WHAT DEFINES A PLASTIC?

DEFINITION OF A PLASTIC....

A plastic is a material of a wide range of synthetic or semi-synthetic organic solids that are moldable. Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, but many are partially natural.

Most plastics contain organic polymers. The vast majority of these polymers are based on chains of carbon atoms alone or with oxygen, sulfur, or nitrogen as well. The backbone is that part of the chain on the main "path" linking a large number of repeat units together. To customize the properties of a plastic, different molecular groups "hang" from the backbone (usually they are "hung" as part of the monomers before linking monomers together to form the polymer chain). The structure of these "side chains" influence the properties of the polymer. This fine tuning of the properties of the polymer by repeating unit's molecular structure has allowed plastics to become an indispensable part of the twenty-first century world.
[edit]Additives
Most plastics contain other organic or inorganic compounds blended in. The amount of additives ranges from zero percentage for polymers used to wrap foods to more than 50% for certain electronic applications. The average content of additives is 20% by weight of the polymer. Fillers improve performance and/or reduce production costs. Stabilizing additives include fire retardants to lower the flammability of the material. Many plastics contain fillers, relatively inert and inexpensive materials that make the product cheaper by weight. Typically fillers are mineral in origin, e.g., chalk. Some fillers are more chemically active and are called reinforcing agents. Since many organic polymers are too rigid for particular applications, they are blended with plasticizers, oily compounds that confer improved rheology. Colorants are common additives, although their weight contribution is small. Many of the controversies associated with plastics are associated with the additives.[2]
[edit]Classification

Plastics are usually classified by their chemical structure of the polymer's backbone and side chains. Some important groups in these classifications are the acrylics, polyesters, silicones, polyurethanes, and halogenated plastics. Plastics can also be classified by the chemical process used in their synthesis, such as condensation, polyaddition, and cross-linking.[3]
[edit]Thermoplastics and thermosetting polymers
There are two types of plastics: thermoplastics and thermosetting polymers. Thermoplastics are the plastics that do not undergo chemical change in their composition when heated and can be molded again and again. Examples include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polytetrafluoroethylene (PTFE).[4] Common thermoplastics range from 20,000 to 500,000 amu, while thermosets are assumed to have infinite molecular weight. These chains are made up of many repeating molecular units, known as repeat units, derived from monomers; each polymer chain will have several thousand repeating units.
Thermosets can melt and take shape once; after they have solidified, they stay solid. In the thermosetting process, a chemical reaction occurs that is irreversible. The vulcanization of rubber is a thermosetting process. Before heating with sulfur, the polyisoprene is a tacky, slightly runny material, but after vulcanization the product is rigid and non-tacky.
[edit]Other classifications
Other classifications are based on qualities that are relevant for manufacturing or product design. Examples of such classes are the thermoplastic and thermoset, elastomer, structural, biodegradable, and electrically conductive. Plastics can also be classified by various physical properties, such as density, tensile strength, glass transition temperature, and resistance to various chemical products.
[edit]Biodegradability
Main article: Biodegradable plastic
Biodegradable plastics break down (degrade) upon exposure to sunlight (e.g., ultra-violet radiation), water or dampness, bacteria, enzymes, wind abrasion, and in some instances, rodent, pest, or insect attack are also included as forms of biodegradation or environmental degradation. Some modes of degradation require that the plastic be exposed at the surface, whereas other modes will only be effective if certain conditions exist in landfill or composting systems. Starch powder has been mixed with plastic as a filler to allow it to degrade more easily, but it still does not lead to complete breakdown of the plastic. Some researchers have actually genetically engineered bacteria that synthesize a completely biodegradable plastic, but this material, such as Biopol, is expensive at present.[5] The German chemical company BASF makes Ecoflex, a fully biodegradable polyester for food packaging applications.
[edit]Natural vs synthetic
Main article: Bioplastic
Most plastics are produced from petrochemicals. Motivated by the finiteness of petrochemical reserves and possibility of global warming, bioplastics are being developed. Bioplastics are made substantially from renewable plant materials such as cellulose and starch.[6]
In comparison to the global consumption of all flexible packaging, estimated at 12.3 million tonnes/year, estimates put global production capacity at 327,000 tonnes/year for related bio-derived materials.[7][8]
[edit]Crystalline vs amorphous
Some plastics are partially crystalline and partially amorphous in molecular structure, giving them both a melting point (the temperature at which the attractive intermolecular forces are overcome) and one or more glass transitions (temperatures above which the extent of localized molecular flexibility is substantially increased). The so-called semi-crystalline plastics include polyethylene, polypropylene, poly (vinyl chloride), polyamides (nylons), polyesters and some polyurethanes. Many plastics are completely amorphous, such as polystyrene and its copolymers, poly (methyl methacrylate), and all thermosets.

knew this was coming!

plas·tic (plstk)
adj.
1. Capable of being shaped or formed: plastic material such as clay. See Synonyms at malleable.
2. Relating to or dealing with shaping or modeling: the plastic art of sculpture.
3. Having the qualities of sculpture; well-formed: "the astonishing plastic beauty of the chorus girls" (Frank Harris).
4. Giving form or shape to a substance: the plastic forces that create and wear down a mountain range.
5. Easily influenced; impressionable.
6. Made of a plastic or plastics: a plastic garden hose.
7. Physics Capable of undergoing continuous deformation without rupture or relaxation.
8. Biology Capable of building tissue; formative.
9. Marked by artificiality or superficiality; synthetic: a plastic world of fad, hype, and sensation.
10. Informal Of or obtained by means of credit cards: plastic money.
n.
1. Any of various organic compounds produced by polymerization, capable of being molded, extruded, cast into various shapes and films, or drawn into filaments used as textile fibers.
2. Objects made of plastic.
3. Informal A credit card or credit cards: would accept cash or plastic in payment

plas·tic (plstk)
adj.
1. Capable of being shaped or formed: plastic material such as clay. See Synonyms at malleable.
2. Relating to or dealing with shaping or modeling: the plastic art of sculpture.
3. Having the qualities of sculpture; well-formed: "the astonishing plastic beauty of the chorus girls" (Frank Harris).
4. Giving form or shape to a substance: the plastic forces that create and wear down a mountain range.
5. Easily influenced; impressionable.
6. Made of a plastic or plastics: a plastic garden hose.
7. Physics Capable of undergoing continuous deformation without rupture or relaxation.
8. Biology Capable of building tissue; formative.
9. Marked by artificiality or superficiality; synthetic: a plastic world of fad, hype, and sensation.
10. Informal Of or obtained by means of credit cards: plastic money.
n.
1. Any of various organic compounds produced by polymerization, capable of being molded, extruded, cast into various shapes and films, or drawn into filaments used as textile fibers.
2. Objects made of plastic.
3. Informal A credit card or credit cards: would accept cash or plastic in payment

You were beaten to it. Only just mind.

plas·tic (plstk)
adj.
1. Capable of being shaped or formed: plastic material such as clay. See Synonyms at malleable.
2. Relating to or dealing with shaping or modeling: the plastic art of sculpture.
3. Having the qualities of sculpture; well-formed: "the astonishing plastic beauty of the chorus girls" (Frank Harris).
4. Giving form or shape to a substance: the plastic forces that create and wear down a mountain range.
5. Easily influenced; impressionable.
6. Made of a plastic or plastics: a plastic garden hose.
7. Physics Capable of undergoing continuous deformation without rupture or relaxation.
8. Biology Capable of building tissue; formative.
9. Marked by artificiality or superficiality; synthetic: a plastic world of fad, hype, and sensation.
10. Informal Of or obtained by means of credit cards: plastic money.
n.
1. Any of various organic compounds produced by polymerization, capable of being molded, extruded, cast into various shapes and films, or drawn into filaments used as textile fibers.
2. Objects made of plastic.
3. Informal A credit card or credit cards: would accept cash or plastic in payment

You were beaten to it. Only just mind.

was going to do it yesterday - scary indeed as we posted virtually same time

Come down the CCS on Friday night and you will see plenty of plastic in the form of fans and empty seats.