How rheological behaviors of concentrated starch affect graft copolymerization of acrylamide and resultant hydrogel

Xianyang Bao; Long Yu; Shirley Shen; George P Simon; Hongsheng Liu; Ling Chen

doi:10.1016/j.carbpol.2019.05.034

How rheological behaviors of concentrated starch affect graft copolymerization of acrylamide and resultant hydrogel

Carbohydr Polym. 2019 Sep 1:219:395-404. doi: 10.1016/j.carbpol.2019.05.034. Epub 2019 May 11.

Authors

Xianyang Bao¹, Long Yu², Shirley Shen³, George P Simon⁴, Hongsheng Liu⁵, Ling Chen⁶

Affiliations

¹ Center for Polymer from Renewable Resources, SFSE, South China University of Technology, Guangzhou, Guangdong, 510640, China; CSIRO Manufacturing, Research Way, Clayton, Vic, 3168, Australia; Department of Materials Science and Engineering, Monash University, Melbourne, Vic, 3800, Australia.
² Center for Polymer from Renewable Resources, SFSE, South China University of Technology, Guangzhou, Guangdong, 510640, China; Sino-Singapore International Joint Research Institute, Guangzhou, Guangdong, 510663, China. Electronic address: [email protected].
³ CSIRO Manufacturing, Research Way, Clayton, Vic, 3168, Australia.
⁴ Department of Materials Science and Engineering, Monash University, Melbourne, Vic, 3800, Australia.
⁵ Center for Polymer from Renewable Resources, SFSE, South China University of Technology, Guangzhou, Guangdong, 510640, China; Sino-Singapore International Joint Research Institute, Guangzhou, Guangdong, 510663, China.
⁶ Center for Polymer from Renewable Resources, SFSE, South China University of Technology, Guangzhou, Guangdong, 510640, China.

PMID: 31151540
DOI: 10.1016/j.carbpol.2019.05.034

Abstract

Corn starches with different amylose/amylopectin ratios were used to explore the effect of rheological behaviors of concentrated system on the graft copolymerization of acrylamide and resultant hydrogels, which sheds a light on their reactive extrusion process. The viscoelastic moduli of starch melts increased with increasing amylose content (AC), leading to a decreased extent of micro-mixing detected by a reduced rheokinetic rate. With increasing AC, the graft efficiency was decreased but with almost similar monomer conversion (about 87.5%) and nearly equivalent graft content. XRD and SAXS spectra revealed that the extent of retrogradation of the starches were increased and two-phase separation was enhanced for hydrogels with increasing AC. Interestingly, microscopic analysis showed the superabsorbent hydrogel from the starch with AC of 50% exhibited a gridding membrane porous structure, resulting in a higher water absorbent capacity of 550 g/g. This was attributed to the moderate crosslinking and the slightly greater graft content.

Keywords: Acrylamide (PubChem CID: 6579); Ammonium persulfate (PubChem CID: 62648); N,N'-Methylenebisacrylamide (PubChem CID: 8041); Sodium hydroxide (PubChem CID: 14798); Starch (PubChem CID: 24836924); Water (PubChem CID: 962); amylose; content; heterogeneous structure; rheology; starch; superabsorbent hydrogel.