| 研究実績の概要 |
In the studies performed before April 2014, we discovered that changing the concentration of poly lactic acid (PLA) in a solution of PLA in dichloromethane yield to a change in the Henry’s law constant for nitrogen. This is crucial because if the solubility of gases in polymer solvents is an important consideration in removing volatile gases from the polymers, we have one more parameter available for designing microcellular/foam or for fabricating biodegradable hollow microcapsules and porous films, which is the final objective of our study.
In the studies performed after April 2014, the effect of dissolved PLA on the solubility of gases (carbon dioxide, nitrogen, and helium) in dichloromethane was investigated, between 288 and 303 K, by measuring the equilibrium pressure in a closed vessel containing a gas and dichloromethane solutions of different types (molecular weights) and concentrations of PLA. The results showed that, in the absence of PLA, the order of the solubility of gases in dichloromethane was helium < nitrogen < carbon dioxide. Furthermore, an increase in the concentration of PLA did not appreciably change the solubility of carbon dioxide in the solutions, but led to a higher solubility of nitrogen and He. The effect of PLA on the increase of gas solubility in dichloromethane was larger for less soluble gases. Semi-empirical correlations of the dependence of the Henry’s law constant of the gases on the temperature and PLA concentration were also derived from the measured data.
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