Vol.:(0123456789) 1 3 Journal of the Brazilian Society of Mechanical Sciences and Engineering (2021) 43:96 https://doi.org/10.1007/s40430-021-02818-8 TECHNICAL PAPER Evaluating mechanical properties of a photosensitive acrylic resin for additive manufacturing with the addition of organophilic clays Willian de Araújo 1  · Juliana Kloss 2  · Neri Volpato 1 Received: 4 May 2020 / Accepted: 8 January 2021 / Published online: 29 January 2021 © The Brazilian Society of Mechanical Sciences and Engineering 2021 Abstract Developing new materials for additive manufacturing (AM) technologies is an important topic, usually targeting cost reduc- tion 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 modifed 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 spectrom- eter (EDS), X-ray difraction (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 fexural strength (14% for Cloisite 20 ® and 10% BN-CT). The formations´ thermal stability (degradation) was not afected by the addition of the clays; therefore, the cheaper BN-CT would be preferred to improve their mechanical properties. Keywords Additive manufacturing · Organophilic clay · Acrylic resin · Cloisite 1 Introduction Technologies that facilitate the development of new prod- ucts or enable the manufacture of small batches of products, without specifc tooling, have become essential to all com- panies. Within this scenario, additive manufacturing (AM) technologies have gained prominence since the end of the 1980s, contributing signifcantly to the product development process [1]. The ISO/ASTM 52,900:2015(E) defned AM as “a pro- cess of joining materials to make objects from the 3D model data, usually layer upon layer, instead of subtractive manu- facturing” [2]. For some AM technologies, the use of liquid photopolymer resins is paramount. These resins are usually based on acrylates and epoxies and their curing occurs via exposure to ultraviolet light (UV) and/or laser. These materi- als are processed mainly in two AM categories, defned by ASTM as vat photopolymerization (e.g., stereolithography) and material jetting (e.g., PolyJet technology) [1, 3]. AM ofers a series of competitive advantages over tra- ditional manufacturing processes since the layer manufac- turing principle allows for greater geometric freedom. This allows for the attainment of parts that would hardly be manu- factured by another process [1]. Despite the many benefts of AM, its use can be limited by the cost of raw material. A previous study aiming to develop a low-cost photosensi- tive material for AM presented a material with unsatisfac- tory mechanical properties, when compared with materials available on the market [4]. An alternative to improve the mechanical and thermal properties and the dimensional sta- bility of this material is to add organophilic clays. Technical Editor: Zilda de Castro Silveira, Ph.D. * Neri Volpato nvolpato@utfpr.edu.br 1 Department of Mechanical Engineering, Federal University of Technology – Paraná (UTFPR), Curitiba, Paraná, Brazil 2 Department of Chemistry and Biology, Federal University of Technology – Paraná (UTFPR), Curitiba, Paraná, Brazil