Glyn O. Phillips Hydrocolloid Research Centre at HBUT, School of Food and Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China; Centre for Polymer from Renewable Resource, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, Guangdong 510640, China.
Centre for Polymer from Renewable Resource, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou, Guangdong 510640, China; Department of Materials Engineering, Monash University, Melbourne, Vic 3168, Australia.
Carbohydr Polym. 2017 Nov 1;175:141-148. doi: 10.1016/j.carbpol.2017.07.071. Epub 2017 Jul 25.
From a microstructural view, the focus of this work was on the water absorption rate of starch-based superabsorbent polymers (starch-SAPs) prepared under high starch concentration (0.27:1w/w starch:water). The effects of starch amylose/amylopectin ratio were disclosed. The increase in amylopectin reduced the amount (C) of polyacrylamide (PAM) in starch-SAPs but increased the ratio of starch carbons grafted with PAM, which eventually decreased the average length (L) of PAM chains. The shorter PAM chains could reduce starch-SAP chain flexibility, thus inducing larger mass fractal gels in swollen starch-SAPs. In general, the increases in C and L were preferable for a higher water absorbent capacity (WAC), whereas the denser fractal gels reduced WAC. Interestingly, all starch-SAPs had a dual-phase absorption process with the first stage showing a higher rate than the second phase (k>k). The shorter PAM chains caused increases in k and k.
从微观结构的角度来看，这项工作的重点是研究在高淀粉浓度（0.27:1w/w 淀粉：水）下制备的基于淀粉的高吸水性聚合物（淀粉-SAP）的吸水率。揭示了淀粉直链淀粉/支链淀粉比例的影响。支链淀粉的增加减少了淀粉-SAP 中聚丙烯酰胺（PAM）的量（C），但增加了与 PAM 接枝的淀粉碳的比例，这最终降低了 PAM 链的平均长度（L）。较短的 PAM 链可以降低淀粉-SAP 链的柔韧性，从而在溶胀的淀粉-SAP 中诱导更大的质量分形凝胶。一般来说，C 和 L 的增加有利于更高的吸水性（WAC），而更密集的分形凝胶会降低 WAC。有趣的是，所有淀粉-SAP 都具有两相吸收过程，第一阶段的吸收速率高于第二阶段（k>k）。较短的 PAM 链导致 k 和 k 的增加。
