Abstract
In the present study, newly design hybrid nanostructures were produced by growing long carbon nanofibers (CNF) on single- and multi-layer graphene oxide (GO) sheets in the presence of catalyst by chemical vapor deposition (CVD). Chemical composition analysis indicated the formation of Fe-C bonds by the deposition of carbon atoms on catalyst surface of Fe2O3 and increasing in C/O atomic ratio confirming CNF growing. These hybrid additives were distributed homogeneously through polyamide 6.6 (PA6.6) chains by high shear thermokinetic mixer in melt phase. Spectroscopic studies showed that the differences in the number of graphene layer in hybrid structures directly affected the crystalline behavior and dispersion state in polymer matrix. Flexural strength and flexural modulus of PA6.6 nanocomposites were improved up to 14.7% and 14% by the integration of 0.5 wt% CNF grown on multi-layer GO, respectively, whereas there was a significant loss in flexural properties of single-layer GO based nanocomposites. Also, the integration of 0.5 wt% multi-layer GO hybrid reinforcement in PA6.6 provided a significant increase in tensile modulus about 24%. Therefore, multi-layer GO with CNF increased the degree of crystallinity in nanocomposites by forming intercalated structure and acted as a nucleating agent causing the improvement in mechanical properties.
Highlights
Graphene having a 2-dimensional carbon nanostructure is a promising reinforcing agent in thermoplastic composite materials due to its high mechanical and thermal properties, and high surface area [1] [2]
PA6.6 based nanocomposites reinforced with single-layer GO, multi-layer thermally exfoliated graphene oxide (TEGO), and their chemical vapor deposition (CVD) grown carbon nanofibers (CNF) hybrids were prepared by a thermokinetic high shear mixer to obtain better dispersion and prevent agglomeration of these nano additives
TEGO has high carbon content of 97.9 at% and oxygen content of 2.1 at% which are obtained from X-ray photoelectron spectroscopy (XPS)
Summary
Graphene having a 2-dimensional carbon nanostructure is a promising reinforcing agent in thermoplastic composite materials due to its high mechanical and thermal properties, and high surface area [1] [2]. There have been few attempts to combine the characteristic properties of graphene with the other carbon-based materials such as carbon nanotubes (CNT) or carbon nanofibers (CNF) to develop an hybrid structure by CVD technique [14] [15]. There is no work about the integration of 3D graphene/CNT hybrid additive in thermoplastic polymers in melt phase and the investigation of the effect of graphene type and its number of layers in this hybrid structure with CNF on the performance of PA6.6 nanocomposites. PA6.6 based nanocomposites reinforced with single-layer GO, multi-layer thermally exfoliated graphene oxide (TEGO), and their CVD grown CNF hybrids were prepared by a thermokinetic high shear mixer to obtain better dispersion and prevent agglomeration of these nano additives. Parallel study was conducted with these two types of bicomponent additives to understand the effect of number of graphene layers on the crystallinity and mechanical properties of PA6.6 nanocomposites
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