Polyvinyl fatigue

Many workers have been exposed to vinyl chloride because of its use in polyvinyl chloride plastic manufacture. The central nervous system, respiratory system, liver, and blood and lymph systems are all affected by exposure to vinyl chloride. Among the symptoms of poisoning are fatigue, weakness, and abdominal pain. Cyanosis may also occur. Vinyl chloride was abandoned as an anesthetic when it was found to induce cardiac arrhythmias. 

When polymers slide on machined metal surfaces, it is quite possible that steady-state wear Involves a combination of abrasive, fatigue, and adhesive wear mechanisms. To study fatigue wear, it would be desirable to minimize the contributions of the abrasive and adhesive wear modes. In this paper, the following polymers polycarbonate, polyvinyl chloride, ultra-high molecular weight polyethylene, siloxane modified epoxies, and polylmldes are tested in experiments in which the fatigue wear mode is predominant. 

This polyvinyl chloride compound family is highly elastomeric and exhibits a dry non-tacky surface even at hardnesses as low as 40 Shore A durom-eter. Their rubber-like resilience, high elongation and low permanent set and fatigue resistance offer advantages over conventional formulations (Tables 4.6, 4.12, and 4.13). 

Due to their good damping properties, soybean oil polymers may also find applications in places where the reduction of noise and prevention of vibration fatigue failure is required (39). Several conventional polymers, such as polyacrylates, polyurethanes, polyvinyl acetate, as well as natural, silicone and SBR rubbers, which are currently used as damping materials, might be replaced by soybean oil polymers. Unlike the above-mentioned thermoplastics, soybean oil polymers are capable of efficient damping over wider temperature and frequency ranges (23). 

Figure 3.20 The effect of molecular weight of polyvinyl chloride on fatigue crack propagation [4],...

Figure 3.30 The effect of adding methacrylate-butadiene styrene rubber (MBS) toughener to polyvinyl chloride on the fatigue crack propagation rate.

Figure 9.25 Fatigue cycles to failure versus stress in tension with a stress ratio of 0.1 at 25°C and 10 Hz for filled and unfilled polyvinyl chloride [11].

Figure 11.47 Fatigue crack propagation (FCP) rate versus stress intensity range for polyvinyl fluoride [2],...

Natural rubber s utility as a blood pump material however was shortlived because of its short fatigue life and its tendency to promote blood clotting and hemolysis. Polyvinyl chloride was used in total artificial hearts (4,5), but this also was soon abandoned because it was cumbersome to handle and the surface was very thrombogenic. 

The photolysis of the various dimers was carried out in a wide range of different solvent and solid media, including the conventional solvents as well as binders such as polyvinyl butyral, cellulose acetate butyrates, etc. Inevitably the photochromic behavior was relatively brief due to the fatigue reaction, which we found to give rise to the parent triaryUmidazoles. 

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