Mechanical property and physical structure changes in highly hot-drawn polycarbonate

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Abstract
The effect of hot stretching on the structure and properties of bisphenol‐A polycarbonate was studied to determine if ordering and conformational changes occur, and their effect on the impact toughness of PC. The mechanical properties of hot‐stretched PC were found to follow the same behavior observed for enthalpy changes, which showed (1) a drop at draw ratios between 2 and 5; (2) a plateau region extending out to a draw ratio of 45; (3) a further drop at draw ratios of 57 and 62. The enthalpy decrease at a draw ratio of 62 is comparable to that found for 15% solvent‐crystallized PC; yet, wide‐angle x‐ray diffraction indicates that no crystallinity is present. Annealing of this highly hot‐drawn PC increased the enthalpy by 7.5 kJ/kg, indicating that this highly hot‐drawn PC must be in an ordered state.