Plastic—The Roots of Extrusions, Forms, and Corrugations

Plastic—A Familiar Product. A polymer is both complex and simple. A polymer is one molecule but is constructed of replicated sub-components. Its physical structure makes it tough and somewhat elastic. Amber, cellulose, rubber, shellac, silk, etc. are “natural” polymers. Bakelite, neoprene, nylon, polyethylene, polystyrene, polyvinyl chloride, silicone, synthetic rubber, etc. are “synthetic” polymers. Natural Plastics—An Ancient Product. American Indians were using natural rubber 3600 years ago. Many cultures were using horn from cattle in art and tools from very ancient times. Casein has been employed in paint and glues for millennia. These and other natural polymers have a long history. Synthetic Plastics—A “Recent” Development. Synthetic polymers have a much shorter history. Alexander Parkes took cellulose and added nitric answer about 150 years ago. The result was “Parkesine,” a synthetic that could be altered in color by pigments and molded with heat. Two decades later Eugen Baumann developed vinyl chloride without commercial application. Three decades later, “Bakelite” was developed by Leo Baekeland using formaldehyde and phenol. B.F. Goodrich Company (PVC, 1926), Imperial Chemical Industries (polyethylene, 1933), BASF (polystyrene, c. 1935), Dow Chemical (expanded polystyrene, 1954), and a myriad of others developed the diverse plastics used today. Plastics—Materials, Forms, Molds, Extrusions Plastics vary with materials in the polymer, its mixing and curing requirements, and its shaping requirements. “Thermoset plastics” (e.g., polyurethanes, polyesters, epoxies, etc.) are mixed, shaped, cooled, and allowed to set. They maintain rigidity. “Thermoplastics” (e.g., polyethylene, polyvinyl chloride, etc.) are similar, but can be softened and altered in shape with heat present. They return to their original shape when cooled. Polyethyolene terephthalate (e.g., Dacron, Mylar, etc.) is a hard...