Poly-p-phenylene-2,6-benzobisoxazole

PBO polymers, 13 377. See also Poly(p-phenylene benzobisoxazole) (PBO) applications of, 13 379 degradation of, 13 379 early syntheses of, 13 378 PB resin, properties of, 20 419t PbSe photoconductors, 19 157 PbS photoconductors, 19 157 PBT molding resins, 20 62-64. See also Poly(butyleneterephthalate) (PBT) PBT polymer... 

Polyphthalamides (PPA), 10 216-217 ASTM standards for, 19 793 Poly(p-phenylene) (PPP), 22 207t 23 717 conducting, 7 523, 527 molecular structure of, 22 211 optical band gap, 7 529t room temperature conductivity, 7 532 water-soluble, electroactive, self-doped sulfonatoalkoxy-substituted, 23 720 Poly(p-phenylene benzobisoxazole) (PBO), 19 714... 

TABLE 1. Poly(p-phenylene Benzobisoxazole-co-nanotube) Properties Prepared at 100°C Using a 1 1 Weight Ratio of Methanesulfonic Acid and Polyphosphoric Acid... 

Davies RJ, Eichhom SJ, Riekel C et al (2004) Crystal lattice deformation in single poly (p-phenylene benzobisoxazole) fibres. Polymer 45 7693-7704... 

TABLE 1. Effect of high temperature and humidity and light exposure on poly (p-phenylene-benzobisoxazole) film strength retention containing various dopants. 

In recent years, poly(p-phenylene benzobisoxazole) (PBO) fibers have become prominent in high strength applications such as body armor, ropes and cables, and recreational equipment. However, degradation of PBO fiber mechanical properties following exposure to moisture has been documented by the manufacturer (7) and at least one failure of PBO-based body armor in the field has occurred (2). The objectives of this study were to compare changes in mechanical and chemical properties of yams extracted from PBO-based body armor that was penetrated by a bullet in the field approximately 6 months after being deployed, with PBO-based body armor panels of the same model aged in the laboratory under elevated temperature and moisture conditions. 

Rodlike polyelectrolytes have been known for a long time. Biological polymers such as DNA [4-8] and xanthane [9-12], or colloidal systems like the ferredoxin virus [13, 14] and the tobacco mosaic virus (TMV) [15, 16], may be the most prominent examples. However, there were also publications on some synthetic rods in the early 1990s when we started our program. Poly(p-phenylene-benzobisoxazoles) and poly(p-phenylene-benzobisthia-zoles) may serve as examples [17-20]. Nevertheless, new rodlike polyelec-... 

The most important development in lyotropic liquid crystalline polymers after Kevlar is probably the synthesis of poly [benzo(l,2-d 4,5-d ) bisthiazole-2,6-diyl]-l,4-phenylene, or for short, poly(p-phenylene benzo-bisthiazole) ( PBT Wolfe and Loo, 1980 Wolfe et al., 1981), and the closely related poly [benzo(l,2-d 5,4-d )bisoxazole-2,6-diyl]-l,4-phenylene or poly(p-phenylene benzobisoxazole) ( PBO Helminiak and Arnold, 1977 Wolfe and Arnold, 1981). Both PBT and PBO are lyotropic liquid crystalline and can be spun into fibers with mechanical properties even superior to that of Kevlar fibers. The molecular structures of these polymers are shown in Figure 5.2. 

Rg. 12.18 Some examples of main-chain liquid-crystal polymers (a) poly(p-phenylene benzobisoxazole) (PBO), lyotropic (b) poly(4-carboxybenzene-propionic acid), thermotropic and (c) a thermotropic polymer with a long flexible decamethylene spacer. 

Bian, L., Xiao, J., Zeng, J., Xing, S., Yin, C., Jia, A. Effects of thermal treatment on the mechanical properties of poly(p-phenylene benzobisoxazole) fiber reinforced phenolic resin composite materials. Mater. Des. 230-235. Elsevier, Amsterdam (2014)... 

There are several other aromatic polymers, not polyamides, but which form fibers with high chain rigidity and similar properties. These would include poly(p-phenylene benzobisthiazole) (PBT) and poly(p-phenylene benzobisoxazole) (PBO) (Ref 4, Chapt. VII) ... 

Zhou G J, Wang S F, Zhang Y, Zhuang Q X and Han Z W (2008) In situ preparation and continuous fiber spinning of poly(p-phenylene benzobisoxazole) composites with oligo-hydroxy-amide-functionalized multi-walled carbon nanotubes, Polymer 49 2520-2530. 

It was also demonstrated that poly(p-phenylene benzobisoxazole) (PBO) fibers displayed improved interfacial adhesion in PBO-BMl composites when dielectric barrier discharge (DBD) plasma was nsed to modify them (Liu et al. 2014) the overall effect on the composites properties strongly depended on the degree of ablation. 

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