Studies on Toughening of Polylactic Acid by Melt-blending with Polyurethane
Date Issued
2008
Date
2008
Author(s)
Lai, Yi-Sheng
Abstract
To toughen polylactic acid (PLA), biodegradable polyurethanes (PUs) synthesized from different types and molecular weights of polyol were melt-blended with the PLA. Mechanical properties, thermal properties, crystalline properties, morphology of fracture surfaces, and toughening mechanism of the blends were compared and discussed. The blends were characterized as an immiscible system for their individual glass transition temperatures in the differential scanning calorimeter (DSC) test. The elongation at break was significantly increased even though only 10% PU was added to the PLA, indicating the toughening effect of the PU on the PLA. The tensile strength was also increased when 10% PU added. But the tensile strength and elongation at break were lower for the PU content more than 30% because of the macro-phase separation. The mechanical properties of the PLA/PU blends were influenced by the crystallinity and crystallization speed of the PU. The blends were more flexible and tough materials and necking formation was observed during the tensile test.
Subjects
Biodegradable
PLA
PU
Polymer blends
Toughening
Type
thesis
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