The Influence on Microstructure of Hap/Cs-CMC Composite Materials in vitro Soaking

The Hap/Cs-CMC (Hydroxyapatite/Chitosan-carboxymethyl cellulose) composite materials with different mass ratio were firstly prepared by liquid co-precipitation method. According to preliminary results, the mass ratio of 50/50 (Hap/Cs-CMC) composite material was selected as the research object. The microstructure, phase and component of surface of the composite material were investigated via soaking in simulated body fluid (SBF) at different time. The purpose was to comparatively investigate these changes based on the degradation behavior and calcium deposition in the physiological solution. The results showed that the phase structure of composite material was relatively stable in SBF solution, and the microstructure of surface had been changed at immersion time period. These changes indicated that the process of ion-exchange, dissolving, deposition, re-crystallization happened between the composite materials and inside of the SBF solution. In addition, the pH value of SBF solution kept basically stable and did not exhibit much variation, and EDS results showed there are some new additional elements (Mg, K, Cl, S, etc) in composite material after materials soaking in SBF solution. The ion-exchange, dissolving, deposition, re-crystallization process occurred on the surface firstly and these processes tended to equilibrium with the increase of soaking time, which generated the Ca/P ratio of Hap/Cs-CMC composite materials maintained unchanged.