Rheological Behavior of Aqueous Poly(vinyl alcohol) Solution during a Freeze–Thaw Gelation Process

• DOI: 10.1021/acs.macromol.0c00488
• Publication Date: 2020-04-09T12:37:34Z
• Authors: Nidhi Joshi; Khushboo Suman; Yogesh M. Joshi
• Keywords: Vinyl alcohol; Gel point; Microcrystalline; Critical point (mathematics)

In this work, we study the rheological behavior of aqueous solution poly(vinyl alcohol) (PVOH) having different molecular weights and concentrations, which are subjected to freeze–thaw process. We observe that, during freezing step, PVOH undergoes a sol–gel transition upon decreasing temperature as defined by Winter criterion, wherein at critical point dynamic moduli show identical power-law dependence on frequency. During thawing with an increase in temperature, material gel–sol but higher than step. Interestingly, fractal dimension gel strength state while observed be those despite former being larger. propose gradually polymer segments indulge hydrogen bonding, forms nuclei for microcrystalline domain formation. Consequently, comes when hydrogen-bonded segments, where domains act junction knots, form three-dimensional percolated network leading transition. Upon increasing consolidated gel, participating crystalline junctions dissolve bring about The experiments suggest that number points increases exponentially it decreases step vicinity point.