The mechanical properties of injection molded plasticized cellulose acetate polymers processed with two different plasticizers (Triacetine and Diethyl phthalate) and various weight fractions comprised between 15 and 30 wt % have been investigated. Plasticized cellulose acetate exhibit a brittle-to-ductile transition from a low impact strength to a high impact strength of order 40 kJ/m². Obtaining a high impact resistance at room temperature requires plasticizer content larger than 25 wt.%. An important strain hardening is obtained for samples with both plasticizers during tensile experiment. At 15 wt.% plasticizer content, the measured strain hardening modulus is around 148 MPa at 60 °C. Different parameters influencing the strain hardening behavior have been identified: the tensile direction as compared to that of the injection flow, the temperature and the plasticizer, consistent with studies on pre-strained samples of synthetic amorphous polymers.
Keywords: Cellulose acetate; Impact strength; Mechanical properties; Strain hardening.
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