Elongational rheometry of polyethylene terephthalate/bisphenol-a polycarbonate blends

The elongational deformation properties of polyethylene terephthalate (PETP) and bisphenol-A polycarbonate (PC) blends were determined using a Rutherford elongational rheometer. The effects of temperature (in the thermoelastic region) and strain rate were studied on blends containing up to 50% PC. Addition of low levels of polycarbonate permits the thermoelastic processing of PETP over a wider temperature range. PETP is particularly sensitive to changes in temperature. Over the range studied, the effect of strain rate on elongational deformation is not very marked. However, the deformation temperature changes the strain levels at which strain stiffening occurs, an important observation in respect of processing and optimisation of physical properties of uniaxially oriented products. The effect of the addition of a phenoxy resin on the blend was studied, and although TEM analysis suggests that it did not compatibilise the blend, it did increase the available extension at higher temperatures.