Morphology, contact angle and color properties of starch-poly vinyl alcohol - cellulose nanocrystal bionanocomposite films

In this research، polyvinyl alcohol (PVA) and cellulose nanocrystal (NCC) were used for improving the different properties of the starch films. Cellulose nanocrystal samples prepared from cotton lint and were investigated with transmission electron microscopy (TEM). The morphological and roughness properties of the films based on starch were studied with atomic force microscopy (AFM). The results showed that adding PVA and NCC to starch based film increased and decreased roughness، respectively. The moisture absorption and contact angle analysis showed that the adding of these materials decrease the hydrophilicity of starch based films; the moisture absorption decreased from 86. 27% for plasticized starch (PS) film to 69. 73% for starch-PVA biocomposite and 54. 81% for starch-PVA-NCC (20%) bionanocomposite. The contact angle analysis showed that starch film had small contact angle after 60 second (24. 06o) and adding PVA and NCC increased contact angle to 31. 17o and 47. 71o for starch-PVA biocomposite and starch-PVA-NCC 20% bionanocomposite، respectively. The colorimetry showed that PVA didn’t affect hunter parameter but NCC increased the transparency and yellowness of starch-PVA films.