Evolution of the morphology and the mechanical properties of ternary PE/PA6/GF composites during annealing

Ternary composites have been prepared via simultaneous melt extrusion of polyethylene (PE), polyamide-6 (PA6) and short glass fibres in a twin screw extruder. If the fibres are compatible with PA6 a network of fibres welded by domains of the minor PA6 phase is build within the matrix (PE) during the processing. Although a small amount of PA6 is added, the presence of the fibres promotes the continuity of this phase. Thus, the ternary mixture resembles the morphology of a co-continuous binary blend. In this paper the stability of the ternary composites upon annealing at temperatures above the melting of PA6 is studied. An increase of the dynamic tensile modulus is observed. Contrary to the behaviour of co-continuous binary blends, for which the properties often deteriorate due to morphology coarsening, in the ternary composites, it leads to the creation of stronger contacts between the fibres and better mechanical performance. This behaviour is accounted for by a recently developed mechanical model.     

Direct dyes on cotton grafted with 2-vinylpyridine and quaternised with alkyl bromides or epichlorohydrin

The dyeing properties of cotton grafted with 2-vinylpyridine and then quaternised with alkyl bromides or epichlorohydrin were studied under various dyeing conditions, using CI Direct Blue 78 and CI Direct Yellow 106. The results have been compared with those obtained on unmodified cotton.     

Toward Optimal Performance and In‐Depth Understanding of Spinel Li4Ti5O12 Electrodes through Phase Field Modeling

Computational modeling is vital for the fundamental understanding of processes in Li‐ion batteries. However, capturing nanoscopic to mesoscopic phase thermodynamics and kinetics in the solid electrode particles embedded in realistic electrode morphologies is challenging. In particular for electrode materials displaying a first order phase transition, such as LiFePO₄, graphite, and spinel Li₄Ti₅O₁₂, predicting the macroscopic electrochemical behavior requires an accurate physical model. Herein, a thermodynamic phase field model is presented for Li‐ion insertion in spinel Li₄Ti₅O₁₂ which captures the performance limitations presented in literature as a function of all relevant electrode parameters. The phase stability in the model is based on ab initio density functional theory calculations and the Li‐ion diffusion parameters on nanoscopic nuclear magnetic resonance (NMR) measurements of Li‐ion mobility, resulting in a parameter free model. The direct comparison with prepared electrodes shows good agreement over three orders of magnitude in the discharge current. Overpotentials associated with the various charge transport processes, as well as the active particle fraction relevant for local hotspots in batteries, are analyzed. It is demonstrated which process limits the electrode performance under a variety of realistic conditions, providing comprehensive understanding of the nanoscopic to microscopic properties. These results provide concrete directions toward the design of optimally performing Li₄Ti₅O₁₂ electrodes.     

Assessment of biodiesel stability under long-term storage and dynamic accelerated oxidation: a comparison approach

Clean Technologies and Environmental Policy - The biodiesel susceptibility to oxidation causes its qualitative deterioration and affects both its handling and long-term storage. This study aims to...     

A methodological approach for designing and developing web-based inventories of mobile Assistive Technology applications

Multimedia Tools and Applications - Mobile technologies provide radical opportunities in the domain of Assistive Technologies (AT) for persons with disabilities and the elderly by facilitating them...     

Mining patterns from graph traversals

In data models that have graph representations, users navigate following the links of the graph structure. Conducting data mining on collected information about user accesses in such models, involves the determination of frequently occurring access sequences. In this paper, the problem of finding traversal patterns from such collections is examined. The determination of patterns is based on the graph structure of the model. For this purpose, three algorithms, one which is level-wise with respect to the lengths of the patterns and two which are not are presented. Additionally, we consider the fact that accesses within patterns may be interleaved with random accesses due to navigational purposes. The definition of the pattern type generalizes existing ones in order to take into account this fact. The performance of all algorithms and their sensitivity to several parameters is examined experimentally.     

Polymerization kinetics and thermal properties of poly(alkyl methacrylate)/organomodified montmorillonite nanocomposites

The effect of the presence of organomodified nano‐montmorillonite (MMT) on the free radical polymerization kinetics of either ethyl methacrylate or butyl methacrylate was investigated. The in situ polymerization technique was selected with dispersion of the MMT nanoparticles into the corresponding monomer and subsequent bulk radical polymerization. Different types and amounts of MMT were used, including a sodium and several organomodified clays under the trade names Cloisite Na⁺ and Cloisite 15A, 25A and 30B. Reaction kinetics was measured gravimetrically and the nanocomposites formed were characterized with X‐ray diffraction (structure), gel permeation chromatography (molar mass distribution) and differential scanning calorimetry (glass transition temperature). Thermal degradation characteristics were measured with thermogravimetric analysis. Additional experiments with styrene as monomer were carried out in order to make clear the effect of the nanofiller on the polymerization kinetics. It was found that the presence of the bulk ammonium salt used as the organic modifier in MMT could influence the reaction kinetics when diffusion‐controlled phenomena occur. Reaction rate was slightly enhanced and nanocomposites with improved thermal stability were formed. In addition, the average molar mass and glass transition temperature of the polymer in the nanocomposites were slightly higher compared to the neat polymer. Copyright © 2012 Society of Chemical Industry     

‘Closing the loop’ in biological systems modeling — From the in silico to the in vitro

This work presents a holistic ‘closed loop’ approach for the development of models of biological systems. The ever-increasing availability of experimental information necessitates the advancement of a systematic methodology to organise and utilise these data. Herein, we present a biological model building framework that maps the treatment of the information from the initial conception of the model, through its experimental validation and finally to its application in model-based optimisation studies. We highlight and discuss current issues associated with the development of mathematical models of biological systems and share our perspective towards a holistic ‘closed loop’ approach that will facilitate the control of the in vitro through the in silico.