Copolymerization Of Ethylene (Propylene) And Conjugated Dienes And Functionalization Of The Copolymers

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, chromao'city, hydrophilicity, comparability and paintability are paramaount. So it is important to prepare the functionalized polyolefins to improve their poor interactive properties. Theoretically, there are three possible approaches to prepare the functionalized polyolefins. They include (1) direct copolymerization of a-olefin with functional monomer, (2) chemical modification 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 have been synthesized by reactive copolymer approach. The copolymerization of ethylene (propylene) and 1,3-butadiene with a newly non-heterogeneous Ziegler-Natta catalyst was described. During the coordination polymerization, trialkylalumium was used as the co-catalyst and n-hexane 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)/l,3-butadiene were effectively performed by these kinds of catalysts. The products have been confirmed to be copolymers containing long ethylene-ethylene (propylene-propylene) and butadiene-butadiene sequence by FTIR, 'H-NMR, 13C-NMR. In the copolymer of ethylene/butadiene, butadiene is incorporated in blocks of trans-l, 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 also studied. The experimental results indicate suggest that the above copolymerization conditions have different effect on the structure and properties of copolymers. The molecular weights and melting point of the copolymers 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 thepolymers easier to be modified. In addition, Mw of the grafted copolymers are hardly decreaed by GPC. Tm and Tc of PEB-g-MAH are decreased but those of PPB-g-MAH are increased.