Abstract
In a first step, 1,3-butadiene was selectively polymerized at 60°C in styrene as solvent using NdV3/DIBAH/EASC as the catalyst system. The catalyst system activation process, the addition order of monomers and catalyst components, and the molar ratios [Al]/[Nd] and [Cl]/[Nd] were studied. The catalyst system allowed the selective 1,3-butadiene polymerization, reaching conversions between 57.5 and 88.1% with low polystyrene contents in the order of 6.3 to 15.4%. Molecular weights ranging from 39,000 to 150,000 g/mol were obtained, while cis-1,4 content was found in the interval of 94.4 to 96.4%. On the other hand, the glass transition temperatures of synthesized materials were established in the range of −101.9 to −107.4°C, explained by the presence of polystyrene segments in the polybutadiene chains; in the same sense, the polybutadienes did not show the typical melting endotherm of high cis-polybutadienes. In a second step, the resulting styrene/high cis-1,4 polybutadiene solutions were used to synthesize ABS (adding a fraction of acrylonitrile monomer) and HIPS via in situ bulk polymerizations and the results were discussed in terms of morphological development, molecular parameters, dynamical mechanical behavior, and mechanical properties.
Highlights
IntroductionThe versatility of the Nd-based catalyst systems has enabled the synthesis of PB even using styrene as a solvent, as reported by Hsieh and Yeh [7] with the binary system NdX3⋅nD/AlR3
The 4f-orbital electrons of neodymium- (Nd-) based catalyst systems, either binary (NdCl3⋅nL/aluminum alkyl, where L = ligand) or ternary (Nd(carboxylated)3/aluminum alkyl/aluminum alkyl halide), constitute an effective option for the stereospecific polymerization of 1,3-dienes [1]
A typical polymerization procedure carried out in runs R1 to R5 and R11 is described as follows: the desired volume of styrene was added to the reactor and it was heated to the set temperature under constant stirring of 100 rpm; thereafter, the reactor was filled with 1,3-butadiene and the catalyst system was added to the reactor in the order by means of a syringe, (i) diisobutylaluminium hydride (DIBAH), (ii) NdV3, and (iii) ethylaluminium sesquichloride (EASC)
Summary
The versatility of the Nd-based catalyst systems has enabled the synthesis of PB even using styrene as a solvent, as reported by Hsieh and Yeh [7] with the binary system NdX3⋅nD/AlR3 The relevance of this feature of Nd-based catalyst systems is the fact that the reaction product, styrene/PB solution, can be used to produce toughened styrenic resins through the in situ bulk polymerization process. The effect of different aspects of the catalyst system based on NdV3/DIBAH/EASC preparation is reported and systematically discussed, such as addition order of components for in situ and ageing preformation process for catalyst activation and ageing time as well as the [Al]/[Nd] and [Cl]/[Nd] molar ratios on the monomer conversion, microstructure, and physicochemical characteristics of the resulting PB obtained with the ternary catalyst system NdV3/DIBAH/EASC in styrene as reaction medium. Using several PB/styrene solutions and via in situ bulk polymerization by a free radical process, different toughened styrenic resins were obtained and analyzed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
