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The structural integrity of wood–polymer composites (WPC) has not been fully investigated, which can be attributed to a lack of applicable test procedures. In this study, wood–polypropylene composites were assessed by High-Energy Multiple Impact (HEMI) testing. The acquired composites were based on wood particles from various sources and different wood fibre contents, respectively. With respect to wood fibre content, a clear relationship between resistance to impact milling (RIM) and unnotched impact bending strength (acU) was obtained. The lower the fibre content of the WPC the more structural integrity was retained. In return, various wood sources had no effect on acU, but a major impact on RIM values. RIM is suggested to be predominantly affected by structural features, such as fibre/particle content and characteristics, particle agglomerations, and spatial void distribution.
Kim C. Krause; Andreas Krause; Sarah E. Pilz; Christian Brischke. High-energy multiple impact (HEMI) tests of wood–polypropylene composites: new insights in structural integrity. Wood Material Science & Engineering 2020, 1 -4.
AMA StyleKim C. Krause, Andreas Krause, Sarah E. Pilz, Christian Brischke. High-energy multiple impact (HEMI) tests of wood–polypropylene composites: new insights in structural integrity. Wood Material Science & Engineering. 2020; ():1-4.
Chicago/Turabian StyleKim C. Krause; Andreas Krause; Sarah E. Pilz; Christian Brischke. 2020. "High-energy multiple impact (HEMI) tests of wood–polypropylene composites: new insights in structural integrity." Wood Material Science & Engineering , no. : 1-4.
In this study, we investigated injection molded wood-polypropylene composites based on various wood sources and their decay resistance against white rot (Trametes versicolor) and brown rot (Coniophora puteana) in a laboratory test according to EN 15534-1:2014. The manufactured composites consisted of poplar (Populus spp.), willow (Salix spp.), European beech (Fagus sylvatica L.), Norway spruce (Picea abies (L.) H. Karst.), and a commercial wood source (Arbocel® C100), respectively. All formulations were compounded on a co-rotating twin screw extruder and subsequently injection molded to wood–PP specimens with a wood content of 60% or 70% by weight. It was found that the test procedure had a significant effect on the mechanical properties. Loss in mechanical properties was primarily caused by moisture and less by fungal decay. Moisture caused a loss in the modulus of rupture and modulus of elasticity of 34 to 45% and 29 to 73%, respectively. Mean mass and wood mass losses were up to a maximum of 3.7% and 5.3%, respectively. The high resistance against fungal decay was generally attributed to the encapsulation of wood by the polymer matrix caused by sample preparation, and enhanced by reduced moisture uptake during the preconditioning procedure. Notable differences with respect to the wood particle source and decay fungi were also observed. Structural characterization confirmed the decay pattern of the fungi such as void cavities close the surface and the deposition of calcium oxalates.
Kim Christian Krause; Christian Brischke; Tim Koddenberg; Andreas Buschalsky; Holger Militz; Andreas Krause. Resistance of Injection Molded Wood-Polypropylene Composites against Basidiomycetes According to EN 15534-1: New Insights on the Test Procedure, Structural Alterations, and Impact of Wood Source. Fibers 2019, 7, 92 .
AMA StyleKim Christian Krause, Christian Brischke, Tim Koddenberg, Andreas Buschalsky, Holger Militz, Andreas Krause. Resistance of Injection Molded Wood-Polypropylene Composites against Basidiomycetes According to EN 15534-1: New Insights on the Test Procedure, Structural Alterations, and Impact of Wood Source. Fibers. 2019; 7 (10):92.
Chicago/Turabian StyleKim Christian Krause; Christian Brischke; Tim Koddenberg; Andreas Buschalsky; Holger Militz; Andreas Krause. 2019. "Resistance of Injection Molded Wood-Polypropylene Composites against Basidiomycetes According to EN 15534-1: New Insights on the Test Procedure, Structural Alterations, and Impact of Wood Source." Fibers 7, no. 10: 92.
In this study, various wood material sources were used for the manufacture of wood-polymer composites (WPC). The materials were categorised as virgin wood particles (VWP), reprocessed WPC particles (RWP) and recycled thermoset composite particles (RCP) and derived from two virgin wood sources, three-layer particleboards, medium-density fibreboards (MDF) boards, or two different wood/polypropylene composites. All produced wood-polypropylene compounds contained 60% wood material and were manufactured using a co-rotating extruder. Malleated polypropylene was used as a coupling agent. Specimens were injection moulded and subsequently tested for their physico-mechanical properties. To characterize particles before and after processing, dynamic image analysis (DIA) measurement were performed. Additionally, X-ray micro-computed tomography (XµCT) was used to characterize the internal structure of the composites and to verify the obtained particle’s characteristics. It was found that length and aspect ratio of particles were remarkably different before and after processing (loss in length of 15–70% and aspect ratio of 10–40%). Moreover, there were notably differences between the particle sources (RCP retained the highest length and aspect ratio values, followed by VWP and RWP). The results suggest that increased aspect ratios can indeed significantly improve mechanical properties (up to 300% increase in impact bending strength and 75% increase in tensile strength, comparing WPC based either on virgin spruce or MDF material). This phenomenon is suggested to be partially superimposed by improved dispersion of particles, which is expected due to lower variance and increased mechanical properties of RWP composites. However, no notable alterations were observed for composite density. Reprocessed WPC and, particularly, RCP material have proved to be an appealing raw material substitute for the manufacturing of wood–polymer composites.
Kim Christian Krause; Philipp Sauerbier; Tim Koddenberg; Andreas Krause. Utilization of Recycled Material Sources for Wood-Polypropylene Composites: Effect on Internal Composite Structure, Particle Characteristics and Physico-Mechanical Properties. Fibers 2018, 6, 86 .
AMA StyleKim Christian Krause, Philipp Sauerbier, Tim Koddenberg, Andreas Krause. Utilization of Recycled Material Sources for Wood-Polypropylene Composites: Effect on Internal Composite Structure, Particle Characteristics and Physico-Mechanical Properties. Fibers. 2018; 6 (4):86.
Chicago/Turabian StyleKim Christian Krause; Philipp Sauerbier; Tim Koddenberg; Andreas Krause. 2018. "Utilization of Recycled Material Sources for Wood-Polypropylene Composites: Effect on Internal Composite Structure, Particle Characteristics and Physico-Mechanical Properties." Fibers 6, no. 4: 86.
X-ray micro-computed tomography (XµCT) allows a non-destructive and three-dimensional study of otherwise complex and opaque wood tissues. In wood research, XµCT datasets are highly useful for the qualitative and quantitative examination of wood structures. In this study, XµCT was introduced and tested for examining X-ray dense silica particles in the Australian turpentine wood (Syncarpia glomulifera). It was possible to three-dimensionally visualize and numerically quantify silica particles. Numerical analysis was performed to scrutinize the size and content of silica particles. In comparative studies of silica size through scanning electron microscopy and silica content through thermo-gravimetric analysis after acid digestion of ash, our findings pointed out that XµCT is indeed a powerful tool for examining silica particles in wood; because XµCT enables a simultaneous visualization and quantification of the silica particles in 3D without being destructive. Despite these benefits, comparative examination through scanning electron microscopy and energy-dispersive X-ray spectroscopy is necessary to verify silica particles in tomographic images. Researchers should also be aware that XµCT also comes with some challenges. XµCT technology might further aid in probing the biological and ecological function of silica in silica-bearing wood species.
Tim Koddenberg; Kim Christian Krause; Andreas Krause. Tomographic analysis of siliceous particulates in Australian turpentine wood (Syncarpia glomulifera) through X-ray micro-computed tomography. Micron 2018, 117, 22 -28.
AMA StyleTim Koddenberg, Kim Christian Krause, Andreas Krause. Tomographic analysis of siliceous particulates in Australian turpentine wood (Syncarpia glomulifera) through X-ray micro-computed tomography. Micron. 2018; 117 ():22-28.
Chicago/Turabian StyleTim Koddenberg; Kim Christian Krause; Andreas Krause. 2018. "Tomographic analysis of siliceous particulates in Australian turpentine wood (Syncarpia glomulifera) through X-ray micro-computed tomography." Micron 117, no. : 22-28.
Softwoods can be nailed with high density solid wood like Santos Rosewood (Machaerium scleroxylon) or nails made of densified laminated beech wood composite by hammering or shooting, for example with air nail guns, without pre-drilling. Shooting with about 30 m/s causes friction between nail surface and softwood matrix, heating up the interface to temperatures high enough to soften lignin. Re-condensation of softened lignin causes wood welding which doubles pull out strength in comparison to wood nails fixed without wood welding. Changes in lignin UV-absorption within the single cell wall layer and deformation of main anatomical features of spruce wood tissue are characterized by scanning UV microspectrophotometry (UMSP) whereas structural deformations of spruce wood tissue are revealed by X-ray micro-computed tomography (µ-CT).
H. Korte; G. Koch; K. C. Krause; Tim Koddenberg; S. Siemers. Wood nails to fix softwoods: characterization of structural deformation and lignin modification. European Journal of Wood and Wood Products 2018, 76, 979 -988.
AMA StyleH. Korte, G. Koch, K. C. Krause, Tim Koddenberg, S. Siemers. Wood nails to fix softwoods: characterization of structural deformation and lignin modification. European Journal of Wood and Wood Products. 2018; 76 (3):979-988.
Chicago/Turabian StyleH. Korte; G. Koch; K. C. Krause; Tim Koddenberg; S. Siemers. 2018. "Wood nails to fix softwoods: characterization of structural deformation and lignin modification." European Journal of Wood and Wood Products 76, no. 3: 979-988.
The distinctive length and morphology characteristics of thermomechanical produced wood fibers make it a promising candidate for the utilization in polymer composites. However, due to the low bulk density of these fibers, the feeding into the compounding process (i.e., extruders) is quite challenging. In this study, a novel simultaneous defibration and compounding process are conducted in order to solve the feed-in problem of thermomechanical fibers. A disc-refiner was used to defibrate wood chips to fibers and compound the fibers with neat polymer granulates in one process step. After the process, the material showed typically thermomechanical fibers with chopped polymer particles which were inseparably attached to the fiber. The observed mechanical properties of the composites were slightly lower than some literature values. With field emission scanning electron microscopy and X-ray microtomography analysis, voids and a polymer enriched surface were found influencing the composites performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45859.
Oliver Mertens; Kim Christian Krause; Andreas Krause. Evaluation of wood fiber composites based on a novel simultaneous defibration and compounding process. Journal of Polymer Science 2017, 135, 1 .
AMA StyleOliver Mertens, Kim Christian Krause, Andreas Krause. Evaluation of wood fiber composites based on a novel simultaneous defibration and compounding process. Journal of Polymer Science. 2017; 135 (7):1.
Chicago/Turabian StyleOliver Mertens; Kim Christian Krause; Andreas Krause. 2017. "Evaluation of wood fiber composites based on a novel simultaneous defibration and compounding process." Journal of Polymer Science 135, no. 7: 1.
Kiri trees are fast-growing species, which are increasingly cultivated on plantations in Europe. This study assesses the application of kiri wood (Paulownia tomentosa) for the production of particleboards. Single-layer particleboards (PBs) were produced from kiri particles (KPs), industrial particles (IPs) and various mixtures of both materials with target densities of 350, 500 and 650 kg m−3, respectively. The composition of the PBs was 100% KPs, 66% KPs, 33% KPs and 0% KPs (100% IPs). PBs based on 100% IPs exhibited the lowest mechanical strength properties, which increased with increasing proportions of KPs within the same density range. The swelling properties of the boards were similar within one density range. The formaldehyde contents of PBs made of KPs were higher compared to PBs based on IPs, but all values were below the threshold value given in EN 13986 (Wood-based panels for use in construction—characteristics, evaluation of conformity and marking, German version. European Committee for Standardisation, Brussels, Belgium, 2004). X-ray micro-computed tomography (XµCT) revealed differences in the structure and compression of the PBs based on KPs and IPs resulting in smaller and more evenly distributed voids between the particles in PBs based on KPs. This study shows that kiri wood is a promising raw material for the PB industry, both alone and in mixtures with other particles.
Philipp A. Nelis; Franz Michaelis; Kim C. Krause; Carsten Mai. Kiri wood (Paulownia tomentosa): can it improve the performance of particleboards? European Journal of Wood and Wood Products 2017, 76, 445 -453.
AMA StylePhilipp A. Nelis, Franz Michaelis, Kim C. Krause, Carsten Mai. Kiri wood (Paulownia tomentosa): can it improve the performance of particleboards? European Journal of Wood and Wood Products. 2017; 76 (2):445-453.
Chicago/Turabian StylePhilipp A. Nelis; Franz Michaelis; Kim C. Krause; Carsten Mai. 2017. "Kiri wood (Paulownia tomentosa): can it improve the performance of particleboards?" European Journal of Wood and Wood Products 76, no. 2: 445-453.
Alternative sources of the raw material wood, such as wood from short rotation coppice (SRC) and low‐value beech wood, were investigated in terms of their suitability for use in the production of wood–plastic composites (WPC). The influence of these wood sources on water absorption, the mechanical properties and the internal structure of the composites was evaluated. The composites based on wood from SRC and on beech wood exhibited a decreased equilibrium moisture content (EMC) and a reduced speed of water absorption in comparison to composites based on wood from Norway spruce. X‐ray microtomography revealed a strong alignment of wood particles near the surface regions, as well as dispersion and encapsulation of particles by polypropylene. The investigation of composite performances revealed that the material properties of the WPC derived from these new wood resources were similar and in some cases even superior to those produced with preferred wood sources such as Norway spruce.
Kim C. Krause; Marcus Müller; Holger Militz; Andreas Krause. Converting Wood from Short Rotation Coppice and Low-Value Beech Wood into Thermoplastic Composites. Bioenergy from Dendromass for the Sustainable Development of Rural Areas 2015, 483 -496.
AMA StyleKim C. Krause, Marcus Müller, Holger Militz, Andreas Krause. Converting Wood from Short Rotation Coppice and Low-Value Beech Wood into Thermoplastic Composites. Bioenergy from Dendromass for the Sustainable Development of Rural Areas. 2015; ():483-496.
Chicago/Turabian StyleKim C. Krause; Marcus Müller; Holger Militz; Andreas Krause. 2015. "Converting Wood from Short Rotation Coppice and Low-Value Beech Wood into Thermoplastic Composites." Bioenergy from Dendromass for the Sustainable Development of Rural Areas , no. : 483-496.