Predicting of mechanical properties of PP/LLDPE/TiO2 nano-composites by response surface methodology

The object of this work is to study the mechanical properties of ternary nano-composites based on polypropylene/linear low density polyethylene/nano-titanium dioxide (PP/LLDPE/TiO₂) using the response surface methodology (RSM). Experiments were designed according to a Box–Behnken method, to quantify the effects of linear low density polyethylene (LLDPE), styrene–ethylene–butylene–styrene (SEBS as a compatibilizer), and titanium dioxide (TiO₂) nano-particles. Three levels were chosen for the considered parameters as follows: LLDPE (20-60 wt%), TiO₂ (0-4 wt%), and SEBS (0-6 wt%). In addition, RSM models were used to develop the desirability function. Finally, the morphology and thermal properties of the samples were evaluated by scanning electron microscopy (SEM) and differential scanning calorimeter (DSC). It was found that the LLDPE content had the main role in mechanical properties and morphology of the nano-composite. The optimal values of the nano-particle were predicted to be 24.85 wt% for LLDPE, 3.02 wt% for TiO₂, and 6 wt% for SEBS. The obtained R² values and normal probability plots indicated a good agreement between the experimental results and those predicted by the model (above 0.95 for all the responses).