THE INFLUENCE OF RESIDUAL-STRESSES ON THE MECHANICAL AND THERMAL-PROPERTIES OF INJECTION-MOLDED ABS COPOLYMER

The mechanical and thermal properties of acrylonitrile-butadiene-styre ne copolymer (ABS) were determined for as-moulded and an neared specim ens in order to assess the influence of residual stresses on these pro perties. Mouldings were heat treated at temperatures below and above t he glass transition temperature, T-g. Annealing below the glass transi tion removes most of the residual stresses arising during the moulding process, while annealing above the glass transition temperature remov es both the residual stresses and molecular orientation. Residual stre sses have a strong bearing on the end-use properties. The thermal beha viour of the mouldings are mostly affected by the stimulation of molec ular motion caused by the relaxation of the residual stresses near the glass transition temperature.