The Effects of MWD on the Rheological Properties of Shear‐Induced Structural Formation for PVA Solutions in DMSO

Abstract

AbstractThe effects of molecular weight distribution (MWD) on the rheological responses of shear‐induced structural formation in the general‐purpose polyvinyl alcohol (PVA) solutions dissolved in dimethyl sulfoxide (DMSO) were investigated. On the whole, time‐dependence of rheological properties was more influenced by the PVA solutions with broad MWD at the similar weight average molecular weight (Mw). The dynamic viscosity (η′) of PVA/DMSO solution with broad MWD was lower than that with narrow MWD at the similar Mw until the second time sweep (T2) of PVA/DMSO solution. After the time‐sweep experiment was repeated, the η′ of PVA/DMSO solution with narrow MWD was lower than that of PVA/DMSO solution with broad MWD at the similar Mw. The G′ until 5 min of relaxation of PVA/DMSO solution with broad MWD was lower than that of PVA/ DMSO solution with narrow MWD at the similar Mw. After the time‐sweep experiment was repeated, the G′ of PVA/DMSO solution with narrow MWD was lower than that of PVA/DMSO solution with broad MWD at the similar Mw. It could be interpreted as a consequence of the formation of three‐dimensional gel structure through the polar interactions by hydroxyl groups whose strength was dependent on shearing conditions and MWD.