ABSTRACT
Plastics are a very broad family of materials that are divided into two distinct groups. This chapter provides a brief history of the development of plastics and of plastic piping systems and discusses the specific materials that find their way into piping systems either through complete systems or components. For the more interested reader, there is an expanded discussion on the chemistry of plastics, with structure and key properties. The development of materials, key physical properties, molecular structure, and current status of products are also given. Whenever possible the ASTM references are given for material classification. Throughout this handbook the seven or eight major thermoplastics used for piping systems take center stage and usually have supporting data provided. Less frequently used materials have data provided if available. II. PLASTICS-A BRIEF HISTORY
John Wesley Hyatt is generally recognized as the original inventor of plastics in the United States with the introduction of what he called “Celluloid” in 1868, when he mixed pyroxylin (made from cotton) with nitric acid and camphor. The product was made in response to a competition sponsored by a manufacturer for a substitute for ivory for billiard balls. The product is still in use today under its chemical name cellulose nitrate. In 1909 Dr. Leo Hendrik Baekeland developed the next major plastic to be itroduced, which he called “Bakelite,” which was a phenolic compound (from phenolformaldehyde) used in telephone and automobile parts. This was the first plastic to gain worldwide acceptance. The third big thrust in plastics development happened in the 1920s with the introduction of cellulose acetate, urea formaldehyde, and polyvinyl chloride. Although vinyl resins were discovered as early as 1838, polyvinyl chloride did not become available commercially until nearly a century later. Between 1927 and 1933, Waldo Semon of the B. F. Goodrich Company worked on the plasticization of polyvinyl chloride to make the resin suitable for molding.Other researchers developed various plastics over the next several decades. 1
The German chemist Otto Rohm had experimented with acrylic resins as early as 1901. In 1931, the Rohm and Haas Company first manufactured acrylics, under the trade name Plexiglas, for use as safety glass. An American chemist, Wallace T. Carothers of the Du Pont Company, headed the group of researchers that discovered nylon in 1935. Nylon was introduced commercially in 1938 and has since found increasing uses as a fiber and a plastic. Today there are several different types and grades of nylon. In 1937, Otto Bayer of Germany conducted the original research that ultimately led to the production of polyurethanes, which were introduced commercially in 1954 [1].In 1938, Roy Plunkett of Du Pont was surprised to find a white powder in what had been in a cylinder of tetrafluoroethylene gas. This powder, polytetra-fluoroethylene (FITE), has become a very important plastic, better known by the Du Pont trade name Teflon. Full-scale commercial production of PTFE began in 1948. Commonly used in nonstick cookware, it also has many other applications. As early as the 19th century it was known that monomers of styrene, like monomers of vinyl chloride and acrylate, could be polymerized. Large-scale commercial production of polystyrene, however, did not begin until the late 1930s.From 1940 to 1950 many more important plastic resins were introduced commercially, including unsaturated polyester, low-density polyethylene (LDPE), fluorocarbons, cellulose propionate, epoxy resins, silicones, and acrylonitrile-butadiene-styrene (ABS). High-density polyethylene (HDPE) was first produced in 1957 by Karl Ziegler of West Germany. That same year, the Italian scientist Giulio Natta, using methods similar to those of Zeigler, was able to polymerize propylene and thereby produce polypropylene. From the 1950s to the 1970s, a number of engineering plastics were developed-plastics that because of their strength and durability are suitable for use in construction, machine parts, aerospace, chemical processing equipment, and other demanding uses. In the 1980s research focused on plastics alloys and blends and reinforced composite plastics. Alloys and blends are combinations of plastics created to improve plastic materials at lower costs. These engineering plastics include acrylonitrile-butadiene-styrene (ABS), polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyetheretherketone (PEEK). The importance of the engineering plastics grew in the 1980s, and newer ones such as liquid crystal polymers continued to be developed today [2]. III. PLASTIC PIPING DEVELOPMENT
While plastics have been around for well over a century, it was only in 1935 that they were first used as a piping material for commercial applications. Research for new products, driven for the most part by the Second World War, lead to the development of a number of new and useful plastic pipe materials such as
cellulose acetate butyrate (CAB), polyethylene (PE), and polyvinyl chloride (PVC). The war also helped spark increase use of plastic as a piping material in Europe and Japan since these products were used for much of the rebuilding of their cities after the destruction. In the 40 years since the war, more than 100 new plastic piping systems and joining methods have been introduced [3],As new products became available, the engineers’ and designers’ desire to use plastic pipe increased tremendously. Gradually, piping materials that had been used for centuries were being displaced by materials that had only been in existence a few years. Tin-lined copper has been replaced by polypropylene or PVC for pure water lines in hospitals, and acid waste systems use flame-retardant polypropylene instead of glass or high-silica iron. Most homes use ABS or PVC drain waste and vent pipes instead of cast iron. Traditional concrete drain culverts are now polyethylene. There are many reasons behind this change away from metal and more traditional piping materials. Among the many benefits of plastic pipe are its lower installed costs, improved operations, long-term cost saving over the life of a system, and improvement of corrosion resistance. Another reason for its rapid growth has been the abundant supply of products. Plastic manufacturers could react quickly and mold intricate, lower cost parts for a rapidly changing market. In today’s industrial market, plastics are being specified to satisfy everything from mundane dirty water lines, to some of the most demanding piping applications in the electronics, pharmaceutical, biotechnical, and chemical process industries (CPI). In fact, from a strictly chemical and temperature compatibility perspective, three out every four piping applications could be installed using plastic [4].
