Poly bulk polymer production

A number of polymerization techniques are used in the transformation of monomers into plastics (Chapter 10). These include bulk, solution, suspension, and emulsion polymerization processes. Each of these polymerization techniques has its advantages and disadvantages and may be more appropriate for the production of certain types of polymer materials. For example, bulk polymerization is ideally suited for making pure polymer products, as in the manufacture of optical-grade poly(methyl methacrylate) or impact-resistant polystyrene, because of rninimal contamination of the product. On the other hand, solution polymerization finds ready application when the end use of the polymer requires a solution, as in certain adhesives and coating processes. 

Even though the hydrolysis eventually produces an acid, polymer erosion rate is controlled by hydrolysis of the ortho ester bonds. The subsequent hydrolysis of the ester bonds takes place at a much slower rate so that the neutral, low molecular weight reaction products can diffuse away from the bulk polymer before hydrolysis to an acid takes place. Thus, unlike the poly (ortho ester) system I, no autocatalysis is observed and it is not necessary to use basic excipients to neutralize the acidic hydrolysis product. 

Bulk polymer structural studies. These include studies on reactions between polyacrylic acid and polymethacrylic acid and polyacrylic acid with poly(4-vinyl pyridine) and poly(2-vinyl pyridene) [259], polybithiophene [260], polyvinyl carbazole sulfonation products [223], 3-hydroxybutyrate and 3-hydroxyvalerate containing Biopol [225]. 

Microalgal hydrocarbons are an example where molecular genetic improvements and transgenic expression can also be tested in the natural host or its close phylogenetic relatives (21). Each feedstock production and conversion system, whether based on plants, microbes, or chemistry, has its pros and cons, and there is no one universal platform for foreseeable future (22). Host-compound choices must therefore be taken on a case-by-case basis. Poly-B-hydroxyalkanoates as biodegradable polyesters are bacterial storage polymers and can be produced by fermentation on cheap starch hydrolysate with high volume and biomass yield (23). Nevertheless, commercialization of the compound as a bulk polymer so far has not been accomplished because the... 

Nanocomposite mixed-matrix membranes have been investigated for close to a decade. Ti02-poly(amide-imide) membranes showed selectivity improvement but suffered loss of productivity when TiOa was added. Nonporous, nanoscale, fumed silica was embedded in a glassy, amorphous polymer, poly(4-methyl-2-pentyne), which resulted in enhancements in both permeability and selectivity for the mixed-matrix membrane. These membranes were discovered to be reverse selective, so the membrane is selective for the larger penetrant. This phenomenon is attributed to increased free volume in the bulk polymer from chain packing disruption, which occurs when the filler is added. ... 

The free radical polymerization of vinylic monomers is one of the major processes for the industrial production of bulk polymers like polystyrene and poly(methyl methacrylate). 

Liquid polyalurninum chloride is acidic and corrosive to common metals. Suitable materials for constmction of storage and handling facilities include synthetic mbber-lined steel, corrosion resistant fiber glass reinforced plastics (FRP), ceramics, tetrafluoroethylene polymer (PTFE), poly(vinyhdene fluoride) (PVDF), polyethylene, polypropylene, and poly(vinyl chloride) (PVG). Suitable shipping containers include mbber-lined tank tmcks and rail cars for bulk shipment and plastic-lined or aH-plastic dmms and tote bins for smaller quantities. Except for aluminum chlorohydrates, PAG products are shipped as hazardous substances because of their acidity. 

Poly(vinyl chloride). Poly(vinyl chloride) (PVC) [9002-86-2] is a thermoplastic for building products. It is prepared by either the bulk or the suspension polymerization process. In each process residual monomer is removed because it is carcinogenic. Oxygen must be avoided throughout the process (see Vinyl polymers). 

Polymethacrylates. Poly(methyl methacrylate) [9011-14-7] is a thermoplastic. Itis the acryUc resin most used in building products, frequendy as a blend or copolymer with other materials to improve its properties. The monomer is polymerized either by bulk or suspension processes. Eor glazing material, its greatest use, only the bulk process is used. Sheets are prepared either by casting between glass plates or by extmsion of pellets through a sHt die. This second method is less expensive and more commonly used. Peroxide or azo initiators are used for the polymerization (see Methacrylic polymers). 

Poly(vinyl chloride-i o-vinyl acetate) [9003-22-9] has found appHcation in flooring, phonograph records, protective coatings, fibers, and some films and sheeting. Because of their low viscosity and good processabihty, such copolymers constitute the bulk of the vinyl tile market. The total production of PVC copolymers in 1989 was 113,500 t (73) (see Vinyl polymers). 

Phosphazene polymers are normally made in a two-step process. First, hexachlorocyclotriphosphazene [940-71 -6J, trimer (1), is polymerized in bulk to poly(dichlorophosphazene) [26085-02-9], chloropolymer (2). The chloropolymer is then dissolved and reprecipitated to remove unreacted trimer. After redissolving, nucleophilic substitution on (2) with alkyl or aryloxides provides the desired product (3). 

On the basis of bulk production (10), poly(ethylene terephthalate) manufacture is the most important ester producing process. This polymer is produced by either the direct esterification of terephthaHc acid and ethylene glycol, or by the transesterification of dimethyl terephthalate with ethylene glycol. In 1990, poly(ethylene terephthalate) manufacture exceeded 3.47 x 10 t/yr (see Polyesters). Dimethyl terephthalate is produced by the direct esterification of terephthaHc acid and methanol. 

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