Análise estatística do efeito de variáveis do processo de síntese no rendimento de microcápsulas de PUF/ENB utilizando planejamento fracionário 24-1

Abstract

Studies involving materials with self-healing capacity have been increasing in recent decades, seeking to enable the repair of damage occurred in a material during use and, consequently, enabling longer life and reducing the need to remove the component for maintenance. In this work, microcapsules of poly(urea-formaldehyde) (PUF) containing 5-ethylidene-2-norbonene (ENB) were obtained through the technique of polymerization in situ. This study is part of a sequential strategy of experimental planning, in which a fractional experimental design 2^4-1 was performed to evaluate the influence of the effect of the variables of the synthesis process on the characteristics of microcapsules obtained. The manipulated variables selected from a previously performed Placket-Burman (PB) planning were pH, stirring speed, poly(ethylene-alt-anhydric maleic) (EMA) content and 1-octanol drops. The response variable analysed was the yield of the synthesis. Other synthesis variables such as the molar ratio of urea/formaldehyde monomers (U/F), ammonium chloride and resorcinol were kept constant, since these variables have no significant effect on the responses evaluated, a fact proven in previous planning. Through the responses obtained in the syntheses performed and statistical analysis performed using the program Protimiza, it was possible to state that the 1-octanol and the agitation speed are the synthesis variables that should be selected to obtain a complete planning to be performed later, considering the polymerization yield.