and sliding applications.

Latest and recent nylon technologies include amorphous, translucent, mouldable grades that, relative to other nylons, have increased efficiency in hot water. Velcro is the brand name for a hook-and-eye combination built on nylon. It utilizes nylon as both the material for the hook and the material for the eye.

Velcro

FUNCTIONALIZED THERMOPLASTICS -THERMOPLASTIC POLYURETHANE (TPU):

The bridge between rubber and plastics is known as thermoplastic polyurethane or TPU. The material tends to be rubber-like, which means that the contact can be highly resilient, robust, and smooth. TPU is commonly used in many industries for coatings, parts, and customer materials for both these properties and compound flexibility. For 3D printing, it is commonly used. Its composition consists of soft and hard chain segments that are bound together.

The number and character of these segments can vary, resulting in a different material strength of TPU from soft to very hard, so both soft engineering plastic and strong rubber are used for these thermoplastic materials. As an additive for reinforcing other components, TPU is commonly used.

Many of the compositions of thermoplastic polyurethane are not biodegradable.  Modern chemical producers provide mixtures of organic blocks in molecular chains that can decay in 3 to 5 years in the soil. Although Biodegradable TPU is generally referred to as such compounds to distance them from standard TPU. If properly manufactured by injection moulding, TPU exhibits high-performance properties. The plastic is non-abrasive, so there’s no need for a special coating on the instruments.

For imperfect parts, some manufacturers prescribe pre-drying and post-treatment steps. The important factors for TPU moulding are mould and nozzle temperature, pressure and plasticizing capacity. TPU components are widespread in different industries, considering specific moulding requirements, and can be processed with traditional thermoplastic manufacturing machinery.

Due to its high-performance properties, thermoplastic polyurethane (TPU) is well known and listed in the medical industry for advanced medical and healthcare products. TPU is very suitable for medical applications because of its excellent mechanical properties, longevity, and tolerance to oils and chemicals. Since TPU does not include plasticizers, it is also an environmentally safe alternative for PVC for the medical industry without losing flexibility.

TPU Phone case

Health TPU uses include diagnostic, anaesthesia, and artificial respiration equipment, mattresses, dental products, compression stockings, cords for medical instruments, orthodontics for gel suits, and wound dressings for healthcare.

TPU is made up of block copolymer molecules with alternating rigid and flexible sections. The rough segments are isocyanates, which, depending on isocyanate, can be categorized as either aliphatic or aromatic. A reacted polyol is composed of the soft segments. The isocyanate form and polyol are responsible for the properties of the resulting TPU, in addition to the ratio of hard to soft segments in a given grade of TPU.

This mixture of fluid, elastic segments give this substance its elastomeric quality with high elasticity and low glass transition temperature, stiff crystallizing segments, and a high melting point. It is possible to vary properties such as stiffness, strength, rigidity, extensibility, and low-temperature stability over a wide range by altering the rigid stage ratio. As a feature of the polyols utilized, a distinction is drawn between polyether and polyester polyurethane.

Natural TPU pellets are Thermoplastic Polyurethane (TPU) polyether-based components for extrusion and injection moulding applications. Excellent hydrolysis and microbial resistance, good oil & solvent resistance, good efficiency at low temperatures, high elasticity, recyclable, and stable processing are the main features.

Resistance against hydrolysis: For outdoor applications, resistance against hydrolysis is necessary. In general, with elevated temperatures, the rate of hydrolytic degradation of the TPU increases.

In addition to hardness, TPUs can be processed with various elements of the base material. Three subgroups available are -polyester, polyether, and polycaprolactone:

TPU polyester is typically preferred for abrasion-prone parts. This group has great tolerance to chemicals and oil, and its properties are stable, resulting in many applications in substance blends.

Polyether TPU-suitable for applications underwater. Properties have excellent resistance to hydrolysis and can tolerate microbes and tear tension, preserving low-temperature flexibility.

Polycaprolactone TPU- which blends longevity and hardness with excellent cold and hydrolysis to deliver the best. Used in seals successfully.

To achieve a certain look and characteristics, including fire-retardancy, biocompatibility, visual consistency, and more, combine TPU with particular agents or various proportions of compounds.

Advantages of thermoplastic polyurethane:

  • High abrasion, wear, oil, radiation resistance can be achieved accurately
  • High elasticity, Strength, Good tactile properties, easily coloured, compound and properties versatility of the products, can be sterilized to obtain products with desired specifications.

Disadvantages of thermoplastic polyurethane:

  • Special manufacturing conditions across all methods are needed
  • Most classes have brief life cycles
  • Compared with other analogues, material prices are higher (like PVC)
  • Regulation of water quantity before processing needs
  • Irreversibly Transparent TPU Yellows

Common and wide Uses of thermoplastic polyurethane:

  • Automotive parts and drive belts
  • Flexible tubes hoses
  • Seals
  • Food processing tools
  • Medical tubes and devices
  • Cases
  • Sports goods and footwear

THERMOPLASTIC POLYURETHANE FABRIC:

TDF, TPU fabric (thermoplastic polyurethane fabric), and PVC fabric (polyvinyl chloride fabric) are two main types of laminating fabrics; all have excellent waterproofing performance, high laminating strength, tensile strength, anti-tearing, and anti-peeling properties. TPU fabrics provide laminating fabrics with excellent efficiency in harsh environmental environments, such as low-temperature tolerance, hydrolysis, bacteria, stretching, and wear, based on consumer requirements.

TPU-covered textiles are UV resistant, can withstand extreme weather conditions and environmental conditions, and can withstand abrasions and punctures. Along with fused or welded seals, these fabrics have excellent air- and liquid-holding performance. This makes it suitable for applications of the bladder type such as:

  • Inflatable systems for watercraft and floatation,
  • Health applications such as mattresses, splints, and lifts for inflatable use,
  • For products such as water, food (such as milk, wine, and oils), medicinal products, and all types of fossil fuels, portable holding tanks and bags
  • Environmental applications including oil booms, barriers/berms, and protection and monitoring of floods and spills. While being waterproof and lightweight, TPU coated fabrics retain their versatility. TPU fabrics can be used to create dry suits, suits for protection, outdoor clothing, and other wear for protection. Garments made from TPU fabrics are resistant to UV. Plus, additives, detergents, body fluids, abrasion, and penetration are resisted, keeping the wearer safe and making washing quick.
Molecular chain TPU
Image Credits: https://omnexus.specialchem.com/selection-guide/thermoplastic-polyurethanes-tpu

Aliphatic thermoplastic polyurethane:

Aliphatic TPU (thermoplastic polyurethane) in a single material that blends toughness and aesthetic properties. This revolutionary product series is ideal for coloured or translucent applications where primary performance criteria are non-yellowing, longevity, and weatherability.

Aliphatic TPUs provide aesthetic components with colour reliability. Ultraviolet emission demonstrates superior longevity and, thereby, superior colour stability while retaining strong mechanical properties. To make it the material of choice for electronic devices, the Aliphatic TPU has just the right property profile and flexibility.

TPO roofing is comparatively cheaper than EPDM and PVC, the two other roofing systems. Also, TPO can help withstand bacteria, soil, UV rays, and many other toxic compounds efficiently.

A single-ply roofing membrane consisting of ethylene-propylene rubber and polypropylene that is polymerized together is TPO roofing or thermoplastic polyolefin. In mechanically connected structures, it can be attached where the roof is uncovered. TPO is more stable than other membranes on the roof and can survive up to 20 years. And, as they contain no chlorine, they are much greener than most membranes.

Two of TPO’s main features are:

  • Less expensive than most membranes
  • Hot-air weld seams that are stronger than seams built on adhesive

In re-covering applications, mechanically fastened devices perform well. Non-reinforced membrane with detail that is easy to mould TPO sheets fulfil the application needs of farming and building machinery, trucking, maritime, motor vehicles, power sports, lawn, and garden goods. The key features of olefin sheets:

  • The available high and low gloss cap surface
  • Tough, high impact structure, high impact structure
  • UV-protective Integral System
  • Outstanding cold crack tolerance
  • Stable in dimension and colourable
  • Sustainable
  • The simplicity of thermoforming (consistent, controlled sag performance for stable processing)
  • Weather worthy
  • Strong chemical resistance
  • Accessible Fire-rated Grade

FLUOROCARBONS-TEFLON THERMOPLASTIC:

Teflon or Polytetrafluoroethylene Teflon is fluoropolymer of tetrafluoroethylene. Polymerisation of tetrafluoroethylene is how Teflon is produced. The Teflon thermoplastic form can be changed over and over again. It is primarily used in the food industry because it is used to coat cooking utensils due to its ability to survive high heat temperatures and is also stable at very low temperatures. It is usually known as PTFE. Teflon is a thermoplastic substance that is very similar in structure to polyethylene, but its melting point goes up to 326 ° C due to the strong C-F bond. It is tough to attain this high temperature in plastics manufacturing techniques.

The C-F bond will also decompose by touching temperature, so the sintering process is typically used to process Teflon material.

TFE is a non-toxic, colourless, odourless gas that is, however, highly flammable. At a minimum temperature and pressure, it is stored as a vapor. PTFE producers also make their own TFE on site due to the difficulties in shipping flammable TFE. A relatively small number of other chemicals are used as initiators in the polymerization process. Coating for non-stick pots and pans is one of the most common and noticeable applications of PTFE. The pan is to be made of aluminium or an alloy of aluminium. To obtain the PTFE, the pan surface must be specially prepared.

Unique properties of Teflon:

  • Very good non-stick properties
  • Excellent chemical inertia
  • Resistant to temperatures up to 250 °C
  • Low dielectric constant
  • Resistant to weathering
  • Sealing tapes

Teflon is widely used for commercial applications. In the food sector, in the chemical industry, in the design of machinery and for medical applications. For industrial uses, Holscot Europe provides a range of PTFE products.

CELLULOSICS-CELLULOSE THERMOPLASTIC:

Due to its wide-ranging uses, cellulose has gained significant interest in various fields, such as packaging, drug delivery, cosmetics, textiles, membranes, bioengineering, and electronics. The outstanding benefits of cellulose include low cost, non-toxicity, good mechanical properties, and outstanding biodegradability and biocompatibility.

Cellulose, however, lacks thermo-plasticity and displays low dimensional durability and tolerance to creases. It is difficult to dissolve cellulose in traditional solvents because of its high crystallinity and a significant amount of intra- and intermolecular hydrogen bonding.

Novel resource-derived green polymers have opened the door to sustainable research and engineering. Typical natural products for the chemical industry are plant oils derived from numerous plants, such as palm, cocoa, sunflower, olive, soy, and peanut. Plant oils can be converted into polymerizable monomers for free radical polymerization by reacting with (meth)acryloyl chloride or methacrylate anhydride.

It is important and beneficial to investigate new monomers that can be synthesized from bioresources, including lignin, terpenes, plant oils, rosin acids, and coumarins, owing to the increased attention paid to biomass-derived thermoplastics and elastomers. The most prevalent natural polymer is cellulose.

Cellulose has formed a resistant microfibril network due to its hydrogen bonds, rendering it solid. Cellulose must be tailored without adversely altering its natural properties to achieve thermo-plasticity. Cellulose fibres are selected as a strengthened thermoplastic filler because of their superior mechanical properties and lower price relative to thermoplastic fibres. Cellulosic important features are:

  • Transparency
  • Deep gloss
  • Natural feel
  • Mildew and mold resistance
  • Toughness
  • Biodegradability

Cellulosics are quickly wet and strongly hydrophilic; this is beneficial in high Applications of absorbency, promoting biodegradability and compost ability. High oxidizing agents and strong alkali are also prone to them. As for fibres and textiles, the special characteristics of warmth, breathability, and absorbency make cellulosic useful. For textiles and clothes, CA fibres are used. They can be coloured and mixed with other fabrics such as rayon, cotton, wool, silk., in several different colours. CA resins have maintained their prominence in the manufacture of household goods such as:

  • Spectacle frames
  • High absorbency products, diapers, and surgical accessories
  • Apparel linings, dresses, home furnishing, draperies, upholstery
  • Tool handles
  • Personal hygiene products including wound dressings
  • Absorbent cloths and wipes
  • Specialty papers
  • Filter media (cigarette filter), etc.
Cellulose Diacetate
Image Credits: https://www.mdpi.com/molecules/molecules-20-05487/article_deploy/html/images/molecules-20-05487-g007.png

POLYKETONE FAMILY- PEEK (POLYETHERETHERKETONE)

These polymers come under the family of polyketones (PEEK, PEEK, PEAK, PEKK, PEKEKK), and PEEK is the most commonly used and large-scale processed polymer. The semi-crystalline, high-performance engineering thermoplastic is polyetheretherketone (PEEK). This rigid opaque (grey) material provides a rare combination of mechanical properties, chemical resistance, wear, fatigue, creep resistance, and extremely high resistance to up to 260°C. PEEK can be processed by traditional injection moulding, extrusion, compression moulding, etc.,

PEEK and its composites are commonly used in aerospace, industrial, structural, high-temperature electrical, and biomedical applications due to these properties.

The added benefit that PEEK products provide by providing the option of making components, considering the polymer’s high price, involves lightweight, resilience, or durability and can withstand longer in harsh environments.

PEEK is a fully recyclable thermoplastic.

Unique Properties of Polyetheretherketone (PEEK)

High volume resistivity and surface resistivity are seen in the polymer. In a wide temperature spectrum and environmental shifts, it can retain strong insulating properties. If liquids and excellent fatigue efficiency, crystallinity provides excellent resistance to a broad range. PEEK in all different solvents is insoluble. It does not undergo hydrolysis and can be used in steam or high-pressure water for thousands of hours without losing existing properties. PEEK demonstrates superior tensile power, HDT, bonding, handling and release of poisonous gases

Other properties of PEEK include:

  • Low friction
  • Good dimensional stability
  • Exception insulation properties
  • Excellent sterilization resistance at high temperature
  • Biocompatible
  • Long life
  • Inherent purity
PEKK (POLYETHERETHERKETONE)
Credits: https://polymerdatabase.com/img2/PEKK.png

Applications:

In demanding applications such as aerospace, automobile, electric, medical, etc., it is widely used. PEEK is used to produce components because of its robustness, including bearings, piston parts, pumps, HPLC columns, compressor plate valves, and cable insulation.

Aerospace: PEEK polymers and their composites in many aircraft materials are replacing aluminium and other metals. Without assembly or alteration, vast quantities of high-volume parts with fine tolerances may be cost-effectively shaped and used.

As the polymer can tolerate elevated temperatures and the tribological activity of interactions between dry and lubricated material, vital engine components. PEEK provides excellent resistance to rain erosion in aircraft exterior materials. The intrinsic flame retardancy and low emission of smoke and poisonous gas in interior materials mitigate the danger in the event of a burn.

The polymer is used to produce convoluted tubing in aircraft electrical systems to secure wires and fibre optic filaments.

 

Medical and Healthcare: Polyetheretherketone offers excellent wear, heat, electrical and chemical resistance for cost-effective, advanced components. In healthcare, its uses consist primarily of dental devices, endoscopes, and dialyzers.

For the grips on dental syringes and sterile boxes containing root canal papers, PEEK substitutes aluminium.

In hot water, steam, solvents, and additives, it retains exceptional mechanical efficiency, excellent stress cracking tolerance and hydrolytic stability. It provides increased biocompatibility of implants with load bearings.

Electrical/mechanical – Polyetheretherketone has superior electrical properties, rendering it a suitable insulator for electrical use.

Dental thermoplastics:

The dental industry has adapted a variety of thermoplastic polymers as alternatives to classical resins. These polymers include polystyrene, thermoplastic substitutes such as polyamides (nylon), acetal resins, epoxy resins, polycarbonate resins, polyurethane, and acrylic thermoplastic resins have been incorporated in dentistry.

The key advantages of the thermoplastic resins used in dentistry are as follows: they are monomer-free and thus non-toxic and non-allergenic, they are infused with special instruments, they are biocompatible, they have advanced aesthetics, and are easy to use.

Thermoplastic resins can be categorized as acetal resins, polycarbonate resins (belonging to the polyester resin group), acrylic resins, and polyamides by their structure (nylons).

For the manufacture of removable partial dentures without metallic parts, thermoplastic materials are appropriate, resulting in the so-called “metal-free removable partial dentures.”

Thermoplastic resin signs include reversible partial dentures, preformed clasps, partial denture structures, provisional or transitional crowns and bridges, full dentures, orthodontic instruments, anti-snoring aids, mouth guards, and splints of various forms. Thermoplastic silicone polycarbonate-urethane can also be made up of several lightweight myofunctional therapy systems used for orthodontic purposes.

Dentures from thermoplastic
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