Thermoplastics, materials that soften or melt when heated and harden when cooled. Thermoplastic polymers consist of long polymer molecules that are not linked to each other. i.e., have no cros...

Thermosets, materials that can not be softened on heating. In thermosetting polymers, the polymer chains are joined (or cross-linked) by intermolecular bonding. Thermosets are usually supplied...

Polyolefins, group of plastics that are polymers of various alkenes, or olefins. The most important are polyethylene and polypropylene.

Polycarbonates, group of clear, thermoplastic polymers used mainly as molding compounds (see plastic). Polycarbonates are prepared by the reaction of an aromatic difunctional phenol with eithe...

Macromolecule, term that may refer either to a crystal such as a diamond, in which the atoms are identical and held by covalent bonds (see chemical bond) of equal strength, or to one of the un...

Polyvinyl chloride (PVC), thermoplastic that is a polymer of vinyl chloride. Resins of polyvinyl chloride are hard, but with the addition of plasticizers a flexible, elastic plastic can be mad...

Actin, a protein abundantly present in many cells, especially muscle cells, that significantly contributes to the cell's structure and motility. Actin can very quickly assemble into long polym...

Glycogen, starchlike polysaccharide (see carbohydrate) that is found in the liver and muscles of humans and the higher animals and in the cells of the lower animals. Chemically it is a highly ...

Polyacrylics, group of thermoplastics that are transparent and highly decorative (see plastic). The polyacrylics, or acrylic plastics, are polymers (and copolymers) of derivatives of acrylic a...

Synthetic textile fibers have revolutionized the textile industry. Such artificial fibers are usually long-chain polymers, produced industrially by the condensation of many small units. Orlon ...