Particle-resin systems for additive manufacturing of rigid and elastic magnetic polymeric composites

Abstract

Fiber-reinforced polymeric composites (FRPCs) with selective fiber orientations are finding applications in building biological constructs, smart materials and energy devices. Field-assisted additive manufacturing (AM) has emerged as one of the promising methods for creating FRPC structures. Compared to other AM processes and due to the liquid form of the raw materials, vat photopolymerization has shown higher potential in building FRPCs with selective fiber orientation. Compared to other methods of controlling the fiber orientation during AM processes, magnetic field-assisted fiber reorientation, is a relatively easy-to-use contactless method that has been effectively paired with vat photopolymerization. One of the major issues in magnetic field-assisted vat photopolymerization is the dispersion instability of the particles in resin system, which leads to separation between the resin components and dispersed particles and results in non-uniform particle distribution during the printing process. In this study, ferromagnetic particle-loaded photocurable resins are developed through surface modification of the particles to achieve more uniform particle dispersion, more dispersion-stable resins systems and enhanced mechanical properties of FRPCs. Magnetite particles were functionalized under silanization reactions and mixed with two photocurable resins. Fourier-transform infrared spectroscopy (FTIR) analysis was used to select the matching composition of silane compounds and verify the functionality of the treated magnetite particles for each resin mixture. Dispersion stability of the developed resin system was verified by visual observation of the resin mixture and image analysis of microscope images. To provide a better guideline for 3D printing the developed resin system, cure depth of each resin system containing different particle fractions is studied. Tensile tests are devised to understand the effects of particle content, orientation, and surface treatment on mechanical properties of the 3D printed FRPCs. Results of this study suggest that an optimized particle-resin system can be developed through surface treatment of magnetite particles with functional groups.