Poly rigid polymer

Uses. Phthabc anhydride is used mainly in plasticizers, unsaturated polyesters, and alkyd resins (qv). PhthaUc plasticizers consume 54% of the phthahc anhydride in the United States (33). The plasticizers (qv) are used mainly with poly(vinyl chloride) to produce flexible sheet such as wallpaper and upholstery fabric from normally rigid polymers. The plasticizers are of two types diesters of the same monohydric alcohol such as dibutyl phthalate, or mixed esters of two monohydric alcohols. The largest-volume plasticizer is di(2-ethylhexyl) phthalate [117-81-7] which is known commercially as dioctyl phthalate (DOP) and is the base to which other plasticizers are compared. The important phthahc acid esters and thek physical properties are Hsted in Table 12. The demand for phthahc acid in plasticizers is naturally tied to the growth of the flexible poly(vinyl chloride) market which is large and has been growing steadily. 

At constant PBT/PTMO composition, when the molar mass of PTMO block is >2000, partial crystallization of the polyether phase leads to copolymer stiffening. The properties of polyesterether TPEs are not dramatically different when PTMO is replaced by polyethers such as poly(oxyethylene) (PEO) or poly(oxypropylene). PEO-based TPEs present higher hydrophilicity, which may be of interest for some applications such as waterproof breathable membranes but which also results in much lower hydrolysis resistance. Changing PBT into a more rigid polymer by using 2,6-naphthalene dicarboxylic acid instead of terephthalic acid results in compounds that exhibit excellent general properties but poorer low-temperature stiffening characteristics. 

In order to determine the necessity and/or the length of the spacer that is required to achieve liquid crystalline behavior from flexible vs. rigid polymers, we have introduced mesogenic units to the backbones of a rigid [poly(2,6-dimethyl-l,4-phenylene oxide) (PPO)] and a flexible [poly(epichlorohydrin) (PECH)] polymer through spacers of from 0 to 10 methylene groups via polymer analogous reactions. 

These poly(isocyanide) polymers form rigid, rodlike helices on the surface of water, which can be easily transferred to a solid substrate by means of the LB method. The resulting films have a Coo symmetry. 

The synthesis of well-defined LCB polymers have progressed considerably beyond the original star polymers prepared by anionic polymerization between 1970 and 1980. Characterization of these new polymers has often been limited to NMR and SEC analysis. The physical properties of these polymers in dilute solution and in the bulk merit attention, especially in the case of completely new architectures such as the dendritic polymers. Many other branched polymers have been prepared, e.g. rigid polymers like nylon [123], polyimide [124] poly(aspartite) [125] and branched poly(thiophene) [126], There seems to be ample room for further development via the use of dendrimers and hyperbran-... 

Glassy polymers with much higher glass transition temperatures and more rigid polymer chains than rubbery polymers have been extensively used as the continuous polymer matrices in the zeolite/polymer mixed-matrix membranes. Typical glassy polymers in the mixed-matrix membranes include cellulose acetate, polysul-fone, polyethersulfone, polyimides, polyetherimides, polyvinyl alcohol, Nafion , poly(4-methyl-2-pentyne), etc. 

Fibers and films obtained from lyotropic solutions of rigid polymers exhibit high tensile modulus and strength and are therefore of interest for structural applications. Poly(p-phenylene benzobisthiazole) (PBT) is a rigid polymer from which high... 

Solutions of rigid polymer molecules (e.g., poly-/)-phenylene terephthalate) may also exhibit extrudate swelling because they too are entropy elastic, molecules exit the capillary in a fairly oriented state and become randomly oriented downstream. 

The moduli of polymers cover a wider range than those of other materials (from 105 N/m2 for rubber to 1010 N/m2 = 10 GPa for rigid polymers), which is one of the reasons why polymers are so versatile in application. Absolute stiffness and strength of polymers are much lower than those of metals, but on the basis of equal weight polymers compare favourably due to their much lower density. The specific moduli, defined as the moduli divided by the density, of isotropic polymers are of the order of one tenth of those of the stronger metals. The hyper-strong and hyper-stiff polymeric fibres such as fully extended polyethylene, stretched poly-(p-phenylene terephthalic amide) and carbon,... 

One of the semi-rigid polymer fibres, which is now produced on a big scale is Poly (p-Phenylene Terephtal Amide) we shall discuss this product in some more detail. 

Thus, at a gradient strength of 300mT/m, this corresponds to a maximum theoretical spatial resolution of approximately 0.36 mm for a rigid polymer such as poly(methyl methacrylate) (PMMA) exhibiting a T2 of 16 ps. 

The imaging performance of the CW-NMRI system can be demonstrated by showing 2- and 3-D images of a rigid polymer such as poly (methyl methacrylate) (PMMA) (Perspex/Plexiglas). Spectroscopic investigations carried out on this... 

According to Thomas elastic polymers often produce open-cell foamed plastics, whereas rigid polymers generally form closed-cell materials. However, there are many exceptions to this rule, owing to the variety of blowing techniques. Closed-cell structures are more likely to be produced from polyurethanes, epoxy resins, silicones, poly(vinyl chloride), polystyrene, etc., whereas open-cell materials mainly result from phenolic and carbamide foamed plastics. 

Polymeric substrate materials in use include highly filled phenolic and epoxy resins for rigid printed circuit boards, polyimides and polyesters for circuit substrates as well as for more general applications, special foamed poly(tetrafluoroethylene) polymers and copolymers, foamed composite materials of the latter, special epoxy fiberglass composites, and polyimide support layers for TAB. In addition, epoxies and silicone polymers are used increasingly in applications as encapsulants, as humidity and environmental barriers within packages, and as packaging materials themselves. 

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