Morphology Of High Impact Polystyrene Research Articles

Reprocessability of high impact polystyrene/clay nanocomposites in extrusion

Plastics' recycling contributes to society with economic, social and environmental benefits. Therefore, recyclability of a material is an important environmental factor to be considered in the development of new materials, such as nanocomposites. In this study, high impact polystyrene (HIPS) and its nanocomposites with 3 and 5 wt% of Cloisite 20A were processed within four extrusion cycles in a single screw extruder having Maddock mixing section. Changes in nanostructure, in thermal, flow and mechanical properties, and in morphology of neat HIPS and its nanocomposites with reprocessing cycles were investigated. X-Ray diffractograms showed that the basal interplanar distance of clay layers increased at the first extrusion cycle, indicating the formation of nanocomposites with intercalated structure, but remained almost constant along extrusion cycles. The MEV micrographs presented improved distribution and dispersion of clay agglomerates with extrusion cycles. The melt flow index and mechanical properties showed a tendency to increase and reduce or vice-versa along extrusion cycles due to competition between crosslinking and chain scission reactions. Since the degradation mechanisms of neat HIPS and its nanocomposites were similar, the observed differences between them were related to reinforcing and barrier effect of clay, content of agglomerates, and their distribution and dispersion along extrusion cycles. A distinct mechanical behavior was observed only for 5wt% clay nanocomposite due to the high proportion of agglomerates present in this composition.

Processing-dependent high impact polystyrene/styrene-butadiene-styrene tri-block copolymer/carbon black antistatic composites

The electrical resistivity and morphology of high impact polystyrene (HIPS)/styrene-butadiene-styrene triblock copolymer (SBS)/carbon black (CB) blends were studied. Their antistatic sheets were prepared by both compression-molding and extrusion calendaring process, with their surface morphology observed using scanning electron microscopy (SEM). The SEM images reveal better dispersion of CB achieved in extrusion-calendering, resulting in low percolation threshold values in HIPS composites. Higher compression ratio and higher drawing speed (corresponding lower sheet thickness) are beneficial to get better CB dispersion, leading to decreased conductivity for the antistatic sheets. SEM images indicate that strong shear forces in extrusion tend to break the conductive network of CB, resulting in increased surface resistivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Modelling of the High‐Impact Polystyrene Morphogenesis

AbstractSummary: High‐impact polystyrene (HIPS) is a hetero‐phase polymer with the so‐called salami morphology. Salami morphology is formed by a continuous PS phase containing micron‐sized PB domains. PB domains contain submicron‐sized irregular PS occlusions. In our modeling work we addressed several weak points of Cahn‐Hilliard model of HIPS salami morphology evolution. The weakest point of Cahn‐Hilliard model is the inherently present Ostwald ripening destabilizing or competing with graft‐stabilized domains. Two mechanism of formation of HIPS morphology are supported by the model: (i) encapsulation of graft‐stabilized PS‐rich domains in PB particles, and (ii) polymerization of styrene dissolved in PB‐rich phase and subsequent phase separation leading to PS occlusions in PB domains.

Rheology and morphology of high impact polystyrene/ polyethylene blends and the effect of compatibilization on their properties

AbstractAttempts were made to study rheology and morphology of high impact polystyrene/polyethylene (HIPS/PE) blends. The Effect of compatibilization using styrene‐butadiene‐styrene copolymer (SBS) and styrene‐ethylene‐butylene‐styrene copolymer (SEBS) on their properties was also studied. The results of linear viscoelastic properties showed negative deviation of viscosity and elasticity from the mixing rules in low HIPS content blends, while positive deviation was observed for high HIPS content blends. The former was related to weak interface and the latter was attributed to the hydrodynamic interaction of PE and PB particles. A wide range of co‐continuity was observed for HIPS/PE blends which decreased using compatibilization. It was found that SEBS had better efficiency of compatibilization than SBS due to lower molecular weight and the presence of ethylene block in SEBS structure. The fracture behavior of low and high HIPS content blends showed different mechanism because of higher volume contraction of PE than HIPS in solidification process and also different mechanical properties of HIPS and PE. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Aspectos Morfológicos e Relação Estrutura-Propriedades de Poliestireno de Alto Impacto

A tenacificação da matriz vítrea de poliestireno (PS) pela adição de borracha polibutadiênica, que tem como conseqüência um aumento de sua resistência ao impacto, origina um polímero com características singulares, o Poliestireno de Alto Impacto (HIPS). Durante a polimerização in situ de estireno em uma solução de borracha, ocorre a formação de cadeias graftizadas de poliestireno no polibutadieno, as quais aumentam a interação interfacial borracha-PS. O HIPS é um material com ampla aplicação na indústria de embalagens e, principalmente, em gabinetes de refrigeradores, a chamada linha branca. O objetivo deste artigo é destacar e discutir as características estruturais e morfológicas do HIPS e a implicação destas na determinação de suas propriedades. Também foram revisadas as técnicas comumente utilizadas na caracterização morfológica e estrutural do HIPS.

Conductive polymer blends with low carbon black loading: High impact polystyrene/thermoplastic elastomer (styrene‐isoprene‐styrene)

AbstractElectrical resistivity and morphology of high impact polystyrene (HIPS)/styrene‐isoprene‐styrene copolymer (SIS)/carbon black (CB) blends were studied. Conductive CB particles locale preferentially within the HIPS phase of the HIPS/SIS blends. The blends studied remain conductive as long as HIPS maintains a continuous phase and the effective CB concentration within HIPS surmounts its percolation threshold. Thus, blends containing 2 phr CB depict significant changes in resistivity with the HIPS/SIS composition, transforming from insulative to conductive. SIS/CB mixtures exhibit an unusual behavior, explained by a physical model suggested in this paper and extended to the HIPS/SIS/CB systems.

On the form and formation of rubber particles in impact polystyrene and their relationship to natural and synthetic materials

Correlations are drawn between the morphological features of high-impact polystyrene (HIPS), bubble assemblies, adipose tissue, pith and foams. It is concluded that their morphological forms are the same and that similar interfacial tensile forces are responsible for the HIPS morphology as for the others. The synthesis of HIPS, from a solution of rubber in styrene, is discussed in terms of a phase diagram and it is concluded that the mechanism is consistent with the generation of that characteristic morphology throughout the sample in the absence of stirring and in resticted volume elements in the presence of stirring during polymerization of the styrene. An example is quoted of the generation of the same morphology in a blend prepared by mixing immiscible solutions of a homopolymer and a copolymer.