Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 351559
Title Polylactide films formed by immersion precipitation: Effects of additives, nonsolvent, and temperature
Author(s) Sawalha, H.I.M.; Schroën, C.G.P.H.; Boom, R.M.
Source Journal of Applied Polymer Science 104 (2007)2. - ISSN 0021-8995 - p. 959 - 971.
Department(s) Food Process Engineering
Publication type Refereed Article in a scientific journal
Publication year 2007
Keyword(s) induced phase-separation - pvdf membrane formation - asymmetric membranes - systems - water - morphology - methanol - transitions - mechanism - behavior
Abstract The influence of nonsolvent, crystallinity of the polymer film, and addition of dodecane (a poor solvent for the polymer and for the nonsolvent) on the morphology of polylactides films has been investigated and was related to phase separation behavior. Both amorphous poly-DL-lactide (PDLLA) and crystalline poly-L-lactide (PLLA) were dissolved in dichloromethane, and subsequently films were made by immersion in nonsolvent baths. PDLLA gave dense films without any internal structure, since the structure was not solidified by crystallization or glassification. PLLA films show varying structure depending on the nonsolvent. With methanol, asymmetric morphologies were observed as a result from combined liquid-liquid demixing and crystallization, while with water symmetric spherulitic structures were formed. As a next step, dodecane was added, which is not miscible with the nonsolvent, and we found it to have a strong influence on the morphology of the films. The PDLLA films with dodecane did not collapse: a closed cell structure was obtained. In PLLA films, dodecane speeds up phase separation and induces faster crystallization in the films, and the porosity, size of the pores, and interconnectivity increased. When the PLLA solutions were subjected to a heat pretreatment, crystallization could be postponed, which yielded a cellular structure around dodecane, which did not contain spherulites anymore
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