Carrier Fibers for the Safe Dosage of Nanoparticles in Nanocomposites: Nanomechanical and Thermomechanical Study on Polycarbonate/Boehmite Electrospun Fibers Embedded in Epoxy Resin.

Natalia Cano Murillo,Farnaz Emamverdi,Dorothee Silbernagl,Vasile-Dan Hodoroaba,Media Ghasem Zadeh Khorasani,Karen Cacua,Heinz Sturm

doi:10.3390/nano11061591

Abstract

The reinforcing effect of boehmite nanoparticles (BNP) in epoxy resins for fiber composite lightweight construction is related to the formation of a soft but bound interphase between filler and polymer. The interphase is able to dissipate crack propagation energy and consequently increases the fracture toughness of the epoxy resin. Usually, the nanoparticles are dispersed in the resin and then mixed with the hardener to form an applicable mixture to impregnate the fibers. If one wishes to locally increase the fracture toughness at particularly stressed positions of the fiber-reinforced polymer composites (FRPC), this could be done by spraying nanoparticles from a suspension. However, this would entail high costs for removing the nanoparticles from the ambient air. We propose that a fiber fleece containing bound nanoparticles be inserted at exposed locations. For the present proof-of-concept study, an electrospun polycarbonate nonwoven and taurine modified BNP are proposed. After fabrication of suitable PC/EP/BNP composites, the thermomechanical properties were tested by dynamic mechanical analysis (DMA). Comparatively, the local nanomechanical properties such as stiffness and elastic modulus were determined by atomic force microscopy (AFM). An additional investigation of the distribution of the nanoparticles in the epoxy matrix, which is a prerequisite for an effective nanocomposite, is carried out by scanning electron microscopy in transmission mode (TSEM). From the results it can be concluded that the concept of carrier fibers for nanoparticles is viable.

Highlights

The presence of aggregates is indicated by the morphology of fibers containing boehmite, which is expected at this range of boehmite nanoparticles (BNP) concentrations
Electrospun polycarbonate fibers were studied in this work as a carrier structure for the local reinforcement of an epoxy matrix
The macroscopic, temperature dependent mechanical properties were investigated by dynamic mechanical analysis (DMA)

Summary

Introduction

Fiber reinforced polymer composites (FRPC) have been widely used as structural materials in applications where high strength and lightweight is needed. For boehmite nanoparticles (BNP), it has been shown that nanoscale effects contribute to the cure chemistry [1] and network formation by forming a soft interphase with the epoxy matrix that successfully dissipates the energy of crack propagation and improves the composite mechanical performance [2,3,4].

Methods

Results

Conclusion