Mechanical and Degradation Behavior of Castor Oil Seed Shells - Recycled Low Density Polyethylene Composites

Low density polyethylene is among the most used polymers globally due to its desirable properties. This work investigated the effect of blending recycled low density polyethylene with castor oil seed shells. The focus was on mechanical and creep behavior of RLDPE/cellulose composites. Samples of RLDPE/ cellulose composites were prepared in the weight ratio 10:0, 9.5:0.5, 9:1, 8.5:1.5, 8:2 by injection molding process. Analysis of dynamic mechanical behavior was carried out using torsional pendulum method within temperature range of 30 °C to 100 °C. Creep strain as well as creep recovery testing were performed at 25°C, 40 °C, 50 °C and 60 °C by exerting a fixed stress for 12 minutes for each respectively. DMA data was analyzed by Fouss-Kirkwood law. Short-term creep strain and creep recovery were analyzed using Burger law and Weibull distribution function, respectively. The long-term creep was analyzed with William-Landle-Ferry law. DMA results showed that between 5-15% strong interactions between cellulose hydroxyl groups and RLDPE chains stiffens the composite which leads to increase in shear storage modulus. The results also showed that between 5-10%, there is increase in loss modulus which is attributed to viscosity increase. Creep measurement showed that for 5% cellulose intake, percentage creep strain decreases due to stiffening of the matrix. Above this, the opposite is seen. The long-term creep results indicated that the effect of cellulose on free volume in relation to temperature was lacking.