Mechanical and thermal properties of polyolefin thermoplastic elastomer blends

Polyolefin thermoplastic elastomers (POEs) are a class of thermoplastic elastomer (TPE) that can be easily processed. POEs have broad applications from automobiles to footwear and it is desirable to be able to alter the microstructure and properties. In this work, a systematic study of how blending and thermal processing of POEs affects mechanical and thermal properties is undertaken. Ethylene-octene copolymer POEs with different degrees of crystallinity are blended, compounded, and moulded and then slow cooled, quenched, or annealed. Differential scanning calorimetry (DSC) results show that the blends are immiscible and that quenching suppresses crystallinity while annealing thickens crystals. More crystals of the same thickness or thicker crystals of the same amount in the blends result in a higher modulus, lower elastic recovery, and more residual strain or permanent deformation after tensile testing. Microstructural control will allow for the optimal design of elastomeric materials with anticipated properties.