Mechanical and thermal properties of yam starch films

Yam starch films were prepared by casting using glycerol as plasticizer. The effects of different film thicknesses (0.07, 0.09, 0.11 mm), glycerol (1.30, 1.65 and 2.00 g/100 g of filmogenic solution) and starch (3.30, 3.65 and 4.00 g/100 g of filmogenic solution) concentrations were evaluated in mechanical properties of these films. Films with high puncture strengths were obtained at higher thickness, higher starch concentration and lower glycerol concentration. Puncture deformation increased with glycerol content. Tensile tests showed that with increasing of glycerol concentration, the films became more flexible, with higher strain at break values and lower stress and Young's Modulus. Glass transition temperatures (Tg) of films were affected by glycerol and starch concentration; films formulated with high yam starch concentrations showed higher Tg values and Tg of film formulated without plasticizer (control sample) were higher than those of plasticized films.