中文摘要：

水凝胶因含水量高及生物相容性好,是一种理想的人工软骨替代材料.通过构建杂化交联双网络,水凝胶的力学性能显著提高,但有关其摩擦机理却较少报道.制备了聚丙烯酰胺/海藻酸钠（PAAm/SA）水凝胶,并分别测定了Na＋、Ca2＋及Fe3＋3种不同价态离子对其弹性模量、含水率、摩擦行为的影响.研究表明,Fe3＋溶液中,PAAm/SA的弹性模量为126 kPa,是初始模量的14倍.PAAm/SA水凝胶摩擦应力在整个速率范围内较PAAm最大有一个数量级降低.随离子价数的增大,SA 和 PAAm/SA 水凝胶摩擦应力均呈现增大趋势.当浸泡溶液由Ca2＋变为Fe3＋时,PAAm/SA水凝胶的摩擦行为由混合润滑变为边界润滑.另外,PAAm/SA 水凝胶在Fe3＋中的摩擦应力对压应力的敏感性随速率增大呈现减小趋势.

英文摘要：

Due to the high water content and excellent biocompatibility,Hydrogel is the ideal substitute for arti-ficial cartilage.The mechanical property of hydrogels can be significantly improved by fabricating hybrid cross-linked double network.However the research is rarely reported on the friction mechanisms of hybrid cross-linked double network.Polyacrylamide/alginate （PAAm/SA）is fabricated and the elasticity modulus,swelling ratio and frictional behavior of PAAm/SA immersed in Na＋,Ca2＋ and Fe3＋ was measured.The elasticity mod-ulus of PAAm/SA in Fe3＋ ionic solutions is 126 kPa which is 14 times of the PAAm/SA immersed in water. The frictional stress of PAAm/SA hydrogel significantly decreases over the entire range of sliding-velocity con-trast to PAAm.The frictional stress of SA and PAAm/SA increased with the valences of ionic.When the solu-tion turn from Ca2＋ to Fe3＋,the friction mechanism of PAAm/SA shift from mixed lubrication to boundary lu-brication.Moreover,the sensitivities about the friction stress of PAAm/SA in Fe3＋ to stress decrease with the slip rate increase.