On Mechanical Properties of 3D-Printed Secondary Recycled Acrylonitrile Butadiene Styrene Composite for Silencer Application in Short-Range Gun

Numerous studies have been reported in the past on the fabrication of short-range gun silencers by 3D printing of virgin acrylonitrile butadiene styrene (ABS)-based composite matrix. But hitherto little has been reported on enhancing the performance of such silencers (in terms of enhanced mechanical and thermal properties) for a long service life of the functional parts. Also, limited work has been reported on the use of secondary recycled ABS composite in such applications. Melamine formaldehyde (MF) is one of the thermosetting having acceptable flame-retardant capabilities (available as waste from kitchenware product manufacturing). In this study, the MF was reinforced in an ABS matrix based on acceptable rheological properties followed by a twin screw extrusion process for the fabrication of feedstock filament for the fused filament fabrication (FFF) in line with the concept of circular economy. The functional prototypes of secondary recycled ABS-MF composite (87.5-12.5% by wt.) were prepared with FFF, and the mechanical properties (tensile, compression, and flexural) were optimized. The study reveals that infill density (ID) is the most significant factor for the best mechanical properties of functional prototypes as ultimate tensile strength of 31.68 MPa, ultimate compressive strength of 52.09 MPa, and ultimate flexural strength of 91.85 MPa (supported by optical photomicrographs based on scanning electron microscopy analysis). For multi-factor optimization of FFF (for ABS-MF composite) in silencer application, zig-zag infill pattern (IP) with 100% ID, 0.15 mm layer height, 0.9 mm top and bottom layer thicknesses, and wall line count of 2, at a print speed of 50 mm/s was observed as the best combination.