Vectra thermoplastics

These LCT materials have very high tensile and flexural strength, and excellent mechanical and chemical resistance properties. Some commercial LCT are Vectra (Hoechst-Celanese) and Xydar (Amoco). Du Pont, ICI, GE, and Dow Chemical are also suppHers. Their appHcation in electronic embedding is stiU. in its infancy because of the high temperature processing requirement. Nevertheless, this class of thermoplastic polymers will play an important role in electronic embedding. 

Injection molded thermoplastic bipolar plates made of Vectra LCP (liquid crystal polymer) and Fortron PPS fabricated by Ticona Engineering Polymers, (http //www.ticona.com/redesign/ index/markets/innovation/fuel cell.htm Ticona Engineering Polymers. 2008 accessed March 2008.)... 

Most of the work to date concerns the area with the greatest potential for commercial exploitation, the blending of LCPs with conventional polymers. While a few studies of solution blending with Kevlar do exist [57-61], most of the work has centered on melt blending thermotropic copolyesters (Vectra, Xydar) with engineering thermoplastics (PET, PC, PEI, etc.). For convenience, this work may be separated into three blend regions based on LCP content, namely ... 

Several liquid cryatalline polymers were melt blended with an amorphous (Ultem) and two semicrystalline (PEEK and PPS) engineering thermoplastics in a single screw extruder. Flat film was processed with different degrees of stretch imparted while the film was being cooled. In the case of Vectra, which was thought to be ideally suited to be blended with PPS based on thermal and rheological... 

Vectra LCPs consist of parallel, closely packed, fibrous chains in injection molded parts which give the polymer a wood-like appearance at fracture surfaces and also give it seU-reinforcing properties that are at least as good as those of conventional fiher-reinforced thermoplastics. ICI supphes LCPs (self-reinforcing polymers) under the trade name Victrex SRP. Excellent physical properties, low comhnstihility and smoke generation, resistance to chemicals and solvents, and stahihty towards radiation are some of the important properties of LCPs. 

In 1985, thermoplastic LCP was introduced by Mitsubishi Kasei (registered name Novaccurate), Unitika (Rodrun) and Polyplastics (Vectra) in Japan. 

Four thermoplastic polymers polypropylene (PP), polycarbonate (PC), poly(ethylaie terephthalate) (PET), and nylon-6 (NY), and four LCPs Vectra A-900 (VA), Vectra B-950 (VB), SBH 1 1 2 (SBH), and SBHN 1 1 3 5 (SBHN) were used. The source and some of the characteristics of the polymers, as well as the compositions of the LCPs, are shown in Table 1. 

Polymers are nsed in fnel cells. Those of particular interest are the polymer electrolyte membrane (PEM) and the phosphoric acid fuel cell (PAFC) designs. The latter design contains the liquid phosphoric acid in a Teflon bonded silicon carbide matrix. In March 2005 Ticona reported that it had bnilt the first fnel cell prototype made solely with engineering thermoplastics. They claimed that this approach rednced the cost of the fuel by at least 50% when compared with fuel cells fabricated from other materials. The 17-cell unit contains injection moulded bipolar plates of Vectra liquid crystal polymer and end plates of Fortron polyphenylene sulfide (PPS). These two materials remain dimensionally stable at temperatures up to 200 "C. The Vectra LCP bipolar plates contain 85% powdered carbon and are made in a cycle time of 30 seconds. 

Fig. 19.1 The plastics pyramid according to thermal literature data of common polymers preferred materials for HT-PEM applications are in the upper right region TPI thermoplastic polyimide, PES polyether sulfone, P P)SU poly(phenylene)sulfone, PE E)K polyether(ether) ketone, LCP liquid crystal polymer, e.g., Vectra, PPS polyphenylene sulfide, PTEE polytetrafluoroethylene.

Fig. 7.8 Comparison of high-performance thermoplastics PAI, polyamide-imide (30% glass fibre) PEEK, polyetheretherketone (30% glass fibre) PEI, polyetherimide (30% glass fibre) PES, polyethersulphone (30% glass fibre) PPS, polyphenylene sulphide (40% glass fibre) Vectra, A130 (30% glass fibre) Xydar, ECHO (40% glass fibre).

Vectra A900 TPE TPE = PBT-polytetramethyleneoxide thermoplastic elastomer high level of LCP fibrillation in extruded samples 633... 

The scientific-research and experimental work on fabrication of high-strength articles from a melt of LC polymers, particularly from a melt of thermotropic polyesters, has now apparently been completed. A new group of industrial self-reinforced thermoplastics (Excel, Xydar, Vectra, Ekonol based on p-hydroxybenzoic acid, hydroquinone, and terephthalic acid with 1,4-dioxydiphenyl and hydroxynaphthoic acid additives) has been created fix)m diem and successfully used in machine construction, in production of optical cables, electronics, and other areas of technology [60]. The Celanese Company (USA) is planning to produce LC polyesters industrially for use in plastic articles, fibers, and films with an output of 2200 tons/year with a subsequent increase in production to 4500 tons ear [61]. Japanese firms are also very interested in these polymers. 

As in the fabrication of the self-reinforcing thermoplastics Xydar, Vectra, etc., it is necessary to use difficultly available monomers for the formation of the... 

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