Morphology and water affinity of superabsorbent hydrogels composed of methacrylated cashew gum and acrylamide with good mechanical properties

Abstract

This paper comprises the characterization of superabsorbent hydrogels based on methacrylated cashew gum (CGMA) co-polymerized with acrylamide (AAm) by measuring of the water uptake, water retention capacity in dependence of time, morphological and mechanical properties. The morphological features of hydrogels were evidenced by SEM images. Stress measurements of hydrogels as a function of temperature were considered as being the necessary force for compressing the hydrogels at 1mm deformation. Stress–strain modeling was used to obtain the compressive elastic modulus and apparent cross-linking density of superabsorbent hydrogels. Hydrolyzed CGMA-co-AAm hydrogels showed highly water absorbing. Another remarkably feature of these hydrogels is the efficiency in the water retaining that was caused by increasing in CGMA content. Higher temperature leads to an enhancement in the stress values of superabsorbent hydrogels because the large content of water that penetrates into superabsorbent hydrogels and expands their polymer network. The increase in the amount of CGMA and AAm were accompanied by an increasing on the apparent cross-linking density of hydrogels. This contributed to increase their elastic modulus, which is inherent to a more rigid structure.