History of Plastic
The development of a commercial phenolic resin in 1900 by Backland was the star of the synthetic plastic industry. His discovery stimulated the search for other plastics and resulted in an industry that has grown to become one of the nation’s top ten in size. The first plastic of industrial significance was cellulose nitrate (Celluloid) and was discovered about the middle of the nineteenth century. It was first used in 1869 by Hyatt who was searching for an ivory substitute.
Cellulose acetate was developed in 1894 as a less flammable material and was used extensively as a base for photographic film and as dope for air plane covering during World War I. From that time on, the introduction of new polymer materials was rapid.
Plastics are often divided into thermosetting, thermoplastic, oil soluble, and protein products as presented in the table Type of Resin and Plastic. On the basic of derivation, they may be grouped as natural resins, cellulose derivatives, protein products, and synthetic resins. In general, except where noted, synthetic resins formed by condensation polymerization resins formed by addition polymerization are thermoplastic (heating soften and cooling hardens). These two polymerization reactions are fundamentally different.
Addition polymerization involves a series of conversions which produce a polymer having a recurring structural unit identical with that of the monomer from which it is formed. Condensation polymerization yields polymers whose recurring units lack certain atoms present in the original monomer. The reaction takes place by the combination of two or more units and the elimination of a small such as water, methanol or hydrogen chloride. During or after, the original polymerization, the long chains of polymer may react with each other to form a cross linked material which is usually harder and tougher than the straight chain polymer. Properties can be varied for special purpose by regulating the amount of cross linking.
Another variation in the type of final product is effected by the simultaneous polymerization of two or more types of monomers. By carefully regulating the relative amounts of the monomers and reaction conditions and initiators, the properties of the final polymer can be controlled. Three types of copolymers may be formed, depending upon conditions.
Random copolymer, M1 M2 M2 M1 M1 M1 M2
Alternating copolymer, M1 M2 M1 M2 M1 M2
Block copolymer, M1 M1 M1 M1 M2 M2 M2 M2
Properties of plastic can be change by reinforcement usually called as filler with various material, usually fibers of some sort. Common reinforcing fibers are cellulose fibers, fiberglass, carbon fiber, aramid fibers, and metal filaments.
Engineering plastic are high strength high performance materials that can be substituted for many metal uses. There are a wide variety of engineering plastics available. Each one has its own special properties. These material are often the usual plastics but have been carefully manufactured to process extra quality properties. These materials show better resistance to wear, impact and corrosive chemicals and have excellent electrical properties. Some of the uses are automobile bumpers and dashboards, pumps, valves, and gears, and driveshaft and transmission heavy-duty equipment. Many of the common resins are in use as engineering plastic such as acetal, fluoroplastics, nylon, polyphenylene oxide, polycarbonate, polyphenilene sulphide, polysulfone, polyesther-imide, polyethersulfone and nylon polyester block amides and several other copolymers.
The common names of plastics are usually the common or even the principal trade names and often are referred to by abbreviations.
Types of Resins and Plastics:
- Phenolic resins; Bakelite, Durez, Catalin, Formica, Indur
- Amino resins; Plaskon, Beetle, Cymel, Micarta, Melmac
- Alkyd resins; Glyptal, Rezyl, Becksol, Dulux
- Epoxy resins; Epon, Araldite, Ren, Epocast, Marblette
- Polyester (unsaturated) and allyl resins; Aropol, Atlac, Dapon
- Silicone resins; Pyrotex, Dow Corning
Thermosetting Resins; Cellulose Derivatives
- Cellulose nitrate; Celluloid, Pyralin, Nitron
- Cellulose acetate; Kodapa, Tenite, Plastacele
- Cellulose propionates; Forticel, Reed
- Cellulose acetate-butyrates; Tenite II, Kedapak II
- Ethyl cellulose; Ethocel, Soplasco, Campco
- Acrylate or polyacrylates; Plexiglass, Lucite, Acryloid
- Vynils; Vinylite, Gelva, Butacite, Kroseal, Alvar, PVA
- Polyvinylydenes; Saran
- Styrene; Styron, Lustrex, Laolin
- Polyamides; Nylon, Zytel, Kevlar, Nomex
- Polyethers; Penton, Calcon, Delrin
- Polyethylene; Polyethylene, Poly-Pro, Pro-fax
- Fluorocarbons; Kel-F, Teflon, Fluorosint
- Polyesters; Mylar, Celanex, Ekonol
- Polycarbonates; Lexan, Merlon
- Plysulfones; Udel, Astreel 360, Victrex, Radel