• Durałek, Paweł
• Boczkowska, Anna
• Latko-Durałek, Paulina
• Dydek, Kamil

Abstract

In the last decade, much research has focused on the implementation of carbonaceous nanofillers in Carbon Fiber Reinforced Polymer (CFRP) to improve its electrical conductivity and mechanical performance. Such highly conductive CFRPs are desirable functional materials for use, for instance, as modules to protect electronic parts from high-energy electromagnetic impulses in the aerospace, defense or automotive sectors.The incorporation of carbon nanofillers can be realized by various approaches which one of them includes the use of thermoplastic nonwoven fabrics which contain conductive nanofillers obtained mainly by immersing neat nonwovens in a filler solution. In this work, a novel type of thermoplastic nonwoven fabrics containing carbon nanotubes (CNTs) was obtained by the pressing method in laboratory conditions and in a half-industrial melt-blown process (developed by TMBK Partners). Both approaches start with thermoplastic pellets containing CNTs obtained by the extrusion method; this results in a well-dispersed nanofiller within the polymer matrix. In lab conditions, thin nanocomposite fibers are produced by extrusion and spinning and then pressed together to form the nonwoven. In the melt-blown process, pellets are melted and then blown to form short fibers that are deposited in the receiving system. These two types of nonwoven fabrics contain up to 7wt% CNTs in the first method and up to 3.5wt% CNT in the half-industrial technique; they differ in obtained areal weight and fiber thickness. Moreover, the production capacity of the melt-blown approach is 25 times higher; this could meet demand from the industrial sector.Thermoplastic nonwovens containing CNTs were interleaved in CFRP by prepreg and resin infusion manufacturing methods. In both cases, due to the high flexibility of the nonwovens used, they were easily implemented in the CFRP and fully impregnated with epoxy resin, as was confirmed by Scanning Electron Microscope (SEM). Generally, the presence of CNTs increased the electrical conductivity of the CFRP throughout the laminate thickness, but the level of improvement is strictly dependent on the type of nonwoven used, especially the amount of CNTs and the thickness of the fabrics. The latter has also an effect on the interlaminar fracture toughness of the laminates and should therefore be kept as low as possible. Furthermore, there is also a strong effect of the manufacturing technique and conditions of the CFRP on the behavior of the nonwovens and the state of CNT dispersion in the final composite panels. Only if the curing temperature is high enough are the thermoplastic nonwovens completely melted, thus forming the homogenous interlayers in the CFRP and creating the conductive pathways between the CNTs. In effect, the final composite panels were characterized by a significant improvement of electrical conductivity, especially in the case of laminates manufactured by resin transfer molding.The research leading to these results has received funding from the National Centre for Research and Development within grant no. DOB-1-3/1/PS/2014, and from the European Union Horizon 2020 Program under Grant Agreement n° 646307.

Topics

• nanocomposite
• impedance spectroscopy
• dispersion
• Carbon
• scanning electron microscopy
• nanotube
• melt
• resin
• thermoplastic
• fracture toughness
• electrical conductivity
• curing
• spinning