Polymer microcrystalline polymers

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. 

Molecules of low molecular weight (e.g., drugs) are likely to adsorb to polymers present in the formulation. Adsorption occurs by the formation of weak (localized) interactions, hydrogen bonds, or ionic bonds between molecules and polymers. Microcrystalline cellulose, which is an important pharmaceutical excipient, has been demonstrated to influence chemical and photochemical reaction mechanisms of adsorbed compounds (Wilkinson et al., 1991). Interactions between drugs and polymeric compounds and the subsequent influence on photoreactivity are further discussed in Chapter 15. 

Mekon White. [Petrolite/Polymers] Microcrystalline wax release agent lubricant processing aid, binder, plasticizer, antiozonant fa coatings, adhesives, inks, plastic modificadon, lacquers, paints, varnishes, ceramics, for potting/filling in elecVdectronic components, rubber, wax size. 

Figure 1. Representation of a noncovalent network of random coils crosslinked by interchain association (a) or by microcrystalline domains (b) non-covalent network of rod-like polymers or polymer aggregates whose "crosslinking" is a manifestation of a brush-pile of rods (c) or fibers (aggregates of aligned rods) (d), or a result of non-nucleated phase separation kinetics (e).

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. 

Figure 10.3 Typical DSC thermograms exhibiting multiple thermal transitions in TPU. (1) Multiple thermal transitions in an unannealed specimen, in which endotherm I represents the disordering of short-range order, endotherm II represents the disordering of long-range order, and endotherm III represents the fusion of microcrystalline phase. (2) Thermal transition in a specimen that was annealed at 130 °C. (3) Thermal transition in a specimen that was annealed at 150 °C for a long period. (Reprinted from Seymour and Cooper, Journal of Polymer Science, Polymer Letter Edition 9 689.

N. Huu-Phuoc, H. Nam-Tran, M. Buchmann and U. W. Kessehing. Experimentally optimized determination of the partial and total cohesion parameters of an insoluble polymer (microcrystalline cellulose) by gas-solid chromatography. Int. J. Pharm. 34,1987, 217. 

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... 

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