Research On Melt Grafting Preparation And Performance Of High Melt Strength Polypropylene

High melt strength polypropylene (HMSPP) was prepared in a twin-screw extrude by melt grafting method, using PP as basic resin, triallyl isocyanurate (TAIC) as grafting monomer and dicumyl peroxide (DCP)/benzoyl peroxide (BPO) as composite initiator. The measurement of grafting degree, gel rate, melt flow rate, sag resistance and mechanical property, together with the analyzation of ATR-FTIR, DSC and TGA were carried out to characterize the structure and performance of PP-g-TAIC. In addition, co-monomer styrene (St) was applied to study the inhibition of the degradation side reaction of PP.The result of FTIR suggested that TAIC was grafted on the PP backbone chain. The test of melt performance of grafted products showed that the addition of TAIC not only promoted the grafting reaction, but also improved the sag resistance and the melt strength. When the content of TAIC was 5 phr, the grafting degree reached a maximum value of 4.54%. Compared with pure PP, the melt strength of PP-g-TAIC was increased by 2.28 times, while DSC of PP-g-TAIC indicated that crystalline temperature and melting point raise 13.10℃and 2.96℃, respectively. The precence of co-monomer showed that styrene could benefit the graft process, causing the grafting degree increase and the gel rate decrease effectively. When TAIC was 3 phr, St was 1 phr, the melt strength of PP-g-St/TAIC was 3.26 times as high as PP. The outcome of TGA revealed that the thermostability of grafted products was enhanced greatly, and the order was presented as following:PP-g-St/TAIC>PP-g-TAIC>PP. The mechanical measurement results showed that the tensile strength of PP-g-TAIC was improved, while the bending and impact performance was lowered remarkably. In addition, compared with pure PP, the tensile strength of PP-g-St/TAIC was improved by 6.60%, notch impact strength 13.71% and blending strength 4.97%, respectively.