Chlorinated polyvinyl chloride, mechanical

Post-chlorinated polyvinyl chloride (cPVC) is a material which offers a combination of mechanical strength, temperature and corrosion resistance and low installation costs, that meets a variety of process uses. This comprehensive article describes cPVC s key properties in detail and highlights the various industries and applications for the polymer, particularly pipes and fittings. 

Chlorinated polyvinyl chloride is very similar in properties to PVC. Table 3.6 lists the physical and mechanical properties. CPVC has an allowable operating temperature of 200°F/93°C which is somewhat higher than the temperature rating for PVC. 

A survey of the modulus as a function of exfoliation efficiency of Cloisite 30B in polyethylene with a varying degree of chlorine content is provided by Kim and White [44]. Polyethylene (2045 LLDPE produced by Dow) was the control. The wt. % chlorine content increased from chlorinated polyethylene (Tyrin random replacement of hydrogen with chlorine on the polymer backbone 36% chlorine, manufactured by DuPont Dow Elastomers), polyvinyl chloride (334 EG 56.7% chlorine, manufactured by OxyVinyl), chlorinated polyvinyl chloride (TempRite, 63.5% chlorine, manufactured by Noveon), to polyvinylidene chloride (Saran, greater than 71.5% chlorine, manufactured by Dow Chemical). The composites were prepared with a Brabender internal mixer at 180°C and 100 r/min. The composites were prepared with 3, 5, and 10 wt.% Cloisite 30B content. The samples for mechanical testing were prepared by compression molding. The composites were characterized by WAXS and TEM. 

Another reaction mechanism that occurs in some chain-growth polymers is solvolysis. In this type of reaction, a species reacts with a C-X bond, where X represents a halogen, and breaks it. Specifically, this becomes important when describing the degradation of polyvinyl chloride. Acidic species act to remove the chlorine atom, forming hydrochloric acid. 

On the other hand, some mechanically compatible blends as well as some dispersed two-phase systems have made respectable inroads into the commercial scene. Many of these are blends of low-impact resins with high-impact elastomeric polymers examples are polystyrene/rubber, poly (styrene-co-acrylonitrile) /rubber, poly (methyl methacrylate) /rubber, poly (ethylene propylene)/propylene rubber, and bis-A polycarbonate/ ABS as well as blends of polyvinyl chloride with ABS or PMMA or chlorinated polyethylene. 

Diffusion. This theory proposes that adhesive macromolecules diffuse into the substrate, thereby eliminating the interface, and so can only apply to compatible polymeric substrates. It requires that the chain segments of the polymers possess sufficient mobility and are mutually soluble. The solvent welding of thermoplastics such as PVC (polyvinyl chloride), softened with a chlorinated solvent, is an example of such conditions being met. Diffusion will also take place when two pieces of the same plastic are heat-sealed. The joining of plastic service pipes for carrying gas and water makes use of the diffusion mechanism. 

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