Synthetic plastic families

During the next four years many additional new polymers were synthesized. Most proved of little commercial value, but the list includes three of the top-ranked popular plastic families - the polyvinyls used for phonograph records and floor tiles polyacrylics (such as Lucite) used in paints, airplane windows and buna N and buna S, two versions of synthetic rubber. Thus few households are not affected by even his early contributions. 

Phenol-Formaldehyde. Phenolic plastics were the first commercial synthetic plastics in 1908, and were the leading commodity plastic for 40 years, until the growth of vinyl and styrenic thermoplastics (Table 15.15). Now quite mature, they remain the second largest family of thermoset plastics. 

Chloroprene rubber (CR) is perhaps the most natural rubberlike of all synthetic plastics or elastomers, particularly with regard to its dynamic response. CRs are a family of elastomers with a property profile that approaches that of natural rubber (NR) but that has better resistance to oils, ozone, oxidation, flame, aging, and heat. CRs are about 25% heavier than NR and do not have the low temperature flexibiUty of NRs. See dynamic elongation polychloroprene rubber/elastomer rabber. 

Phenols Formaldehyde. Phenol-formaldehyde resins were the first commercial synthetic plastics. Since their invention in 1908, they have grown and matured into the second most important family of thermoset plastics, with a U.S. market volume of 4 bU-hon Ib/yr (see Table 3.6). 

Biodegradable plastics can be categorized in a number of ways. They can be divided into synthetic plastics and natural plastics, into biobased and nonbiobased plastics, or by polymer family. The reported chemical compositions of various biodegradable plastics, as compiled from various sources, are shown in Table... 

Poly(3-hydroxyalkanoates) (PHAs) are a family of polyesters accumulated as inclusion bodies (Fig. 1) by a wide variety of bacteria. They are water-insoluble, relatively resistant to aqueous hydrolysis but are readily biodegraded in any natural environment where microbial diversity exists. They can be produced from renewable resources and waste materials and, although temperature-sensitive, are potentially recyclable. Many PHAs have mechanical properties similar to those of common synthetic plastics. 

Other materials were gradually introduced. The first of the totally synthetic plastics was the family of phenol-formaldehyde resins discovered initially in 1907 by Baekeland (i.e., Bakelite). Other modified natural polymers (rayon, cellulose acetate) were introduced by the 1920s. 

Cellulosic is a family name that applies to a wide group of thermoplastics. They are not synthetic plastics but rather are made from a natui y occurring polymer, cellulose, which is obtained from wood pulp and cotton linters. Cellulose can be made into a film as cellophane or a fiber, rayon, but it must be chemically modified to produce TPs. Because it can be compounded with many different plasticizers in widely varying concentrations, its property range is broad. These plastics are normally specified by their flow, according to ASTM D 569, which is controlled by the plasticizer content. Cellulosics are all processed by conventional TP methods. They include the following types. 

Acrylic Rubber n (AR) A synthetic rubber made at least partly from acrylonitrile, or from ethyl acrylate copolymerized with many of the monomers or block polymers of the synthetic-rubber family (Harper CA (ed) (2002) Handbook of plastics, elastomers and composites, 4th edn. McGraw-Hill, New York). 

Commodity Phthalate Esters. The family of phthalate esters are by far the most abundandy produced woddwide. Both orthophthaUc and terephthahc acid and anhydrides are manufactured. The plasticizer esters are produced from these materials by reaction with an appropriate alcohol (eq. 1) terephthalate esterification for plasticizers is performed more abundandy in the United States. Phthalate esters are manufactured from methanol (C ) up to Qyj alcohols, although phthalate use as PVC plasticizers is generally in the range to The lower molecular weight phthalates find use in nitrocellulose the higher phthalates as synthetic lubricants for the automotive industries. 

It is usual to think that plastics are a relatively recent development but in fact, as part of the larger family called polymers, they are a basic ingredient of animal and plant life. Polymers are different from metals in the sense that their structure consists of very long chain-like molecules. Natural materials such as silk, shellac, bitumen, rubber and cellulose have this type of structure. However, it was not until the 19th century that attempts were made to develop a synthetic... 

There are three principal families of styrene containing polymers, which are used to make commercial plastic products. The first family is pure polystyrene, the second family comprises random copolymers, and the final family consists of polystyrene chains grafted to blocks of rubbery polymers. There are also synthetic rubbers that contain significant concentrations of styrene, but these are outside the scope of this book. 

In nature, starch is based on crystalline beads of about 15-100 microns in diameter. Crystalline starch beads in plastics can be used as fillers or can be transformed into thermoplastic starch, which can either be processed alone or in combination with specific synthetic polymers. To make starch thermoplastic, its crystalline structure has to be destroyed by pressure, heat, mechanical work or use of plasticisers. Three main families of starch polymer can be used pure starch, modified starch and fermented starch polymers. 

Alkyd resins have been the workhorse for the coatings industry over the last half century. The term alkyd was coined to define the reaction product of polyhydric alcohols and polybasic acids, in other words, polyesters. However, its definition has been narrowed to include only those polyesters containing monobasic acids, usually long-chain fatty acids. Thus thermoplastic polyesters typified by polyethylene terephthalate (PET) used in synthetic fibers, films, and plastics and unsaturated polyesters typified by the condensation product of glycols and unsaturated dibasic acids (which are widely used in conjunction with vinylic monomers in making sheet molding compounds or other thermosetting molded plastics) are not considered as part of the alkyd family and are beyond the scope of the present discussion. 

A good reason to look at history is to select those parts we should like to repeat. One part of science history that both polymer chemists and businessmen would surely like to see emulated is the unprecedented, explosive burst of creativity, invention, and successful development that occurred in the 1950s and gave the world a new class of polymers (stereoregular), a family of new plastics (linear and stereoregular polyolefins), a family of new synthetic rubbers, including the first duplication of a natural high polymer... 

A different approach was used by the Ferruzy Company, the main difference being the use of high boiling-point plasticizer instead of water for the destructuration of starch. In this technology, starch was plasticized together with polymers such as polyethylene-vinyl alcohol (EVOH), EAA, poly-e-caprolactone, with small amounts of moisture, in a twin-screw extruder [49], to produce an intimate mixture between starch and the synthetic polymer. The commercial trade name of this product family is Mater-Bi . 

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