Abstract
The tensile strength and the ultimate elongation of an acrylonitrile-methylacrylate copolymeric fiber in wet state were measured at various temperatures under a condition of constant load and compared with the values for dry condition reported previously. Results obtained are summarized as follows:
(1) The time-temperature superposition method applied to the ultimate properties in dry state was also applicable to the results in wet state.
(2) The relation between the shift factor along the logarithmic axis of the time to break in wet state versus temperature followed an equation of the Arrhenius form of which the apparent activation energy showed different values in accordance with the temperature regions below and above 65°C. The apparent activation energy was calculated as 44.0kcal/mol below 65°C, and the value above 65°C was obtained as 73.0kcal/mol which was the same as that obtained in dry state above 80°C.
(3) The curves in wet state and in dry state, plotting the values of the logarithmic shift factor along the logarithmic axis of the ultimate elongation against temperature, showed identical shape and could be reduced to a single curve by using a reduced temperature T-Tc, where T is temperature and Tc is a characteristic temperature. It was obtained from the reduction noted above that the difference between the values of the characteristic temperature in wet state and in dry state was 20°C.
(4) As the characteristic temperature in wet state was determined at 65°C, the value in dry state was obtained as 85°C. The characteristic temperature seems to correspond to the glass transition temperature obtained in each state.
(5) Comparing the composite curves of the tensile strength at the characteristic temperature in wet state with that in dry state, the value of strength in wet state was related as 0.66 times to that in dry state over 8 decades of the time to break. The above result seems to show that a critical condition of rupture in wet state is the same as that in dry state.
