Natural plastic polyamide

Oxidized castor oils are excellent nonmigrating, nonvolatile plasticizers (qv) for ceUulosic resins, poly(vinyl butyral), polyamides, shellac, and natural and synthetic mbber (see Rubber, natural). The high viscosity products are also used as tackifiers in gasket compounds and adhesives (qv) because of good oil and solvent resistance. They also serve as excellent pigment grinding media and as a base for inks (qv), lubricating oils, and hydrauHc oils (62). 

The thermoplastic or thermoset nature of the resin in the colorant—resin matrix is also important. For thermoplastics, the polymerisation reaction is completed, the materials are processed at or close to their melting points, and scrap may be reground and remolded, eg, polyethylene, propjiene, poly(vinyl chloride), acetal resins (qv), acryhcs, ABS, nylons, ceUulosics, and polystyrene (see Olefin polymers Vinyl polymers Acrylic ester polymers Polyamides Cellulose ESTERS Styrene polymers). In the case of thermoset resins, the chemical reaction is only partially complete when the colorants are added and is concluded when the resin is molded. The result is a nonmeltable cross-linked resin that caimot be reworked, eg, epoxy resins (qv), urea—formaldehyde, melamine—formaldehyde, phenoHcs, and thermoset polyesters (qv) (see Amino resins and plastics Phenolic resins). 

Plastics, in the modem meaning, are synthetic materials capable of being molded. The Greek word plastikos means to form. Natural products, while plastic, are usually excluded. Resins may be natural or synthetic. The distinction between plastics and resins is arbitrary - many synthetic materials are both. Historically, the term resin was applied to synthetic substitutes for the natural product plastic was applied to compositions involving molding in their fabrication. Cuslomarily, the fiber industry is considered to be distinct from the plastics industry, although it uses the same ra v materials - polyamides (nylon), cellulose, and cellulose acetate. 

The use of oleochemicals in polymers has a long tradition. One can differentiate between the use as polymer materials, such as linseed oil and soybean oil as drying oils, polymer stabilizers and additives, such as epoxidized soybean oil as plasticizer, and building blocks for polymers, such as dicarboxylic acids for polyesters or polyamides (Table 4.2) [7]. Considering the total market for polymers of ca. 150 million tonnes in 1997 the share of oleochemical based products is relatively small - or, in other terms, the potential for these products is very high. Without doubt there is still a trend in the use of naturally derived materials for polymer applications, especially in niche markets. As an example, the demand for linseed oil for the production of linoleum has increased from 10000 tonnes in 1975 to 50 000 tonnes in 1998 (coming from 120000 tonnes in 1960 ) [8a]. Epoxidized soybean oil (ESO) as a plastic additive has a relatively stable market of ca. 100000 tonnes year-1 [8b]. 

Plasticizers are used in combination with cellulosics, vinyls, acrylic, and styrene resins, as well as polyvinylacetate, polyamides, polycarbonate, and other synthetic and natural resins. Because PVC consumes about 70% of all plasticizers produced, the plasticizer market is closely related to the vinyl resins production. During the last ten years, the vinyl market grew at an average rate of 18% per year and has reached 1.6 billion pounds in 1964. The growth in vinyl resins and plasticizer production was paralleled by a drop in resin price and a shift towards more effective and less expensive plasticizers. 

The above equations illustrate via the double arrows an important facet of polyamides—the equilibrium nature of the polymerization reactions. Achieving and maintaining useful molecular weights (about 10,000 or more) for plastics applications require low moisture contents in order... 

Presently, the sebacic acid synthesis is carried out industrially only in the USSR (capacity about 2000 tonnes/year). Fairly large amounts are produced from castor oil, a naturally renewable raw material. The capital costs for large plants are indeed considerable. Sebacic acid is used, for example, as a component in polyamides. Seba-cates are used as special plasticizers and synthetic lubricants. 

Polyamide (nylon) Acetone, methyl ethyl ketone 1. Abrasion. Grit or vapor blast or abrade with 100-grit emery cloth followed by solvent degreasing. 2. Prime with a spreading dough based on the type of rubber to be bonded in an admixture with isocyanate. 3. Prime with resorcinol formaldehyde adhesives. Sand or steel shot is suitable abrasive Suitable for bonding polyamide textiles to natural and synthetic rubbers Good adhesion to primer coat with epoxy adhesives in metal-to-plastic joints... 

The development of plastics also reflects economic history. Restrictions on imported latex, wool, silk and other natural materials to Europe during the Second World War resulted in the rapid development of alternative synthetic plastics. Table 1 shows that between 1935 and 1945, many new polymers were introduced including polyethylene, polyamides, poly(methyl methacrylate), polyurethanes, poly(vinyl chloride) (PVC), silicones, epoxies, polytetrafluoro-ethylene and polystyrene. Polyethylene was incorporated into radar systems while PVC replaced the limited stocks of natural rubber as cable insulation. 

Despite its origin form the nature, PLA s good stiffness and strength has enabled it to compete with other existing chemically based commodity plastics. Previous study on the mechanical properties of neat PLA by Jacobsen et al. [1] showed that PLA has great potential to be a substitute polymer for petroleum based plastics. The respective values of mechanical properties of PLA [2] with comparison of other petroleum based plastics e.g. polypropylene (PP) [3], polystyrene (PS) [4], high density polyethylene (HOPE) [5], polyamide (PA6) [6] shown in Fig. 11.2. 

In this long list of different compounds used in plasticization of polyamide, the great majority is used for either experimental or specific purposes. N-butylbenzenesulfonamide and 2-ethylhexyl-4-hydroxybenzoate are the two plasticizers of various polyamides in most commercial applications. Due to the nature of the polymers, plasticizers are most usually polar compounds. 

A large mrmber of polymeric materials are involved in a web coating. These include poly-virtylchloride, polyurethanes (thermoplastic and thermoset solvent-based and water-based), natural, nitrile, chloroprene, and ethylene-propylene rabbers, silicones, polyethylene (chlorinated and chlorositifonated), polyamide, polyester, acrylic resins, polyvinylal-cohol, polytetrafluroethylene, and ethylene-vinyl acetate copolymer as the main matrix polymers of coating compositions. Most of these polymers are not plasticized or seldom... 

In order to maximize pipe performance, the plasticization is not frequently used unless required by a brittle nature of polymer (e.g., polyamide). Formulation in the next section shows that the most popular pipes are used without a plasticizer. 

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