Dynamic mechanical properties of polystyrene, polyethylene, and polytetrafluoroethylene at low temperatures

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Abstract
A study of the dynamic mechanical properties of several high polymers has been made over a temperature range from 80°K. to above room temperatures and at frequencies in the range from 200 to 4000 cps. For amorphous polymers such as polystyrene the mechanicalloss rises sharply in the neighborhood of 80°C. but over the rest of the temperature range studied exhibits no relaxation peaks. For partly crystalline polymers such as polymethylene, polytetrafluoroethylene, and nylon the loss curve exhibits one or more definite internal friction peaks in the temperature range studied. The observed relaxation behavior is discussed in terms of possible molecular mechanisms and the results correlated with specific heat measurements and other mechanical loss measurements where such data are available.