ABSTRACT:The rheological properties of adhesive miscible blends of high-molecular-weight poly(N-vinyl pyrrolidone) (PVP) with short-chain poly(ethylene glycol) (PEG) under oscillatory and steady-state shear flow have been examined with dynamic mechanical and squeezing-flow analysis. The latter allows the rheological characterization of adhesive blends under conditions modeling adhesive-bond formation as a fixed compressive force is applied to an adhesive film. The most adhesive PVP blend with 36 wt % PEG has been established to flow like a viscoplastic (yield stress) liquid with a power-law index of about 0.12. The study of the apparent yield stress as a function of the PVP-PEG composition, content of sorbed water, molecular weight of PVP, and temperature shows that the occurrence of a yield stress in the blends results most likely from a noncovalent crosslinking of PVP macromolecules through short PEG chains by means of hydrogen bonding of both terminal OH groups of PEG to the complementary functional groups in PVP monomer units. A molecular mechanism of PVP-PEG interaction was established earlier by direct and independent methods.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.