Thermal and dynamic mechanical properties of hydroxypropyl cellulose films

Abstract

Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) were used to characterize the morphology of slovent cast hydroxypropyl cellulose (HPC) films. DSC results were indicative of a semicrystalline material with a melt of 220°C and a glass transition at 19°C (T₁), although an additional event was suggested by a baseline inflection at about 80°C (T₂). Corresponding relaxaions were found by DMTA. A secondary relaxation at -55°C was attributed to the interaction between hydroxyl groups of the polymer and residual diluent. The tan δ peak at T₂ was found to arise from an organized phase, presumably from a liquid-crystal mesophase formed while in solution. Crosslinking with a diisocyanate increased the peak temperature of the two primary relaxations, and resulted in a more clearly defined peak for the T₂ transition. From this behavior it was concluded that both T₁ and T₂ are similar to glass transitions (T_g's) associated with an amorphous component and a more highly ordered phase (due to a residual liquid crystal superstructure) in the HPC bulk.

Citation

Rials, Timothy G.; Glasser, Wolfgang G. 1988. Thermal and dynamic mechanical properties of hydroxypropyl cellulose films. Journal of Applied Polymer Science 36:749-758