以硅酸钠和硝酸为原料,采用溶胶-凝胶法制备了硝酸钠/氧化硅(NaNO3/SiO2)复合定形相变材料,分析了材料的组成、物相、热稳定性和相变性能.结果表明,原位生成的NaNO3作为相变物质分散在载体SiO2的多孔网络结构中形成定形相变材料,仅是NaNO3与SiO2的物理复合,制备和焙烧过程中都没有产生新物质.材料在低于600℃时具有良好的热稳定性,融熔热和结晶热分别为144.1和142.6 k J/kg,融熔和结晶温度分别为302.3和301.2℃.经100次热循环后,材料的相变热和相变温度基本保持不变.
The melting and recrystallization behaviour of poly（vinylcyclohexane）-b-poly（ethylene）-b-poly（vinylcyclohexane）（PVCH-PE-PVCH） triblock copolymer in supercritical carbon dioxide(CO2) was investigated by（using） of DSC.The effect of the rate of the depressurization of CO2 on the crystallization of the samples was also examined.It is found that there are three melting peaks on each DSC curve of the samples treated in supericritical CO2 at the temperature above tm of the untreated PVCH-PE-PVCH.They corresponded to the 'hard' confined crystallization of PE blocks homogeneous nucleation,the 'soft' confined crystallization of PE blocks homogeneous nucleation and the self-seeding nucleation free crystallization of PE blocks respectively.Furthermore,these three kinds of crystallization could be controlled by changing the competition between the crystallization of PE block and the vitrifaction of PVCH block in the samples,which depended on the rate of the depressurization of CO2.
