Thermoplastic, also known as a
thermosoftening plastic, is a
polymerA polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently. Most thermoplastics are high-
molecular-weightThe molecular mass of a substance is the mass of one molecule of that substance, in unified atomic mass unit u...
polymerA polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
s whose chains associate through weak
Van der Waals forceIn physical chemistry, the van der Waals force , named after Dutch scientist Johannes Diderik van der Waals, is the sum of the attractive or repulsive forces between molecules other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral...
s (
polyethylenePolyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...
); stronger
dipole-dipoleIn physics, there are several kinds of dipoles:*An electric dipole is a separation of positive and negative charges. The simplest example of this is a pair of electric charges of equal magnitude but opposite sign, separated by some distance. A permanent electric dipole is called an electret.*A...
interactions and
hydrogen bondA hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond...
ing (
nylonNylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
); or even stacking of aromatic rings (
polystyrenePolystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
). Thermoplastic polymers differ from
thermosettingA thermosetting plastic, also known as a thermoset, is polymer material that irreversibly cures. The cure may be done through heat , through a chemical reaction , or irradiation such as electron beam processing.Thermoset materials are usually liquid or malleable prior to curing and designed to be...
polymers (
Bakelite) in that they can be remelted and remoulded. Many thermoplastic materials are
addition polymerAn addition polymer is a polymer which is formed by an addition reaction, where many monomers bond together via rearrangement of bonds without the loss of any atom or molecule...
s; e.g.,
vinylA vinyl compound is any organic compound that contains a vinyl group ,which are derivatives of ethene, CH2=CH2, with one hydrogen atom replaced with some other group...
chain-growth polymers such as polyethylene and
polypropylenePolypropylene , also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes...
. This is the basic theory.
Theory
Thermoplastics are elastic and flexible above a
glass transition temperatureThe liquid-glass transition is the reversible transition in amorphous materials from a hard and relatively brittle state into a molten or rubber-like state. An amorphous solid that exhibits a glass transition is called a glass...
Tg, specific for each one—the midpoint of a
temperatureTemperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
range in contrast to the sharp
melting pointThe melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...
of a pure
crystalA crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
line substance like
waterWater is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
. Below a second, higher melting temperature,
Tm, also the midpoint of a range, most thermoplastics have crystalline regions alternating with
amorphousIn condensed matter physics, an amorphous or non-crystalline solid is a solid that lacks the long-range order characteristic of a crystal....
regions in which the chains approximate
random coilA random coil is a polymer conformation where the monomer subunits are oriented randomly while still being bonded to adjacent units. It is not one specific shape, but a statistical distribution of shapes for all the chains in a population of macromolecules...
s. The amorphous regions contribute
elasticityIn mechanics, and physics, Hooke's law of elasticity is an approximation that states that the extension of a spring is in direct proportion with the load applied to it. Many materials obey this law as long as the load does not exceed the material's elastic limit. Materials for which Hooke's law...
and the crystalline regions contribute strength and rigidity, as is also the case for non-thermoplastic
fibrous proteinScleroproteins, or fibrous proteins, constitute one of the three main classes of proteins, alongside globular proteins and conjugated proteins.Keratin, collagen, elastin, and fibroin are all scleroproteins...
s such as
silkSilk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...
. (Elasticity does not mean they are particularly stretchy; e.g., nylon
ropeA rope is a length of fibres, twisted or braided together to improve strength for pulling and connecting. It has tensile strength but is too flexible to provide compressive strength...
and
fishing lineA fishing line is a cord used or made for angling. Important parameters of a fishing line are its length, material, and weight...
.) Above
Tm all crystalline structure disappears and the chains become randomly inter dispersed. As the temperature increases above
Tm,
viscosityViscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
gradually decreases without any distinct
phaseIn the physical sciences, a phase is a region of space , throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, and chemical composition...
change.
Some thermoplastics normally do not crystallize: they are termed "amorphous" plastics and are useful at temperatures below the
Tg. They are frequently used in applications where clarity is important. Some typical examples of amorphous thermoplastics are PMMA,
PSPolystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
and
PCPolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...
. Generally, amorphous thermoplastics are less chemically resistant and can be subject to
environmental stress crackingEnvironmental Stress Cracking is one of the most common causes of unexpected brittle failure of thermoplastic polymers known at present. Environmental stress cracking may account for around 15-30% of all plastic component failures in service.ESC and polymer resistance to ESC have been studied...
. Thermoplastics will crystallize to a certain extent and are called "semi-crystalline" for this reason. Typical semi-crystalline thermoplastics are
PEPolyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...
,
PPPolypropylene , also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes...
,
PBTPolybutylene terephthalate is a thermoplastic engineering polymer, that is used as an insulator in the electrical and electronics industries. It is a thermoplastic crystalline polymer, and a type of polyester...
and
PETPolyethylene terephthalate , commonly abbreviated PET, PETE, or the obsolete PETP or PET-P, is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination...
. The speed and extent to which crystallization can occur depends in part on the flexibility of the polymer chain. Semi-crystalline thermoplastics are more resistant to solvents and other chemicals. If the crystallites are larger than the wavelength of light, the thermoplastic is hazy or opaque.
Semi-crystalline thermoplastics become less brittle above 'T'
g. If a plastic with otherwise desirable properties has too high a
Tg, it can often be lowered by adding a low-molecular-weight
plasticizerPlasticizers or dispersants are additives that increase the plasticity or fluidity of the material to which they are added; these include plastics, cement, concrete, wallboard, and clay. Although the same compounds are often used for both plastics and concretes the desired effects and results are...
to the melt before forming (
Plastics extrusionPlastics extrusion is a high volume manufacturing process in which raw plastic material is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weather stripping, fence, deck railing, window frames, adhesive tape and wire insulation.-Process:In the extrusion of...
;
moldingMolding or moulding is the process of manufacturing by shaping pliable raw material using a rigid frame or model called a pattern....
) and cooling. A similar result can sometimes be achieved by adding non-reactive
side chainIn organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called "main chain" or backbone. The placeholder R is often used as a generic placeholder for alkyl group side chains in chemical structure diagrams. To indicate other non-carbon...
s to the
monomerA monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
s before
polymerizationIn polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
. Both methods make the polymer chains stand off a bit from one another. Before the introduction of plasticizers,
plasticA plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
automobileAn automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
parts often cracked in cold winter
weatherWeather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
. Another method of lowering
Tg (or raising
Tm) is to incorporate the original plastic into a copolymer, as with graft copolymers of polystyrene, or into a
composite materialComposite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...
. Lowering
Tg is not the only way to reduce brittleness.
DrawingDrawing is a metalworking process which uses tensile forces to stretch metal. It is broken up into two types: sheet metal drawing and wire, bar, and tube drawing. The specific definition for sheet metal drawing is that it involves plastic deformation over a curved axis...
(and similar processes that stretch or orient the molecules) or increasing the length of the polymer chains also decrease brittleness.
Thermoplastics can go through melting/freezing cycles repeatedly and the fact that they can be reshaped upon reheating gives them their name. This quality makes thermoplastics recyclable. The processes required for recycling vary with the thermoplastic. The plastics used for soda bottles are a common example of thermoplastics that can be and are widely recycled.
Animal hornA horn is a pointed projection of the skin on the head of various animals, consisting of a covering of horn surrounding a core of living bone. True horns are found mainly among the ruminant artiodactyls, in the families Antilocapridae and Bovidae...
, made of the
proteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
α-keratinKeratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...
, softens on heating, is somewhat reshapable, and may be regarded as a natural, quasi-thermoplastic material.
Although modestly vulcanized natural and synthetic rubbers are stretchy, they are
elastomerAn elastomer is a polymer with the property of viscoelasticity , generally having notably low Young's modulus and high yield strain compared with other materials. The term, which is derived from elastic polymer, is often used interchangeably with the term rubber, although the latter is preferred...
ic thermosets, not thermoplastics. Each has its own
Tg, and will crack and shatter when cold enough so that the
crosslinkedCross-links are bonds that link one polymer chain to another. They can be covalent bonds or ionic bonds. "Polymer chains" can refer to synthetic polymers or natural polymers . When the term "cross-linking" is used in the synthetic polymer science field, it usually refers to the use of...
polymer chains can no longer move relative to one another. But they have no
Tm and will decompose at high temperatures rather than melt. Recently,
thermoplastic elastomerThermoplastic elastomers , sometimes referred to as thermoplastic rubbers, are a class of copolymers or a physical mix of polymers which consist of materials with both thermoplastic and elastomeric properties...
s have become available.
Melting point and glass transition temperature of various thermoplastics
| Polymer |
Tm |
Tg |
| Acrylonitrile butadiene styrene Acrylonitrile butadiene styrene is a common thermoplastic. Its melting point is approximately 105 °C ....
(ABS) |
|
| Acrylic (PMMA) |
130–140 °C |
|
| Celluloid Celluloid is the name of a class of compounds created from nitrocellulose and camphor, plus dyes and other agents. Generally regarded to be the first thermoplastic, it was first created as Parkesine in 1862 and as Xylonite in 1869, before being registered as Celluloid in 1870. Celluloid is...
|
|
|
| Cellulose acetate Cellulose acetate , first prepared in 1865, is the acetate ester of cellulose. Cellulose acetate is used as a film base in photography, as a component in some adhesives, and as a frame material for eyeglasses; it is also used as a synthetic fiber and in the manufacture of cigarette filters and...
|
|
|
| Cyclic Olefin Copolymer Cyclic Olefin Copolymer is an amorphous polymer made by several polymer manufacturers. COC is a relatively new class of polymers when compared to polypropylene and polyethylene...
(COC) |
|
|
| Ethylene-Vinyl Acetate Ethylene vinyl acetate is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene....
(EVA) |
|
|
| Ethylene vinyl alcohol Ethylene Vinyl Alcohol, commonly abbreviated EVOH, is a formal copolymer of ethylene and vinyl alcohol. Because the latter monomer mainly exists as its tautomer acetaldehyde, the copolymer is prepared by polymerization of ethylene and vinyl acetate to give the ethylene vinyl acetate copolymer...
(EVOH) |
|
|
| Fluoroplastics A fluoropolymer is a fluorocarbon based polymer with multiple strong carbon–fluorine bonds. It is characterized by a high resistance to solvents, acids, and bases.-History:Fluoropolymers were accidentally discovered in 1938 by Dr. Roy J...
(PTFE, alongside with FEP, PFA, CTFE, ECTFEECTFE is a fluorocarbon-based polymer , a kind of plastic. It is marketed under the brand name Halar ECTFE by Solvay Solexis...
, ETFEEthylene tetrafluoroethylene, ETFE, a fluorine based plastic, was designed to have high corrosion resistance and strength over a wide temperature range. ETFE is a polymer, and its systematic name is poly. ETFE has a very high melting temperature, excellent chemical, electrical and high energy...
) |
|
|
| Ionomer An ionomer is a polymer that comprises repeat units of both electrically neutral repeating units and a fraction of ionized units...
s |
|
|
| Kydex KYDEX is a line of thermoplastic acrylic-polyvinyl chloride alloy sheet grades. It is frequently used as an alternative to leather in the production of firearm holsters and sheaths for knives...
, a trademarked acrylic/PVC alloyAn alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
|
|
|
| Liquid Crystal Polymer Liquid-crystal polymers are a class of aromatic polyester polymers. They are extremely unreactive and inert, and highly resistant to fire.-Background:...
(LCP) |
|
|
| Polyoxymethylene Polyoxymethylene , also known as acetal, polyacetal, and polyformaldehyde, is an engineering thermoplastic used in precision parts that require high stiffness, low friction and excellent dimensional stability....
(POM or Acetal) |
166°C |
|
| Polyacrylates (Acrylic) |
|
|
| Polyacrylonitrile Polyacrylonitrile is a synthetic, semicrystalline organic polymer resin, with the linear formula n. Though it is thermoplastic, it does not melt under normal conditions. It degrades before melting. It melts above 300 degrees Celsius only if the heating rates are 50 degrees per minute or above...
(PAN or Acrylonitrile) |
|
|
PolyamideA polyamide is a polymer containing monomers of amides joined by peptide bonds. They can occur both naturally and artificially, examples being proteins, such as wool and silk, and can be made artificially through step-growth polymerization or solid-phase synthesis, examples being nylons, aramids,...
(PA or Nylon) |
|
|
| Polyamide-imide Polyamide-imides are thermoplastic amorphous polymers that have exceptional mechanical, thermal and chemical resistant properties. These properties put polyamide-imides at the top of the price and performance pyramid. Polyamide-imides are produced by Solvay Advanced Polymers under the trademark...
(PAI) |
|
|
| Polyaryletherketone Polyaryletherketone is a family of semi-crystalline thermoplastics with high-temperature stability and high mechanical strength.-Properties:...
(PAEK or Ketone) |
|
|
PolybutadienePolybutadiene is a synthetic rubber that is a polymer formed from the polymerization process of the monomer 1,3-butadiene.It has a high resistance to wear and is used especially in the manufacture of tires, which consumes about 70% of the production...
(PBD) |
|
|
| Polybutylene Polybutylene is a polyolefin or saturated polymer with the chemical formula n. It should not be confused with polybutene, a low molecular weight oligomer with a different repeat unit....
(PB) |
|
|
Polybutylene terephthalatePolybutylene terephthalate is a thermoplastic engineering polymer, that is used as an insulator in the electrical and electronics industries. It is a thermoplastic crystalline polymer, and a type of polyester...
(PBT) |
160°C |
40°C |
PolycaprolactonePolycaprolactone is a biodegradable polyester with a low melting point of around 60°C and a glass transition temperature of about −60°C. PCL is prepared by ring opening polymerization of ε-caprolactone using a catalyst such as stannous octoate. Recently a wide range of catalysts for the ring...
(PCL) |
62 °C |
|
PolychlorotrifluoroethylenePolychlorotrifluoroethylene is a fluoropolymer with the molecular formula n. It is chemically related to PTFE....
(PCTFE) |
|
|
| Polyethylene terephthalate Polyethylene terephthalate , commonly abbreviated PET, PETE, or the obsolete PETP or PET-P, is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination...
(PET) |
260 °C |
75 °C |
| Polycyclohexylene dimethylene terephthalate (PCT) |
|
|
PolycarbonatePolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...
(PC) |
267 °C |
|
| Polyhydroxyalkanoates Polyhydroxyalkanoates or PHAs are linear polyesters produced in nature by bacterial fermentation of sugar or lipids. They are produced by the bacteria to store carbon and energy. More than 150 different monomers can be combined within this family to give materials with extremely different properties...
(PHAs) |
|145| |
PolyketonePolyketone Density1240 kg/m3Young's modulus 1500 MPaTensile strength 55 MPaElongation @ break350 %notch test20 kJ/m2Glass temperature15°Cmelting point220°CVicat B205heat transfer coefficient 0.27 W/...
(PK) |
|
|
| Polyester Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
|
260 C |
75 C |
| Polyethylene Polyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...
(PE) |
105–130 °C |
| Polyetheretherketone (PEEK) |
343 °C |
143 °C |
| Polyetherketoneketone (PEKK) |
|
|
| Polyetherimide (PEI) |
|
|
| Polyethersulfone (PES)- see Polysulfone Polysulfone describes a family of thermoplastic polymers. These polymers are known for their toughness and stability at high temperatures. They contain the subunit aryl-SO2-aryl, the defining feature of which is the sulfone group. Polysulfones were introduced in 1965 by Union Carbide...
|
|
|
| Chlorinated Polyethylene (CPE) |
|
|
PolyimidePolyimide is a polymer of imide monomers. The structure of imide is as shown. Polyimides have been in mass production since 1955...
(PI) |
|
|
| Polylactic acid Poly or polylactide is a thermoplastic aliphatic polyester derived from renewable resources, such as corn starch , tapioca products or sugarcanes...
(PLA) |
50–80 °C |
|
| Polymethylpentene Polymethylpentene is a thermoplastic polymer of methylpentene monomer units. It is used for gas permeable packaging, autoclavable medical and laboratory equipment, microwave components, and cookware...
(PMP) |
|
|
| Polyphenylene oxide (PPO) |
|
|
| Polyphenylene sulfide (PPS) |
|
|
| Polyphthalamide Polyphthalamide is a thermoplastic synthetic resin of the polyamide family that is used to replace metals in high temperature automotive applications, as the housing for high temperature electrical connectors and multiple other uses. It has found a degree of favor for use in cutlery...
(PPA) |
|
|
PolypropylenePolypropylene , also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes...
(PP) |
160 °C |
|
PolystyrenePolystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
(PS) |
240 °C |
|
| Polysulfone Polysulfone describes a family of thermoplastic polymers. These polymers are known for their toughness and stability at high temperatures. They contain the subunit aryl-SO2-aryl, the defining feature of which is the sulfone group. Polysulfones were introduced in 1965 by Union Carbide...
(PSU) |
|
|
| Polytrimethylene terephthalate Polytrimethylene terephthalate, or PTT, is a polymer synthesized and patented in 1941. It is produced by a method called condensation polymerization or transesterification. The two monomer units used in producing this polymer are: 1,3-propanediol and terephthalic acid or dimethyl terephthalate...
(PTT) |
|
|
PolyurethaneA polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
(PU) |
|
|
| Polyvinyl acetate Polyvinyl acetate, PVA, PVAc, poly, is a rubbery synthetic polymer with the formula n. It belongs to the polyvinyl esters family with the general formula -[RCOOCHCH2]-...
(PVA) |
|
32 °C |
Polyvinyl chloridePolyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...
(PVC) |
|
80 °C |
Polyvinylidene chloridePolyvinylidene chloride is a polymer derived from vinylidene chloride.-History:Ralph Wiley, a Dow Chemical lab worker, accidentally discovered polyvinylidene chloride in 1933. While cleaning laboratory glassware, he came across a vial he could not scrub clean...
(PVDC) |
185 °C |
40 °C |
| Styrene-acrylonitrile (SAN) |
|115| |
Terminology
The literature on thermoplastics is huge, and can be quite confusing, as the same chemical can be available in many different forms (for example, at different molecular weights), which might have quite different physical properties. The same chemical can be referred to by many different tradenames, by different abbreviations; two chemical compounds can share the same name; a good example of the latter is the word "Teflon" which is used to refer to a specific polymer (PTFE); to related polymers such as PFA, and generically to
fluoropolymerA fluoropolymer is a fluorocarbon based polymer with multiple strong carbon–fluorine bonds. It is characterized by a high resistance to solvents, acids, and bases.-History:Fluoropolymers were accidentally discovered in 1938 by Dr. Roy J...
s.
Testing
Testing of thermoplastics can take various forms.
Tensile tests—ISO 527 -1/-2 and ASTM D 638 set out the standardized test methods. These standards are technically equivalent. However they are not fully comparable because of the difference in testing speeds. The modulus determination requires a high accuracy of ± 1 micrometer for the
dilatometerA dilatometer is a scientific instrument that measures volume changes caused by a physical or chemical process. A familiar application of a dilatometer is the mercury-in-glass thermometer, in which the change in volume of the liquid column is read from a graduated scale...
.
Flexural tests—3-points flexural tests are among the most common and classic methods for semi rigid and rigid plastics.
Pendulum impact tests—impact tests are used to measure the behavior of materials at higher deformation speeds. Pendulum impact testers are used to determine the energy required to break a standardized specimen by measuring the height to which the pendulum hammer rises after impacting the test piece.