孔隙率对多孔聚乙烯醇缩甲醛凝胶性能的影响

通过成孔剂法制备不同孔隙率的聚乙烯醇缩甲醛凝胶(PVFM)，其具有对含水量变化快速响应的特性，研究其在吸水、脱水过程中孔隙率对体积、质量、力学性能变化的影响。研究表明，多孔凝胶的孔隙率越高，其吸水、脱水的速度越快。而其力学性能及随含水量变化的敏感性却相应降低。在流量控制、湿度调节等多孔凝胶驱动控制的系统中．缩短凝胶响应时间的同时，要保证其力学行为随含水量变化的敏感性。

EFFECTS OF POROSITY ON PROPERTIES OF MACROPOROUS POLY(VINYL FORMAL) HYDROGELS

The nonionic poly(vinyl formal) hydrogels with different porosities were synthesized by adding pore-forming agents, their swelling/deswelling behaviors and mechanical properties were measured in order to evaluate the effects of porosity. The swelling/deswelling behaviors of hydrogels are depended strongly on the pore diameter and quantities. Higher the porosity, more the absorbed water, faster the response rate. However, the mechanical properties, e.g. swelling pressure, compressive modulus and so on, decrease with the increase of porosity; furthermore, the sensitivity of mechanical behavior to water content decreases accordingly too. In the hydrogel-actuated intelligent material structure and system, selecting the hydrogels with optimum porosity as sensor and actuator is necessary to ensure the fast response rate and the satisfied mechanical behaviors.