Study on biodegradability and thermal behaviour of composites using poly lactic acid and gamma-irradiated fibres of Luffa cylindrica.

Surface modification of natural fibres by gamma irradiation is an economical and potent technique. The biodegradability of gamma irradiated Luffa cylindrica (LC) fibres having response of doses (0.5Gy, 1Gy and 2Gy) is studied. The degradation process is carried out in various environments like compost, sand, soil, salt water, brackish water and sweet water for a period of 90 days and microbial degradation using bacteria and fungi for a period of 90 days. The rate of biodegradation was calculated by measuring the loss of weight of composites at an interval of 30 days in each environmental condition. Preliminary results reported that the bacterial environment was the most prominent medium for degradation than fungi. B8 composites showed degradation of 27.5% and 3.59 in bacterial and fungal medium respectively. A minimum degradation was observed in compost medium (0.29%, 2.52%, 0.21%, 0.08%, 0.11%, 0.13%, 0.17%, 1.25% and 1.51% for B1-B9 respectively). For exploring the use of the composites in the field of biomedical sciences, the LC fibres are modified using calcium salts before reinforcement. The thermal properties like crystallization temperature (T), glass transition temperature (T), melting peak temperature (T) and thermal stability of the bio-composites were analyzed using Differential scanning calorimetry (DSC) in temperature range from 30 °C to 250 °C and the thermogravimetric analysis (TGA) was done in the temperature range of 20 °C to 700 °C. With increase in irradiation dose, crystallization temperature and glass transition temperature increased. Increasing in the irradiation dose, thermal stability of the composites decreased.