Polyamide-amorphous polyimide

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/... 

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... 

Materials The materials in this work includ< a lyotropic polyamide (PBTA) composed of terephthaloyl dichloride and 2,2 -dimethyI-4,4-diamino-biphenyl two amorphous polyimides respectively con sting of 3,3 4,4-benzophenone tetracarboxylic dianhydride (BTDA) and 2,3,5,6-tetrameth -p-phenylene diamine (TMPD), as well as 4,4 -(hexafluoroisopropylidene)>bis(phthalic anhydride) (6FDA) and 2,2-dimethyl-4,4-diamino-biphenyl (DMDB) and the block copolymers composed of PBTA and those two polyimides with various compositions. Ilie PBTA/PI block copolymers and the corresponding homopolymers were prepared according to our previous work(79). 

Cycloahphatic diamines react with dicarboxyUc acids or their chlorides, dianhydrides, diisocyanates and di- (or poly-)epoxides as comonomers to form high molecular weight polyamides, polyimides, polyureas, and epoxies. Polymer property dependence on diamine stmcture is greater in the linear amorphous thermoplastic polyamides and elastomeric polyureas than in the highly crosslinked thermo set epoxies (2—4). 

An empirical method for predicting the chemical compositions of random or partially ordered condensation copolymers which are capable of exhibiting mesophases (either in solution or in the melt) was devised by the author in 1989, while working on liquid crystal copolymer synthesis for BP Chemicals. A brief description of the method and its application to the chemical synthesis of amorphous thermotropic polyamides has been given in a previous paper [45] and a further more detailed description of the method is to be published shortly [46]. Subsequently, the method has been updated and applied to polycarbonates and polyimides. Thermotropic polyimides have also been synthesised by the author resulting from the use of the predictive method [43]. 

Polymer Specimens. The materials used in this work were polyimide (PI),polyamide-imide (PAl), polyether-ether-ketone (PEEK), polyphenylene sulfide (PPS) and polyether sulphone (PES). The chemical formulas and physical properties of the specimen polymers are summarized in Table I. The specimen polymers, except PPS, were unfilled while the PPS specimen was filled with glass fiber of Uo wt. %. PAI and PES are amorphous polymer with considerably high glass temperature. The polymers, except PI, can flow at hi temperatures and allow the use of injection molding. 

Polyamide-imides are thermoplastic amorphous polymers that possess exceptional mechanical, thermal, and chemical- and wear-resistant properties. They are inherently nonflammable, have outstanding electrical properties, and possess enormous temperature stability from cryogenic to 300°C. These properties place polyamide-imides at the top of the price and performance pyramid with polyketones and polyimides. 

Chang K Y and Lee Y D (1993) Molecular composite. 1. Novel block copolymers of liquid-crystaUine polyamide and amorphous polyamide/polyimide, J Polym Sci Part A Polym C iem 31 2775-2784. 

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]. 

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