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Hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA) are important polymers in pharmaceutical, food and other industries being largely used as encapsulation agents. The characterization of two reference grades of HPMC (Pharmacoat® 603 and Pharmacoat® 615) and one reference grade of PVA (Mowiol® 4-98), through X-ray diffraction (XRD) and thermogravimetry (TG) is described. Specific analyses were performed by means of dynamic vapour sorption analysis of water adsorption/desorption from vapours at 10, 25, 40, 55 and 70 °C. Guggenheim–Anderson–de Boer (GAB), Brunauer–Emmett–Teller (BET), Park and n-layer BET models were successfully used to fit the experimental data. The glass transition temperature as function of water content was measured by means of differential scanning calorimetry (DSC). The experimental data were analysed according to Linear, Gordon–Taylor, Fox and Roos equations. XRD studies revealed amorphous structure for the Pharmacoat® 603 and Pharmacoat® 615 and crystalline for Mowiol® 4-98. Single and multi-step temperature degradation point was found for Pharmacoat® 603 and Pharmacoat® 615 and Mowiol® 4-98, respectively. The water uptake is higher for Pharmacoat® 603 and Pharmacoat® 615 than Mowiol® 4-98. The influence of temperature on water uptake is opposite for the two types of polymers. GAB and n-layer BET were found to better model Pharmacoat® 603 and Pharmacoat® 615 and Mowiol® 4-98 data, respectively. The water makes the glass transition to decrease quite drastically. Gordon–Taylor is better fitting the experimental data both for Pharmacoat® 603 and Pharmacoat® 615 and Mowiol® 4-98.

Thermo-physical characterization of Pharmacoat® 603, Pharmacoat® 615 and Mowiol® 4-98