| Ethylene-Vinyl Acetate Copolymer(EVA),with the improved flexibility,transparency,impact resistance and heat-sealing performance because of the introduction of vinyl acetate monomer(VA),is widely used in agricultural films,foam shoes,packaging film,pour point depressant,wire and cable and hot melt adhesives and other fields.However,as a material,some disadvantages of EVA,such as poor material compatibility,high brittleness at low temperature,and poor adhesion performance,limit its further application.The preparation of EVA grafted polymers by graft polymerization can achieve longevity and avoidance,improve its performance and broaden its application field.In recent years,the application of various types of graft polymers in the field of electro-spinning and blending compatibilizers has become a research hotspot.In this paper,EVA-g-MAH graft polymers were synthesized by solution grafting method,and the microspheres and microfibers were prepared by electro-spinning for the first time.The EVA-g-MAH graft polymer was used as a blend compatibilizer to mechanically blend two polymer blend systems.EVA is one of the most widely used as crude oil pour point depressants.The wax crystals in crude oil undergo eutectic action with the main chain polyethylene groups.The polar VA groups adsorb wax crystals to interfere with their growth and thus reach the pour point of pour point effect.However,as the composition of crude oil extracted becomes more and more complex,the effect of EVA on dewetting is obviously poor.Therefore,it is of great significance to develop new EVA copolymers and their derivative pour point depressants.Through the following parts of the dissertation research :(1)EVA-g-MAH graft polymers with grafting ration of 4.87 mol%-12.3 mol% were synthesized by solution grafting method.The EVA-g-MAH microfibers were first prepared by electro-spinning,and the effects of polymer concentration on the morphology of the microfibers were studied.The role of EVA-g-MAH graft polymer in compatibilizing the HDPE/PC blend system and improving the impact resistance of PA6/EVA blends was investigated.(2)A monomeric N-octadecylmaleimide(NODMI)was synthesized and EVA-g-NODMI polymers with different grafting ratios(22.98 mol%-36.36 mol%)was prepared by solution grafting method.The chemical structures of NODMI and EVA-g-NODMI were confirmed by high temperature1H-NMR,13C-NMR and FT-IR analysis.(3)By the hydrolysis,a copolymer(EVAL)with a hydroxyl group in the side chain wasconverted from EVA and transformed to the chain transfer agent EVAL-CTA1 by the reaction with acyl chloride.Then,RAFT polymerization of vinyl acetate(VA)is carried out with EVAL-CTA1 as chain transfer agent.The EVAL-g-PVA graft polymer with a specific structure was finally synthezied and its chain structure was determined by high temperature1H-NMR and FT-IR.(4)Study on the pour point depressing performance of synthesized EVA graft polymer in wax-containing simulation oil system: through freezing point test,differential scanning calorimetry(DSC)determination,wax crystal morphology polarization microscope observation and rheological curve.The tests were performed to characterize the relative performance of wax-containing simulated oil systems before and after addition of pour point depressant.The effect of EVA-g-NODMI(29.19 mol%)grafted polymer on the deagglomeration of Daqing crude oil was preliminary investigated,and the research and development ideas for pour point depressant were improved. |
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