Polymer microcrystalline

Battiste, O.A. Microcrystalline Polymer Science McGraw-Hill London, 1975. 

In order to understand special features of additives effect on microcrystalline polymer structure it is necessary to pay attention to features of the structure of PETP - polymer blocks. 

As mentioned earlier, poly[bis(trifluoroethoxy)phosphazene] is a fiber-forming, microcrystalline polymer that can be fabricated into microfibers by solution extrusion from THF into a nonsolvent such as heptane. Alternatively, it can be electrospun to nanofibers from a solution in THF. The structure-property relationships for this polymer are fairly well understood, and these provide a basis for expanding the understanding to polymers with other side groups. 

A. Battista, Microcrystalline Polymer science, pp. 208, McGraw-Hill, New York. (1975). 

Cheimg DL, McMahon DP, Troisi A (2009) A realistic description of the charge carrier wave function in microcrystalline polymer semieonductors. J Am Chem Soc 131 11179... 

The polymeric alloys described in section 4.3.1 were principally investigated for use in waveguide applications, and so, to avoid optical losses, concentrations that did not give crystalline precipitates in the polymer were used. Through-plane optics can, however, tolerate poorer optical quality samples, and so microcrystalline polymer samples have been investigated for these applications. 

Polymers are difficult to model due to the large size of microcrystalline domains and the difficulties of simulating nonequilibrium systems. One approach to handling such systems is the use of mesoscale techniques as described in Chapter 35. This has been a successful approach to predicting the formation and structure of microscopic crystalline and amorphous regions. 

Applications. Among the P—O- and P—N-substituted polymers, the fluoroalkoxy- and aryloxy-substituted polymers have so far shown the greatest commercial promise (14—16). Both poly[bis(2,2,2-trifluoroethoxy)phosphazene] [27290-40-0] and poly(diphenoxyphosphazene) [28212-48-8] are microcrystalline, thermoplastic polymers. However, when the substituent symmetry is dismpted with a randomly placed second substituent of different length, the polymers become amorphous and serve as good elastomers. Following initial development of the fluorophosphazene elastomers by the Firestone Tire and Rubber Co., both the fluoroalkoxy (EYPEL-F) and aryloxy (EYPEL-A) elastomers were manufactured by the Ethyl Corp. in the United States from the mid-1980s until 1993 (see ELASTOLffiRS,SYNTHETic-PHOSPHAZENEs). 

UF suspensions comprise a family of Hquid products in which the UF reaction products are present as a microcrystalline dispersion of longer-chain UF polymers (CWIN) in a water solution of urea and water-soluble UF compounds. Typically, these products contain about 25% of the total nitrogen as CWIN. 

Mascaramatic mascaras have the largest share of the market. Emulsion mascaramatics are cream-type mascaras dispensed from containers that include a closure provided with a wand ending in a small bmsh. In solvent mascaramatics, mascara masses are pigment suspensions in thickened hydrocarbon solvents such as isoparaffins and petroleum distillates. The thickeners include waxes (microcrystalline [63231 -60-7] camauba [8015-86-9] or ouricury [68917-70-4], polymers (hydrogenated polyisobutene [61693-08-1]), and esters (propylene glycol distearate [6182-11-2] or trilaurin [538-24-9]). 

For suspensions primarily stabilized by a polymeric material, it is important to carefully consider the optimal pH value of the product since certain polymer properties, especially the rheological behavior, can strongly depend on the pH of the system. For example, the viscosity of hydrophilic colloids, such as xanthan gums and colloidal microcrystalline cellulose, is known to be somewhat pH- dependent. Most disperse systems are stable over a pH range of 4-10 but may flocculate under extreme pH conditions. Therefore, each dispersion should be examined for pH stability over an adequate storage period. Any... 

Some tablets combine sustained-release and rapid disintegration characteristics. Products such as K-Dur (Key Pharmaceuticals) combine coated potassium chloride crystals in a rapidly releasing tablet. In this particular instance, the crystals are coated with ethylcellulose, a water-insoluble polymer, and are then incorporated into a rapidly disintegrating microcrystalline cellulose (MCC) matrix. The purpose of this tablet is to minimize GI ulceration, commonly encountered by patients treated with potassium chloride. This simple but elegant formulation is an example of a solid dosage form strategy used to achieve clinical goals. 

An aqueous base is the least expensive vehicle and poses no toxicity problems. A solution of the drug in water or water and cosolvent is made. Glycerin, glycols, natural and synthetic gums, and/or polymers are used to increase viscosity, cohesiveness, and plasticity. To overcome syneresis, or water separation in the gel, a common problem with aqueous bases, one can use absorbing materials such as microcrystalline cellulose, kaolin, colloidal silicon dioxide, starch, etc. 

Microcrystalline, fllm-and fiber-forming polymer stable to water, hydro-phobic)... 

Chromatographic resolution is also dependent on column efficiency (i). Column efficiency is directly dependent on the nature of the support matrix and how well that support is packed in its column. Available chromatographic supports are based on dextran, agarose, polystyrene, acrylic, cellulose, silica gel and a variety of other polymers. Althou cellulosic supports are manufactured in both microcrystalline and leaded forms, most supports are beaded. Newer supports may use hybrid bead construction where the base support is coated with a second materid (e.g., dextran or silica coated with agarose). 

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