Real-time monitoring of segmental dynamics during crystallization of poly(l(-)-lactide) by simultaneous DRS/SALS technique |
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Authors: | Benjamin D Fitz,Sa&scaron a Andjeli? |
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Affiliation: | Department of Polymer and Suture Technologies, Ethicon, a Johnson and Johnson Company, P.O. Box 151, Route 22, West Somerville, NJ 08876-0151, USA |
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Abstract: | A novel experimental set up consisting of dielectric spectroscopy and small angle light scattering (or potentially any other optical technique used in combination) is introduced. The sample is enclosed in a Dielectric-Optical-Shear (DOS) cell capable of precisely controlling temperature and thickness. This method allows for simultaneous in situ, real-time monitoring of the changes in the molecular dynamics and corresponding development of supramolecular structure of a given polymer system during various time-sensitive processes. The DOS cell is utilized to investigate relaxation phenomena related to the glass transition, Tg, of poly(l(−)-lactide) during isothermal crystallization under quiescent, partially constrained conditions. A decrease in Tg was observed in situ via a shift in dipolar relaxation to higher frequency (confirmed calorimetrically, ex situ). The shift was most rapid in the spherulitic impingement stage of crystallization, at approximately 30% overall crystallinity. |
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Keywords: | Dielectric spectroscopy Small-angle light scattering Poly( smallcaps" >l-lactide) |
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