Miscibility in poly ( L-lactide )-b-poly ( ε-caprolactone ) double crystalline diblock copolymers

Content Provider	Semantic Scholar
Author	Laredo, E. Abecassis De Prutsky, N. Bello, Alfredo Grimau, M. Canela Castillo, Roberto Vásquez Müller, Alejandro J. Dubois, Ph.
Copyright Year	2007
Abstract	Thermally stimulated depolarization currents, TSDC, wide-angle X-ray scattering, WAXS, differential scanning calorimetry, DSC, and polarized light optical microscopy, PLOM, have been used to examine poly(L-lactide)-b-poly(ε-caprolactone) diblock copolymers in a wide composition range. Both components are crystallizable and the miscibility in the amorphous phase has been determined from the behavior of the primary relaxations which are the dielectric manifestation of the glass transition, and also from the superstructural morphology revealed by PLOM and the compositional dependence of the melting points as determined by DSC. Distinct segmental mobilities in the amorphous phase which can be well resolved by TSDC are present; the α mode of the slower component shifts to lower temperatures as the PCL content increases while the glass transition of neat PCL is present for all compositions. A relaxation times bimodal distribution is apparent for PCL-rich copolymers. The composition dependence of the multiple glass transitions detected in these weakly segregated copolymers are predicted by the self-concentration model for a miscible blend made of components with a large Tg contrast. PACS. 64.70.Pf Glass transitions – 77.22.Gm Dielectric loss and relaxation – 77.84.Jd Polymers; organic compounds – 64.70.Nd Structural transitions in nanoscale materials
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