Viscoelasticity of cellulose polymers and mucociliary transport on frog palates

Abstract

The viscoelastic propertied of model polymer, hydroxypropylmethylcellulose (HPMC), in ternary solvent mixtures and the variation of viscoelastic properties under dilution with water were investigated. HPMC was dispersed in mixtures of glycerol formal (GF) or ethyl alcohol, propylene glycol (PG), and water. Each polymeric sample was oscillated at different frequencies with fixed stress amplitude and the changes in elastic modulus, viscous modulus, and apparent viscosity were measured at 30[deg]C. The moisture absorption rate of HPMC in PG:GF solvent mixtures in a 94% relative humidified environment was also studied. A linear relationship between the elastic modulus or viscous modulus and polymer concentration was observed for the HPMC samples. The relative mucociliary transport rate tested on the non-depleted frog palate model revealed a curvilinear correlation with the loss tangent (a ratio of the viscous modulus to the elastic modulus) of the polymeric solution. Using GF as a solvent for HPMC resulted in a formation of a rigid gel with the highest elastic modulus and viscous modulus among solvents selected. A higher affinity for water was found for HPMC in the PG:GF 90:10 mixture compared with HPMC in the PG:GF 70:30 mixture. However, the elastic modulus and viscous modulus were much higher for HPMC in the PG:GF 70:30 mixture.