Influence of nanosilver on thermal stability of chitosan

Nanoadditives for polymers have many valuable features: e.g. the ability to change the properties of polymers: mechanical strength, stability and heat resistance and resistance to radiation. These properties make them an interest in recent years. Studies of polymer composites with nanoadditives leads to discovering more, unique types of nanoadditive interactions on a structure and properties of the polymer. One of the most widely used nanoadditive is nanosilver, which have antibacterial and antifungal properties. An important aspect is thus to investigate the effect of this additive on thermal stability of the polymer composite. The aim of this study was to investigate the effect of nanosilver on the thermal stability and properties of chitosan. Chitosan composites with nanosilver in the form of films with a thickness of 10-30um and the content of silver 0.5 and 1% was obtained by casting. In order to study the thermal stability samples were subjected to a temperature of 120°C (time 0-90h). Studies on influence of nanosilver on the thermal stability of the polymer was performed using infrared spectroscopy (FTIR). This allows to observe changes in the chemical structure of polymer. The changes in the major functional groups was observed: 1420cm-1(bending vibration of -C-H group), 1577cm-1 (bending vibrations of the amine group-NH2), 1655cm-1 (vibrations of C=O in amide group). Mechanical strength test of chitosan composites subjected to high temperature was also performed. Tensile tests (using the Instron 5325 apparatus) were conducted to determine changes in values of Young's modulus, maximum stress and elongation at break. The study showed an effect of the presence of nanosilver on the structural and mechanical properties of chitosan. Nanosilver improves the thermal stability of studied functional groups of chitosan.