Estudo da Intercalação de DMSO em Caulim e sua Influência nas Propriedades Mecânicas de Compósitos Epoxídicos.

Abstract

Epoxy resin is a high-performance thermosetting polymer, yet its application is often limited by its inherent brittleness and cost. The incorporation of mineral fillers, such as kaolin, appears as an alternative to modify these properties, but the hydrophilic nature and agglomerated structure of the in natura clay hinder its dispersion. This work investigated the effect of the mechanochemical activation of kaolin with dimethyl sulfoxide (DMSO), via wet ball milling for up to 120 hours, on the mechanical properties of epoxy composites. Structural changes of the filler were monitore by XRay Diffraction (XRD) and Scanning Electron Microscopy (SEM), while mechanical performance was evaluated by tensile tests on composites with 2 wt% filler loading. XRD results revealed that prolonged milling promoted total amorphization of kaolinite, evidenced by the disappearance of crystalline peaks in the 60h and 120h samples. SEM images corroborated this transformation, showing the transition from large lamellar tactoids (0h) to dense, amorphous globular agglomerates (120h). In mechanical tests, the addition of untreated kaolin (0h) acted as a structural defect, reducing tensile strength (24.53 MPa) compared to pure resin (28.91 MPa). In contrast, the 60h treatment resulted in the stiffest composite, with a 25% increase in Young's Modulus (986.85 MPa), but with a severe reduction in ductility. The 120h processing time proved to be the ideal equilibrium point, maintaining high stiffness (882.38 MPa) and recovering strain at break (19.73%) to levels similar to those of pure resin. It is concluded that mechanochemical amorphization is an effective route to transform kaolin from an inert filler into a functional reinforcement, allowing the development of epoxy composites with improved stiffness without compromising toughness.