Quantification of stress transfer in a model cellulose nanocrystal/graphene bilayer using Raman spectroscopy

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record The dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.1303Graphene and cellulose possess a multitude of unique and useful properties for applications in electronics, sensors and composites which has led to significant scientific interest over the past 5–10 years. Despite this interest, there has been no experimental work investigating the interface or stress transfer efficiency between these materials, which limits future developments in this field. With the aim of investigating this interface, we have created a model bilayer composite, consisting of a tunicate derived cellulose nanocrystal (T-CNC) film and a monolayer of graphene produced by chemical vapour deposition. Raman spectroscopy has been used to monitor the four-point bending of this model bilayer composite. Shifts in the position of Raman bands, unique for both the cellulose and graphene components of this model composite, are recorded. Using a novel analysis of these Raman band shifts, we have formed an expression which deconvolutes the total stress transfer efficiency of the model system. Using this deconvolution, a stress transfer efficiency of 66% has been derived at the cellulose/graphene interface. In addition, splitting of the graphene Raman G band has allowed calculation of the shear strain in the graphene, which is assumed to be equal to that at the cellulose-graphene interface. The individual T-CNCs in the reference samples showed location dependent preferential orientations. The film was found to be stiffer when the T-CNCs were oriented parallel to the loading axis. It was intended that the varying stiffness of the cellulose film could be used to analyse the effects of underlying film stiffness on stress transfer efficiency, but conclusions from this test were limited. The detailed interface analysis presented here will help to inform design in future cellulose/graphene devices.Engineering and Physical Sciences Research Council (EPSRC

Tensile testing of cellulose based natural fibers for structural composite applications

A series of tensile tests were conducted on a Lloyd LRX tensile testing machine for numerous natural fibers deemed potential candidates for development in composite applications. The tensile tests were conducted on the fibers jute, kenaf, flax, abaca, sisal, hemp, and coir for samples exposed to moisture conditions of (1) room temperature and humidity, (2) 65% moisture content, (3) 90% moisture content, and (4) soaked fiber. These seven fibers were then tested for the four conditions and the mechanical properties of tensile strength, tensile strain to failure, and Young's modulus were calculated for the results. These results were then compared and verified with those from the literature, with some of the fibers showing distinctly promising potential. Additionally, a study on the effect of alkalization using 3% NaOH solution was carried out on flax, kenaf, abaca, and sisal to observe impact that this common fiber pre-treatment process has on fiber mechanical properties. The result of the investigation indicated that over treatment of natural fibers using NaOH could have a negative effect on the base fiber properties. It is consequently apparent that a treatment time of less than 10 min is sufficient to remove hemicelluloses and to give the optimum effect

Search for leptophobic Z ' bosons decaying into four-lepton final states in proton-proton collisions at root s=8 TeV

Peer reviewe

Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at root s=13 TeV

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Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV

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Measurement of the mass difference between top quark and antiquark in pp collisions at root s=8 TeV

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Search for high-mass diphoton resonances in proton-proton collisions at 13 TeV and combination with 8 TeV search

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Search for heavy resonances decaying into a vector boson and a Higgs boson in final states with charged leptons, neutrinos, and b quarks

Peer reviewe

Measurement of the Z boson differential cross section in transverse momentum and rapidity in proton-proton collisions at 8 TeV

We present a measurement of the Z boson differential cross section in rapidity and transverse momentum using a data sample of pp collision events at a centre-of-mass energy s=8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The Z boson is identified via its decay to a pair of muons. The measurement provides a precision test of quantum chromodynamics over a large region of phase space. In addition, due to the small experimental uncertainties in the measurement the data has the potential to constrain the gluon parton distribution function in the kinematic regime important for Higgs boson production via gluon fusion. The results agree with the next-to-next-to-leading-order predictions computed with the fewz program. The results are also compared to the commonly used leading-order MadGraph and next-to-leading-order powheg generators. © 2015 CERN for the benefit of the CMS Collaboration