不同壁材辣素微胶囊的化学法制备与性质研究 Ⅱ:热降解与缓释动力学

Preparation and Research of Microencapsules Containing Capsaicine with Ditterent Walls Using Chemical Methods:(Ⅱ) Thermal Decomposition and Slow-Released Kinetics

以热重法和Achar-Brindley-Sharp-Wendworth计算方法,进行了微胶囊热降解动力学的研究,获得了热分解活化能与反应机理函数.结果表明全部微胶囊热分解过程属于二级反应和一级反应的范畴,有时会产生二级反应过渡到一级反应的情况.释放动力学的研究以甲醇为溶出介质,在290 nm时辣素产生特征羰基吸收峰.结果表明,多孔性、低结晶度微胶囊的释放动力学在表观上比较符合零级规律,突释效应明显;无孔、高结晶度微胶囊的释放动力学在表观上比较符合Higuchi或一级释放规律.

The TGA data of all microencapsules which were obtained by single scanning rate method were analyzed by Achar- Brindley- Sharp- Wendworth methode. The kinetics parameters such as activation energy and kinetics mode function were determined. The resuhs showed that the course of thermal decomposition of mieroencapsules could be regarded as second or first order reaction, and sometimes the transition from second to first order exists. Slow - released kinetics experiments were taken in methanol, and densities of capsine were measured by UV at 290 nm. The data were gathered to deduce the S - R equation. The characterization of release kinetics were also analyzed. The results showed that the release rule of microencapsules with porosity and low crystallinity were fit for zero level, on the other hand, the release rule of microeneapsules with ; imperforation and high crystallinity were fit for Huiguehi mode or first order level.