a b s t r a c tIn this research, a novel cryogenic CO 2 capture system based on Stirling coolers has been developed. By the capture system designed, an effective separation can be achieved according to differences in condensation and desublimation. From the capture process, H 2 O and CO 2 can condense and desublimate at different parts of the capture system, while residual gas flows out without properties change. It is noteworthy that in the process, CO 2 can be captured in a solid form, thus avoiding the use of the solvents and consideration of pressure in other methods. Furthermore, two significant parameters (the temperature of Stirling coolers and the flow rate of the gas stream) were investigated in detail. The results showed that under the optimal temperature and flow rate, CO 2 recovery of the cryogenic process can reach 96%, which demonstrated that the system can capture CO 2 gas effectively.

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The melting temperatures of a syndiotacticity-rich poly(viny1 alcohol)-water gel were measured for concentrations below 70g.d1r-~. In the gel chilled at a temperature below about 15°C the melting point first decreased monotonously then sharply in a jump and again monotonously with decreasing concentration, whereas in the gel chilled above 20°C the melting point decreased monotonously throughout. The change of the shear modulus of a gel chilled at 0°C with the rise of temperature from 0°C to the melting point was also measured. Initially the shear modulus decreased, then increased to a maximum value, and at last decreased towards the melting temperature, whereas a gel chilled at 40°C kept an almost constant value during heating from 40°C up to a high temperature and then decreased with further rise of temperature. The turbidity of dilute solutions chilled at 0°C passed a minimum and maximum with the rise of temperature in accord with the minimum and maximum of the shear modulus. It is thus concluded that in the gel chilled at temperatures below 15°C the junctions grow to some extent with the rise of temperature.

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Aqueous solutions of syndiotacticity-rich poly(vinyl alcohol) (s-PVA) form gels easily. The optimum condition of growth of the calcium tartrate crystal formed by diffusing calcium chloride into hydrogels containing tartaric acid was studied with use of s-PVA of a syndiotacticity of 56 % and a degree of polymerization of 1460. The crystal grew in the gel of the concentrations of 2 % s-PVA and of 0.5 N tartaric acid at pH = 4. The relation between the formation of Liesegang rings and shear modulus of a gel was studied by diffusing silver nitrate into gels containing potassium chromate. The distance between rings decreased with increasing shear modulus of a gel in the range from 670 to 7500 dyne/cm 2. The Liesegang rings were not formed for the shear modulus gel for 280 and 16200 dyne/cm 2.