Observation of rheological behavior of poly (vinyl alcohol), methylcellulose, and their hybrids with second electron image

摘要

The adhesive interfaces had been observed in the cement-based composites with a fixed amount of the hybrid of polyvinyl alcohol (PVA) and methylcellulose (MC), though the lipophilic interfaces were observed in the composites with PVA or MC. To investigate the formative mechanism of adhesive interface, the microstructures and variation mechanism of hybrid of PVA and MC, and the physical and chemical behaviors of the blending of PVA and MC had been widely studied by observing the fresh sections of dehydrated hybrids. The solid texture with air bubbles in PVA implied that the viscosity of PVA solution at 20wt % concentration was higher than MC and hybrid solution at the same concentration. The network texture without air bubble in hybrids showed that the MC in hybrid actually acted as anti-bubbling agent. The physical and chemical process such as rotation, entanglement, and graft copolymerization probably took place during preparing the hybrid solution at 20wt% concentration by comparing the configuration of-MC molecule at the same concentration. The uniform network textures were always observed in the hybrids at 2wt%, 4wt% and 20wt% concentrations with a PVA-to-MC ratio of 1:1. To investigate further the rheoiogical behavior of hybrid of PVA and MC in the cement-based composites, the microcosmic morphology of the surfaces of dehydrated bodies of PVA, MC and their hybrids had been observed with second electron image.