ORIENTATION OF POLY(ETHYLENE TEREPHTHALATE) IN INCOMPATIBLE BLENDS WITH AN ELASTOMER: INFLUENCE OF FUNCTIONALIZATION

摘要

Drawing of PET and its blends with an elastomer with and without a compatibilizer was performed from their amorphous states at a constant strain rate and at a temperature just above PET glass transition temperature. Crystallinity values of drawn PET blends were determined by differential scanning calorimetry (DSC) whereas their crystalline orientations were measured by infrared linear FTIR dichroism. The stress-strain curves during stretching indicated stronger strain-hardening and higher yield stress in blends where the elastomer was compatibilized. They also have earlier strain-induced crystallization onsets as suggested by the thermal and orientation measurements. Lower PET crystalline orientation was observed in blends containing compatibilized elastomer dispersions in comparison with those of uncompatibilized blends and neat PET. Tilting of the crystals at 45 degrees to drawing direction was found by bimodal atomic force microscopy indicating interfacial shear alignment during uniaxial drawing which could be a direct consequence of the improved interfacial adhesion. This interfacial shear alignment may explain the observed crystalline orientation reduction in compatibilized blends.