Thermoplastics are one of two forms of plastics; thermosets are the other. When heat is applied, thermoplastics become flexible and pliable, then harden when cooled. The viscosity of thermoplastic melts is often greater than that of thermoset melts (but not necessarily for highly-filled materials). Polyethelene (including HDPE, LLDPE/LDPE), Polypropylene (PP), Polyvinyl Chloride (PVC), and Polyethylene Terephthalate (PET) are the most extensively used thermoplastics.
What are thermoplastics?
Polymers that can be melted and recast practically forever are known as thermoplastics. When heated, they become molten and solidify as they cool. A thermoplastic, on the other hand, becomes glassy and susceptible to fracture when frozen. These reversible properties, which give the material its name, allow it to be warmed, molded and frozen several times. Thermoplastics are thus mechanically recyclable. Polypropylene, polyethylene, polyvinyl chloride, polystyrene, poly ethyl enetheraphthalate, and polycarbonate are some of the most prevalent thermoplastics.
Properties of thermoplastics
Thermoplastics are made up of chemically independent macromolecules and have a simple molecular structure. They are softened or melted when heated, then molded, molded, welded, and solidified after cooling. Heating and cooling cycles can be repeated several times, allowing for reprocessing and recycling.
Applications of thermoplastics
Thermoplastics have been used for a significant period and are still used in daily life. As an illustration:
- ABS (acrylonitrile butadiene styrene) is a thermoplastic that is used to make:
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- Sporting goods.
- Toys
- Parts for automobiles
- Polycarbonate is used to create the following items:
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- Plastic CDs and DVDs
- Bottles for drinking water
- Containers to store food
- Lenses for prescription glasses
- Polyethylene is the most popular thermoplastic and is used to create the following items:
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- Bottles of shampoo
- Grocery bags are made of plastic.
- Bullet-proof vests are available.
Types of Thermoplastics
These kinds of thermoplastics have long, separate, and large molecules arranged side by side. Thermoplastic polymers such as polyethylene (PE), polyvinyl chloride (PVC), and polystyrene (PS) are examples of materials that are often used in the packaging industry. Acrylics, fluoropolymers, polyesters, polyimides, and nylons are some of the other types of thermoplastics available. There are numerous different shapes and sizes that can be created by melting down each of these classes. The various types of thermoplastics are discussed below.
Cellulose derivatives
Cellulose nitrate is generally obtained by treating the cellulose with a mixture of nitric acid and sulfuric acid. It has high toughness, good resistance to moisture, and is highly inflammable. It is mostly used for making spectacle frames, toilet wares, pen bodies, etc.
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Cellulose acetate
It is obtained by treating the cellulose with acetic acid. It is inserted and compressed in the mold for better stability and to obtain high mechanical strength. It has the tendency to absorb moisture and is lighter in weight. It is used for manufacturing photographic films, buttons, radio panels, sheets, tubes, toys, etc.
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Ethylcellulose
It is the lightest of all cellulose derivatives. It has very good electrical properties, chemical resistance, surface hardness, and strength. Generally used for making jigs, fixtures, nozzles, and molded articles.
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Cellulose acetate butyrate
It is obtained by treating cellulose with acetic acid and butyric acid. It has good stability against light, heat, and moisture absorption tendencies. Cellulose acetate can also be used for injection molding. It is used for making radio cabinets, pipes, steering wheels, handles, and coatings.
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Cellophane
It is generally available in its extruded form. It has an attractive appearance and good resistance to moisture, solvents, and fire. It is generally used for making curtains and packaging materials.
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Cellulose propionate
It has a low tendency for moisture absorption. Cellulose propionate can withstand temperatures of up to 93 °C and can be easily molded and used for making fountain pens, telephones, and flashlight cases.
Synthetic resin
The following are the synthetic resins.
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Polyethylenes
It has a very high resistance to acids and alkalizes, and the solvents can also be made flexible, tough, and good insulators. It has low water absorption. It is used for making fabrics, trays, pipes, corrosion-resistant coatings, and packaging.
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Polystyrene
It is available in any form and in any color. It has good dimensional stability and strain resistance. Polystyrene is easily joined by cementing. It is used for making boxes, cases, radio parts, tableware, and insulation parts.
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Acrylic resins
It has a high transparency tendency. It is made in any color with high dielectric properties, good strength, resistance to moisture, and very good light-transmitting power. This material can be cast, injection-molded, extruded, and can be stretched into sheets. It is used for manufacturing tubes, plates, lamination, display cases, helmets, and valves.
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Vinyles
It is generally called PVC. They are flexible and rigid. It has good electrical and weather resistance. These are resistant to water and available in a variety of colors.
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Poly tetrafluoroethylene
It is named after Teflon. It has good chemical resistance and can withstand temperatures up to 288°C. it cannot be dissolved in any solvent. It has high electrical resistance, low friction, and very low adhesion to other substances. It is mostly available in the form of sheets, rods, and tubes. It is used for making gaskets, electrical insulators, etc.
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Nylon
It is also known as polyamide. It has high strength, toughness, and elasticity. It can be molded and extruded into rods. The powder metallurgy methods can also be used for this type of plastic. It is a good insulator and has good wear resistance. Used for making Yarn for making clothes, insulation wires, and combs.
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Methyl methacrylate
Its trade name is Lucite and plexiglass. It is easily formed at temperatures around 120°C. it is known for its clear color and high light transmission ability. Used or manufactured aircraft parts, bowls, contact lenses, and various surgical instruments.
Thermoplastic factors to be considered are:
The following thermoplastic variables must be considered:
- The viscosity of the resin must be low enough to permeate the reinforcement.
- CDs and DVDs made of plastic
- Water bottles
- Food storage containers
- Prescription glass lenses
- Size of molding – because cure reactions are frequently exothermic, if the molding is thick, the rate of the curve may need to be lowered to avoid an uncontrolled rise in temperature during the curing process, which might harm the molding.
- The rate of particle creation is influenced by the speed of reaction.
- Reinforcement compatibility – the resin must moisten and stick to the reinforcement.
- Moisture level – certain polymers may not perform as well in wet settings as others, which is one of the reasons why vinyl ester resins are preferred over polyester resins. Moisture infiltration into a laminate can result in a significant loss of characteristics.
FAQs on Thermoplastics
What are the applications of thermoplastic polymers?
Thermoplastic polymers soften when heated, making them easier to mold into a variety of forms. They also lend themselves to recycling. Pipes, ropes, belts, insulators, and adhesives are all common applications for thermoplastic polymers.
Is thermoplastic hazardous to one’s health?
Any product or substance can be potentially or intrinsically harmful or safe depending on a variety of criteria. Thermoplastic isn’t always harmful; it’s quite harmless in many cases. It’s also employed in biomedical applications. Polymer toxicity might be caused by a variety of reasons.
What is thermoplastic?
A thermoplastic, also known as thermosoftening plastic, is a type of plastic polymer that becomes flexible or moldable at a high temperature before solidifying when cooled. The majority of thermoplastics have a high molecular weight.
What distinguishes thermosetting plastics from other types of plastics?
The principal thermosetting polymers include epoxy resin, melamine-formaldehyde, polyester resin, and urea-formaldehyde. A healthy electrical insulator is robust, yet fragile until strengthened, and chemically resistant. Adhesives are utilized for casting and encapsulating, as well as for gluing other components.
What kind of thermoplastics are there?
Polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybenzimidazole, acrylic, nylon, and Teflon are examples of thermoplastics. Thermo-softening plastic, often known as thermoplastic, becomes soft and pliable at certain temperatures before solidifying when cooled.
