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The effects of using 100% larch bark (Larix decidua Mill) as a raw material for composite boards on the thermophysical properties of this innovative material were investigated in this study. Panels made of larch bark with 4–11 mm and 10–30 mm particle size, with ground bark oriented parallel and perpendicular to the panel’s plane at densities varying from 350 to 700 kg/m3 and bonded with urea-formaldehyde adhesive were analyzed for thermal conductivity, thermal resistivity and specific heat capacity. It was determined that there was a highly significant influence of bulk density on the thermal conductivity of all the panels. With an increase in the particle size, both parallel and perpendicular to the panel´s plane direction, the thermal conductivity also increased. The decrease of thermal diffusivity was a consequence of the increasing particle size, mostly in the parallel orientation of the bark particles due to the different pore structures. The specific heat capacity is not statistically significantly dependent on the density, particle size, glue amount and particle orientation.
Lubos Kristak; Ivan Ruziak; Eugenia Tudor; Marius Barbu; Günther Kain; Roman Reh. Thermophysical Properties of Larch Bark Composite Panels. Polymers 2021, 13, 2287 .
AMA StyleLubos Kristak, Ivan Ruziak, Eugenia Tudor, Marius Barbu, Günther Kain, Roman Reh. Thermophysical Properties of Larch Bark Composite Panels. Polymers. 2021; 13 (14):2287.
Chicago/Turabian StyleLubos Kristak; Ivan Ruziak; Eugenia Tudor; Marius Barbu; Günther Kain; Roman Reh. 2021. "Thermophysical Properties of Larch Bark Composite Panels." Polymers 13, no. 14: 2287.
The potential of tree bark, a by-product of the woodworking industry, has been studied for more than seven decades. Bark, as a sustainable raw material, can replace wood or other resources in numerous applications in construction. In this study, the acoustic properties of bark-based panels were analyzed. The roles of the particle size (4–11 mm and 10–30 mm), particle orientation (parallel and perpendicular) and density (350–700 kg/m3) of samples with 30 mm and 60 mm thicknesses were studied at frequencies ranging from 50 to 6400 Hz. Bark-based boards with fine-grained particles have been shown to be better in terms of sound absorption coefficient values compared with coarse-grained particles. Bark composites mixed with popcorn bonded with UF did not return the expected results, and it is not possible to recommend this solution. The best density of bark boards to obtain the best sound absorption coefficients is about 350 kg/m3. These lightweight panels achieved better sound-absorbing properties (especially at lower frequencies) at higher thicknesses. The noise reduction coefficient of 0.5 obtained a sample with fine particles with a parallel orientation and a density of around 360 kg/m3.
Eugenia Tudor; Lubos Kristak; Marius Barbu; Tomáš Gergeľ; Miroslav Němec; Günther Kain; Roman Réh. Acoustic Properties of Larch Bark Panels. Forests 2021, 12, 887 .
AMA StyleEugenia Tudor, Lubos Kristak, Marius Barbu, Tomáš Gergeľ, Miroslav Němec, Günther Kain, Roman Réh. Acoustic Properties of Larch Bark Panels. Forests. 2021; 12 (7):887.
Chicago/Turabian StyleEugenia Tudor; Lubos Kristak; Marius Barbu; Tomáš Gergeľ; Miroslav Němec; Günther Kain; Roman Réh. 2021. "Acoustic Properties of Larch Bark Panels." Forests 12, no. 7: 887.
The current work deals with three dimensionally molded plywood formed parts. These are prepared in two different geometries using cut-outs and relief cuts in the areas of the highest deformation. Moreover, the effect of flax fiber reinforcement on the occurrence and position of cracks, delamination, maximum load capacity, and on the modulus of elasticity is studied. The results show that designs with cut-outs are to be preferred when molding complex geometries and that flax fiber reinforcement is a promising way of increasing load capacity and stiffness of plywood formed parts by respectively 76 and 38% on average.
Johannes Jorda; Günther Kain; Marius-Catalin Barbu; Matthias Haupt; Ľuboš Krišťák. Investigation of 3D-Moldability of Flax Fiber Reinforced Beech Plywood. Polymers 2020, 12, 2852 .
AMA StyleJohannes Jorda, Günther Kain, Marius-Catalin Barbu, Matthias Haupt, Ľuboš Krišťák. Investigation of 3D-Moldability of Flax Fiber Reinforced Beech Plywood. Polymers. 2020; 12 (12):2852.
Chicago/Turabian StyleJohannes Jorda; Günther Kain; Marius-Catalin Barbu; Matthias Haupt; Ľuboš Krišťák. 2020. "Investigation of 3D-Moldability of Flax Fiber Reinforced Beech Plywood." Polymers 12, no. 12: 2852.
The aim of this study is to investigate the formaldehyde content and emissions of bark-based insulation panels bonded with three types of adhesives: urea formaldehyde, melamine urea-formaldehyde, and tannin-based adhesives. These panels were produced at two levels of density—300 and 500 kg/m3—and a thickness of 20 mm, and the influence of the adhesive amount and type on the formaldehyde emissions and content was measured. Other mechanical and physical properties such as modulus of rupture, modulus of elasticity, internal bond, and dimensional stability were also scrutinized. With one exception, all the panels belonged to the super E0 classification for free formaldehyde content (perforator value ≤1.5 mg/100 g oven dry mass of panels). The measurements using the desiccator method for formaldehyde emissions assigned all the testing specimens in the F **** category for low-emission panels according to the Japanese International Standards.
Marius Cătălin Barbu; Yasmin Lohninger; Simon Hofmann; Günther Kain; Alexander Petutschnigg; Eugenia Mariana Tudor. Larch Bark as a Formaldehyde Scavenger in Thermal Insulation Panels. Polymers 2020, 12, 2632 .
AMA StyleMarius Cătălin Barbu, Yasmin Lohninger, Simon Hofmann, Günther Kain, Alexander Petutschnigg, Eugenia Mariana Tudor. Larch Bark as a Formaldehyde Scavenger in Thermal Insulation Panels. Polymers. 2020; 12 (11):2632.
Chicago/Turabian StyleMarius Cătălin Barbu; Yasmin Lohninger; Simon Hofmann; Günther Kain; Alexander Petutschnigg; Eugenia Mariana Tudor. 2020. "Larch Bark as a Formaldehyde Scavenger in Thermal Insulation Panels." Polymers 12, no. 11: 2632.
Larch bark is an interesting resource for the production of insulation panels. As it consists of a sugar-rich inner bark and an outer bark containing more durable components, there is the requirement to separate these compartments. Additionally, bark is often mixed with wooden pieces after industrial debarking processes. In this study, the wet density, dry density, and specific gravity of wood, whole bark, and inner and outer bark are investigated using the pycnometer method, which has been proven to be adequate for the volume measurement of irregularly shaped, light objects such as bark flakes. Soaked with water, the density of the inner bark is highest, followed by wood, and the lightest is the outer bark. Because of different moisture contents, the wet density is not directly comparable. The outer bark sucked up less water than the inner bark. Focusing on the specific gravity, the wood is the heaviest, followed by the outer bark and the inner bark. The differences are significant for both methods, displaying a promising physical basis for separation methods based on density differences. These might be a means to pick out more durable and less hygroscopic outer bark particles from a bark mixture in order to produce optimized bark composites.
Günther Kain; Marco Morandini; Marius-Catalin Barbu; Alexander Petutschnigg; Jan Tippner. Specific Gravity of Inner and Outer Larch Bark. Forests 2020, 11, 1132 .
AMA StyleGünther Kain, Marco Morandini, Marius-Catalin Barbu, Alexander Petutschnigg, Jan Tippner. Specific Gravity of Inner and Outer Larch Bark. Forests. 2020; 11 (11):1132.
Chicago/Turabian StyleGünther Kain; Marco Morandini; Marius-Catalin Barbu; Alexander Petutschnigg; Jan Tippner. 2020. "Specific Gravity of Inner and Outer Larch Bark." Forests 11, no. 11: 1132.
Tree bark is a byproduct of the timber industry which accrues in large amounts, because approximately 10% of the volume a log is bark. Bark is used primarily for low-value applications such as fuel or as a soil covering material in agriculture. Within the present study, thermal insulation panels made from larch, pine, spruce, fir and oak tree bark with different resins (urea formaldehyde, melamine formaldehyde, Quebracho, Mimosa) as a binder are discussed. Also, the properties of panels made from larch bark mixed with industrial popcorn are investigated. The physical-mechanical properties of the panels, which are dependent on panel density, bark species, resin type, resin content and particle size, are analyzed. The bark species has a minor effect on the mechanical characteristics of the panels, while the compression ratio is important for the panel strength, and hence, barks with lower bulk density are preferable. Under laboratory conditions, panels made with green tannin resins proved to have adequate properties for practical use. The addition of popcorn is a means to lower the panel density, but the water absorption of such panels is comparably high. The bark type has a minor effect on the thermal conductivity of the panels; rather, this parameter is predominantly affected by the panel density.
Günther Kain; Eugenia Mariana Tudor; Marius-Catalin Barbu. Bark Thermal Insulation Panels: An Explorative Study on the Effects of Bark Species. Polymers 2020, 12, 2140 .
AMA StyleGünther Kain, Eugenia Mariana Tudor, Marius-Catalin Barbu. Bark Thermal Insulation Panels: An Explorative Study on the Effects of Bark Species. Polymers. 2020; 12 (9):2140.
Chicago/Turabian StyleGünther Kain; Eugenia Mariana Tudor; Marius-Catalin Barbu. 2020. "Bark Thermal Insulation Panels: An Explorative Study on the Effects of Bark Species." Polymers 12, no. 9: 2140.
Wooden shingles are a traditional roofing material on many culturally important building artifacts. Currently, the roof space of many traditional buildings is used for residential purposes and, consequently, cold roof constructions with ventilation layers are applied. In this study, it is evaluated whether the moisture content of wooden shingles is adversely affected by such constructions, compared with unvented shingle roofs over cold attics and whether a temporary closing of the ventilation gaps at the eaves contributes to a lower wood moisture content. Various sensors were installed in and around a building with wooden shingles on a ventilated roof and temperature, air moisture, and air speed in the ventilation layer were measured throughout a year. The findings show that the air speed in the ventilation layer can be adjusted from 0.06 to 0.25 m/s depending on the layout of the eaves. A hygrothermal model was applied to evaluate the effects of different ventilation operation modes and cardinal orientations of the roof on the moisture content of the wooden shingles. The results show that roof ventilation results in a 1% lower shingle moisture content on average than an unventilated roof over a cold attic. Finally, it is shown that the wood moisture content repeatedly reaches dangerous levels above 25% throughout a year, which is worse on north-facing roofs and, hence, measures to increase the dry-out are relevant.
Günther Kain; Friedrich Idam; Franz Federspiel; Roman Réh; Ľuboš Krišťák. Suitability of Wooden Shingles for Ventilated Roofs: An Evaluation of Ventilation Efficiency. Applied Sciences 2020, 10, 6499 .
AMA StyleGünther Kain, Friedrich Idam, Franz Federspiel, Roman Réh, Ľuboš Krišťák. Suitability of Wooden Shingles for Ventilated Roofs: An Evaluation of Ventilation Efficiency. Applied Sciences. 2020; 10 (18):6499.
Chicago/Turabian StyleGünther Kain; Friedrich Idam; Franz Federspiel; Roman Réh; Ľuboš Krišťák. 2020. "Suitability of Wooden Shingles for Ventilated Roofs: An Evaluation of Ventilation Efficiency." Applied Sciences 10, no. 18: 6499.
The current trend for sustainable utilisation of limited resources is stimulating the scientific research for previously neglected raw materials that could also be used for new value added products. Bark, which is a natural insulation material of trees, could be used as technical insulation material. This paper focuses on the effects of particle orientation in light larch (Larix decidua) bark insulation boards on their physical–mechanical and thermal properties. The experimental design is based on the variation of the particle orientation (orthogonal or parallel to the panel plane) and the board density (200–500 kg/m3). The mechanical properties, water absorption, thickness swelling and thermal conductivity of the boards were tested. The results showed a significant influence of the particle orientation and the density on the measured properties of the bark panels. This implies that the bark particle orientation is an important factor when producing insulation panels with specific characteristics. Suggestions for efficient use of bark particleboard are given.
Günther Kain; Bernhard Lienbacher; Marius-Catalin Barbu; Klaus Richter; Alexander Petutschnigg. Larch (Larix decidua) bark insulation board: interactions of particle orientation, physical–mechanical and thermal properties. European Journal of Wood and Wood Products 2017, 76, 489 -498.
AMA StyleGünther Kain, Bernhard Lienbacher, Marius-Catalin Barbu, Klaus Richter, Alexander Petutschnigg. Larch (Larix decidua) bark insulation board: interactions of particle orientation, physical–mechanical and thermal properties. European Journal of Wood and Wood Products. 2017; 76 (2):489-498.
Chicago/Turabian StyleGünther Kain; Bernhard Lienbacher; Marius-Catalin Barbu; Klaus Richter; Alexander Petutschnigg. 2017. "Larch (Larix decidua) bark insulation board: interactions of particle orientation, physical–mechanical and thermal properties." European Journal of Wood and Wood Products 76, no. 2: 489-498.
Building owners are increasingly interested in a healthy and sustainable living environment, which is a trend favoring ecological building materials with outstanding structural physical parameters. Insulation boards from particles of larch bark (Larix decidua Mill.) bonded with a formaldehyde-free tannin resin were pressed and evaluated for their mechanical and physical properties. It could be shown that light (target density 250 kg/m3) boards can be pressed, and their thermal conductivity is low (0.065–0.09 W/(m*K)). With regard to mechanical characteristics, the influence of panel density was studied, and it was found that a certain compaction (ρ ≥ 400 kg/m3) is necessary to meet the requirements of the relevant standard. Interestingly, the resin amount did not influence the mechanical board properties as strongly as expected, and panel density is the most important variable in this respect. The study proved that tree bark cannot only be used for substantially upgraded insulation panels but can also be bonded with a formaldehyde free tannin resin.
Günther Kain; Viola Güttler; Marius-Catalin Barbu; Alexander Petutschnigg; Klaus Richter; Gianluca Tondi. Density related properties of bark insulation boards bonded with tannin hexamine resin. European Journal of Wood and Wood Products 2014, 72, 417 -424.
AMA StyleGünther Kain, Viola Güttler, Marius-Catalin Barbu, Alexander Petutschnigg, Klaus Richter, Gianluca Tondi. Density related properties of bark insulation boards bonded with tannin hexamine resin. European Journal of Wood and Wood Products. 2014; 72 (4):417-424.
Chicago/Turabian StyleGünther Kain; Viola Güttler; Marius-Catalin Barbu; Alexander Petutschnigg; Klaus Richter; Gianluca Tondi. 2014. "Density related properties of bark insulation boards bonded with tannin hexamine resin." European Journal of Wood and Wood Products 72, no. 4: 417-424.