Properties of sodium montmorillonite-starch based bionanocomposites: Surface topography, moisture absorption, contact angle, color properties

In this research، starch - poly vinyl alcohol –nanoclay nanocomposites made from casting method and the effects of poly vinyl alcohol (PVA) and nanoclay (MMT (on the morphological and roughness properties، were studied. Afterward the effects of adding PVA and MMT content on the barrier properties have investigated. The results from atomic force microscopy (AFM) showed that، adding of PVA، increased the roughness of starch film، while adding MMT decreased its roughness. The results from moisture absorption showed that starch film show the highest moisture absorption (86. 25%) after 72 h and with adding PVA the moisture absorption decreased to 69. 73%. with adding of MMT، the moisture absorption decreased too and the lowest content was in 7% of MMT content (48. 4%). The results from contact angle test confirmed the results from moisture absorption and showed that adding of PVA increased the contact angle from 24. 06º to 31. 17º after 60 second. With adding of MMT the contact angle increased significantly from 31. 17º to 42. 55º for starch-PVA-0% MMT and starch-PVA-7% MMT films. The colorimetry showed that PVA didn’t affect hunter parameter but MMT increased the transparency of starch-PVA films and the optimum content for transparency were 5 & 7% MMT contents.