| Abstract: | Functional ultra-high molecular weight transparent styrene-butadiene block copolymer possesses both high transparency and impact resistance and has excellent comprehensive properties prior to other transparent resins. In this paper we not only use anionic polymerization process which includes 1 time addition of initiator and 3 time addition of monomers, but also introduce functional coupling agent for the fist time to prepare mentioned functional block copolymer.The typical preparation process is described as the following: (a) Adding cyclohexane, styrene and initiator to the polymerizer, the polymerization is carried out at 50～75℃; (b) adding a mixture of styrene, butadiene and cyclohexane, the polymerization is carried out at 50～70℃ ;(c) adding a mixture of butadiene and cyclohexane, the polymerization is finished at 60～70℃ ;(d) adding coupling agent which is a substituted trimethoxysilane being expressed as N-silane, O-silane and being converted into a functional group (-NH, -OH) of mentioned block copolymer, coupling at 75～90℃ for 1 hr; (e) The amounts of coupling agent are about one sixth to one third of the initiator; (f) treating the prepared copolymer solution with some water and Carbon dioxide at 50～70℃ for 15 min.The copolymer is from three-arm to six-arm mono-modal radial block copolymer having 75～90%styrene, 10～25% butadiene and functional group of-NH or-OH. of the copolymer, Mw is from 30×104 to 120×104, Mw/Mn from 2.0 to 2.5, Izod notched impact strength 50～65 J/m,light transmission not less 87.5%, tensile strength not less 45 Mpa.The exploratory research shows that the mole ratio and feed rate of the random copolymerized styrene-butadiene, as well as the total ratio of styrene-butadiene have greater influence on the properties of the copolymer. The following model is established:Y=bo +∑3j=1 bjxj+∑3j=1bkjxkxj+∑3j=1bjjx2j (k＜j)Where: Y is the light transmission, tensile strength, elongation, Izod notched impact strength and heat deflection temperature; Xj (j is 1,2,3) is the total ratio of styrene-butadiene, the mole ratio and feed rate of random styrene-butadiene.Due to the presence of these molecular internal functional groups in the polymer chains, the copolymer have special antioxidation, thermoresistance, abrasion resistance and excellent interface adhesion with other materials Compared with copolymer without the above functional groups. |
