a Heydari - Department of Chemical and Petroleum Engineering, Sharif University of Technology, Azadi Avenue, Tehran, Iran
i Alemzadeh - Department of Chemical Engineering, University of Mohaghegh Ardabili, Daneshgah Avenue, Ardabil, Iran
m Vossoughi - Institute for Biotechnology and Environment (IBE), Sharif University of Technology, Azadi Avenue, Tehran, Iran

In this study, biodegradation of corn starch/glycerol/Na-MMT nanocomposites by soil burial tests were carried out for up to 6 months. Films were prepared by casting method according to central compositedesign and response surface methodology was applied for analysis of the results. The effects offormulation on the water solubility, contact angle and tensile strength of starch films were investigated. Increasing in Na-MMT content decreased biodegradability; while presence of glycerol, increased it. The effect of nanoparticles content might have been attributed to interactions between starch and Na-MMTthat further prevented enzymatic attack on the biopolymer. In addition, the films with higher initial contact angle and lower water solubility revealed slower biodegradation. The effect of glycerol is debated becausehigher hydrophilicity and weaker mechanical roperties enhanced the amylase attack on the samples. Furthermore, weight loss due to soluble matters caused an increase to account of the biodegradability. Byincreasing in glycerol amount as a water holding agent, the films could store sufficient water content for microbial activities around the buried samples. According to FTIR spectra for partially biodegraded films, the intensity of the peaks at 1150 and 1040 cm-1 associated with starch glycosidic linkages decreasedwhich indicates the action of alpha-amylase produced by soil microorganisms.

Biodegradability,Corn Starch,Nanocomposite,Response Surface Methodology,Soil Burial