Modelagem e otimização multiobjetivo de propriedades mecânicas em compósitos de polietileno e polipropileno reforçados com concha de molusco

Abstract

Mechanical properties of polymeric composites based on natural or synthetic fillers are being studied in order to reduce the environmental impact generated by these materials. The northeast coast of Brazil has in abundance CaCO3 rich fillers, such as mollusc shells (CM). However, this material is underutilized. Several studies evaluate the mechanical properties of these fillers with certain polymeric materials. Therefore, it is necessary to analyze these variables in a more robust way, mathematically and statistically. For this purpose, modeling and optimization of manufacturing processes and materials are widely used methods to support the development of new technologies and products. This study, therefore, aims to apply these techniques allied Design of Experiments (DOE) to analyze mechanical properties of recycled high density polyethylene (HDPE) composites reinforced with mollusc shell and mixed with recycled polypropylene (PPrec) modified with maleic anhydride (PPAM). A general full factorial design of these composites was developed. Regression models were created to explain mechanical properties measured from tensile and flexural tests. This by varying the input factors, which are PPAM and the percentage of mollusc shell. In addition, the properties were optimized from the Desirability method. In a scenario that aims to maximize all responses, adding PPAM plus 8% of mollusc shell brings satisfactory results. However, some variables are negatively correlated. Therefore, each variable was optimized individually. In the tensile test, the yield stress ( e  ), the yield deformation ( e  ) and the deformation up to rupture ( r  ) showed better results when adding the PPAM. While the modulus of elasticity (E) has higher values without PPAM and with 2% of CM. In the flexural test, the yield strength ( r  ) and modulus of elasticity (E) are optimized without the addition of PPAM and with 2 or 5% of CM. Finally, it indicates the possible application of these combinations.