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|Type:||Artigo de periódico|
|Title:||Precipitation of LDPE-EPDM and LDPE-EVA mixtures from ternary solutions|
|Abstract:||The fast precipitation of mixtures of low-density polyethylene (LDPE) with ethylene-propylene-diene terpolymer (EPDM) and ethylene-vinyl acetate (EVA) copolymer, from xylene solutions by cooling, leads to fractionation of the mixtures; LDPE/EPDM mixtures are also fractionated by cooling followed by nonsolvent addition. Studies by density-gradient centrifugation, IR spectroscopy, optical microscopy and wide-angle X-ray diffraction showed that the composition and morphology of LDPE/EPDM fractions depend on the precipitation procedures. LDPE crystalline structure in each fraction is different, changes with the time and depends on EPDM content. EVA fractions that co-precipitate are richer in -CH2-CH2-units. LDPE/EPDM and LDPE/EVA precipitates showed chemical composition distribution and morphological characteristics different among themselves. Larger aggregates were observed in the LDPE/EPDM precipitates. These differences were attributed to differences in the phase diagrams and in the phase separation mechanisms. (C) 1997 Elsevier Science Ltd.|
|Editor:||Pergamon-elsevier Science Ltd|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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