Effect of extension rate on the stress–strain characteristics of grafted casein film

Casein was grafted with a binary mixture of acrylonitrile and n-butyl methacrylate. The mechanical properties of the grafted casein films were studied at various extension rates. The fractured surfaces were analyzed using scanning electron microscopy. With the increase in extension rate, the strain at yield increases to a maximum value and then decreases to a limiting value. The stress at yield and the energy at break steadily increase with the increase in the rate of extension.