447 research outputs found

    Artificial turf developments and sport applications at Ghent University

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    In the past decades artificial turf fields have developed into a worthy alternative for natural grass in outdoor sports appliance such as football, rugby and hockey. Heavy rainfall and periods of drought can affect a natural pitch. Several sport clubs own only a limited number of pitches and therefore are obligated to make full advantage of them. This is one of the reasons why many of these clubs are changing towards fields made of artificial turf which are always available, provided that the correct materials and maintenance are considered and regulated testing procedures are followed. The installation cost may be higher but an artificial turf field can be used more frequently than its natural counterpart and therefore be more profitable on the long run due to the lower overall maintenance costs. Furthermore, natural grass fields need enough sunlight for the grass to grow and cannot grow well in desert or extreme cold environments, whereas artificial turf can be used in many environments. Ghent University has a long history in the development and testing of artificial turf , which will be highlighted in this contribution

    Elegant design of carbon nanotube foams with double continuous structure for metamaterials in a broad frequency range

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    Carbon nanotube (CNT) foams with negative permittivity and permeability are successfully prepared by chemical vapor deposition (CVD) and post-treatment. A double negative metamaterial in the 1-1000 MHz frequency range with double continuous structure results by effectively compounding the CNT foam with a polymer material, i.e. epoxy or nanosilver silicone resin. The negative permeability is specifically attributed to the three-dimensional CNT interactions as clear from the study of the relation of the material microstructure and the macroscopic measurements. Compared to CNT foam/epoxy composites, CNT foam/nanosilver/silicone composites have a lower permeability but a more excellent electrical conductivity or permittivity. It is also shown that the carbon source time during CVD and post-pressurization can be adjusted to allow for both negative permittivity and permeability. This contribution highlights a convenient method to obtain a metamaterial in a much larger frequency range (ca. 1 to 1000 MHz) than the state-of-the-art. It thus supports the expansion of the application range of metamaterials and simplifies their preparation, which is of great significance for the wider use of these materials

    Evaluating the exit pressure method for measurements of normal stress difference at high shear rates

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    A challenge for polymer rheology is the reliable determination of shear dependent first normal stress difference (N-1 values) at high shear rates (>10 s(-1)). Here, we evaluate the correctness of the commonly applied exit pressure method focusing on polypropylene and high and low density polyethylene melts at 200 degrees C. It is demonstrated that the linear extrapolation of pressure values toward the die exit, which is a key step in the application of the exit pressure method, is affordable to determine N-1 values despite that these extrapolated exit pressure values are characterized by a relative deviation of 25%-40%. The validity of the exit pressure method is further supported by an excellent match with rheological data from the Laun rule (exponent close to 0.7) and a representative simulation of extrudate swelling data in the width and height direction, considering tuned parameters for the Phan-Thien-Tanner constitutive model. Also, the absence of a significant viscous heating effect near the die exit is highlighted based on numerical analysis. (c) 2020 The Society of Rheology

    Artificial turf developments and sport applications at Ghent University

    Get PDF
    In the past decades artificial turf fields have developed into a worthy alternative for natural grass in outdoor sports appliance such as football, rugby and hockey. Heavy rainfall and periods of drought can affect a natural pitch. Several sport clubs own only a limited number of pitches and therefore are obligated to make full advantage of them. This is one of the reasons why many of these clubs are changing towards fields made of artificial turf which are always available, provided that the correct materials and maintenance are considered and regulated testing procedures are followed. The installation cost may be higher but an artificial turf field can be used more frequently than its natural counterpart and therefore be more profitable on the long run due to the lower overall maintenance costs. Furthermore, natural grass fields need enough sunlight for the grass to grow and cannot grow well in desert or extreme cold environments, whereas artificial turf can be used in many environments. Ghent University has a long history in the development and testing of artificial turf , which will be highlighted in this contribution

    Efficient design of piezoresitive sensors based on carbon black conductive composites

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    Flexible and stretchable sensors are widely investigated taking into account their potential for wearable electronics, such as electronic skin, healthcare monitoring, human-machine interfaces, and soft robotics. In this contribution, highly sensitive conductive polymer composites (CPCs) for piezoresistive sensing are summarized, considering a straightforward manufacturing process based on extrusion of thermoplastic polyurethane (TPU) and/or olefin block copolymer (OBC), carbon black (CB), and additionally polyethylene-octene elastomer (POE) grafted with maleic anhydride (POE-g-MA). The design of the formulation variables is successfully performed to enable both low and high strain sensing, as highlighted by both static and dynamic testing
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