Rubber-Toughened Styrene Polymers

Commercial Polymer Blends

“…Hence, the rubber-modified styrenics such as HIPS and ABS, which combine a good level of impact strength with moderate heat resistance, have become more widely accepted in many molding and extrusion applications. Structurally, HIPS and ABS may themselves be considered as blends, since they contain !5 % polybutadiene rubber as a discrete phase, dispersed as 0.1-5 mm-size particles in the matrix of polystyrene or SAN copolymer (Echte 1989). However, the rubber phase in these resins is incorporated during the free radical polymerization of styrene or S-AN monomer mixture via a mass, suspension, or emulsion polymerization process that results in the graft-coupling of the rubber phase to the matrix phase.…”

“…ABS/PC blend is an essentially immiscible blend (Echte 1989;Suarez and Barlow 1984;Kim and Burns 1988) with three distinct phases, viz., the PC phase, the SAN copolymer phase, and the grafted polybutadiene rubber phase dispersed within the SAN phase (as in the ABS to begin with). Depending upon the blend ratio, the continuous phase can either be the ABS (or more correctly, the SAN phase) or the PC phase.…”

Modelling of the High‐Impact Polystyrene Morphogenesis

“…The relations between morphology and application properties of HIPS, such as impact resistance and gloss, were empirically described by Echte. [1] The process of salami morphology evolution in a batch reactor with freeradical polymerization was experimentally investigated by Fischer and Hellman [2] and in a more detail by Leal and Asua. [3] These experimental studies provide a similar description of HIPS morphology evolution from the initially homogeneous mixture of polybutadiene dissolved in styrene: (i) phase separation at low styrene conversion resulting in precipitation of small PS domains, (ii) grafting reaction stabilizing PS domains by PB-g-PS chains, (iii) phase inversion at medium conversion of styrene resulting in continuous PS þ styrene phase and particulate PB þ styrene phase containing graft-stabilized PS occlusions, thus resulting in salami morphology.…”

Determinação de temperatura de transição dúctil-frágil de plásticos através de testes de impacto instrumentado

“…Estes materiais pertencem a classe dos chamados plásticos estirênicos sendo obtidos através da interpolimerização de copolímeros de estirenoacrilonitrila com borracha de polibutadieno. As propriedades de impacto desses materiais dependem fortemente da morfologia e das características intrín-secas dos componentes do sistema tenacificado -basicamente da estrutura e dispersão da fase rica em polibutadieno na matriz SAN e da quantidade de SAN enxertado em relação ao SAN total presente na mistura [12] . A utilização de impacto instrumentado na caracterização do ABS permite o monitoramento das componentes parciais de energia de impacto e determinação de transições dúctil-frágil como função da morfologia do sistema ou da temperatura de teste.…”