基于高缠结纤维素水凝胶的力学作用机制研究

Mechanical Action Mechanism Study of High Entangled Cellulose

采用丙烯酰胺(AM)和羧甲基纤维素(CMC)构建高力学性能双网络(DN)水凝胶,探讨第一网络聚丙烯酰胺(PAM)的交联与缠结以及第二网络CMC的氢键作用,对水凝胶力学性能的作用机制。研究结果表明:对于第一网络,PAM在C=10^(-5)(C=n_(交联剂)/n_(单体)为水凝胶的交联度)下能形成显著的缠结结构,在应力作用下能通过滑动分子链逐渐形成缠结结构来实现能量耗散;PAM在C=10^(-2)下会形成高交联网络,在应力作用下通过化学键的断裂来耗散能量。对于第二网络,当水凝胶中CMC的质量分数Q=5.0%时,通过冻融能形成显著的氢键,并有效提高网络的作用力,从而提高水凝胶的力学性能。在C=10^(-5)、Q=5.0%时,水凝胶的应力达到0.328 MPa。CMC较大的渗透压会引起凝胶的溶胀,降低聚合物密度。此外,引入CMC还会影响第一网络PAM的缠结结构。

Double network(DN)hydrogels with high mechanical properties were constructed by acrylamide(AM)and carboxymethyl cellulose(CMC).The mechanism of crosslinking and entangling of the first network polyacrylamide(PAM)and hydrogen bonding of the second network CMC on the mechanical properties of the hydrogel was investigated.The results show that,for the first network,PAM can form a significant entanglement structure at C=10^(-5)(C=n_(crosslinking agent)/n_(monomer)is the crosslinking degree of hydrogel),and can gradually form entanglement structure by sliding molecular chains under stress to achieve energy dissipation.PAM forms a highly crosslinked network at C=10^(-2),dissipating energy through the breaking of chemical bonds under stress.For the second network,with the mass fraction of CMC in the hydrogel Q=5.0%,significant hydrogen bonds can be formed through freeze-thaw,and the force of the network can be effectively improved,thus improving the mechanical properties of the hydrogel.With C=10^(-5)and Q=5.0%,the hydrogel stress reaches 0.328 MPa.The high osmotic pressure of CMC will cause the gel to swell and reduce the polymer density.In addition,the introduction of CMC will also affect the entanglement structure of the first network PAM.