Preparation and properties of a poly(vinyl alcohol) hydrogel-melamine formaldehyde foam composite

In the present research, a novel gel-foam composite was prepared by filling poly(vinyl alcohol) (PVA) hydrogel into melamine formaldehyde (MF) foam. Aqueous PVA solution experienced cyclic freezing-thawing to form the hydrogel in the MF skeleton network. The structure and properties of the PVA/MF gel-foam composite, including crystallization, morphology, viscoelasticity, water resistance, and mechanical properties, were systematically investigated and compared with neat PVA gel. MF shows good compatibility with PVA via hydrogen bonding interaction. Besides, it can serve as a nucleating agent to promote the crystallinity of PVA. Based on the network of MF skeleton and physical crystal net of PVA, an interpenetrating double network structure was constructed, thus resulting in the mechanical properties enhanced. Meanwhile, PVA/MF gel-foam displayed better water-resistance than neat PVA gel due to higher crystallization degree and the shield effect of MF skeleton. The improved properties made the material more suitable for a microorganism carrier applied in the biological treatment of wastewater. (c) 2018 Society of Plastics Engineers