Evaluating mechanical properties of a photosensitive acrylic resin for additive manufacturing with the addition of organophilic clays

Abstract

Developing new materials for additive manufacturing (AM) technologies is an important topic, usually targeting cost reduction or better physical properties, or both. This research aims to evaluate the mechanical properties and thermal stability of a non-commercial basic photosensitive acrylic material by the addition of organophilic clays. The organophilic clays Cloisite 20® and organophilic bentonite clay modified with cetyltrimethyl ammonium bromide (BN-CT) were dispersed—0.5, 1.0 and 1.5 (wt%)—in the monomer trimethylolpropane triacrylate, using two dispersion methods. The samples were obtained by the AM principle, similar to the vat photopolymerization technology, in which the deposition and curing were performed layer by layer with Ultraviolet-C radiation. The formulations were checked for viscosity, shrinkage, warping, and strength (tensile and bending test), and analyzed using a scanning electron microscope (SEM), an energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), and thermogravimetry (TGA). The characterization of the formulations obtained from the two organophilic clays, Cloisite 20® and BN-CT, by the two methods of dispersion, in principle, indicated the formation of a material with an intercalated hybrid morphology structure. The formulations showed improvements in tensile strength (15% for Cloisite 20® and 18% for BN-CT) and flexural strength (14% for Cloisite 20® and 10% BN-CT). The formations´ thermal stability (degradation) was not affected by the addition of the clays; therefore, the cheaper BN-CT would be preferred to improve their mechanical properties.