Preparation And Properties Of Functionalized Polypropylene

In this work,2-acrylamido acetic acid (AAAA) functionalized polypropylene (PP) wasprepared through two methods: solid phase grafting and aqueous suspension grafting. Themonomer AAAA was synthesized by the reaction of acryloyl chloride and glycine in alkaliaqueous solution, and the chemical structure of AAAA was characterized using nuclearmagnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR), the graftingdegree was measured by chemical titration, crystal morphology of PP and functionalized PPwas characterized by polarized light microscopy (POM). The crystallization and meltingbehavior of the functionalized polypropylene was studied by differential scanning calorimetry(DSC), the isothermal crystallization behavior of the functionalized polypropylene wasdescribed by Avrami equation, while the non-isothermal crystallization behavior wasdiscussed by using the Jeziorny method.PP-g-AAAA/Vac with a grafting degree of6.8%was obtained by aqueous suspensionmethod using vinyl acetate as a comonomer at95℃when the mass ratio of PP/AAAA/vinylacetate (Vac)/BPO/xylene/H2O was100/25/25/2/10/300. FTIR spectrum proved that themonomer was successfully grafted onto the PP backbone. The DSC results showed that thecrystallization temperature of PP-g-AAAA/Vac increased about13~15℃than that of pure PP,while the melting temperature decreased about2~6℃. The primary crystallization behavior offunctionalized polypropylene was well described by Avrami equation: the index of n wasbetween2and3, which indicated that the crystallization process of both pure polypropyleneand the functionalized polypropylene were controlled by heterogeneous nucleation. Thejeziorny method was used to discuss the non-isothermal crystallization behavior of PP andPP-g-AAAA/Vac. The results showed that the crystallization process was largely affected bycooling rate, and the curve was deviated straight line of primary crystallization part in thesecondary crystallization stage.PP-g-AAAA/St with a grafting degree of4.1%was prepared by solid phase grafting atoptimum conditions. FTIR spectrum showed that the monomers were successfully graftedonto the PP matrix, and the DSC results indicated that the crystallization and meltingtemperature markedly changed. The isothermal crystallization of the pure PP andPP-g-AAAA/St at different temperature indicated that the rate of crystallization decreasedwith increasing crystallization temperature. At a certain temperature, crystallization rate of the functionalized PP was much higher than that of PP. The parameters of non-isothermalcrystallization were obtained by the Jeziorny method, it was found that the initiate, summitand terminate crystallization temperature of the pure PP were much higher than that of thefunctionalized PP.