Modificação quimica da borracha natural pela tecnica de polimerização em emulsão poe semente : propriedades coloidais, estrutura quimica e comportamento viscoelastico

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The chemical modification of natural rubber (NR) by grafting of copolymers in the backbone of the hydrophobic substrate, poly-cis-isoprene, by free radical polymerization, using a seeded emulsion polymerization system, has been demonstrated. Two copolymers were grafted, a hydrophilic of dimethylaminoethylmethacrylate (DMAEMA) or a hydrophobic of methyl methacrylate (MMA) in the sites of grafting from a couple of redox initiators, CHP and the base TEPA, at low temperature. The hydrophobic seed of poly-cis-isoprene, as natural rubber latex (NRL), was grafted with poly-DMAEMA to form a copolymer in the core-shell morphology type "hairy-Iayer" -a diffuse layer of hydrophilic chains grown from radicais created on the surface of the NR particles. On the other hand the grafting with poly-MMA formed the same core-shell morphology, this time named inclusion or "fruit-cake" - domains of hydrophobic chains grown from radicais created inside the particles of the seed. The modified natural rubber was characterized in terms of colloidal properties, chemical structure and viscoelastic behavior. The results from this work showed that the grafted rubber became more resistant to deformations as weIl as more hydrophilic, increasing its utilization in others segments of the rubber industry, specialIy in the formulations of blends and composites, recycling of tires and civil construction

ASSUNTO(S)

polimerização em emulsão borracha quimica da borracha

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