パーオキサイド架橋EPDMの構造と動的特性に関する研究第5報 : 貯蔵弾性率と網目鎖濃度および分子運動性の関係

概要

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Peroxide-crosslinked EPDMs were examined by dynamic mechanical analysis. In a rubbery state, a plot of storage modulus (E) vs. temperature gave an approximately linear relationship. The slope of the approximated line increased with an increase in apparent crosslinking density (νS) which was calculated from equilibrium swelling. However, E of peroxide-crosslinked EPDMs were not proportional to absolute temperature (T). For the EPDMs crosslinked above 400mol/m3 of νS, straight lines approximating the relationships between E and T gave a constant T-intercept at E=0. This indicates that E in a rubbery state is proportional to the difference between T and a reference temperature (T0). Assuming E proportional to T-T0, effective crosslinking density (νS) was calculated from E as T0=150K. Spinspin relaxation time of network component (T2n) and the fraction (Fn) were measured by 1H pulsed NMR with Hahn echo method. At each temperature, 1/T2n (or Fn/T2n) showed good linear correlation with E. Over the temperature range 343 to 423K, the plot of 1/T2n (or Fn/T2n) vs. νE gave a straight line independent on the temperature at which E and T2n were measured.