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Institute: search.filters.UBSInstitut.Fakultätsübergreifend / Sonstige EinrichtungAuthor: search.filters.author.Gresser, Götz T.

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    ItemOpen Access
    Impact of long-term weathering on the properties of a digestate-based biocomposite
    (2021) Gebhardt, Marion; Milwich, Markus; Gresser, Götz T.; Lemmer, Andreas
    Natural fibre composites are increasingly used. For many applications, the long-term stability of the mechanical properties is crucial. Therefore, the effects of weathering of a biocomposite made from fibrous digestate and bio-based thermoset are investigated. The fibre component of the composite comes from digestate of a German biogas station which processes hop vines as main substrate. The matrix is a plant-oil-based epoxy resin. The samples were alternately exposed to UV radiation and moisture for various lengths of time. Afterwards, the material strength and water absorption were tested. As a result, the weathering leads to a decrease of strength but not to a high increase of water uptake.
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    ItemOpen Access
    The influence of background materials on the radiative cooling performance of semi-transparent and opaque textiles : a theoretical and experimental analysis
    (2024) Zimmermann, Lea; Aili, Ablimit; Stegmaier, Thomas; Kaya, Cigdem; Gresser, Götz T.
    This paper investigates the theoretical and experimental cooling performance of textile materials utilizing radiative cooling technology. By applying Kirchhoff’s law, the emissivity of surfaces is determined, revealing that materials with high transmission values can achieve comparable cooling performance to those with high reflection values. Notably, materials exhibiting moderate reflectance and transmittance in the solar range tend to absorb minimal solar radiation, thus offering high theoretical cooling performance. However, practical applications like building envelopes or clothing present challenges due to the impact of background radiation on overall cooling capacity. Despite their intrinsic cooling properties, a significant portion of solar radiation is transmitted, complicating matters as the background can significantly affect overall cooling performance. This study provides a solution that accounts for the influence of background materials. Based on spectral data, various background materials and their impact on different semi-transparent comparison materials can be considered, and cooling performance can be simulated. This enables the simulation of cooling performance for various application scenarios and facilitates comparisons between transparent, semi-transparent, and opaque textile materials.