Processing, characterization, and modeling of carbon nanotube-reinforced multiscale composites

We describe the preparation and characterization of a green and renewable polyelectrolyte complex (PEC) containing phosphorus, nitrogen and carbon elements, based on the ionic complexation between chitosan and phytic acid. Introduction of this PEC to ethylene–vinyl acetate copolymer (EVA) leads to an improvement of the flame retardancy. As for the EVA/PEC composites with 20.0 wt % of PEC (EVA/20PEC), the char residue at 600 °C is 12 wt % higher than that of the pristine EVA under nitrogen atmosphere. Compared to the pristine EVA, the peak heat release rate and total heat release of EVA/20PEC show 249 W g–1 and 5.6 kJ g–1 decreases, respectively. The char residue of EVA/20PEC is full and compact, demonstrating excellent intumescent effect. Introduction of this PEC also contributes to a slight increase of the Young’s modulus while maintains the excellent ductility. This work provides a new approach for the development of environmentally friendly intumescent flame retardant system.

Chitosan/Phytic Acid Polyelectrolyte Complex: A Green and Renewable Intumescent Flame Retardant System for Ethylene–Vinyl Acetate Copolymer

The present paper discusses the key issues of carbon nanotube (CNT) dispersion and effect of functionalisation on the mechanical properties of multiscale carbon epoxy composites. In this study, CNTs were added in epoxy matrix and further reinforced with carbon fibres. Predetermined amounts of optimally amine functionalised CNTs were dispersed in epoxymatrix, and unidirectional carbon fiber laminateswere produced. The effect of the presence of CNTs (1.0 wt%) in the resin was reflected by pronounced increase in Young's modulus, inter-laminar shear strength, and flexural modulus by 51.46%, 39.62%, and 38.04%, respectively. However, 1.5wt% CNT loading in epoxy resin decreased the overall properties of the three-phase composites. A combination of Halpin-Tsai equations and micromechanics modeling approach was also used to evaluate the mechanical properties of multiscale composites and the differences between the predicted and experimental values are reported. These multiscale composites are likely to be used for potential missile and aerospace structural applications.

https://downloads.hindawi.com/journals/jnm/2014/837492.pdf

Three-phase carbon fiber amine functionalized carbon nanotubes epoxy composite: processing, characterisation, and multiscale modeling

Polymer nanocomposites have existed for decades, as carbon black, pyrogenic silica and diatomite were used as additives in polymers. Nevertheless, their characterizations and the effect of properties induced by the nanometric scale of fillers was not fully understood at these times. The real starting point, corresponding to an understanding of the action of these fillers, is generally considered as corresponding to the first papers on a polyamide-6 filled with nanoclays published by Usuki et al. (1993) and Okada A. (1995), from Toyota R&D. Both these papers called it "Hybrid" material. Rapidly, research increased, and the first use of the term "nanocomposites" appeared in 1994 [Lan & Pinnavaia (1994), Lan et al. (1995), Giannelis (1996)]. After these pioneers, a lot of researches started on various fillers. The demand for continual improvement in the performances of thermoplastic and thermoset polymer materials has led to the emergence of these new technologies. Nanofillers lists increased within years (nanoclays, nano-oxides, carbon nanotubes, POSS , etc.), as well as the matrix in which they are used and interactions with traditional fillers. Nowadays, the development of polymer nanocomposites is one of the most active area of development of nanomaterials. The properties imparted by the nanoparticles are various and focus particularly on strengthening the electrical conduction and barrier properties to temperature, gases and liquids as well as the possible improvement of fire behaviour. As a method which consists of reinforcing polymer chains at the molecular scale in the same way than the fibres at the macroscopic scale, nanocomposites [Biron (2004), Gloaguen & Lefevre (2007)] represent the new generation of two-phased materials, associating a basic matrix to nanofillers inserted between polymer chains. Nanofillers can significantly improve or adjust the different properties of the materials into which they are incorporated, such as optical, electrical, mechanical, thermal properties or fire-retardant properties, sometimes in synergy with conventional fillers. The properties of composite materials can be significantly impacted by the mixture ratio between the organic matrix and the nanofillers.

/pdf/properties-of-nanofillers-in-polymer-frudp40izz.pdf

Properties of Nanofillers in Polymer

As the utilization of advanced composites in structural applications grows, the need for improving their through-thickness properties becomes imperative. Although the behavior of composite laminate...

Janos BNagy

Papers

The influence of the matrix polarity on the morphology and properties of ethylene vinyl acetate copolymers–carbon nanotube nanocomposites