This study examines the effect of pulp type on the formability and elongation of paperboard, which are of key importance when producing 3D packages. Material performance was studied with a press-forming machine using laboratory handsheets as substrates. The handsheets were prepared from bleached softwood and hardwood kraft pulps, chemithermomechanical pulp, recycled newsprint, and mixtures of birch kraft and other pulps. The effect of microfibrillated cellulose (MFC) on substrate properties and material formability was also investigated. The 3D elongation of MFC-free handsheets varied between 1.2 and 5.5%. Depending on the pulp type and sheet composition, three essential sheet properties were recognized. These properties were bulk, elastic modulus and bending stiffness, the first two of which
An experimental study of artificial weathering of two outdoor coatings pigmented with natural indigo from Isatis tinctoria was carried out. The two coatings, natural indigo‐pigmented boat varnish and outdoor paint, were exposed to cycles of ultraviolet light, water condensation and water spray for 40 days in a QUV test chamber. Synthetic indigo and commercial ultramarine pigment were employed as reference materials. The effects of artificial weathering on the coatings were evaluated with CIELab parameters, as well as visual inspection. Coating and pigment stability during artificial weathering were studied with reflectance spectrometry, hyperspectral imaging technology and Fourier Transform–infrared spectroscopy. According to the results, coatings with indigo proved to be more resistant to visual and spectral changes than unpigmented or commercially pigmented coatings.
Lignocellulosics, microalgae, and SDS were used to generate stable and colored wet foams intended for camouflage use. It was found that the addition of microalgae increased the foam stability. The hyperspectral and thermal properties were studied.
Our study presents lightfastness properties of polylactic acid colored with plantbased natural indigo. Indigo is a blue colorant which is widely used in textile industry as a vat dye in coloration of jeans. Problematically, it is most commonly synthesized from petroleum-based sources. However, indigo can also be extracted from various plants, for example woad (Isatis tinctoria), thus offering a natural alternative for synthetic indigo. Woad is a biperennial plant, which produces extractable precursors of indigo in its leaves. It grows especially well in the harsh Northern European climate, making it a desirable plant-based source of indigo in Finland. Even though woad indigo is well known in the textile coloration field, little research has been done to determine lightfastness performance of woad indigo in non-textile applications. Thus, for our lightfastness study, natural indigo from woad was obtained and added to plastic matrices via extrusion. The extruded plastic filaments were injection molded into sample rods suitable for artificial weathering. After that, all the indigo-colored plastics and uncolored reference plastics were subjected to the artificial weathering test (ISO 4892-3:2016). Appearance and color fastness of the sample rods were assessed with visual inspection, reflectance spectrophotometry and hyperspectral imaging before and after the artificial weathering test. Hitherto, our results have showed that the natural indigo pigment produces a uniform color comparable to that obtained with synthetic indigo pigment, but the color fastness properties of the natural indigo samples are substantially worse than those of synthetic indigo samples.
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