Maleic anhydride (MAH)⁻divinyl benzene (DVB) multi-monomer melt-grafting onto isotactic polybutene-1 (iPB-1) was carried out in a torque rheometer. The effects of dicumyl peroxide (DCP), MAH, and DVB concentrations, and temperature, on the reaction, were investigated. The optimized conditions were 170 °C, DVB/MAH = 4:6 (mass ratio). DVB as a comonomer enhanced the grafting degree (Gd) and grafting efficiency (Ge) of iPB-g-MAH better than styrene. The initiator DCP had little effect on Gd as its concentration over 0.2 phr, but the grafts' melt flow rate (MFR) increased significantly, and relative molecular weight decreased remarkably with increased DCP concentration. With increasing Gd, the contact angle of grafts with water decreased, and there was a larger crystallization rate. The study of iPB-1 and iPB-g-MAH (Gd = 1.5%)-modified polyamide 6 (PA6) showed that iPB-g-MAH had an obviously toughening effect on PA6. With increasing iPB-g-MAH concentration, the blends of impact strength and elongation at break increased obviously, tensile strength decreased slightly, and MFR decreased prominently, which greatly slowed the processing degradation of PA6. The properties of iPB-1/PA6 blends deteriorated. Both DSC curves and SEM micrographs confirmed that PA6/iPB-g-MAH blends had much better compatibility than PA6/iPB. The reason was that the anhydride group in iPB-g-MAH reacted with amide group in PA6 to improve the compatibility between two phases, and iPB-g-MAH is an excellent modifier for PA6.
Keywords: divinyl benzene; isotactic polybutene-1; maleic anhydride; modification; polyamide 6.