Study Of Synthesize Butadiene-Styrene Diblock Copolymer Used For Enhancing The Toughness Of Polystyrene

Butadiene styrene diblock copolymer is a material with low solution viscosity, low gel content and high grafting efficient. Hence ,it is a good toughness enhancer in HIPS and ABS manufacture. In this thesis,investigation has been carried out in the butadiene-styrene copolymer LBS 1601,a grade specially used for ABS with Sinochem International's continous bulk technic. Focus is on the improvement of fluctuation of Mooney viscosity and 55st solution viscosity,as well as gel accumulation.(1) Different polymerization methods was studied. With "one step method",e.g.polymerization was initiated as monomers butadiene and styrene all exist in system, high quantity of styrene taper-block exists in the SB product.while,with the method of polystyrene block first,and then the polybutadine block,SB block copolymer can be obtained,but an impurity of styrene monomer always generates. It was found that with the polymerization process of polybutadiene block first,both styrene taper-block and monopolymer peak did not appear, the ~1H-NMR shows that increase of the reaction time can not reduce the mass of styrene non-block. The TEM shows the result that the SB diblock with 15%st has the similar morplology as the sample with styrene content 20%,25%,30%.The DSC result shows that LBS1601 we synthesizd has the same Tg with 610A.The dynamic rheology demonstrated that SB diblock of 15% st has the same rheological behavior with that of 20% st,but different from 610A which has the content of styrene 17%.(2)The relation of Molecular weight, bonded styrene , mass of non-block and the mooney viscosity, 5%SV.was studied.The results shew that with the increase of molecular weight and the reduce of bonded styrene, 5%SV increased. With the increase of molecular weight bonded styrene Mooney viscosity increased,mass of non-block has an effect to Mooney viscosity.(3) In the experiment range, monomer concentraion, molecular weight did not cause gel accumulation in the system.Temperature is main factor that caused gel. 1,2-Butadine was an efficient gel deminator ,though it can reduce the rate of polymerization and widen the molecular mass distribution if unsuitable adding quantity.