Muhammad Muddassir

• Thermoplastic composite materials are being widely used in the automotive and aerospace industries. Due to the limitations of shape complexity, different components need to be joined. They can be joined by mechanical fasteners, adhesive bonding or both. However, these methods have several limitations. Components can be joined by fusion bonding due to the property of thermoplastics. Thermoplastics can be melted on heating and regain their shape on cooling. This property makes them ideal for joining through fusion bonding by induction heating. Joining of non-conducting or non-magnetic thermoplastic composites needs an additional material that can generate heat by induction heating. Polymers are neither conductive nor electromagnetic so they don’t have inherent potential for inductive heating. A susceptor sheet having conductive materials (e.g. carbon fiber) or magnetic materials (e.g. nickel) can generate heat during induction. The main issues related with induction heating are non-homogeneous and uncontrolled heating. In this work, it was observed that to generate heat with a susceptor sheet depends on its filler, its concentration, and its dispersion. It also depends on the coil, magnetic field strength and coupling distance. The combination of different fillers not only increased the heating rate but also changed the heating mechanism. Heating of 40ºC/ sec was achieved with 15wt.-% nickel coated short carbon fibers and 3wt.-% multiwalled carbon nanotubes. However, only nickel coated short carbon fibers (15wt-.%) attained the heating rate of 24ºC/ sec. In this study, electrical conductivity, thermal conductivity and magnetic properties testing were also performed. The results also showed that electrical percolation was achieved around 15wt.-% in fibers and (13- 6)wt.-% with hybrid fillers. Induction heating tests were also performed by making parallel and perpendicular susceptor sheet as fibers were uni-directionally aligned. The susceptor sheet was also tested by making perforations. The susceptor sheet showed homogeneous and fast heating, and can be used for joining of non-conductive or non-magnetic thermoplastic composites.