Abstract
Polymer sheets, made from recycled poly (ethylene terephthalate) (R-PET) flakes, were hot stretched uniaxially and biaxially at around the glass transition temperature of PET. The structure and property changes were investigated as a function of draw ratio by using differential scanning calorimetry (DSC), mechanical analysis, wide angle X-ray diffraction (WAXD), dynamic-mechanical analysis (DMA) and a microwave orientation measurement. The crystallisation and the orientation of PET in the R-PET sheets could be induced by both uniaxial and biaxial stretching. The uniaxial and biaxial stretching methods make sheets with different crystallisation and orientation levels. For uniaxially stretched sheets, large orientation effects were obtained in the stretching direction, as well as improved properties.