Synthesis And Application Research Of Hydroxy-functionalized Polypropylene

Polypropylene is still keeping fastest growth rate among five thermoplastic, due to its excellent thermostability, chemical stability, processability and recyclability. However, because of the lack of functional groups, there are some inherent shortcomings which limits further performance and wider applications of polypropylene. Recently, the research on the synthesis of functionalized-polypropylene via coordination polymerization in labs and the research on polymerization process of pilot-scale test is rarely. In this paper, we synthesized copolymers of polypropylene and propylene/10-undecene-1-ol with different hydroxyl content through high-pressure direct-copolymerization approach and also investigated the properties and application of these cpolymers.First, polypropylenes containing different hydroxyl content are obtained via copolymerization of propylene and diisobuty(10-undecene-1-oxy)aluminum with rac-([Me2Si(2-Me-4-Ph-Ind)2]ZrCl2-MMAO/BHT catalytic system. The effect of polymerization pressure and comonomer feed ratio on polymerization activity, comonomer incorporation, comonomer conversation, molecular weight, molecular weight distribution and melting temperature is analyzed. On the same polymerization pressure, with the increasing of comonomer feed ratio, polymerization activity decreased and comonomer incorporation increased. When the comonomer feed ratio is the same, with increase of polymerization pressure, polymerization activity increased. When the polymerization is 8bar, polymerization activity can up to 4.45×104 kg/(mol·h), and is quintuple as high as 2bar. Comonomer conversation and utilization can be controlled and homogeneous polymers can be obtained through the command of polymerization pressure. When polymerization pressure is 2 and 8 bar, high and low hydroxyl content functionalizedpolypropylene can be obtained respectively, and the yield of polymers are more than 30 g. Hydroxy-functionalized polypropylenes with narrow molecular weight distribution(around 2.5), unimodal GPC curves, different molecular weight and different hydroxyl content can be obtained through the adjustment of polymerization pressure. When polymerization pressure is 2 and 8bar, 1.5×105 and 3.0×105 molecular weight polymers are obtained separately.The thermal, crystallization, mechanical, and hydrophilic property of hydroxyl-functionalized polypropylene and hydroxyl-functionalized polypropylene/polypropylene blending system are researched. With the increase of hydroxyl content, the hydrophilic and tensile strength are improved obviously. When hydroxyl content is 2mol%, the water contact angel of functional polypropylene decreased by 20° and tensile strength were improved 11 MPa. With the increase of hydroxyl-functionalized polypropylene additive amount, water contact angel of blending system decreased and tensile strength improved, but the modulus and elongation at break decreased. When the comonomer content of blending system is 15wt%, water contact angel drop to 83° and hydrophilic is improved obviously. When the comonomer content of blending system is 10wt%, tensile strength can up to 50 MPa and improved 10 MPa.