Effect of draw ratio on the morphologies and properties of in situ microfibrillar POE/PTT composites

The microfibrillar composites (MFCs) were fabricated by multistage stretching extrusion using different draw ratios (viz., 4, 7, 10, 13, and 16) from polyolefin elastomer/polytrimethylene terephthalate (POE/PTT) blends. Scanning electron microscopy (SEM) studies showed that the aspect ratio of PTT microfibrils increased with the draw ratio increased. The tensile strength of the MFCs was the largest at draw ratio of 13. DSC results showed that PTT microfibrils could improve the crystallization temperature (T-c) while decrease the melting temperature (T-m) of POE phase compared with the neat POE. Moreover, the storage modulus ( G), loss modulus ( G) values, the complex viscosity( ) and the radius of Cole-Cole circle were the largest for the MFCs prepared at draw ratio 13, while the differences became negligible at high frequency (>10 rad/s), It's remarkable that when the draw ratio increased to 16, the tensile strength decreased sharply. Furthermore, the G, G, and values had a significant drop at high frequency. This may be due to that too strong drawing could damage the structures of the microfibrils, which is adverse to improve the mechanical and rheology properties. POLYM. COMPOS., 40:E629-E637, 2019. (c) 2018 Society of Plastics Engineers