O2 barrier of Composite Membranes comprised of Polyvinyl alcohol and Natural Zeolite

Y.R. SPADA; M. G. GARCÍA; J. MARCHESE; N. A. OCHOA

Sitges

Conferencia; Fourth International Conference on Multifunctional, Hybrid and Nanomaterials (Hybrid Materials 2015) HYMA 2015; 2015

Elsevier

Polyvinyl alcohol (PVA) is a synthetic polymer derived from petroleum which depicted excellent oxygen (O2) barrier properties. However, this polymer is hydrophilic and absorbs high quantities of water molecules from ambient moisture. Water acts as a plasticizer of PVA inducing polymer chain separation, increasing fractional free volume (FFV) and, consequently, causing the loss of O2 barrier ability. Zeolites are a class of porous materials which have the ability of adsorb polar gas molecules selectively. Natural zeolites have the advantage of being an abundant and low cost raw material. However, they have no reached a wide application to gas separation in comparison to synthetic zeolites and other adsorbent materials. This is due to the impurities and low surface areas relative to the more uniform synthetic zeolites. Despite these disadvantages natural zeolites composed of clinoptilolite and chabazite are judged the most versatile, while also offering unique adsorption characteristics. In this work a natural zeolite (58 % clinoptilolite - heulandite, 14 % mordenite and 12 % montmorillonite) obtained from Tasajereas (Cuba) deposit was used as the inorganic filler to prepare composite membranes for O2 barrier applications such as food packaging. Composite membranes were prepared varying the amount of zeolite in the range of 1, 3, 5, 10 and 15 wt. % regarding to PVA. The influence of zeolite content on O2 barrier, water sorption and mechanical properties was studied. Diffusion and solubility coefficients were also analyzed through solution-diffusion model. Results indicated that zeolite not only favored O2 barrier but also prevented water sorption in composite membranes. PVA/3 % Zeo showed higher flexibility (elongation at break 74.80 %), best O2 barrier property and significant O2 solubility.