Study On Copolymerization Of Propylene And Polar Monomer 3-Buten-1-ol

As one of the most important commodity polyolefins, commercial polypropylene is characterized by good impact strength, rigidity and chemical resistance and is low in cost. However, the lack of functional groups in polypropylene significantly limits the areas in which it can be applied. Introducing polar groups to polypropylene chains is one effective way to improve the character of polypropylene. The addition of functional groups to polypropylene by means of copolymerization can not only keep the intrinsic performance of polypropylene, but also change some important properties of polypropylene, such as toughness, adhesion properties, surface performances and compatibility with solvent and other polymers.In this work, the copolymerization of propylene and 3-buten-1-ol as polar monomer was achieved by using metallocene catalyst rac-[Et(Ind)₂]ZrCl₂. Functional groups in polar monomers not only influence the reactive activity of coordinative polymerization, but also form stable complex with the coordinative catalyst, which can prevent copolymerization from taking place. Therefore, polar group in monomers should be protected before copolymerization with olefins. In this work, hydroxyl end-group of 3-buten-1-ol was by protected reacting with TIBA at -78℃ and room temperature sequentially. The resultant of this reaction was termed as BB1. ¹H-NMR, ¹³C-NMR and FTIR have confirmed that the copolymer of propylene and 3-buten-1-ol were obtained through copolymerization of propylene and BB1.Effects of polymerization temperature, amount of added BB1, Al/Zr molar ratio and the concentration of given metallocene catalyst on the copolymerization processes and the structure and properties of its products have been studied. It has been found there exist an optimum reaction temperature about 50 ℃, at which polymerization activity reached maximum. Increase in catalyst concentration and Al/Zr molar ratio and decrease in BB1 amount can increase polymerization activity. Molecular weight of copolymer was decreased when temperature, Al/Zr molar ratio or catalyst concentration was increased. However, molecular weight of copolymer was increased when BB1 amount was increased. More BB1, less Al/Zr molar ratio, highertemperature or higher catalyst concentration would lead to high polar monomer ratio in copolymers. The melt temperature of copolymer was increased with the increase in either molecular weight or polar monomer ratio in copolymers..Copolymerization of propylene and BB1 have been also carried out using supported catalysts to avoid reactor foul. It has been found that effects of temperature, amount of added BB1, Al/Zr molar ratio and the concentration of catalyst on the copolymerization processes and the structure and properties of its products were similar to that found in homogeneous processes. Compared with the copolymer obtained with homogeneous catalyst, the one obtained with the supported catalysts has higher molecular weight, polar monomer ratio and melt temperature. However, the activities of supported catalysts were much lower than that of homogeneous catalyst.