The Synthesis, Characterization Of Polypropylene Graft Aliphatic Polyester Polymer And Its Application As Blending Compatibilizer

Polypropylene(PP) is one of the most widely used polymeric materials due to its outstanding performance, such as high melting point, high tensile strength, stiffness, and excellent chemical resistance. However, the application of PP is limited by its nonpolar nature. Since the discovery of Ziegler-Natta catalysts, it has been a long scientific interest and a technologically important subject to investigate the routes of incorporating polar groups or polar chains into a polypropylene chain, which can give PP the properties of hydrophilia, dyeability or compatibility with other polar polymers.In this thesis, we accomplished the copolymerization of propylene with α-undecene-ω-iodine using the pyridylamidohafnium dimethyl as the catalyst, and got the copolymers with high molecular weight, high isotactic selectivity. The abundant iodine groups of the resultant copolymers could be easily transformed into hydroxyl groups via nucleophilic substitution of copolymers with mercaptoethanol. Using PP containing pendant hydroxyl groups as initiator and stannous octoate as catalyst, a serial of well-defined polypropylene-graft-polycaprolactone or polypropylene-graft-polylactide polymers were synthesized via ring opening polymerization, and the structures of the polymers were characterized by1H NMR, IR, DSC and WAXD. In addition, the influence of temperature, comonomer incorporation and time on the grafting reaction was studied. The results showed that the optimal reaction temperature was90℃; the grafting densities could be controlled by regulating the comonomer incorporation and the grafting lengths could be controlled by regulating reation time. Furthermore, the functional polypropylene was used as compatibilizer for polypropylene/nylon-6blends, and the influence of compatibilizer on the blends was investigated by SEM and tensile test. The SEM revealed that the interfacial tension and dimensions of separated phases were markedly reduced while interfacial adhesion was greatly enhanced because of the addition of the compatibilizer. The tensile test results revealed that the tensile strength of the blends was dramatically improved. The compatibilizing effect was the most obvious when the graft polymers contained the same amount of PP and aliphatic polyester.