RESUMO
Textiles can provide effective protection against UV radiation because they reflect, absorb and scatter solar wavelengths. Properly designed, they significantly increase the area of covered skin. The optimal combination of thickness, fabric density, mass per unit area, knitted structure, yarn type and yarn linear density, facilitate the production of textiles with high UV protection properties. The objective of this research was to evaluate the impact of elastane on UV protection properties of viscose and polyacrylonitrile knitted structures. The investigation illustrated that wet relaxed elasticized knits show good UV radiation protection with UPF 20-40. In contrast, non-elasticized viscose and polyacrylonitrile knits are inappropriate for UV radiation protection. Comparing viscose samples, UPF is higher for dry relaxed elasticized structures, whilst for polyacrylonitrile samples, UPF is higher for wet relaxed elasticized structures. For non-elasticized structures, the UPF of polyacrylonitrile samples is greater than that of viscose samples. Generally, polyacrylonitrile knits investigated ensure better UV protection than viscose knits.
RESUMO
In the material extrusion of the thermoplastic filaments, known as Fused Deposition Modelling, usually, pure thermoplastic polymers are used. Recently, the focus of the research is given to the development of new biocomposite thermoplastic materials. In our research, 3D printable biocomposite filaments, made with the addition of 50 wt.% of cardboard dust to the HDPE and PLA polymer matrix were studied. The influence of the added cardboard dust on structural, morphological and mechanical properties of the 3D printable biocomposite filaments was investigated. With the addition of the corrugated cardboard dust into the HDPE and PLA polymer matrix the changes in density, uniformity, chemical structure and transition temperatures of the samples were detected. The addition of the cardboard dust into the HDPE polymer matrix lead to low tenacity, toughness, deformability resulting in brittleness of the 3D printable biocomposite filament, whereas the addition of the cardboard dust into the PLA polymer matrix lowered tensile properties, but didn't affected bending toughness and has even improved compression strength of the 3D printable filament.
RESUMO
BACKGROUND: Many studies have been devoted to the problem of harmful effects of UV radiation on human skin. The incidence rate for all forms of skin cancer is rising quickly. Considering this fact, there is currently a need for diligent preventive work, not only from dermatologists but also from other doctors and scientists. Textiles represent simple and effective protection against UV radiation. Good protective clothing can reduce UV radiation on the surface of skin by at least 95%. Even though numerous studies present the effects of various textile parameters on UV protection, not many have been conducted for determining the degree of agreement between in vivo and in vitro measurements of UPF. METHODS: This study presents the effect of various constructional parameters on UPF values (determined using spectrophotometry). The phenomenon of minimal erythema doses on the skin of test subjects was tested based on in vitro calculated UPF values. RESULTS: Despite some differences in values, the study nevertheless showed a good correlation between both methods and confirms the congruity of in vivo and in vitro UPF values. CONCLUSIONS: It is clear that both methods are needed for a more precise look at the UV protection offered by textiles.