Polyphenylene benzobisthiazole

As the laser beam can be focused to a small diameter, the Raman technique can be used to analyze materials as small as one micron in diameter. This technique has been often used with high performance fibers for composite applications in recent years. This technique is proven to be a powerful tool to probe the deformation behavior of high molecular polymer fibers (e.g. aramid and polyphenylene benzobisthiazole (PBT) fibers) at the molecular level (Robinson et al., 1986 Day et al., 1987). This work stems from the principle established earlier by Tuinstra and Koenig (1970) that the peak frequencies of the Raman-active bands of certain fibers are sensitive to the level of applied stress or strain. The rate of frequency shift is found to be proportional to the fiber modulus, which is a direct reflection of the high degree of stress experienced by the longitudinally oriented polymer chains in the stiff fibers. 

Polyphenylene benzobisthiazole (PBT, PBZ) n. A hquid-crystalline polymer from which very strong and heat-resistant fibers are made. 

In addition to these, several other categories are being developed. These include the vapor-phase (CVD) fibers which offer promise for the development of whiskers, and fibers based on other precursors, such as polyvinyl chlorides, Saran and polyphenylene benzobisthiazole.l These fibers are still experimental and have yet to reach the production stage. 

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