Tensile at break

Tensile at break (psi) Elongation at break (%) Hardness (Shore D)... 

ATM—do not try to manipulate modulus and tensile at break by varying the type and loading of plasticizer. There are too many possible combinations and the resultant changes too small to make the effort worthwhile. Adjust the plasticizer type and loading to optimize the specific characteristic desired and (e.g., low-temperature flex, hardness) then go back to the cure system, polymer grade, and fillers to correct the other physical properties. 

Specimens used in tests were sections of cables with PVC outer coating. PVC was plasticized with DOF softener. The materials considered were exposed to the radiation and thermal aging. The samples have been irradiated at room temperature by hard gamma rays with 10 rad/sec dose power. A number of samples had been heated for long different times at 90°C. Besides a special specimens were cut out from outer coating for test on tensile machine like "Instron". The total doses of irradiation, times of heating and elongations at break obtained with "Instron" are listed in Table 1. 

Material Percent neutralized Melt index at 190°C, dg/min Secant modulus, % extension, MPa Ultimate tensile strength, MPa Elongation at break, %... 

Content of Ot-Olefin. An increase in the a-olefin content of a copolymer results in a decrease of both crystallinity and density, accompanied by a significant reduction of the polymer mechanical modulus (stiffness). Eor example, the modulus values of ethylene—1-butene copolymers with a nonuniform compositional distribution decrease as shown in Table 2 (6). A similar dependence exists for ethylene—1-octene copolymers with uniform branching distribution (7), even though all such materials are, in general, much more elastic (see Table 2). An increase in the a-olefin content in the copolymers also results in a decrease of their tensile strength but a small increase in the elongation at break (8). These two dependencies, however, are not as pronounced as that for the resin modulus. 

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