Resumo

ENRIQUEZ-MEDRANO, Francisco Javier et al. Synthesis and Characterization of NBR's by RAFT Technique and their use as Rubber Precursor in ABS Type Resins. J. Mex. Chem. Soc [online]. 2014, vol.58, n.2, pp.194-201. ISSN 1870-249X.

Different rubbers based on polybutadiene were synthesized in solution by the reversible addition-fragmentation chain-transfer polymerization (RAFT) technique using 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl] pentanoic acid as RAFT agent and 1,1'-azobiscy clohexanecarbonitrile (Vazo-88) as initiator. The results obtained in the polymerization of polybutadiene and poly(butadiene-co-acrylonitrile) (NBR) are discussed in terms of molecular weight distribution, composition and microstructure. Composition of polybutadiene in NBR's was kept constant along the copolymerization, and the vinyl, cis and trans isomers are shown in values of around 12, 26 and 62% in all cases. Resulting rubbers were used to synthesize acrylonitrile-butadiene-styrene (ABS) type resins through an in situ bulk polymerization. Dynamic-mechanical properties and the morphology were analyzed in all the different ABS resins. In DMA analyses, the rubber component presented two transitions as well as an increase in the magnitude of the transition located around -75 °C, which is explained by the significant amount of SAN occlusions in the morphology, analyzed by TEM.

Palavras-chave : Nitrile rubber; RAFT; ABS resin; TEM; DMA.

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