Relationship between the structure and thermophysical property of a starch-synthetic polymer composite under heated and pressurized conditions

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Use of agriculturally derived products such as starch and replacement for totally synthetic polymers reduce our dependence on petrochemically derived monomers, and are currently an active research area because of the biodegradability of these plant-derived materials, It is important to acquire the fundamental data such as the thermophysical properties for the design and optimization of the apparatus to produce such materials, In the present work, the thermal conductivity of a starch-synthetic polymer composite was measured under heated and pressurized conditions, and the following conclusions were obtained.1) Development of the probe to measure thermal conductivity of the materialThe probe for thermal conductivity measurement of food materials under heated (- 150ﾟC) and pressurized conditions (-20MPa) has been developed, being based on the transient hot wire method.2) Thermal conductivity measurement of starch gelAfter the validity of the data measured using the probe was verified by c … More omparison with published data of water, the thermal conductivity of gelatinized potato starches was determined at 25-80ﾟC, 50-80 % moisture, and 0.2-10 MPa. It was found that the thermal conductivity of the starch gel increases with temperature and moisture content, and that it increases with pressure up to I MPa, above which it remains almost constant. The pressure dependency can be justified by considering the presence of entrapped fine air bubbles which could have penetrated into the sample during the preparation process.3) Thermal conductivity measurement of starch-synthetic polymer compositeThe thermal conductivity of starch-graft-poly(methylacrylate), which was prepared by ceric ammoniumnitrate-initiated polymerization of methylacrylate onto granular corn starch, was determined at 20-80ﾟC, 7-35%moisture and 0.2-8 MPa. It was found that the thermal conductivity increases with temperature and moisture content, although the temperature dependency is so small. Also, the thermal conductivity increases with pressure due to the same reason as 2). Less