Synthetic polymers refining

The Textile Eiber Product Identification Act (TEPIA) requires that the fiber content of textile articles be labeled (16). The Eederal Trade Commission estabhshed and periodically refines the generic fiber definitions. The current definition for a polyester fiber is "A manufactured fiber ia which the fiber-forming substance is any long-chain synthetic polymer composed of at least 85% by weight of an ester of a substituted aromatic carboxyUc acid, including but not restricted to terephthalate units, and para substituted hydroxyben2oate units."... 

The refinement (2) proceeded in the same way as for the x-ray work, except that o and S q were refined as additional variables. We assumed that the scattering was kinematic. The cross sectional dimensions of the microfibrils are 200xl0C)X and our previous work on synthetic polymer single crystals showed that the kinematic approximation was adequate for such small crystallites. Intensity measurement presented considerable difficulty in that multiple film exposures could not be obtained. Sequential exposures of the same area of the specimen led to problems of beam damage, and patterns from different areas were not comparable due to differences in the preferred orientation. As a result, only the 28 strongest non-meridional intensities could be measured. These were all for reflections which could be indexed by the Meyer and Misch unit cell, and thus the two chain unit cell was used for the refinement. 

Later reports [49-51] provided further insight into the blend morphology for several of the cellulose/synthetic polymer blend systems fisted in Table 1. In particular, refining efforts were devoted to precise quantification of the scale of homogeneity in the blends. A dielectric relaxation... 

Benzene and toluene, the simplest aromatic hydrocarbons obtained from petroleum refining, are useful starting materials for synthetic polymers. They are two components of the BTX mixture added to gasoline to boost octane ratings. 

X-ray diffraction techniques are the only way of determining the crystal structure of natural and synthetic polymers, although the x-ray data itself obtained from a crystalline polymeric fiber or film is not sufficient to allow complete refinement of the structure. Conformational analysis and electron diffraction represent complementary methods which will facilitate the determination of the structure. The necessary requirements for the x-ray approach are crystallinity and orientation. X-ray data cannot be Obtained from an amorphous sample which means that a noncrystalline polymeric material must be treated in order to induce or improve crystallinity. Some polymers, such as cellulose andchitin, are crystalline and oriented in the native state.(1 )... 

Resin, synthetic (synthetic polymer). A Resin that has been produced from simple materials, or intermediates made from such chemicals, by either addition or condensation polymerization. Of the commercial plastics, all but the cellulosics are based on synthetic resins. Among commercial elastomers, only natural rubber, or refined from the sap of the Hevea tree, is natural. 

Abstract Aromatic amines are widely used industrial chemicals as their major sources in the environment include several chemical industry sectors such as oil refining, synthetic polymers, dyes, adhesives, rubbers, perfume, pharmaceuticals, pesticides and explosives. They result also from diesel exhaust, combustion of wood chips and rubber and tobacco smoke. Some types of aromatic amines are generated... 

Chemical admixtures They are generally water-soluble, added mainly to control setting and early hardening of fiesh concrete, and to reduce water requirements. Chemical admixtures include accelerators, normal water reducers, superplasticizers, and retarders. The accelerators may contain calcium chloride, alkali hydroxide, calcium formate, calcium nitrate, etc. Examples of retarders are Na, Ca, or NH4 salts of lignosulfonic acids, hydroxy carboxylicacids,orderivativesofcarbohydrates.Normal water reducers may contain salts of refined lignosulfonic acids, hydroxycarboxylic acids, hydroxylated polymers, etc. Superplasticizers may contain sulfonated melamine formaldehyde, sulfonated naphthalene formaldehyde, car-boxylated synthetic polymers, etc. 

The theoretical and practical application of these studies in chemistry or physical chemistry are quite evident. It is also certain that the learning gained by study of synthetic polymers can contribute to the refinement of the techniques used to purify and study biopolymers and the interpretation of measurements through progress made in biophysical chemistry. But there is still more. 

The ultimate starting materials for synthetic polymers are few in number. Petroleum, natural gas, coal tar, and cellulose are the main sources. In recent years, ethylene and propylene from natural gas and petroleum refining have been used as a starting point for a variety of monomers as well as serving as key monomers. The process of building up polymers from simple repeating units (monomers) can proceed with many variations. We can classify some of these as follows ... 

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