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Elastomers are the main material component for footwear and tires contact applications. However, they exhibit low traction on wet ice, resulting in slips and falls for individuals and vehicles during wintertime. Textured elastomeric short fiber composites can be manufactured in a scalable manner with conventional processing techniques such as injection molding, and have promising wet ice slip resistance behavior. However, the state-of-the-art textured composite approaches employs one-dimensional (1D) micron-scale fibers that are prone to mechanical abrasion on hard surfaces, resulting in their ice traction decay over time. Here, we demonstrate a novel microstructural design strategy for developing durable slip-resistant composites using nanomaterials. To this aim, a series of micron- and nanoscale 1D and 2D fibers as additives in the textured elastomers are evaluated for surface morphology, ice-traction, and wear-resistance. We show that unlike 1D and other 2D counterparts, hexagonal graphene nanoplatelets (GNP) exhibit superior wear-resistance and an anomalous wear-induced increase in ice-traction functionality. Specifically, the partially agglomerated morphology of the GNP surfaces results in a hierarchical surface texturing, which imparts the surface with a 64% ice traction improvement (0.46 ± 0.11; p < 0.0001) at a low surface weight loss (2.44 mg cm−2). This study provides new microstructural design pathways for designing durable non-slip composites and can shed light on new applications for the diverse class of 2D nanomaterials. [ABSTRACT FROM AUTHOR]

The increasing quantity of hardwood growing in the Swiss forest represents an opportunity for the future of the wood industry. Glued laminated timbers made of hardwood offer higher strength and stiffness properties than the softwood equivalents, and they are often used in combination with softwood for local reinforcement. Additionally, their visual aspect can be an attractive selling argument. Until now, phenol resorcinol adhesive (PRF, Aerodux 185) has preferably been used for the bonding of ash wood. Despite its high bonding performance, this adhesive has several disadvantages, including a dark brown glue line and a strong emission of formaldehyde both during the gluing process and when in use. One-component polyurethane (1C-PUR) adhesives, widely used in load-bearing structures made of softwood, represent an interesting alternative for hardwood gluing. These formaldehyde-free adhesives require no mixing and present an invisible glue line without any emissions after full curing. Preliminary results have shown that the combination of a slow-reacting 1C-PUR adhesive with a water-based primer system obtained similar results as Aerodux 185 in laboratory conditions with respect to shear strength and delamination resistance. This paper focuses on the optimization of the gluing process of two different 1C-PUR adhesives and their combination with a special primer on ash wood to develop an economically attractive industrial application process. The influence of several factors, such as primer-water concentration, primer activation time and primer quantity, were investigated using a delamination test according to EN 302-2. It was shown that it is possible with 1C-PUR to reach the normative standard requirements according to EN 15425. The best results were obtained with a primer-water concentration of 10% and a primer-water applied quantity of 20 g/m 2 . The influence of the primer activation time was shown to have only a small effect. 1C-PUR with a long closed assembly time was shown to perform even better. Additionally, the reduction of the lamellar thickness led to a reduction of delamination. By considering these parameters, it was possible to develop an industrial process for producing high-performance glued laminated timber out of ash wood and glued with a certified and commercially available 1C-PUR adhesive. [ABSTRACT FROM AUTHOR]

In recent years one-component polyurethane (1C-PUR) adhesives have been increasingly applied in loadbearing timber constructions. However, a low wood fracture percentage at wet stage and a comparatively low performance in delamination tests need to be overcome to fulfill certain technical standards and to achieve an even higher acceptance in the global market of wood adhesives. Via the use of suitable primers, in this case a water-soluble primer (WSP) system, it is possible to significantly improve these parameters. Nevertheless, the exact mode of action of the primer remains so far unclear. In this study, primer treated wood surfaces were characterized in detail by atomic force microscopy (AFM) and the influence of the primer on the penetration of the 1C-PUR adhesive into wood cell walls was further analyzed by confocal Raman spectroscopy imaging. AFM investigations of primer treated surfaces reveal a significant increase in adhesion compared to non-primer treated surfaces and indicate a penetration of the primer into the cell wall. However, Raman spectroscopy shows that the primer application does not lead to a substantial and deep penetration of the 1C-PUR adhesive into wood cell walls. Slight changes in the spectral properties of the primer treated samples at the interface between the bond line and the adjacent cell wall, point towards changed interactions between wood and polyurethane. [ABSTRACT FROM AUTHOR]

Abstract: The thermal stability of adhesives for load-bearing construction has been one of their key parameters since engineered wood products were introduced in timber construction. In the case of one-component moisture-curing polyurethane (1C PUR) adhesives, knowledge about relationships between their chemical structure and the resulting bonding properties is limited, especially under high-temperature conditions. In this study the structure–property relationships of 1C PUR prepolymers were analyzed in the temperature range from 20 to 200°C by means of mechanical and rheological tests. NCO-terminated urethane prepolymers were prepared from systematically varied MDI and polyether mixtures. The structural parameters investigated were the urea and urethane group content, cross-link density, ethylene oxide content and the adjustment of functionality via NCO or polyether component. Bonded wood joints were tested for their tensile shear strength and polymer films were analyzed by means of DMA and DSC. The results revealed a significant influence of hard segment content and cross-link density on the thermal stability of the prepolymers. Not all parameters that affect the film properties significantly influence bonding. [Copyright &y& Elsevier]

Objectives This study sought to test the effects of rostral fluid displacement from the legs on transpharyngeal resistance (R ph ), minute volume of ventilation (V min ), and partial pressure of carbon dioxide (PCO 2 ) in men with heart failure (HF) and either obstructive (OSA) or central sleep apnea (CSA). Background Overnight rostral fluid shift relates to severity of OSA and CSA in men with HF. Rostral fluid displacement may facilitate OSA if it shifts into the neck and increases R ph , because pharyngeal obstruction causes OSA. Rostral fluid displacement may also facilitate CSA if it shifts into the lungs and induces reflex augmentation of ventilation and reduces PCO 2 , because a decrease in PCO 2 below the apnea threshold causes CSA. Methods Men with HF were divided into those with mainly OSA (obstructive-dominant, n = 18) and those with mainly CSA (central-dominant, n = 10). While patients were supine, antishock trousers were deflated (control) or inflated for 15 min (lower body positive pressure [LBPP]) in random order. Results LBPP reduced leg fluid volume and increased neck circumference in both obstructive- and central-dominant groups. However, in contrast to the obstructive-dominant group in whom LBPP induced an increase in R ph , a decrease in V min , and an increase in PCO 2 , in the central-dominant group, LBPP induced a reduction in R ph , an increase in V min , and a reduction in PCO 2 . Conclusions These findings suggest mechanisms by which rostral fluid shift contributes to the pathogenesis of OSA and CSA in men with HF. Rostral fluid shift could facilitate OSA if it induces pharyngeal obstruction, but could also facilitate CSA if it augments ventilation and lowers PCO 2 . [ABSTRACT FROM AUTHOR]