Abstract
The effect of annealing on the mechanical and thermal properties of polycarbonate resin has been investigated. The previously observed increases in yield strength and decreases in impact strength have been confirmed and it has been shown further that annealed polymer shows a larger strain softening effect after yield than untreated material. This is reflected in an increased negative slope in the stress-strain curve. After yielding the endothermic D.S.C. peak due to annealing is largely eliminated. The extra mechanical energy required to deform the annealed polymer is similar in magnitude to the thermal energy associated with the D.S.C. peak. The reduction in impact strength during annealing is ascribed to greater plastic instability and to the consequent reduction in volume of the zone of plastic yielding in the impact test. This conclusion is confirmed by the examination of annealed and untreated impact test pieces in polarized light.
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Adam, G.A., Cross, A. & Haward, R.N. The effect of thermal pretreatment on the mechanical properties of polycarbonate. J Mater Sci 10, 1582–1590 (1975). https://doi.org/10.1007/BF01031859
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DOI: https://doi.org/10.1007/BF01031859