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Electrospinning is a process to generate a nanofibrous material. Although the working principle of electrospinning is rather straight forward, it is influenced by many parameters. There is still a serious lack of knowledge concerning the influence of the ambient parameters, for which preliminary knowledge reveals that the relative humidity is of primary importance. This article reports the influence of the relative humidity on electrospun polyamide 6 nanofibres. Mixtures of formic acid and acetic acid are used for steady state electrospinning of polyamide 6 nanofibres, for which a steady state table is determined. When the relative humidity increases, the average fiber diameter decreases and the fraction of the less stable c-phase crystals in the polyamide diminishes. This effect is explained by absorbed water acting as a plasticizer, reducing the Tg of the polyamide. This article shows the importance of working in climatized conditions during electrospinning to obtain reproducible nanofibres.

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SUMMARYThe aim of this paper is to study the combustion characteristics of loose fibrous cellulosic compounds through cone calorimeter measurements. The challenge in studying loose fibrous materials by cone calorimeter in a reproducible manner is met by optimizing various process parameters such as sample weight, heat flux and grid type. The method is validated using cotton fibres and fabrics with a range of flame retardant properties. Good correlations are obtained between the flame retardant content of samples and the heat release parameters for both the fibres and the fabrics. In addition, fibres from specific cotton cultivars showed statistically significant differences in heat release characteristics. This shows that valuable data concerning the combustion behaviour and the corresponding kinetics of loose fibrous compounds can be successfully gathered using a cone calorimeter. Thus, such data can be exploited to well define future fibre breeding programmes or fibre modification research.

Recently, the use of repellents for preventing the transmission of mosquito-borne diseases is getting increasingly more attention. However, most of the current repellents are volatile in nature and must be frequently re-applied as their efficacy is only limited to a short period of time. Therefore, a slow release and abrasion-resistant mechanism is needed for prolonging the protection time of the repellents. The focus of this study is on the direct micro-encapsulation of repellents from an emulsion and integration of already encapsulated repellents into nanofibres via electrospinning. Different repellents were electrospun in polyvinyl alcohol (PVA) nanofibrous structures, namely p -menthane-3,8-diol micro-capsules, permethrin, chilli and catnip oil. The repellents were successfully incorporated in the nanofibres and the tensile properties of the resulting samples did not have a significant change. This means that the newly created textiles were identical to current PVA nanofibrous textiles with the added benefit of being mosquito repellent. Principally, all incorporated repellents in the nanofibrous structures showed a significantly reduced number of mosquito landings compared to the control. Consequently, the currently described method resulted in a new and very effective repelling textile material that can be used in the prevention against mosquito-associated diseases.

The aim of this paper is to establish a test method for the screening of bioengineered cotton fibers with an improved reactivity through the incorporation of positively charged nitrogen moieties. For this purpose a spectrophotometric method based on the absorption of a negatively charged dye (Acid Orange 7) is extensively studied. The processing parameters have been optimized for analyzing small amounts of fibers and the feasibility of the method is examined by using two other well established techniques for nitrogen analysis. Good correlations were obtained between the different methods, however, the reproducibility of the Acid Orange 7 was superior to the other two methods. Moreover, statistically significant differences were found between fibers from cotton lines designed to produce oligochitin and control fibers without oligochitin. This shows that the proposed method is capable of accurately detecting increased nitrogen levels in bioengineered cotton fibers

The energy crisis in the 1970s led to increasingly stricter building codes, resulting in the currently required nearly zero-energy buildings. Nonetheless, the energy saving potential of further increasing insulation packages decreases as a result of the inverse correlation of thermal transmittance with insulation thickness. Therefore, a balance is required between the potential energy savings and the material impact using Life Cycle Assessment (LCA). This balance is studied for a demonstration building called 'The Mobble'. For the LCA, the Ecoinvent database and impact assessment method ReCiPe H/A (2016) are used. For the potential energy savings dynamic energy simulations are run in Modelica/Dymola. To ensure equal comfort, thermal comfort is modelled using Human Thermal Module. An optimisation using the trade-off between material impact and operational energy by considering the optimal insulation thickness is executed on three levels: (1) building envelope (insulation, glazing type), (2) HVAC system efficiency (constant, demand based, personal comfort systems) and (3) electricity mix. This additionally enables to assess the robustness of imposing strict insulation requirements in e.g. building codes. The results show that even when extremely advanced demand based systems are adopted, the optimal insulation thickness ranges between 22 cm and 28 cm and is thus hardly affected, neither by user behaviour. However, the choice of energy mix does have a considerable impact on this optimal insulation thickness, and entails a shift in optimal insulation thickness from 20 cm -30 cm-10 cm -20 cm when a lower environmental impact for the electricity mix is considered (compared to the current Belgian electricity mix).