Dynamic Mechanical Properties of Polyoxymethylene. II

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Abstract
Real and imaginary parts of complex rigidity of melt-grown polyoxymethylene are measured over a frequency range from 3.0 to 0.01 Hz at various temperatures from -3°C to 138°C by a new torsional pendulum apparatus. Master curves for real and imaginary parts of complex rigidity in the range of α-dispersion are composed by performing a suitable superposition for the dispersion curves. Empirical relation for the time-temperature reduction obtained from the superposition procedures can be theoretically interpreted on the basis of the concept of “smearing-out effect of crystalline field” arising from incoherent lattice vibration in polymer crystals. The apparent activation energy of the α-dispersion evaluated from the temperature dependence of reducing factor is 32 and 25 kcal./mol. in the temperature regions above and below about 95°C respectively. However, it becomes very large in the temperature region below about 40°C.