双层定向/随机冷冻对纤维素基气凝胶孔结构及吸水性能的调控OA

This study utilized carboxylated nanocellulose,polyvinyl alcohol,and whey protein isolate as matrix materials.By regulating freezing tem-perature and orientation,a bilayer directional/random frozen aerogel(DF/RF-20)was developed,combining-20℃random freezing and-196℃direc-tional freezing.It was compared with aerogels prepared under-20℃slow random freezing(RF-20),-196℃fast random freezing(RF-196),and-196℃directional freezing(DF),to investigate the effects of freezing methods on the microstructure,density,porosity,mechanical properties,and wa-ter absorption performance of the aerogels.The results showed that RF-20 exhibited large pore sizes with a dispersed pore distribution and a water ab-sorption capacity of 42.21 g/g,but poor compressive strength(44.37 kPa).DF showed ordered and dense through-pores formed from bottom to top,with better compressive performance(73.39 kPa)but weaker water absorption ability(35.80 g/g).In comparison,DF/RF-20 combined high compressive strength(73.90 kPa),excellent wet-state compressive strength(25.75 kPa at 500%water content),and good water absorption capacity(43.30 g/g).Its surface water absorption rate was approximately 15 times higher than that of RF-20.After drying at 25℃for 12 h,it demonstrated good water retention performance(water retention rate of 86.76%)and maintained stable liquid absorption capability under different pH and ionic environments.