It is formed by polymerization from the monomer ethylene. The macromolecular polymer with a long chain structure is called polyethylene. Polyethylene is a homopolymer. Polyethylene is the most commonly produced polymer type in the world. Polyethylene is produced by two basic methods: high- and low-pressure processes. Low-density polyethylene and its copolymer are produced using high-pressure process, while high-density polyethylene is produced using low-pressure process. Polyethylene acts like a wax at temperatures ranging from 80 to 130 °C. While polyethylene materials have a translucent or opaque appearance in bulk, they are transparent in film form. Polyethylene has very low density. It is highly elastic as well as being impact resistant at low temperatures. Its mechanical properties vary depending on melting point and density. Other advantages offered by polyethylene are its low water absorption and versatile workability. It has high electrical insulating properties. In addition, it is extremely resistant against chemicals. They can be used in many places due to their affordable price. The most important areas of use include packaging films, greenhouse covering, shopping bags, etc.
Polypropylene is produced by polymerization from high purity propylene gas under high pressure with the help of catalysts. It has a crystalline structure. Its density ranges between 0.90–0.91g/cm³. Polypropylene is the lightest polymer among thermoplastics. It is a translucent white thermoplastic. It is a rigid polymer, maintaining its rigidity after repeated bending. It is resistant to chemicals, heat and extreme fatigue. As with polyethylene, the mechanical properties of polypropylene rely on density and melting point. Polypropylene has higher strength and surface hardness than polyethylene, delivering good thermal properties.
It is cost-efficient and has good impact resistance. It has a low coefficient of friction and provides very good electrical insulation. It is water-permeable yet with low absorption property. They are resistant to bacteria and fungi depending on the conditions of use. The drawbacks of polypropylene are that it is easily degraded under the influence of heat and light (it undergoes a change by radiation), it is not easy to color, it has low resistance to UV lights and outdoor conditions as well as high thermal expansion, and it is capable of being oxidized. The applicable processing methods are injection molding, extrusion, extrusion flow molding, rotational molding, thermoforming and casting. It is a thermoplastic polymer used in a multitude of areas such as the automotive, textile and packaging industries.
Polyvinyl chloride (PVC)
Polyvinyl chloride is produced by polymerization from the monomer vinyl chloride. PVC is an amorphous thermoplastic. Its properties rely on the average degree of polymerization, production method and plastic content. PVC is a white or light-yellow powder polymer. It is possible to process polyvinyl chloride without additives at temperatures up to 60ºC. However, heat stabilizers should be added to it so that it can be processed at temperatures exceeding 60°C. Polyvinyl chloride (PVC) is a lightweight, long-lasting, non-flammable, water-proof thermoplastic with good insulating properties. This polymer, which is rigid and firm, has increased flexibility when combined with plasticizers. Plasticizers are the most pivotal additives for PVC. Plasticizers, when added in different amounts, can give the polymer to the varied softness, thus providing different and various areas of use. Its specific gravity is approximately 1.4 g/cm3. While soft PVC has insufficient mechanical properties, its tensile strength increases up to 4-5 times when it is given a rigid (hard, brittle) form with the addition of various additives. PVC, which is a thermoplastic, is suited to almost all plastic processing methods. It can be easily shaped in the form of sheets, films, pipes and profiles. It is widely used in PVC cable manufacturing due to its positive features, such as ease of manufacture, cost efficiency and resistance to ambient conditions. In addition, PVC is widely used in the production of various plastic articles, such as window profiles, flooring materials, soft dolls, and water hoses.
Acrylonitrile butadiene styrene (ABS)
ABS polymers are produced by the dispersion of a phase containing butadiene of rubber-like toughness as particles in the continuous phase consisting of styrene-acrylonitrile copolymer. Its color is ivory to white. The structure of an ABS polymer acquires different properties depending on the type and amount of mixing materials for many fillers. Additionally, it has colors varying from brand to brand due to the variety of these fillers. The resistance to combustion is enhanced using PVC and other halogenated materials. ABS is a hard, rigid, tough material with brightness that can highlight the visuality. ABS is one of the most widely used thermoplastics. Its specific gravity is approximately 1.02–1.06 g/cm2 for pure polymers. ABS polymers can be processed by injection molding, extrusion or blow molding methods. Injection molding and extrusion methods are commonly used. The material can be easily given color. It delivers very good electrical insulation. It has good resistance to high temperatures. It is widely used in bags and suitcases, TV cabinets, telephone housings, various automotive headlights, various automobile items suitable for electrolyte coating, and electric switchboards.
Polystyrene is produced after polymerization of the monomer styrene. It remains in a transparent and solid state at temperatures below 100°C, whereas it becomes soft and fluid at higher temperatures.
Polystyrene offers further advantages compared to other thermoplastics due to its amorphous structure. Because it requires less energy when it changes into the melt state. The less amount of energy allows the material to be heated and cooled quickly, which provides the advantage of rapid molding process.
Polystyrene is divided into GPPS (General purpose polystyrene) and HIPS (High impact polystyrene). GPPS is crystalline, transparent and widely used in food packaging. HIPS, on the other hand, is an opaque polystyrene with polystyrene rubber to modify the impact, delivering high impact resistance performance.
Polystyrene is the best of all polymer types regarding electrical insulating properties. It has good chemical resistance as well as high resistance to acids and salts, good water resistance, and high impact and tensile strength. It is hard, brittle and shiny. Its mechanical properties rely on the conditions during its production. As it has low UV resistance, it is not suitable for use alone in environments exposed to direct sunlight. It is widely used in industry for being cost-effective and easy to process and for displaying good fluidity and high thermal stability. It plays a major role in sheet, film, profile and foam production. The intended uses can be listed as food packaging, radio and television cabinets, refrigerator components, decorative items, toys, and furniture among others.
Polyethylene Terephthalate (PET)
Polyethylene terephthalate is a thermoplastic material coming from the polyester family. PET can be amorphous or semi-crystalline depending on the heat treatment it is subjected to. The melting point varies between 235°C and 260°C depending on the degree of crystallization and degree of polymerization. While PET is transparent in amorphous state, it is white in semi-crystalline state. The production conditions determine whether commercial PET will be amorphous or semi-crystalline. If PET at the melting temperature is cooled rapidly to a temperature below its glass transition temperature, a more amorphous and transparent structure is formed.
Styrene Acrylonitrile (SAN)
Styrene Acrylonitrile is a copolymer produced by polymerization from styrene and acrylonitrile. As it contains acrylonitrile in its chain, the glass transition temperature is above 100 degrees, which shows that the material is resistant even to boiling water. Its thermal resistance is the most important factor in its widespread use in substitution for polystyrene. It has good mechanical properties and chemical resistance due to its long acrylonitrile content. It is a transparent polymer. The longer the acrylonitrile gets, the yellower plastic is formed.
In general, Styrene Acrylonitrile polymers are used in applications that require impact resistance and chemical resistance. SAN polymers are easy to process. As with ABS polymer, it is hygroscopic (absorbs moisture), so a pre-drying process is recommended.
It has a wide range of uses since it is well workable, has high heat resistance, is a tougher material, has better resistance to dissolution than PS, and is rigid and transparent. It is used in telephone components, cosmetic containers, refrigerator components, decorative panels and manufacture of plastic transparent parts of small household appliances, etc.
It is a structure formed by the bonding of carbon groups in long molecular structures. Polycarbonates are easily worked, molded, and thermoformed. These are the plastics that have a wide range of uses in the modern manufacturing industry. They are transparent and have good light transmission. Polycarbonate is more durable and costly despite its structural similarity to Polymethyl methacrylate (PMMA). It is a polymer with good corrosion resistance, which extinguishes itself and changes little in size when interacting with heat. It has very low moisture absorption. It is an amorphous thermoplastic. It has a high glass transition temperature and can consequently be processed in the melt state. It has a high grade of toughness.
In addition, polycarbonate sheets with single or double surface coated with UV-protective material are manufactured as solid and multiwall porous plates in various colors, thicknesses, properties and sizes, which makes them an elastic coating material that can be used to cover any openings (skylights, vaults, tube passages, domes, etc.) in the construction industry. It is used as an alternative to glass and nylon in greenhouses due to its good heat insulation and strength. Given its durability, the material called solid polycarbonate is used widely, especially in the glasses of armored vehicles, though with auxiliary materials.
The most common commercial type is BPA (Bisphenol A) polycarbonate. It has a very high energy absorption value (1.5 times that of carbon steel). It replaces metals due to both their strength and being much lighter than metals, and can be used wherever metals are used. It features UV absorption. It can be easily colored.
It is used in the making of refrigerator crispers, automobile headlights, eyeglasses, airplane glasses and safety helmets and on the front panel of automobiles due to its shock absorption property and in air conditioning panels, computer cases, etc. due to its thermal stability.
Polyamides are thermoplastic polymers containing an amide group as a repeated part of the polymer chain, which are synthesized by condensation.
Existing in many types, polyamide has extensive properties. Due to its chemical and mechanical properties, it plays a key role in engineering fields aligned with technology. It comes in varieties such as engineering polymers including polyamide 6, polyamide 7, PA 6/6, PA 6/8, PA 6/10, polyamide 6/12, PA 11, PA66 and cast polyamide. These numbers are assigned depending on the aliphatic (amino acids with no cyclic sets in their side chains and with straight side chains) length. The greater this length is, the lower the melting temperature becomes. Additionally, glass fiber reinforced PAs are widely used as well. The glass fiber reinforcement is used in products to boost mechanical strength, to enhance resistance to static loads at high temperatures and to provide dimensional stability.
Polyamide has very good fatigue strength and low friction coefficient as well as good impact strength and chemical resistance. The low degree of crystallinity acts on the rigidity, strength and heat resistance of PA, while enhancing its toughness, elongation and impact strength. Glass fiber reinforced PA products are used, particularly in the aviation industry, due to their being lightweight and highly resistant compared to metals.
It is easily formed by injection and extrusion processes. Its greatest drawback is that it absorbs high amounts of water. It absorbs water due to the existence of amide groups in its structure. When containing moisture above 0.2%, the product has not only diminished mechanical properties, but also surface defects and dimensional changes.
PA6 and PA66 are widely used in the manufacture of flexible packaging products. In addition, the items that we use in our daily life, such as textiles, toothbrushes, fishing lines, carpets, airbags, automobile components, parachutes and tents, are other products made from polyamide.
Ethylene Vinyl Acetate (EVA)
EVA is a copolymer which is produced by copolymerization with vinyl acetate (VA) and has a hard or rubbery composition depending on the amount of VA it contains. Containing approximately 4% VA, EVA is a thermoplastic elastomer material and is named thermoplastic ethylene-vinyl acetate copolymer.
A semi-crystalline or amorphous and polar copolymer is produced depending on the amount of VA contained in EVA. It becomes harder for the copolymer to crystallize as the branching on the PE chain will increase upon any rise in the amount of VA, and the copolymer becomes completely amorphous at a value ranging between 40-50% VA by weight. The difference in VA amount and crystallinity changes the polymer's mechanical, thermal and chemical properties. The structure becomes rubbery upon decrease in crystallinity and increase in chain entanglement, consequently undermining mechanical properties, such as surface hardness and tensile strength, while increasing specific values such as elongation at break. EVA has a tendency for yielding at low VA ratios due to the abundance of crystalline parts, whereas no yield occurs as VA increases. The greater the VA is, the higher the density becomes.
Due to their higher tensile strength and surface hardness, copolymers containing low amounts of VA are preferable in film applications or other applications such as profile extrusion molding. In addition, copolymers with very low VA content are usually used for the modification of low-density polyethylene. EVA containing over 20% vinyl acetate by weight is used in a range of extrusion and molding applications. EVA containing 2-5% vinyl acetate behaves similarly to PE, but has higher impact strength, better low-temperature flexibility, and lower thermal adhesion temperature. EVA containing 7.5-12% vinyl acetate has higher flexibility and very good impact resistance. These copolymers are used in high-performance film coatings. Since the properties of EVA copolymer change depending on the amount of VA it contains, it is available for use in many different areas. It is used in wire insulation, packaging films, adhesives and paper coatings, carpet floors, drug release systems and medical applications. In addition, it is developed in foam form and used in inner / outer soles, acoustic and thermal insulation materials, insulation tapes, floor coverings, and protective equipment, such as bulletproof vests, helmets and knee pads.
Poly Methyl Methacrylate (PMMA)
Poly Methyl Methacrylate (PMMA) is synthesized from methyl methacrylate monomers using the radical chain-growth polymerization method. Commercially known as acrylic glass or plexiglass, PMMA is a colorless and transparent thermoplastic. Its most important property is that it provides good light transmission. It allows 92% more light to pass through glass or other thermoplastics. While the transparency of glasses decreases as their wall thickness increases, PMMA maintains its transparency up to 30 to 35 cm thicknesses. PMMA is the thermoplastic featuring the highest surface hardness. This makes the material well resistant to scratches. Its Tensile Impact strength is as high as HIPS. Inherently, it is highly resistant to UV lights. PMMAs have a low water absorption rate. The greatest benefit delivered by PMMAs is that they are 100% recyclable. This allows them to be reused.
Additionally, all these good properties of PMMA can be enhanced using appropriate additives. The modified PMMAs are used very extensively.
The most common intended uses are glass-like transparent ceilings and greenhouses because they are not affected by outdoor conditions, such as sunlight and rain. Sheet-formed PMMAs are used in signboards on the exterior of buildings. They are used in the interior display housings in the automotive industry as well as in mobile phone lenses, street lamps, etc. The aviation industry uses PMMAs in airplanes rather than glass due to the potential damage caused when the glass breaks. They are preferable in places where polycarbonates should be used since they are more cost-effective.
Acrylonitrile Styrene Acrylate (ASA)
ASA is produced by adding acrylic ester elastomer during the copolymerization reaction between styrene acrylonitriles. In fact, ASA was originally produced as an alternative to ABS. For this reason, it is structurally very similar to ABS. It is produced by chemical combination with styrene-acrylonitrile copolymer chains instead of butadiene in the same composition. Since double bonds present in ABS do not exist during this series of reaction, ASA has a much better weather resistance than ABS.
It has very good mechanical properties. It is highly resistant to impact. As it contains no double bonds, it has very good UV resistance and anti-aging performance. Due to its antistatic properties, it holds less dust on the surface. It offers good impact resistance at high temperatures thanks to its high thermal stability. It is highly resistant to chemicals.
It is used in a multitude of outdoor applications due to its excellent resistance to weather conditions. It is used especially in the automotive industry in vehicle parts, such as exterior equipment, rear-view mirrors, headlights, fenders and radiator grilles. Similarly, it is used in lawn mower enclosures, irrigation equipment and siding and window materials due to its resistance to outdoor conditions.
Polybutylene Terephthalate (PBT)
PBT is a crystalline thermoplastic polymer produced by polymerization of terephthalic acid or dimethyl terephthalate with butanediol using special catalysts. It has similar properties to PET.
PBT has high strength. It displays good strength even at high temperatures. This property can be enhanced further using glass fiber reinforcements. It has good abrasion and friction resistance. It delivers good dimensional stability and is resistant to environmental stress cracking. It is highly resistant to chemicals. Its water absorption capacity is very low. Due to its good workability, it can be produced by both extrusion and injection methods.
It is used in many areas thanks to its superior qualities. In the automotive industry, it is used in wipers, door control devices, airbag tapes and ignition system sensors. It is also widely used in the electrical industry where main areas of use are connectors, coils, sockets and electrical switches.
Thermoplastic Elastomer/ Thermoplastic Polyurethane (TPE/ TPU)
Also named thermoplastic rubber, Thermoplastic Elastomers are structures composed of minimum two polymeric phases: one hard and the other soft. The other variety of TPE is TPU. TPU, a block copolymer, is structurally similar to TPE. As TPEs are two-phase systems, they have all the properties of glassy or semi-crystalline thermoplastic polymer and elastomer together.
Due to the elastomer phase contained, TPE has similar properties to rubber materials, delivering flexibility and high mechanical strength as well as easy workability thanks to the plastic phase. It is suited to injection, extrusion and blow molding processes. It is 100% recyclable since it becomes soft when heated and hard when cooled. It can be colored as well. It has good wear (abrasion) resistance. While TPUs have similar properties to TPE, they deliver higher performance. Any products made of TPU are highly resistant to friction. They are harder materials than TPE, with better resistance to chemicals. Generally, they can elongate at least twice their length at room temperatures and return to their original state when the force is removed. The most apparent difference between TPE and TPU is that TPU emits an irritating odor when burned.
For all these properties, they are used in many areas. They are used in the making of shoe soles, flexible bollards, vehicle mats, roof membranes, instrument panel doors, medical devices, cable and sealing elements (gaskets and wicks), orthopedic equipment, etc.
Tritan is the raw material synthesized to eliminate the harmful effects of BPA. BPA (bisphenol A) is an organic compound originating from the combination of two phenol and polycarbonate molecules. BPA is a chemical component that exists in rigid plastics and is usually found in food or beverage packaging. Tritan is produced to replace BPA that causes severe harms to human health.
Tritan is a transparent and durable material derived from bisphenol-free polymers. While the finished products made from other transparent polymers lose their transparency over time, the products made from tritan preserve their brightness and appearance. Known for its similarity to glass, tritan has high fracture resistance and is not brittle like glass. In addition, it is far lighter than glass. It can be easily formed and colored.
Especially, it is widely used in baby bottles, pacifiers, storage containers, vacuum bottles, and containers suitable for use in microwave ovens.
Polylactic Acid (PLA)
Polylactic acid (PLA) is a polymer produced by fermentation of edible carbohydrate sources, such as corn starch and sugar cane, under controlled conditions. It is a thermoplastic polymer. It is categorized as a bioplastic due to being produced from edible sources.
Since it has thermoplastic structure, PLA can be melted and reformed, with its properties remaining unchanged during this process. When the biodegradation of PLA takes place under controlled conditions, it takes about 3 months. Compared to Polystyrene and Polypropylene thermoplastic polymers, Polylactic Acid has much better mechanical properties, such as tensile strength and bending strength. PLA is flammable like other polymers. It can be worked like other thermoplastics, but humidity control is very important before processing. Because its greatest drawback is that it retains moisture inside. Pre-drying should be performed to eliminate any deformation and structural weakness following the process.
PLA is widely used in sportswear due to its high moisture absorption and rapid propagation and drying properties. In addition, it is used in many textile products such as carpets and blankets. PLA is used in drinking glasses, bottles, packaging, tableware, hot-cold beverage bottle caps because it is ecofriendly compared to the polymer PET. It is used in outdoor applications since it is resistant to UV rays. Because PLA is non-toxic, it is compatible with the human body and is consequently used in surgical screws and bone fixation devices. The filament PLA is used for printing in 3D printers. Filament is a plastic production material that enables to print out patterns coded with 3D printers. There is a great variety of thermoplastic filaments to work with different properties and at different temperatures. The most common PLA is filament. The PLA Filament is preferable because it allows for printing at lower temperatures and is biodegradable and emits no bad odors during printing.
Polyoxymethylene (POM) is a widely used engineering plastic, referred to as acetal. It can be produced by two different methods. The anionic polymerization from formaldehyde is called homopolymer polyoxymethylene (POM-H), and the one produced by copolymerization is called copolymer polyoxymethylene (POM-C). Due to its higher crystalline structure, POM-C is preferable to POM-H in areas where dimensional stability and chemical resistance are key factors.
POM is a very rigid material. While it is inherently an opaque white material, it can be colored. It is used in precision engineering components due to the high strength it delivers under the influence of mechanical forces and the excellent dimensional stability it demonstrates even at high temperatures. It has good resistance to chemicals. Additionally, its good resistance to friction allows good workability. In addition, it is commonly used in the form of semi-finished products by being extruded as thin films and pipes. It has a low moisture absorption rate. It emits very intense toxic gas when burned. Its poor UV resistance is another drawback of POM. The other drawback is that toxic gases such as formaldehyde are released when processed. Due to its good electrical insulation, it can be used in the electrical industry as well. It is 100% recyclable.
POM is widely used in gas meters and electrical insulation materials. Since it is dimensionally stable, it can be used in sensitive parts such as measuring instruments and in valves among pump components. Additionally, it is used in gears, springs, screws, zippers and clips thanks to its mechanical strength.