Investigation of concentration dependent property variations of High Density Polyethylene/Styrene Ethylene Butylene Styrene blends

Binary polymer blends of High Density Polyethylene (HDPE) and Styrene Ethylene Butylene Styrene (SEBS) are developed by varying the SEBS concentration from 1 to 10 wt%. The relation between the concentration of SEBS in HDPE and the physical, mechanical, and thermal properties of the resulting blends has been investigated. The physical properties almost remain unaffected by the addition of SEBS to HDPE. In mechanical characterization, a reduction in modulus is observed with each incremental addition of SEBS. Blends with 10% SEBS concentration reveal a nine fold increase in tensile elongation along with a 15.4% and 26.4% increase in room and low temperature impact resistance. In thermal characterization, Thermogravimetric Analysis (TGA) of the polymer blends reveals a slight decline in thermal stability with increasing SEBS concentration. Heat Deflection Temperature (HDT) declines sharply beyond 5 wt% SEBS concentration, thermograms obtained from Differential Scanning Calorimetry (DSC) portray an increase in crystallinity till 5 wt% and then declines with further addition of SEBS. A temperature and composition dependent molecular mobility between the polymer phases is evident from Dynamic Mechanical Analysis (DMA). A transition from immiscible two phase droplet-matrix separation phase to a partially miscible morphology is evident from analysis under Scanning Electron Microscope (SEM).