Polyimide-liquid-crystalline polyamide

Acid anhydrides, 391 Amino hydrochloride water solutions, lyotropic phases, 306-308,310/ Amorphous polyimide-liquid-crystalline polyamide composites. See Liquid-crystalline polyamide-amorphous polyimide composites Amphiphilic liquid crystal(s), establishment, 235,236/... 

Thechemical structures [43] ofthermotropicpolyimideandpolyamideLCP s are described in Chapter 3, along with their crystallization kinetic studies. Kircheldorf et al. [44] carried out XEiD and PLM characterization studies of these TLCPs and found the polyimide to be a smectic liquid crystalline. Pramoda et al. [45] studied the thermal degradation kinetics of TLC-PI (thermotropic liquid crystalline polyimide) and TLC-PA (thermotropic liquid crystalline polyamide). The apparent activation energy in the case of TLC-PI is found to be higher than the TLC-PA for degradation. 

Molecular Composites of Liquid-Crystalline Polyamides and Amorphous Polyimides... 

In this article, the synthesis, characterization, rheology, solution processing, and mechanical properties of novel molecular composites are discussed. These molecular composite are block copolymers composed of a liquid-crystalline polyamide and two amorphous polyimides. Also, the rheological properties of both isotorpic and anisotropic solutions of PBTA homopolymers and PBTA/PI block copolymers are... 

Whang and Wu [3] have described the liquid crystalline state of polyimide precursors and shown that certain polyamic acids derived from pyromellitic anhydride exhibit lyotropic behaviour. Liquid crystal phases have also been observed by Wenzel et al. [4] in polyimides derived from pyromellitic anhydride and 2,5-di-n-alkoxy-1,4-phenyl ene diisocyanate. Dezern [5] has disclosed a synthesis for linear polyamide-imides derived from benzophenone dianhydride but the occurrence or otherwise of mesophases is not mentioned. 

Polymeric nanocomposites are a class of relatively new materials with ample potential applications. Products with commercial applications appeared during the last decade [1], and much industrial and academic interest has been created. Reports on the manufacture of nanocomposites include those made with polyamides [2-5], polyolefins [6-9], polystyrene (PS) and PS copolymers [10, 11], ethylene vinyl alcohol [12-15], acrylics [16-18], polyesters [19, 20], polycarbonate [21, 22], liquid crystalline polymers [8, 23-25], fluoropolymers [26-28], thermoset resins [29-31], polyurethanes [32-37], ethylene-propylene oxide [38], vinyl carbazole [39, 40], polydiacethylene [41], and polyimides (Pis) [42], among others. 

By laminating conventional polyethylene and polypropylene microporous membranes together, it is possible to obtain a separator with the desired shutdown function together with protection from rupture. Microporous membrane of liquid crystalline polyester, polyphenylene ether, aromatic polyamide, polyimide, polyamide imide resin, acrylic resin, and cross-linked polymer are now being studied as candidates for lamination with polyethylene in order to gain even greater heat resistance. 

It is significant that the reinforcement degree corresponds to a class of polymer forming a nanocomposites matrix. The largest values of / are obtained for polymers whose chains are able to stretch on the silicate platelet surface (rigid-chain polyimide, crystallising polypropylene and thermotropic liquid crystalline polyester), intermediate values for polymers whose chains are able to stretch only partly (polycarbonate, poly (butylenes terephthalate) and amorphous polyamide-6) and the smallest values for nanocomposites on the basis of epoxy polymer, the capability of chains stretching of which decreases sharply because of the availability of transverse covalent bonds network [30]. 

---