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Authors
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Zhang, Y.L. ; Müller, M.T. ; Boldt, R. ; Stommel, M.
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Title
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Crystallinity effect on electron-induced molecular structure transformations in additive-free PLA
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Date
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16.01.2023
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Number
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60863
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Abstract
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Additive-free biodegradable polylactides (PLAs) with different crystallinities from 0 to 13.3% (according to x-ray diffraction, XRD) were used as starting materials modified by the electron beam (EB) with several irradiation doses at 25 °C (below glass transition temperature, <Tg) and 80 °C (>Tg) in nitrogen. The crystallinity effects on radical decay and molecular structure transformation were investigated. After irradiation, the main stable radical remained in PLA is –O–C*(CH3)–CO–. During irradiation, radical reactions were inhibited by high crystallinity. Large amounts of EB-induced crosslinking and long-chain branching (LCB) were introduced by performing irradiation at 80 °C. An increasing crystallinity has been found that restrained crosslinking and LCB due to the poor chain mobility in the crystalline areas. An increase of crystallinity from 0 to 13.3% obviously decreased the saturated crosslink content from 65% to 43% and restrained LCB formation. This study also verified that strict moisture control combined with applying an irradiation temperature above Tg can be a universal method to introduce large amounts of crosslinking and LCB in different grades of additive-free PLA.
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Publisher
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Polymer
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Wikidata
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Citation
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Polymer 265 (2023) 125609
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DOI
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https://doi.org/10.1016/J.POLYMER.2022.125609
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Tags
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