Abstract
In order to investigate the elastic property of BLDPE-tetralin gel, the static shear modulus G of the gel was measured at 25°C as a function of polymer concentration. The size of crystalline junction ζ (i. e., ethylene-unit length in a crystallite) was estimated from gel-melting temperatures using Takahashi's theory. BLDPEs having different numbers of long-chain branches (LCB) and different molecular weights (MW) were used. As a result, both G and ζ became large with increasing MW, but became small with increasing number of LCB. Further, G increased with increasing ζ. The concentration dependence of G was analyzed by the following power law equation: G ∝ (C-C0) t, where C0 is the critical gelation concentration. In the region near C0, the elasticity exponent t was found to be ca. 2 without regard to the difference in LCB and MW of samples. The value observed is in agreement with the critical exponent expected from the percolation theory in dimensionality d=3.
