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Blending and foaming thermoplastic starch with poly (lactic acid) by CO 2 ‐aided hot melt extrusion
Author(s) -
Chauvet Margot,
Sauceau Martial,
Baillon Fabien,
Fages Jacques
Publication year - 2021
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.50150
Subject(s) - extrusion , thermoplastic , materials science , supercritical fluid , plastics extrusion , lactic acid , porosity , rheology , starch , composite material , expansion ratio , reactive extrusion , chemical engineering , chemistry , organic chemistry , biology , bacteria , engineering , genetics
Biomaterials are materials that can be biodegradable or obtained from renewable resources. Among them, poly (lactic acid) (PLA) and thermoplastic starch (TPS) represent an interesting alternative to replace petro‐sourced thermoplastics. In this study, blends made by TPS addition to PLA were subjected to a foaming process using supercritical CO 2 ‐aided extrusion. Extruder die temperature and CO 2 content were the most prominent parameters explaining the structure of the foams obtained. Both parameters were intimately linked since the CO 2 flow depends on the melt temperature, the lower the temperature, the higher the CO 2 solubility. Therefore, the die temperature was chosen to pilot the process. Whatever the experimental conditions, a 50/50 (in wt%) blend was poorly foamed due to the strong incompatibility between both biopolymers. However, the blend made of 80 wt% PLA and 20 wt% TPS gave evenly foamed samples. In terms of expansion and type of porosity this blend behaved like pure PLA with high porosity, up to 96%, and the presence of a threshold die temperature separating a close cell porosity at lowest temperatures and an open cell structure above the threshold. This temperature threshold was however significantly lower to that obtained with pure PLA.