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A B S T R A C T Infrared (IR) spectroscopy is used to find how the applied mechanical stress imposed upon a sample is distributed among the interatomic bonds. The distribution is highly heterogeneous: 80--95% of the bond population experience stresses close to the applied stress, the stress on the rest of the bond population varies over a wide range and reaches 1000--2000 kg/mm 2. The overstressed interatomic bonds lie in the amorphous regions of the polymer and are oriented in the direction of the mechanical force. The maximum stress on interatomic bonds is determined by the magnitude of the breaking stress on them. The breaking stress is shown to be a function of the applied stress, time, and temperature. This dependence is due to scission of stressed bonds induced by thermal fluctuations.Int. Journ. of Fracture, 11 (1975) 789-801

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An attempt was made to evaluate stresses on chemical bonds in axially stressed polymers from the shift of skeletal vibration frequencies in chain molecules. The maximum stress on chemical bonds was found to be at least ten times the average stress on the specimen.

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Temperature dependencies of the thermal expansion coefficient for segments of macromolecular helices, ol(T), were obtained for polymers by infrared (IR) spectroscopy. It was shown that the a ( T ) are complicated (nonlinear) over a wide temperature range. Wunderlich and Bauer's idea concerning "freezing out" of normal vibrations of polymer chains was used to describe them. It was shown that the substitution of the classical rather than quantum statistics for both torsional and bending vibrational modes of macromolecules causes complications in a ( T ) . Mechanical properties of drawn linear polymers are connected with the thermal expansion. Therefore, such an approach may be used to describe the temperature dependence of Young's modulus and failure strength for drawn polymers in the range from cryogenic to melting temperatures.

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