Search

The morphology formation in the blends comprising a high density polyethylene (HDPE) and selected ethylene/1‐octene copolymers (EOCs) was studied with variation of blend compositions using atomic force microscopy (AFM). The binary HDPE/EOC blends studied showed well phase‐separated structures (macrophase separation) in consistence with individual melting and crystallization behavior of the blend components. For the blends comprising low 1‐octene content copolymers, the lamellar stacks of one of the phases were found to exist side by side with that of the another phase giving rise to leaflet vein‐like appearance. The formation of large HDPE lamellae particularly longer than in the pure state has been explained by considering the different melting points of the blend components. The study of strain induced structural changes in an HDPE/EOC blend revealed that at large strains, the extensive stretching of the soft EOC phase is accompanied by buckling of HDPE lamellar stack along the strain axis and subsequent microfibrils formation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1887–1893, 2007 [ABSTRACT FROM AUTHOR]

Correlation between morphology and micromechanical deformation behaviour of blends consisting of a lamellae-forming linear styrene/butadiene block copolymer and polystyrene homopolymer (hPS) was studied by different microscopic techniques (transmission electron microscopy and scanning electron microscopy) and rheo-optical Fourier transformed infrared spectroscopy. Attributable to a change in morphology from well-ordered lamellae to a distorted one, a transition in deformation mechanism from homogeneous plastic flow of the lamellae to formation of local craze-like deformation zones was observed on addition of hPS. The latter led to a drastic reduction in elongation at break. An abrupt depression in the degree of orientation of the polystyrene (PS) and the polybutadiene (PB) phases in the blends suggested that the failure occurs at the interface between the added hPS and PS blocks of the block copolymer. [ABSTRACT FROM AUTHOR]

The micromechanical behaviour of multilayered tapes made of two brittle incompatible amorphous polymers PS and PMMA was studied by means of an optical and a High Voltage Electron Microscope (HVEM). Microlayers of PS and PMMA were coextruded with varying number of layers: 64, 512 and 4096 layers. Mechanical properties of the PS/PMMA tapes were also examined. An increase in layer numbers was found to lead to a decrease in layer thickness that, in turn, resulted in: a) formation of thicker and longer crazes and, therefore, increased volume of the material involved in the plastic deformation; b) a noticeable increase in strength and strain at break (i.e. of toughness) of the samples. Enhanced toughness of the multilayered tapes is accounted for by massive cooperating crazing and yielding of both PS and PMMA phases. [ABSTRACT FROM AUTHOR]