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Type: Artigo de periódico
Title: Structure and morphology of poly(epsilon-caprolactone)/chlorinated polyethylene (PCL/PECl) blends investigated by DSC, simultaneous SAXS/WAXD, and elemental mapping by ESI-TEM
Author: Plivelic, TS
Cassu, SN
Goncalves, MD
Torriani, IL
Abstract: In this work, the structure and morphology of miscible blends of poly(epsilon-caprolactone) and chlorinated polyethylene with 48% chlorine weight content (PCL/PECl) were studied by differential scanning calorimetry (DSC), simultaneous small and wide-angle X-ray scattering (SAXS/WAXD), and electron spectroscopy imaging in the transmission electron microscope (ESI-TEM). A unique glass transition temperature was obtained in each blend. In addition to this, the heat capacity and the width of the glass transition did not have a linear behavior with blend compositions. These facts correlate with the presence of microheterogeneities originated from different local compositions and densities of interactions in each blend. A consistent picture of the mode of segregation of PECl in the blend was obtained. For higher concentration of PCL, the volume fraction of lamellar stacks in the samples decreased as a function of the PECl content, indicating preferential interfibrillar localization of the amorphous component. For lower PCL concentration, interespherulitic segregation was the dominant mode. Elemental maps of chlorine confirmed these results and also revealed changes in the concentration of this element depending on its localization in the microstructure of the system. Gradients of chlorine concentration were measured in larger amorphous regions of the 40/60 and 20/80 PCL/PECl blends. Calculations of the one-dimensional correlation function probed the reduction of the lamellar thickness of PCL when the quantity of PECl in the blend was increased. Such a tendency could be rationalized if the reduction of the fold surface free energy was a dominant factor in terms of the reduction of the degree of supercooling in the final crystal thickness.
Country: EUA
Editor: Amer Chemical Soc
Rights: fechado
Identifier DOI: 10.1021/ma061265m
Date Issue: 2007
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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