Abstract

• Plastic materials are not easily degradable and produce hazardous waste, causing environmental problem. In order to solve this problem, the uses of biodegradable polymers from renewable sources were generated. In this study, polymer films of polyvinyl alcohol (PVA)–white sticky rice starch were prepared by casting method. White sticky rice starch was extracted from white sticky rice grains collected from Myothit Township, Magway Region, and yield percentage was 64 %. Physicochemical properties such as pH, moisture percent, true density and bulk density and porosity of sticky rice starch were determined as 7.10, 10.51 %, 3.85 g mL-1 , 2.41 g mL-1 and 37.50 %, respectively. Semi-crystalline nature of the sticky rice starch with the average crystallite size of 51.65 nm was shown by XRD. Nanoclay was prepared from volcanic mud of Nagarpwak Taung in Minbu Township, Magway Region and the crystallite size was 30.79 nm. Nanocomposite films of PVA – starch – clay- glycerol were prepared by varying the ratios of nanostarch and nanoclay, i.e., 50:50 and 75:25. PVA – starch – clay- glycerol (75:25) film was found to have more flexible and plasticizing effect than the film with the ratio of 50:50. Biodegradability of these films was tested by soil burial method and the film with nanostarch and nanoclay with the ratio of 75:25 completely degraded after 18 days. For fruit coating application tomato fruits were dipped in prepared nanocomposite film and the tomato fruits were still fresh after 25 days compared to 8 days of noncoated tomato fruit.