Synthetic Of Functional Polyolefin Copolymers And Stuctural Characterization

The non-polarity and low surface energy of polyolefins has limited their applications,especially in the areas of coating,blends,and composites,in which adhesion,chromaticity,hydrophilicity,comparability and paintability are paramaount.So it is important to prepare the functionalized polyolefins to improve their poor interactive.Theoretically,there are three possible approaches to prepare the functionalized polyolefins.They include(1) direct copolymerization ofα-olefin with functional monomer,(2) chemical modifcation of the performed polymer,and(3) reactive copolymer approach,incorporating reactive comonomers that can be selectively and effectively interconverted to functionalized groups.In this paper,functionalized polyethylene and polypropylene has been synthesized.The copolymerization of ethylene(propylene),butylene and 1,3-butadiene with a newly non-heterogeneous Ziegler-Natta catalyst was described. During the coordination polymerization,n-hexane was used as the solvent.The influences of Al/Ti ratio,reaction temperature,pressure,the amount of 1,3-butadiene etc,on copolymerization activity were investigated.It was found that the copolymerization of ethylene(propylene)/bulylene/1,3-butadiene were effectively performed by these kinds of catalysts.The products have been confirmed to be copolymers containing long ethylene-ethylene(propylenepropylene) and butadiene-butadiene sequence by FTIR,¹H-NMR,¹³C-NMR.In the copolymer of ethylene/bulylene/butadiene,propylene/butadiene is incorporated in blocks of trans-1,4-units,while there are some amount of 1,2-butadiene units in propylene/butadiene copolymer.Influences of copolymerization conditions on copolymers structure and property were studied. The molecular weights and melting point of the polymers are strongly decreased with the increase of the amount of butadiene.The grafting of maleic anhydride(MAH) on to the copolymers was studied in solution.Benzoyl peroxide(BPO) and xylene were used as initiator and solvent respectively.The effects of reaction conditions,such as time,reaction temperature, the amount of BPO and MAH,the content of butadiene in copolymers on grafting ratio(Gr) and grafting efficiency(Ge) were investigated.The experimental results suggest that the presence of a small amount of unsaturated units greatly promotes the reactivity of polymers for graft reaction,which makes the polymers easier to be modified.In addition,M_w of the grafted copolymers were almostly not decreaed by GPC.T_m and T_c of PEB-g-MAH were decreased but those of PPB-g-MAH were increased.