Study On The Blending Of Polypropylene And Styrene Maleic Anhydride And Molecular Dynamics

Polypropylene has some shortcomings which are low abrasion resistance, low heat deflection temperature and poor dye-ability, so how to overcome these shortcomings has an important theoretical and practical significance. In this research project the heat resistance and polarity of PP were improved by blending modification, and polymer-blending was studied by molecular dynamics (MD) simulation. In this paper, firstly the PP-g-(MAH-co-St) graft copolymer was prepared by melt grafting, and the effects of the contents of MAH, St, DCP and temperature on graft reaction were studied. Then the influence of the amounts of SMA and PP-g-(MAH-co-St) on mechanical property, water contact angle and heat resistance of blends were discussed by adding PP-g-(MAH-co-St) as compatibilizer. Finally the compatibility, binding energy and mechanical property of polymers were researched by MD simulation. The detailed research results obtained are summarized as follows:1. PP-g-(MAH-co-St) with grafting yield of 1.12% was prepared by melt grafting with using MAH as the grafting monomer, St as the grafting co-monomer and DCP as initiator. The optimum conditions were MAH 6phr, St 6phr, DCP 0.4phr and temperature 170℃.2. The heat resistance and polarity of PP were obviously improved by adding SMA. The compatibility of alloying was improved well by using PP-g-(MAH-co-St) as compatibilizer, and the polarity and heat resistance of PP were enhanced. The optimum recipe of preparing ternary blends was PP 100phr, SMA 5phr, PP-g-(MAH-co-St) 5phr. The preparing material's mechanical properties were tensile strength 30.9Mpa, Izod unnotched impact strength 65.3 kJ/m2, elongation at break 426%, water contact angle 83.4°.3. PP and SMA can form a kind of partially compatible blends which was proved by the difference in the solubility parameter value between of them. Pair correlation function proved that the interaction pattern of components intermolecular was Vander Waals, and they also can form a kind of partially compatible blends. The glass transition temperature of blends which was obtained by the curves of specific volume versus temperature was in between two glass transition temperature of pure polymer, it also proved they can form a kind of partially compatible blends. The simulation results agreed with experimental observations. 4. The binding energy of ternary system was higher than the binary system's by comparing the binding energy and nonbonding energy obtained by simulation after adding PP-g-(MAH-co-St), and PP-g-(MAH-co-St) played an important role of compatibilization. SMA polymer chains in ternary system had higher mobility than that in binary system according to the mean square displacement versus time, and it also proved that PP-g-(MAH-co-St) played an important role of compatibilization. The mechanical properties of polymer by MD simulation agreed with experimental results. The diffusion velocity of oxygen atom in pure PP was faster than that in ternary system based on the simulation results.5. MD simulation was proved to be an important method which was made use of studying polymer blending and mechanical properties. It was also a promising technique to study the micromolecule diffusing in polymers.