Comparative Study of Plasticized Polyvinyl Alcohol and Hydroxypropyl Methylcellulose Films for Pharmaceutical Applications: Mechanical, Thermal, Structural and Disintegration Properties

Polyvinyl alcohol (PVA) and hydroxypropyl methylcellulose (HPMC) films plasticized with glycerin or polyethylene glycol (PEG) were investigated to elucidate structure–property relationships in hydrophilic polymeric film systems. Films were prepared by solution casting at a fixed polymer concentration of 2.7% w/w with plasticizer contents ranging from 0.49 to 1.33% w/w, yielding continuous, free-standing films with good surface integrity. Polymer type and plasticizer dosage strongly affected film breakdown behavior. HPMC films with high plasticization swelled and disintegrated. Effective plasticization was shown by a steady drop in tensile strength and elastic modulus and a significant rise in elongation at break. PVA films plasticized better than HPMC films in PEG-containing solutions. Fourier transform infrared spectroscopy verified hydrogen bonding-driven polymer–plasticizer interactions, with glycerin outperforming PEG. Increasing plasticizer percentage reduced crystallographic order and thermal transition temperature in X-ray diffraction and differential scanning calorimetry. Scanning electron microscopy indicated smooth and uniform surfaces at intermediate plasticizer levels, but variability at higher loadings. Among the studied formulations, PVA films containing 1.33% w/w plasticizer and HPMC films containing 1.05% w/w plasticizer provided the most balanced combination. These findings support physiochemically rational PVA and HPMC film design for pharmaceutical applications.