Mexico Pest Analysis
Material is any 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.
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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.
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).  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.