Effects of Temperature on Dynamic Properties of a Biodegradable Polymer Made from Corn Starch

概要

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The effect of strain rate on compressive properties of starch-based biodegradable plastics (Nihon Cornstarch Co., CPR-M2) was examined. Dynamic stress-strain curves of starch-based biodegradable plastics were measured over a wide range of strain rates from 10-5 s-1 to 104 s-1, using a quasi-static compression testing machine and a split Hopkinson pressure bar (SHPB) system. The strain rate slightly affected Youngs modulus and considerably increased 7% flow stress. Empirical equation for 7% flow stress was derived for the strain rates from 10-5 s-1 to 104 s-1. In addition, the effect of temperature on Youngs modulus and flow stress was also examined in a range from 4°C to 63°C. A master curve of 7% flow stress, reduced to 24°C, was made. The values of activation energies related to the α and β relaxation processes were respectively estimated from the master curve of 7% flow stress and from the best fit of equations based on Ree-Eyring theory and Bauwens treatment. Temperature measurement of specimens was also made using thermocouples during dynamic compression.