Mechanical and thermal characterizations of non-metallic components recycled from waste printed circuit boards

Abstract

In the framework of reuse of non-metal (woven fiberglass layers (WFG) and epoxy resin (ER)) recovered from waste printed circuit boards (WPCBs) as received and maximization of economic and environmental benefits, this research aims to investigate mechanical and thermal properties of recycled woven fiberglass and ER extracted from WPCBs after separation by using chemical (organic solvent) and ultrasonic treatment The experiments were conducted on five samples cut from five different types of waste motherboards according to ASTM D5035 standard. Also, another sample not containing any notches or holes was cut from a blank PCB in order to be used as a reference for strength tests when compared with motherboard samples. Di-methyl formamide (DMF) was used to dissolve ER of all six samples at a low temperature in a simple reactor developed specifically for this purpose (WPCB separator). The new separator was equipped with a high-frequency ultrasonic wave generator used to accelerate the rate of breakage of internal van der Waals’ bonds of brominated epoxy resin (BER) by DMF thus reducing the dissolution time and facilitating separation of woven fiberglass layers against metal layers. After that, a rotary decompression evaporator was used to extract ER from DMF/ER solution. Universal testing machine was used to characterize mechanical behavior of recovered woven fiberglass, while thermogravimetric (TG-DTG) and calorimetric analyses (DSC) were used to investigate the thermal behavior of recovered ER. The results showed that the average strength of recovered fiberglass decreased by 48% in comparison with the blank PCB due to the presence of notches and degradation while the reduction in elastic modulus was slight. Also, the recovered ER showed high properties in terms of melting temperature and crystalline degree.