Shape memory behavior of 4D printed CF/PEKK high temperature composite under subsequent thermomechanical cycles

Abstract

Shape memory effect (SME) in high temperature polymers (HTPs) has great significance in space for making self-deployable structures, needing high strength and stiffness during operation, signifying the necessity of exploring HTP composite with SME. This work investigates the SME of 4D printed carbon fiber/polyether ketone ketone (CF/PEKK) HTP composite under subsequent thermomechanical cycles for the first time. Scanning electron microscopy (SEM) revealed a uniform distribution of CFs in the developed composite, the extruded composite filament, and the composite prints with seamless raster and layer deposition, confirming a suitable selection of processing parameters. The CF/PEKK composite prints exhibited an excellent shape fixity, R<inf>f</inf> = 90 % and 91 %, and shape recovery, R<inf>r</inf> = 96 % and 89 % in the first and the tenth cycle, respectively. A significant loss of 7 % in R<inf>r</inf> is observed in the tenth cycle. Glass transition (T<inf>g</inf>) and degradation temperature (T<inf>d</inf>) of the CF/PEKK composite prints are observed to be 162 °C and 568 °C, while storage modulus is found 157.69 % and 38.69 % higher than the existing PEKK and PEEK, respectively. This study revealed an excellent SME of 4D printed CF/PEKK composite with outstanding T<inf>g</inf> and T<inf>d</inf>, showing great potential for space applications. © 2024 Elsevier B.V.