Preparation Of High Impact Polystyrene Via Neodymium SIBR Based On In-situ Bulk Polymerization

The in-situ bulk polymerization method of high impact polystyrene (HIPS) get rid six production sections of the traditional bulk method. With the simple and efficient process, the method has a broad prospect of industrial application. But the impact modifier is confined to polybutadiene rubber and styrene-butadiene rubber. In this paper, HIPS with remarkable toughening effect are prepared based on in-situ bulk polymerization process, using poly(styrene/isoprene/butadiene) terpolymer synthesized by neodymium rare earth catalysts (Nd-SIBR) as impact modifier and the impact strength of HIPS could be up to24.8kJ/m2.The ternary integrated rubber Nd-SIBR are synthesized successfully by using bis(2-ethyl hexyl)phosphonic acid ester neodymium (Nd(P204)3, Nd), diisobutyl aluminium hydride (Al(i-Bu)2H, Al) and chloroform (CHCl3, Cl) as neodymium rare earth catalyst, with styrene as solvent and monomer, isoprene and butadiene as monomers. The effect of the process parameters such as dosage of catalyst, ratio of monomers are examined on the terpolymerization. The results show that the styrene mother liquor of Nd-SIBR could be synthesized under the conditions of a catalyst mole ratio of [Al]/[Nd]=10-20,[Cl]/[Nd]=3-9,[Nd]/(Bd+Ip)=(6-8)×lO-6mol/g, a monomer weight ratio of St/Ip/Bd=(5～10)/1/1, and the polymerization temperature of50℃for6h. The Nd-SIBR are random distribution terpolymers with the conjugated diene component of cis1,4-structure content which could be greater than94%and the controllable content of each component, molecular weight.The HIPS are prepared successfully based on the in-situ bulk polymerization method using the synthesized styrene mother liquor Nd-SIBR, with the bifunctional oxide DP275B and three faculties oxide TETMTPA as initiators. When Nd-SIBR content raises from10%to29%, the impact strength of HIPS resin increases from5.3kJ/m2to22.2kJ/m2, elongation at break increases from7.4%for nearly13times.The impact energy factor of HIPS which calculated by the instrumented impact curves can be the quantitative characterization of the brittle-ductile changes. The Section morphology by scanning electron microscopy (SEM) analysis can discuss the toughening mechanism of the material:with the increase of Nd-SIBR content, HIPS transform from brittle to ductile, and the toughening reasons change form cavitation effect to crazing cut, shear yield effect.