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Optimization of Injection Process Parameters of Plastic Reinforced Composites Using Response Surface Methodology and Central Composite Design



The injection molding process is among the most efficient processes for mass production of polymer products with complex geometry at optimal cost. This study investigates the effect of the injection parameters on the cavity pressure, tensile and microstructural properties of plastic-reinforced composites and optimized the process to determine the optimum injection parameters using the Response Surface Methodology and central composite design. The two polymer composite materials used for this work are low-density polyethylene reinforced with aluminium powder (LDPE/Al) and low-density polyethylene reinforced with carbon black (LDPE/CB) at 250 and 200oC injection temperature respectively. The analysis of the results obtained from both the numerical and physical experimentations were used to obtain two predictive models which correlate cavity pressure and tensile strength as a function of the independent process parameters namely, injection pressure and time. An injection pressure of 70 MPa and time of 1.00 sec was found to be optimum producing a cavity pressure of 37.658 MPa while an injection pressure of 70 MPa and time of 1.75 sec was found to be optimum producing a material with tensile strength of 7.41 MPa. The results indicate that the cavity pressure increases with an increase in the injection pressure but decreases with an increase in the injection time for the two analyzed polymer composites. The study shows that process parameters have significant effects on the cavity pressure, mechanical and microstructural properties of LDPE/Al and LDPE/CB.


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