Morphology and properties of polyurethane-based blends

Abstract

The morphology and the properties of injection-moulded samples of thermoplastic polyurethane-based blends have been investigated as function of composition and chemical nature of the second component (ABS, PS, ASA and SAN). The examination of the overall morphology shows that in the blend specimens the minor component forms separated domains. This evidence is gained using etching techniques in the case of ABS-, ASA- and SAN-containing blends while for TPU/PS the domains of PS are directly visible by SEM on the surface of fractured samples. Dynamic mechanical investigation supports the morphological findings. In the case of TPU/ABS blends it has been found that on increasing the ABS content, materials are obtained with a higher flexural modulus and Shore hardness but with a reduced density. On the other hand, TPU/ABS blends show a reduction of the elongation at break and the tensile strength. The impact behaviour of TPU/ABS alloys depends on temperature and composition. At low temperatures ABS acts as a toughening agent. At higher temperatures ABS acts as reinforcing agent. The influence of processing conditions on the morphology and properties of TPU/ABS blends is also discussed.