In recent years, much attention has been focused on research to replace petroleum-based commodity plastics, in a cost-effective manner, with biobased plastics offering competitive mechanical properties. Starch is one of the important example of biopolymers. However, a major drawback associated with starchy materials is their brittleness. This is related to the glucosic chain rigidity. Therefore, they need plasticisers. In research, the most common plasticizer used for starch-based films is glycerol, due to its effectiveness, stability and low price. The purpose of this study is to improve the knowledge on the plasticization mechanisms of polar polymers in general, and more specifically here on amorphous/low-crystalline starch (amylopectin) with glycerol as a plasticizer. We are using a combined experimental and molecular dynamics (MD) approach to predict mechanical and thermal properties of the material. Several techniques are used to determine experimentally the properties of the material, including modulated DSC and tensile testing. MD simulations are conducted on 3-10 polymer chains (1176 atoms/chain) using the CHARMM and AMBER force fields. The glass transition temperatures and elastic modulus were obtained from computed specific volume-temperature curves and stress-strain curves; then compared with experimental values. The results show that the thermal and mechanical properties computed from MD simulations are in good agreement with experimental data on systems with a plasticizer content of 0-50 wt.%.

Prediction of plasticization mechanisms for biobased plastics through a combined experimental and molecular dynamics simulations approach

256th National Meeting (2018)

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