加硫度の動特性におよぼす影響
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概要
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Dynamic mechanical properties of polybutadiene (BR) and ethylenepropylene rubber with a wide range of degree of crosslinking were studied. Dynamic shear modulus (G′) of BR increases with increasing the degree of crosslinking, while G′ of EP rubber decreases. This result of EP rubber is observed up to 70°C and frequency of over 3 cps.Since it is believed that the decrease of G′ can be attributed to the effect of chain entanglement, the molecular weight between entanglements (Me) was calculated from the G′ on the base′s of theories of rubber elasticity.From this calculation, EP rubber shows a large Me value. This is probably due to a small amount of aggregation based on the blockness in a long -(CH2)n- sequence.This result may suggest that the measurment of dynamic modulus as a function of degree of crosslinking is a good method for evaluating the blockness.In addition, it is found that experimental values of log G′/G60 (static modulus) is propotional to the average molecular weight between crosslinks in the network.
- 一般社団法人 日本ゴム協会の論文