Analysis of wear mechanism in TPU-steel contact pair by means of long stroke tribometer tests

A complete wear characterisation of a thermoplastic polyurethane (TPU) sliding against steel is presented. Wear tests were performed using a long stroke tribometer under sliding reciprocating movement and dry conditions. The dependence of some of the most significant parameters was studied. Before and after wear tests, complementary observations, analyses and measurements were also performed on both contacting materials. These various characterisations involved weight loss of TPU, physico-chemical and thermo- mechanical analyses of TPU, included topographical measurements and morphological observations of worn surfaces of contacting pairs and calculations of the temperature rise generated by friction

Dynamic Acidity in Defective UiO-66

The metal organic framework (MOF) material UiO-66 has emerged as one of the most promising MOF materials due to its thermal and chemical stability and its potential for catalytic applications. Typically, as-synthesised UiO-66 has a relatively high concentration of missing linker defects. The presence of these defects has been correlated with catalytic activity but characterisation of defect structure has proved elusive. We refine a recent experimental determination of defect structure using static and dynamic first principles approaches, which reveals a dynamic and labile acid centre that could be tailored for functional applications in catalysis.Comment: 5 figure

Characterisation of construction materials: a chemical comparison of historical mortars

[EN] This text outlines the results obtained in a case study about construction materials analysis, concerning a set of watchtowers scattered throughout the territory of Cuenca Province, Spain. The complete understanding of these buildings has been possible thanks to different approaches. Territorial analysis, historic study, surveys and construction definition have been the key-factors of architectural research. But a good result could not be possible without a rigorous chemical study. Samples carried out on mortars from different watchtowers have been compared and analyzed. In this frame, a wide range of microanalysis methods has been applied to the samples (i.e. light microscopy, FTIR spectroscopy, scanning electron microscopy-X-ray, X-ray diffraction, granulometric analysis, insoluble residue) with the purpose of confirming the constructive homogeneity and technology of the buildings, as interesting examples of Spanish Christian Reconquest.This research has been made possible thanks to the Project “Trazabilidad Histórica Y Perspectivas Para Los Materiales Sostenibles Vinculados A La Tradición Constructiva De La Comunidad Valenciana” Ayudas GV 2014/014, Conselleriad’Educació, Cultura i Esport, GVA, main researcher V. Cristini.Ruiz Checa, JR.; Cristini ., V.; Valcuende Payá, MO.; Osete Cortina, L. (2015). Characterisation of construction materials: a chemical comparison of historical mortars. WIT Transactions on Engineering Sciences (Online). 90:83-94. https://doi.org/10.2495/MC150081S83949

Landfill mining: resource potential of Austrian landfills – evaluation and quality assessment of recovered municipal solid waste by chemical analyses

Since the need for raw materials in countries undergoing industrialisation (like China) is rising, the availability of metal and fossil fuel energy resources (like ores or coal) has changed in recent years. Landfill sites can contain considerable amounts of recyclables and energy-recoverable materials, therefore, landfill mining is an option for exploiting dumped secondary raw materials, saving primary sources. For the purposes of this article, two sanitary landfill sites have been chosen for obtaining actual data to determine the resource potential of Austrian landfills. To evaluate how pretreating waste before disposal affects the resource potential of landfills, the first landfill site has been selected because it has received untreated waste, whereas mechanically–biologically treated waste was dumped in the second. The scope of this investigation comprised: (1) waste characterisation by sorting analyses of recovered waste; and (2) chemical analyses of specific waste fractions for quality assessment regarding potential energy recovery by using it as solid recovered fuels. The content of eight heavy metals and the net calorific values were determined for the chemical characterisation tests. </jats:p

Probing the charged state of layered positive electrodes in sodium-ion batteries : reaction pathways, stability and opportunities

Sodium-ion batteries have received significant interest as a cheaper alternative to lithium-ion batteries and could be more viable for use in large scale energy storage systems. However, similarly to lithium-ion batteries, their performance remains limited by the positive electrode materials. Layered transition metal oxides, with chemical formula NaxMO2, have been extensively investigated and appear to show the most promise. However, the inability to reversibly extract large amounts of sodium ions from these layered structures, by charging to high voltages, has limited the useful capacity and cycle life of these materials. To address this, numerous studies have attempted to resolve the structural and chemical changes that take place in positive electrode materials upon cycling. This is particularly important at and near the charged state, which is where the materials\u27 structures are highly sodium deficient. Following a brief introduction into the status of sodium-ion battery positive electrodes, this work focuses on the development of knowledge and understanding into the structure of layered oxides at the charged state by highlighting cutting edge characterisation techniques that have been utilised. Finally, a perspective on future development is provided to direct further structural characterisation research which will enable the rational design of new and improved energy storage materials

Edge functionalisation of graphene nanoribbons with a boron dipyrrin complex : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nanoscience at Massey University, Manawatū, New Zealand

Chemical modification can be used to tune the properties of graphene and graphene nanoribbons, making them promising candidates for carbon-based electronics. The control of edge chemistry provides a route to controlling the properties of graphene nanoribbons, and their self-assembly into larger structures. Mechanically fractured graphene nanoribbons are assumed to contain oxygen functionalities, which enable chemical modification at the nanoribbon edge. The development of graphene nanoribbon edge chemistry is difficult using traditional techniques due to limitations on the characterisation of graphene materials. Through the use of a chromophore with well-defined chemistry, the reactivity of the edges has been investigated. Small aromatic systems were used to understand the reactivity of the boron dipyrrin Cl-BODIPY, and with the aid of spectroscopic and computational methods, the substitution mechanism and properties of the compounds have been investigated. The synthetic procedure was then applied to graphene nanoribbons. Results from infrared and Raman spectroscopy studies show that edge-functionalisation of graphene nanoribbons with BODIPY was successful, and no modifications to the basal plane have been observed

Quantum materials with strong spin-orbit coupling : challenges and opportunities for materials chemists

ASG acknowledges funding through an EPSRC Early Career Fellowship EP/T011130/1.Spin-orbit coupling is a quantum effect that can give rise to exotic electronic and magnetic states in the compounds of the 4d and 5d transition metals. Exploratory synthesis, chemical tuning and structure-property characterisation of such compounds is an increasingly active area of research with both fundamental and application-related outlooks, but requires great care with regards to the chemistry of these materials that has not always been considered. This Perspective will give an accessible introduction to topical materials with strong spin-orbit coupling, their crystal chemistry, and their structure-property relationships, which overlaps with the contemporary investigation of some of the same materials within different communities. It will also outline some of the challenges faced in their synthesis and characterisation, and the contributions that materials chemists can make to overcoming these.Publisher PDFPeer reviewe

Hypercrosslinked materials : preparation, characterisation and applications

This review article provides an overview of hypercrosslinking technology. In particular, it covers the preparation and characterisation of hypercrosslinked materials and their applications. The synthesis section examines the different monomers, precursor polymers and reagents used to prepare hypercrosslinked materials, but also the different synthetic approaches disclosed in the literature. The various chemical modification reactions relevant to this area are also reviewed. Several examples of applications for hypercrosslinked materials are described; these applications are grouped into thematic areas such as chromatography, gas storage and the trapping of organic contaminants

Analytical transmission electron microscopy at organic interfaces

Organic materials are ubiquitous in all aspects of our daily lives. Increasingly there is a need to understand interactions between different organic phases, or between organic and inorganic materials (hybrid interfaces), in order to gain fundamental knowledge about the origin of their structural and functional properties. In order to understand the complex structure–property–processing relationships in (and between) these materials, we need tools that combine high chemical sensitivity with high spatial resolution to allow detailed interfacial characterisation. Analytical transmission electron microscopy (TEM) is a powerful and versatile technique that can fulfil both criteria. However, the application of analytical TEM to organic systems presents some unique challenges, such as low contrast between phases, and electron beam sensitivity. In this review recent analytical TEM approaches to the nanoscale characterisation of two systems will be discussed: the hybrid collagen/mineral interface in bone, and the all-organic donor/acceptor interface in OPV devices