Composite manhole covers prepared with recycled printed circuit boards as a reinforcing filler

Waste circuit boards particles (CBPs) were utilized as a reinforcing filler to prepare bulk molding composites (BMCs) for the manufacture of composite manhole covers (CMCs) without reinforcing ribs. The effects of CBPs and conventional CaCO₃ on the mechanical properties of the BMCs were comparatively determined. Compared to CaCO₃, CBPs showed a higher compatibility with unsaturated polyester resin (UPR) while effectively improving the fluidity of premix and the mechanical properties of the BMC. To enhance the interfacial adhesion between the glass fiber (GF) and UPR, three kinds of amine, epoxy, and vinyl modified silanes (namely KH‐550, KH‐560, and KH‐570, respectively) were used. The surface tension (γ) of the GF significantly decreased upon modification with the coupling agents. Fourier transform infrared spectroscopy (FT‐IR) and scanning electron microscopy (SEM) characterizations revealed a strong adhesion between the GF and UPR, thereby enhancing the mechanical properties of the composite material. The BMC material showed optimal flexural strengths upon addition of KH‐560 and KH‐570 coupling agents at 4 wt%. With the aim of evaluating its mechanical performance, a constant loading test combined with an ANSYS finite element analysis was performed over the prepared CMC. According to the constant loading test, the CMC material showed a stress loading of 7.8 tons, which was close to the value obtained by ANSYS simulation. POLYM. COMPOS., 39:4532–4541, 2018. © 2017 Society of Plastics Engineers