Compression and tensile properties of self-reinforced poly(ethylene terephthalate)-composites

Tensile and compression properties of self-reinforced poly(ethylene terephthalate) (SrPET) composites has been investigated. SrPET composites or all-polymer composites have improved mechanical properties compared to the bulk polymer but with maintained recyclability. In contrast to traditional carbon/glass fibre reinforced composites, SrPET composites are very ductile, resulting in high failure strains without softening or catastrophic failure. In tension, the SrPET composites behave linear elastically until the fibre-matrix interface fails, at which point the stiffness starts decreasing. As the material is further strained, strain hardening occurs and the specimen finally fails at a global strain above 10%. In compression, the composite initially fails through fibre yielding, and at higher strains through fibre bending. The stress-strain response is reminiscent of an elastic-perfectly plastic material with a high strain to failure (typically over 10%). This indicates that SrPET composites are not only candidates as semi-structural composites but also as highly efficient energy absorbing materials.