Examination of starch preprocess drying and water absorption of injection‐molded starch‐filled poly(lactic acid) products

This article focuses on the drying of native maize starch before compounding with poly(lactic acid) (PLA) and on the water absorption of injection-molded starch-filled PLA products. The mass loss of starch was examined while drying in a vented oven at various temperatures, and a proposal was made for complete drying. A temperature-dependent mathematical model was established to describe the moisture loss of native starch. The dried starch was mixed with PLA, compounded with a twin-screw extruder, and finally injection-molded into 80 × 80 mm2 area, 2-mm-thick flat specimens. These specimens were placed into distilled water to analyze the water uptake and the change in mechanical properties and deformation caused by water uptake for 1 month. Another mathematical model was established to describe the water absorption of the specimens. With the proper drying of starch and PLA, a 30 wt% starch content PLA product was injection-molded with significantly higher tensile strength compared with literature data. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

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