Polyvinyl alcohol fiber

In the cavernous halls of the Shanghai Industrial Exhibition, one can see a cornucopia of consumer goods (clothes of polyester, polyacrylic, and polyvinyl alcohol fiber shoes and sandals of polyvinyl chloride suitcases and television set frames of acrylonitrile-butadiene-styrene plastic toys and containers of polyethylene, and many other plastic products (China produced approximately 800,000 tons of plastics in 1980) of convenience we take for granted in the West) that the Chinese government will try to deliver, in quantity, to its citizens in the years to come. 

Sakurada, I., T. Okasa, Hatakeyama, and F. Kimura. Radiation-induced graft copolymerization onto cellulose and polyvinyl alcohol fibers with binary mixtures of comonomers. J. Polymer Sci. C 4, 1233 (1964). 

I. Sakurada, Polyvinyl Alcohol Fibers. Marcel Dekker, New York, 1985. 

Similar results are obtained in the radiation-induced graft copolymerization of butadiene-acrylonitrile and styrene-acrylonitrile onto polyvinyl alcohol fibers (22). 

Shrinkage of Heat-Treated Polyvinyl Alcohol Fibers in Water of Varying Temperatures... 

Polyvinyl alcohol fiber was spun from an aqueous solution by a eonventional method with moderate drawing and air-drying at room temperature, and, thereby, a starting fiber for a series of fibers with different degrees of crystallinity was obtained. Crystallinity was changed. 

FIGURE 4.13 Outline of the regular process for wet-spinning of polyvinyl alcohol fiber. 

FIGURE 4.14 Flow sheet of the regular process for wet-spinning of polyvinyl alcohol fiber. 1. vertical machine 2. coagulation bath 3. bath heater 4. evaporator 5. godet rollers 6. take-up rollers 7. hot second bath 8. driers 9. drawing 10. heat treatments 11. winder. 

FIGURE 4.15 Microphotogaraph of a typical cross section of polyvinyl alcohol fiber obtained by the regular process of wet-spinning with a sodium sulfate coagulation bath. 

FIGURE 4.17 Relation between tenacity ratio and draw ratio of polyvinyl alcohol fibers drawn by various methods. (From Osugi, T., Tanabe, T., Suda, T., Morimoto, T., and Miyazaki, S., Sen-i Gakkaishi, 16, 155, 1960. With permission.)... 

In experiments on the rate of crystallinity [113], the heat treatment was carried out with an apparatus similar to that used in the industry. Polyvinyl alcohol fiber was subjected to heat treatment at 235°C for various lengths of time, and crystallinity increase was followed by x-ray diffractometry the results are shown in Figure 4.18. It can be seen that crystallinity increases very rapidly from 1 to 10 sec and then levels off. A second experiment was carried out at varying temperatures, from 120 to 230°C, to discover the effect of temperature on crystallinity the time of heat treatment was 45 s for each. The results are shown in Figure 4.19. It can be seen that crystallinity increases almost linearly from 120 to 230°C. It was difficult to extend the experiment beyond 235°C due to the melting of the sample. 

Airvol Polyvinyl Alcohol, Product Bulletin 1990, Air Products and Chemicals, Inc., Allentown, PA. 10.1. Sakurada, Polyvinyl Alcohol Fibers, Marcel Dekker, New York, 1985. 

Polyvinyl Alcohol and Acetals. Polyvinyl alcohol fibers are solution-spun, and then cross-linked with formaldehyde (Fig. 3.72) to make them resistant to water. Polyvinyl formal is cross-linked with phenolic resole to make baked coatings on electrical wire. Polyvinyl butyral is cross-linked with phenolic resin to make extremely tough bullet-proof helmets. 

Synthetic polymers Polyamide, polyester, aramid, and polyvinyl alcohol fibers... 

Observational studies Polyvinyl alcohol fibers and films are used in medicine and pharmacology because of their ability to swell, absorb toxic products, decompose necrotic masses, and reduce blood loss [78 ]. A mixture of polyvinyl alcohol with ketoprofen has been used to reduce pelvic pain after uterine artery embolization [79 ] in a randomized prospective study in 80 patients, 40 of whom received ketoprofen mixed with polyvinyl alcohol particles and 40 polyvinyl alcohol alone. During embolization, only five patients recorded a pain score of 1-2. One had an allergic reaction to the contrast medium 13 of the patients who received pol)rvinyl alcohol alone reported severe or very severe pain, compared with none of those who received ketoprofen plus poljrvinyl alcohol. 

K. Kawai, Polyvinyl Alcohol Fibers , Modern Plastics Encyclopedia, pp. 376, 378 (1972-73)... 

G. Xu, S. Magnani and D.J. Hannant, Tenile behavior of fiber-cement hybrid compsoites containing polyvinyl alcohol fiber yarns , ACi Mater. J. 95,1998,667-674. A.E. Naaman, Ferrocement and Laminated Composites, Techno Press 3000, USA, 2000. 

Carbochain polymer based fibers are higher resistant to microbiological damages. These polymers are-polyolefins, polyvinyl chloride, polyvinyl flnoride, polyacrylonitrile, and polyvinyl alcohol. Fibers based on heterochain polymers polyamide, polyether, polyurethane, and so on, are less bioresistant. 

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