Rubber formulation Elongation

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). 

Natural rubber and poly(isobutylene) (Figure 4.28) were the earliest polymers used for formulating medical PSAs due to their high peel strength, elongation and ease of acceptance by skin tissue. 

Compared with similar natural rubber compositions of the same hardness, styrene butadiene rubber (SBR) formulations are characterized by lower tensile strength, elongation, and resilience, lower resistance to tear, flexing, abrasion, ozone, and sunlight, and higher permanent set. The freeze resistance and permeability to gases of styrene butadiene are equivalent to those of comparable natural rubber, and so are the electrical characteristics. 

Cured silicone LIM rubber can be fabricated with physical properties equivalent to heat-cured rubber (500). Shore A hardness can range from 30 to 70, depending on formulations. Typical physical properties include tensile strengths as high as 9.7 MPa (1400 psi), elongations at break of 500-775%, and tear strengths... 

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