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Encyclopedia > Thermoplastic

A thermoplastic is a plastic that melts to a liquid when heated and freezes to a brittle, very glassy state when cooled sufficiently. Most thermoplastics are high molecular weight polymers whose chains associate through weak van der Waals forces (polyethylene); stronger dipole-dipole interactions and hydrogen bonding (nylon); or even stacking of aromatic rings (polystyrene). Thermoplastic polymers differ from thermosetting polymers (Bakelite; vulcanized rubber) as they can, unlike thermosetting polymers, be remelted and remoulded. Many thermoplastic materials are addition polymers; e.g., vinyl chain-growth polymers such as polyethylene and polypropylene. Look up plastic in Wiktionary, the free dictionary. ... Physics In physics, melting is the process of heating a solid substance to a point (called melting point) where it turns liquid. ... A material is brittle if it is subject to fracture when subjected to stress i. ... This article is about the material. ... The molecular mass (abbreviated Mr) of a substance, formerly also called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... When chain refers to a sequence, it can refer to: A chain of islands such as in an archipelago A chain of molecules such as in Nylon A chain of hills or mountains such as would form a mountain range Terms which use the term chain to refer to a... In chemistry, the term van der Waals force originally referred to all forms of intermolecular forces; however, in modern usage it tends to refer to intermolecular forces that deal with forces due to the polarization of molecules. ... its made by jaypeeng magandang google wikepedia For other uses, see Force (disambiguation). ... This article does not cite any references or sources. ... The Earths magnetic field, which is approximately a dipole. ... An example of a quadruple hydrogen bond between a self-assembled dimer complex reported by Meijer and coworkers. ... For other uses of this word, see nylon (disambiguation). ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... Polystyrene (IPA: ) is a polymer made from the monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. ... Thermosetting plastics (thermosets) are polymer materials that cure, through the addition of energy, to a stronger form. ... Bakelite is a material based on the thermosetting phenol formaldehyde resin, polyoxybenzylmethylenglycolanhydride developed in 1907–1909 by Belgian-American Dr. Leo Baekeland. ... Vulcanization refers to a specific curing process of rubber involving high heat and the addition of sulfur. ... This does not cite any references or sources. ... An 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. ... Chemical structure of the vinyl functional group. ... Polypropylene lid of a Tic Tacs box, with a living hinge and the resin identification code under its flap Micrograph of polypropylene Polypropylene or polypropene (PP) is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including food packaging, ropes, textiles, plastic parts...


Temperature dependence

Thermoplastics are elastic and flexible above a glass transition temperature Tg, specific for each one — the midpoint of a temperature range in contrast to the sharp freezing point of a pure crystalline substance like water. Below a second, higher melting temperature, Tm, also the midpoint of a range, most thermoplastics have crystalline regions alternating with amorphous regions in which the chains approximate random coils. The amorphous regions contribute elasticity and the crystalline regions contribute strength and rigidity, as is also the case for non-thermoplastic fibrous proteins such as silk. (Elasticity does not mean they are particularly stretchy; e.g., nylon rope and fishing line.) Above Tm all crystalline structure disappears and the chains become randomly inter dispersed. As the temperature increases above Tm, viscosity gradually decreases without any distinct phase change. Image File history File links Tempdependence. ... The glass transition temperature is the temperature below which the physical properties of amorphous materials vary in a manner similar to those of a solid phase (glassy state), and above which amorphous materials behave like liquids (rubbery state). ... For other uses, see Temperature (disambiguation). ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... For other uses, see Crystal (disambiguation). ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Wax and paraffin are amorphous. ... Illustration of a 3-dimensional polypeptide A random coil is a polymer conformation where the monomer subunits are oriented randomly while still being bonded to adjacent units. ... Hookes law accurately models the physical properties of common mechanical springs for small changes in length. ... Fibrous proteins, also called scleroproteins, are long filamentous protein molecules that form one of the two main classes of tertiary structure protein (the other being globular proteins). ... For other uses of this word, see Silk (disambiguation). ... Coils of rope used for long-line fishing A rope (IPA: ) is a length of fibers, twisted or braided together to improve strength for pulling and connecting. ... Fishing line is any cord made for fishing. ... For other uses, see Viscosity (disambiguation). ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ...


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 pop bottles are a common example of thermoplastics that can be and are widely recycled. Animal horn, made of the protein α-keratin, softens on heating, is somewhat reshapable, and may be regarded as a natural, quasi-thermoplastic material. Highland cow, a very old long-horned breed from Scotland. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Not to be confused with kerogen or carotene. ...


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, PS and PC. Generally, amorphous thermoplastics are less chemically resistant and can be subject to stress cracking. Thermoplastics will crystallize to a certain extent and are called "semi-crystalline" for this reason. Typical semi-crystalline thermoplastics are PE, PP, PBT and PET. 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 Tg. If a plastic with otherwise desirable properties has too high a Tg, it can often be lowered by adding a low-molecular-weight plasticizer to the melt before forming (Plastics extrusion; molding) and cooling. A similar result can sometimes be achieved by adding non-reactive side chains to the monomers before polymerization. Both methods make the polymer chains stand off a bit from one another. Before the introduction of plasticizers, plastic automobile parts often cracked in cold winter weather. 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 material. Lowering Tg is not the only way to reduce brittleness. Drawing (and similar processes that stretch or orient the molecules) or increasing the length of the polymer chains also decrease brittleness. Plasticizers are additives that soften the materials (usually a plastic or a concrete mix) they are added to. ... Plastic extruder with barrel cut open to show the screw Plastics extrusion is a high volume manufacturing process in which raw plastic material is melted and formed into a continuous profile. ... One half of a bronze mould for casting a socketed spear head dated to the period 1400-1000 BC. There are no known parallels for this mould. ... The term Side chain can have different meanings depending on the context: In chemistry and biochemistry a side chain is a part of a molecule attached to a core structure. ... In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ... An example of alkene polymerisation, in which each Styrene monomer units double bond reforms as a single bond with another styrene monomer and forms polystyrene. ... This article or section does not cite any references or sources. ... “Car” and “Cars” redirect here. ... Winter is one of the four seasons of temperate zones. ... For the geological process, see Weathering or Erosion. ... A heteropolymer, also called a copolymer, is a polymer formed when two different types of monomer are linked in the same polymer chain. ... A graft copolymer has polymer chains of one kind growing out of the sides of polymer chains with a different chemical composition. ... A cloth of woven carbon fiber filaments, a common element in composite materials Composite materials (or composites for short) are engineered materials made from two or more constituent materials with significantly different physical or chemical properties and which remain separate and distinct on a macroscopic level within the finished structure. ... Drawing is a manufacturing process for producing a wire, bar or tube by pulling on a material until it increases in length. ...


Although modestly vulcanized natural and synthetic rubbers are stretchy, they are elastomeric thermosets, not thermoplastics. Each has its own Tg, and will crack and shatter when cold enough so that the crosslinked 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 elastomers have become available. The term elastomer is often used interchangeably with the term rubber, and is preferred when referring to vulcanisates. ... Vulcanization is an example of cross-linking. ... A thermoplastic elastomer is a material which is both a thermoplastic (i. ...


List of thermoplastics

Monomers in ABS polymer Acrylonitrile butadiene styrene, or ABS, (chemical formula (C8H8· C4H6·C3H3N)n is a common thermoplastic used to make light, rigid, molded products such as piping, golf club heads (used for its good shock absorbance), automotive body parts, wheel covers, enclosures, protective head gear, and toys including... Structure of methyl methacrylate, the monomer that makes up PMMA Polymethyl methacrylate (PMMA) or poly(methyl 2-methylpropenoate) is the synthetic polymer of methyl methacrylate. ... 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. ... Cellulose acetate, first prepared in 1865, is the acetate ester of cellulose. ... Ethylene-vinyl acetate (also known as EVA or sometimes simply as acetate) is the copolymer of ethylene and vinyl acetate. ... A fluoropolymer is a polymer that contains atoms of fluorine. ... An ionomer is a polyelectrolyte that comprises copolymers containing both electrically neutral repeating units and a fraction of ionic units (usually no more than 15%). Categories: Chemistry stubs | Polymers | Plastics ... KYDEX® is a line of thermoplastic acrylic-polyvinyl chloride alloy sheet grades. ... An alloy is a homogeneous hybrid of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... // Background: Liquid Crystal Polymers (LCP) are a unique class of wholly aromatic polyester polymers that provide previously unavailable high performance properties. ... Polyoxymethylene, also known as acetal resin, polytrioxane, polyformaldehyde, and paraformaldehyde, is an engineering plastic used to make gears, bushings and other mechanical parts ( nylon, teflon, UHMWPE). ... Structure of methyl methacrylate, the monomer that makes up PMMA Polymethyl methacrylate (PMMA) or poly(methyl 2-methylpropenoate) is the synthetic polymer of methyl methacrylate. ... Polyacrylonitrile (PAN) is a resinous, fibrous, or rubbery organic polymer. ... A polyamide is a polymer containing monomers joined by peptide bonds. ... Polyamide-imides are thermoplastic amorphous polymers which enjoy exceptional mechanical, thermal and chemical resistant properties. ... Polybutadiene is a synthetic rubber that has a high resistance to wear and is used especially in the manufacture of tires. ... Wikipedia does not have an article with this exact name. ... Polybutylene terephthalate (PBT) is a plastic that is used as an insulator in the electrical and electronics industries. ... Polyethylene terephthalate (aka 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 with glass fiber. ... Polycarbonates are a particular group of thermoplastic polyesters. ... Polyhydroxyalkanoates or PHAs are linear polyesters produced in nature by bacterial fermentation of sugar or lipids. ... Polyketones are a family of high-performance thermoplastic polymers. ... SEM picture of a bend in a high surface area polyester fiber with a seven-lobed cross section Polyester is a category of polymers, or, more specifically condensation polymers, which contain the ester functional group in their main chain. ... This article does not cite any references or sources. ... This article is about the resin. ... Polyetherimide ( PEI ) is an amorphous, amber transparent, high-performance thermoplastic with the characteristics similar to PEEK. Relative to PEEK, it is less temperature-resistant, less expensive, and lower in impact strength. ... Polysulfone, or PSU, is a polymer thermoplastic material. ... Polyimide (sometimes abbreviated PI) is a polymer of imide monomers. ... This article does not cite any references or sources. ... Chemical structure of polymethylpentene Polymethylpentene is a thermoplastic polymer of methylpentene monomer units. ... Sulfar fiber (1983) is a nonconductive fiber that has excellent resistance to chemical and thermal attack; it has changed industry with filter fabrics for coal boilers, papermaker felts, electrical insulation, specialty membranes, gaskets, and packings. ... Polyphthalamide (aka. ... Polypropylene lid of a Tic Tacs box, with a living hinge and the resin identification code under its flap Micrograph of polypropylene Polypropylene or polypropene (PP) is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including food packaging, ropes, textiles, plastic parts... Polystyrene (IPA: ) is a polymer made from the monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. ... Polysulfone, or PSU, is a polymer thermoplastic material. ... Polyvinyl chloride Polyvinyl chloride, (IUPAC Polychloroethene) commonly abbreviated PVC, is a widely used thermoplastic polymer. ... Polyvinylidene chloride is a polymer derived from vinylidene chloride. ... Spectralon is a material with very high diffuse reflection; almost a perfect lambertian surface. ...

See also


  Results from FactBites:
 
Heat seamable flame retardant roof sheeting with highly crystalline thermoplasticity promoters and method for covering ... (5739 words)
It is another object of the present invention to provide compositions which have sufficient crystallinity to show thermoplastic behavior during the formation of a seam using both heat and pressure, but which will continue to maintain its flame resistance.
The highly crystalline thermoplasticity promoters listed in Table I are necessary, when the polymer blend comprises increasing amounts of the halogenated olefin type elastomer having less than 2 weight percent crystallinity.
It is to be understood that the invention is not limited to the specific types of halogenated olefinic elastomers or thermoplasticity promoters exemplified herein or by the disclosure of other typical halogenated olefinic elastomers provided herein, the examples having been provided merely to demonstrate the practice of the subject invention.
Thermoplastic at AllExperts (495 words)
A thermoplastic is a material that is plastic or deformable, melts to a liquid when heated and freezes to a brittle, glassy state when cooled sufficiently.
Most thermoplastics are high molecular weight polymers whose chains associate through weak van der Waals forces (polyethylene); stronger dipole-dipole interactions and hydrogen bonding (nylon); or even stacking of aromatic rings (polystyrene).
Thermoplastic polymers differ from thermosetting polymers (Bakelite; vulcanized rubber) which once formed and cured, can never be remelted and remolded.
  More results at FactBites »

 
 

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