A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

Mechanical and thermal properties of ABS/montmorillonite nanocomposites for fused deposition modeling 3D printing

Reference EPFL-ARTICLE-184271doi:10.1016/j.compositesa.2012.08.001View record in Web of Science Record created on 2013-02-27, modified on 2017-05-10

Composites Part A: Applied Science and Manufacturing

Fused deposition modelling (FDM) is one of the fastest-growing additive manufacturing methods used in printing fibre-reinforced composites (FRC). The performances of the resulting printed parts are limited compared to those by other manufacturing methods due to their inherent defects. Hence, the effort to develop treatment methods to overcome these drawbacks has accelerated during the past few years. The main focus of this study is to review the impact of those defects on the mechanical performance of FRC and therefore to discuss the available treatment methods to eliminate or minimize them in order to enhance the functional properties of the printed parts. As FRC is a combination of polymer matrix material and continuous or short reinforcing fibres, this review will thoroughly discuss both thermoplastic polymers and FRCs printed via FDM technology, including the effect of printing parameters such as layer thickness, infill pattern, raster angle and fibre orientation. The most common defects on printed parts, in particular, the void formation, surface roughness and poor bonding between fibre and matrix, are explored. An inclusive discussion on the effectiveness of chemical, laser, heat and ultrasound treatments to minimize these drawbacks is provided by this review.

FDM-Based 3D Printing of Polymer and Associated Composite: A Review on Mechanical Properties, Defects and Treatments.

Industrial hemp fibres were treated with sodium hydroxide, acetic anhydride, maleic anhydride and silane to investigate the influence of treatment on the fibre structure and tensile properties. It was observed that the average tensile strength of sodium hydroxide treated fibres slightly increased compared with that of untreated fibres, which was believed to be as a result of increased cellulose crystallinity. The average tensile strength of acetic anhydride, maleic anhydride, silane and combined sodium hydroxide and silane treated fibres slightly decreased compared with that of untreated fibres, which was believed to be as a result of decreased cellulose crystallinity. However, the average Young’s modulus of all treated fibres increased compared with untreated fibres. This was considered to be as a result of densification of fibre cell walls due to the removal of non-cellulosic components during treatment.

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Effect of various chemical treatments on the fibre structure and tensile properties of industrial hemp fibres

Mechanical behaviour of ABS: An experimental study using FDM and injection moulding techniques

The global interest in environmentally friendly material over the past few years has led to the development of new research areas in the field of renewable materials and biocomposites. Within this scope, several researches have been conducted to modify natural fibres aiming at an improved compatibility with polymeric matrices. In this study, fibres from the spadix stem of the date palm tree were treated with sodium hydroxide over different times. The effect of the alkali treatment on the structure, thermal and mechanical behaviour of the fibres was verified through chemical analysis, FTIR spectroscopy, TGA, and tensile testing. Comparing the different alkalisation parameters, promising results are obtained with a 2% sodium hydroxide solution over a treatment time of 2 h.

Optimization of the alkali treatment process of date palm fibres for polymeric composites

Additive manufacturing, commonly referred to as 3D printing, is one of the most hyped fields in the manufacturing field today. This article presents an overview of the state of the technologies for polymeric materials, with special emphasis on established processes for thermosetting resins. Furthermore, the last section of the article is dedicated to the 3D printing of fiber reinforced polymer composites. The processes and their related research breakthroughs are laid out describing the advantages and limitations of each. Common materials, fields of applications, and key players are presented.

A review of additive manufacturing technologies and markets for thermosetting resins and their potential for carbon fiber integration

Strain sensing behaviour of 3D printed carbon black filled ABS

The investigation of the shear behaviour of technical natural fibres is vital for the insurance of aesthetics and performance of light weight, high strength, and eco-friendly composites. In this study, Egyptian jute fibre plain weave fabrics of various areal densities were investigated to describe their shear behaviour in terms of shear forces, shear angles and shear lock angles, using the Bias-Extension and the Picture Frame test methods. Results show that both methods are valid for natural fibres and produce comparable results. Whereas the Bias-Extension test presents a fast and simple test procedure, the analysis of the results is more complex due to the interaction of non-shear components. On the other hand, the Picture Frame test proves to be time consuming and in need of a more complex test rig, but results in pure shear deformations throughout the sample.

Iman Taha

Papers

Mechanical behaviour of ABS: An experimental study using FDM and injection moulding techniques

Optimization of the alkali treatment process of date palm fibres for polymeric composites

A review of additive manufacturing technologies and markets for thermosetting resins and their potential for carbon fiber integration

Strain sensing behaviour of 3D printed carbon black filled ABS

Comparison of picture frame and Bias-Extension tests for the characterization of shear behaviour in natural fibre woven fabrics