TED-AJ03-167 INHIBITION OF RECRYSTALLIZATION OF ICE GRAINS MADE FROM POLY (VINYL ALCOHOL) SOLUTIONS
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概要
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Antifreeze proteins (AFPs) derived from fish living in cold regions prevent recrystallization of ice. From an engineering viewpoint, they are effective in preventing ice slurries from agglomeration. However, AFP is too expensive and unstable to use in practical applications. Therefore, we have proposed poly (vinyl alcohol) (PVA) as a substitute for AFP to inhibit agglomeration of ice slurries. In this study, we observed recrystallization of ice grains, the initial size of which is less than 50μm each, after 5-hour annealing at the temperature between -2.3 and -2.0℃, and then examined the effect of several additives, such as PVA, poly (ethylene glycol), poly (acrylic acid), some surfactants, and so forth, on recrystallization of ice in liquid quantitatively. Especially for PVA, we examined the effectiveness varying the concentration, molecular weight, and percentage of hydrolyzation, by using five types of PVA as shown in Table A-1. Figure A-1 shows the maximum size of ice grains made from PVA solutions as well as AFP solutions after annealing, as a function of the concentration. As the concentration, weight-average molecular weight, and percentage of hydrolyzation of PVA increased, the effectiveness in inhibiting recrystallization of ice became higher. PVA was the most effective additive after AFP in inhibiting recrystallization of ice among the additives used in this study. Further, to estimate the effect of additives on agglomeration of practical ice slurries, we measured the percentage of agglomeration of ice cubes, each measuring 7.9×7.9×5.2mm, in solutions of PVA (d), ethylene glycol, and poly (ethylene glycol), after leaving them for 4 hours at 0.0℃. Contrary to the above-mentioned results, PVA was less effective in inhibiting agglomeration of the ice cubes than ethylene glycol. These results show that the effects of additives on inhibiting recrystallization or agglomeration of ice have differences, depending on the size of ice crystals.[table][figure]
著者
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Lu Shu
School Of Chemistry And Chemical Engineering Sun Yat-sen University
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Inada Takaaki
Institute For Energy Technology National Institute Of Advanced Industrial Science And Technology (ai
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NUDEJIMA Shinichi
Institute for Energy Technology, National Institute of Advanced Industrial Science and Technology (A
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Nudejima Shinichi
Institute For Energy Technology National Institute Of Advanced Industrial Science And Technology (ai