Preparation and Characteristics of Polyvinyl Alcohol-based Hydroel Containing Natural Microbentonite

Abstract

: In this work, polyvinylalcohol (PVA)-based interpenetrating-hydrogels containing natural microbentonite (NMB) were prepared in a bench scale reflux-reactor using water as solvent in an optimized condition in the presence of constant compositions of acrylicacid (AA) and N,N’-methylenebisacryamide (MBA) as comono-mers as well as ammoniumpersulphate [(NH 4 ) 2 S 2 O 8 , APS] as initiator. Results of interpenetrating-hydrogels, with various loadings of NMB (2, 5, 10 and 15%) were moulded and cooled to form film specimens, and then characterized for their properties. First of all, their mechanical properties and chemical structure were measured using tensile testing (ASTM D882) and infrared spectroscopy (FTIR), then their thermal properties were analysed using differential scanning calorimetry (DSC), and their morphological properties were tested using scanning electron microscopy (SEM). Results showed that optimum composition weight ratio of PVA/AA/NMB/MBA/APS = 60/40/10/1/0.5 enhanced highest tensile modulus of the interpenetrating-hydrogel microcomposites 25% in compare to its neat hydrogel counterpart. FTIR analysis of the film speci-mens after exhaustive extraction in n-hexane still contained stable AA-carbonyl (C=O) peak at 1725 cm -1 . Thermal properties of the optimized composition of the hydrogel showed slight improved of thermal stability (decomposition temperature increase from 280 – 285 o C). Morphological properties of the interpenetrating-hydrogel microcomposite also showed finely distributed of the microfiller, which is responsible for its improved mechanical and thermal properties. It is recommended that the interpenetrating-hydrogels can be further developed for application as biomedical materials.