机械活化淀粉制备水凝胶及其尿素的控释性

以机械活化60 min的木薯淀粉、氢氧化钾部分中和的丙烯酸和丙烯酰胺为原料,合成农用淀粉基离子/非离子型复合高吸水树脂(SCSA),采用FT-IR和SEM对样品的官能团和表面形貌进行表征。以SCSA在5.0 mol·L^-1的尿素溶液中平衡溶胀后所得的水凝胶(SCH)为尿素在水溶液中的释放材料,考察合成工艺条件和释放环境对尿素释放过程的影响。结果表明,尿素从SCH中的释放过程符合Fickian扩散机理;SCH的溶胀率越大,尿素的释放速率越慢;释放温度越高,尿素的释放越快。在丙烯酸和丙烯酰胺质量比为3:3,交联剂N,N'-亚甲基双丙烯酰胺溶液用量为1.0 ml(浓度为0.02 mol·L^-1)的条件下制备的SCH对尿素的释放活化能为17.28 kJ·mol^-1。

Preparation of mechanically activated starch-based composite hydrogel for controlled release of urea

The starch based ionic and nonionic composite superabsorbent(SCSA)used for agriculture was synthesized from mechanically activated cassava starch(60 min ball milling),partially neutralized acrylic acid by KOH and acrylamide.The functional groups and granular morphology of the samples were characterized by FT-IR and SEM,respectively.The SCSA was swollen in urea solution(5.0 mol·L^-1)until equilibrium swelling and then the hydrogel(SCH)was obtained.The SCH was used as the release material for urea in aqueous solution.The effects of synthesis conditions and release environment on the release process were investigated.It was found that the release of urea from SCH was controlled by Fickian diffusion mechanism,and the release rate decreased with increasing swelling ratio and increased with increasing temperature.The activation energy for releasing urea from the SCH prepared under the conditions of m_AA:m_AM=3:3 and dosage of N,N'-methylenebisacrylamide solution 1.0 ml(0.02 mol·L^-1)was 17.28 kJ·mol^-1.