Search results for "A2"

Influence of pulp bleaching and compatibilizer selection on performance of pulp fiber reinforced PLA biocomposites

2019

A plasticity model for predicting the rheological behavior of paperboard

2017

The sorption of water into the paperboard exposes a container to reversible and irreversible deformations under relative humidity variations. In this study, an elasto-plastic material model is used to demonstrate how through-thickness dry solids content gradients can generate permanent in-plane strains in paperboard. The measurements presented in this paper indicate that in consecutive loading-unloading cycles, the yield stress either remains roughly constant or decreases, and an additional permanent set of strain is obtained even when the maximum tension of repetitions stays constant. Two modified approaches concerning elasto-plastic hardening behavior based on the measurements of this wor…

Electron refrigeration in hybrid structures with spin-split superconductors

2017

Electron tunneling between superconductors and normal metals has been used for an efficient refrigeration of electrons in the latter. Such cooling is a nonlinear effect and usually requires a large voltage. Here we study the electron cooling in heterostructures based on superconductors with a spin-splitting field coupled to normal metals via spin-filtering barriers. The cooling power shows a linear term in the applied voltage. This improves the coefficient of performance of electron refrigeration in the normal metal by shifting its optimum cooling to lower voltage, and also allows for cooling the spin-split superconductor by reverting the sign of the voltage. We also show how tunnel couplin…

The Impact of Janus Nanoparticles on the Compatibilization of Immiscible Polymer Blends under Technologically Relevant Conditions

2014

Several hundred grams of Janus nanoparticles (d ≈ 40 nm) were synthesized from triblock terpolymers as compatibilizers for blending of technologically relevant polymers, PPE and SAN, on industry-scale extruders. The Janus nanoparticles (JPs) demonstrate superior compatibilization capabilities compared to the corresponding triblock terpolymer, attributed to the combined intrinsic properties, amphiphilicity and the Pickering effect. Straightforward mixing and extrusion protocols yield multiscale blend morphologies with "raspberry-like" structures of JPs-covered PPE phases in a SAN matrix. The JPs densely pack at the blend interface providing the necessary steric repulsion to suppress droplet …

Progress in development of a new luminescence setup at the FinEstBeAMS beamline of the MAX IV laboratory

2019

The main funding for the FinEstBeAMS beamline has been obtained from the European Union through the European Regional Development Fund (project “Estonian beamline to MAX-IV synchrotron”, granted to the University of Tartu) and from the Academy of Finland through the Finnish Research Infrastructure funding projects ( FIRI2010 , FIRI2013 , FIRI2014 ). The authors also acknowledge the funding contributions of the University of Oulu , University of Turku , Tampere University of Technology , the Estonian Research Council ( IUT 2-25 , IUT 2-26 , PRG-111 ), as well as the Estonian Centre of Excellence in Research “Advanced materials and high-technology devices for sustainable energetics, sensorics…

Nanotribological, nanomechanical and interfacial characterization of atomic layer deposited TiO2 on a silicon substrate

2015

Abstract For every coating it is critical that the coatings are sufficiently durable to withstand practical applications and that the films adhere well enough to the substrate. In this paper the nanotribological, nanomechanical and interfacial properties of 15–100 nm thick atomic layer deposited (ALD) TiO 2 coatings deposited at 110–300 °C were studied using a novel combination of nanoscratch and scanning nanowear testing. Thin film wear increased linearly with increasing scanning nanowear load. The film deposited at 300 °C was up to 58±11 %-points more wear-resistant compared to the films deposited at lower temperatures due to higher hardness and crystallinity of the film. Amorphous/nanocr…

Thermal atomic layer deposition of AlOxNy thin films for surface passivation of nano-textured flexible silicon

2019

Abstract Aluminum oxynitride (AlOxNy) films with different nitrogen concentration are prepared by thermal atomic layer deposition (ALD) for flexible nano-textured silicon (NT-Si) surface passivation. The AlOxNy films are shown to exhibit a homogeneous nitrogen-doping profile and the presence of an adequate amount of hydrogen, which is investigated by Time-of-Fight Elastic Recoil Detection Analysis (ToF-ERDA). The effective minority carrier lifetimes are measured after the NT-Si surface passivation; the minimum surface recombination velocity (SRV) of 5 cm-s−1 is achieved with the AlOxNy film in comparison to the Al2O3 and AlN films (SRV of 7–9 cm-s−1). The better SRV with AlOxNy film is due …

Failure Estimates for SiC Power MOSFETs in Space Electronics

2018

Silicon carbide (SiC) power metal-oxide-semiconductor field effect transistors (MOSFETs) are space-ready in terms of typical reliability measures. However, single event burnout (SEB) due to heavy-ion irradiation often occurs at voltages 50% or lower than specified breakdown. Failure rates in space are estimated for burnout of 1200 V devices based on the experimental data for burnout and the expected heavy-ion linear energy transfer (LET) spectrum in space. peerReviewed

Effect of doping and crystallite size on the electrochemical performance of Li4Ti5O12

2016

Abstract Defect spinel phase lithium titanate (Li 4 Ti 5 O 12 ) has been suggested as a promising negative electrode material for next generation lithium ion batteries. Flame spray pyrolysis has been shown to be a viable fast, one-step process for synthesis of nanoparticulate Li 4 Ti 5 O 12 . However, due to the rapid quenching that is integral to the process the crystallite size remain very small and non-uniform. To overcome this shortcoming a vertical flow tube furnace was used to increase the high-temperature residence time. This resulted in an increase in the crystallite size and crystallinity of the product. As a result of this increase the electrochemical performance of the Li 4 Ti 5 …

X-ray micro-computed tomography investigation of fibre length degradation during the processing steps of short-fibre composites

2014

The mechanical properties of composites in the fibre direction are mainly attributed to the fibre slenderness, or aspect ratio. A trade-off between performance and processability is usually required, and dependent on the intended application. If the fibre length could be retained or not severely degraded during various processing steps towards the injection-moulded component, a stiffer and stronger composite product could be obtained. The processing steps for injection moulded wood-fibre composites here include: Pulping, commingling, extrusion, pelletizing, and injection moulding. To tune the processing parameters systematically for retained fibre length, it would be useful to investigate t…