18 results match your criteria: "Fraunhofer Institute for Wood Research⁻Wilhelm-Klauditz-Institut WKI[Affiliation]"

Itaconates available from renewable resources constitute a group of monomers that are used in several types of polymerizations. Their use in free-radical polymerizations (FRPs) is still limited due to the low propagation rate coefficients resulting in low polymerization rates and the occurrence of depropagation which is responsible for limited monomer conversion. Since FRP is considered very robust with few requirements concerning monomer purity, it is still interesting to investigate how itaconate FRP may become feasible.

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The fire performance of epoxy and carbon-fiber-reinforced polymer (CFRP) composites with and without fire retardants (FR) (i.e., ammonium polyphosphate (APP), aluminum trihydroxide (ATH), melamine (MEL), expandable graphite (EG)) was investigated.

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Mechanical Properties and Durability of Textile Reinforced Concrete (TRC)-A Review.

Polymers (Basel)

September 2023

Centre for Light and Environmentally-Friendly Structures, Fraunhofer Wilhelm-Klauditz-Institut WKI, Riedenkamp 3, 38108 Braunschweig, Germany.

Textile reinforced concrete (TRC) is an innovative structure type of reinforced concrete in which the conventional steel reinforcement is replaced with fibre textile materials. The thin, cost-effective and lightweight nature enable TRC to be used to create different types of structural components for architectural and civil engineering applications. This paper presents a review of recent developments of TRC.

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In the quest toward sustainable thermosets, research has been conducted on various polymer classes like epoxy, benzoxazines, acryl-/methacrylates, etc. One particular group that can also be utilized as sustainable inks for additive manufacturing is itaconic acid-based unsaturated polyester resins. However, due to increased viscosity of the resins, the use of reactive diluents is required to increase their processability.

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This research focuses on exploring the potential of mycelium as a sustainable alternative to wood or solid foam in pultruded glass fiber-reinforced plastic (GFRP) sandwich profiles. The study evaluates the performance and the environmental sustainability potential of this composite by mechanical tests and life cycle assessment (LCA). Analysis and comparison of pultruded sandwich profiles with mycelium, polyurethane (PUR) foam and chipboard demonstrate that mycelium is competitive in terms of its performance and environmental impact.

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In this study, the compressive performance of sisal fiber-reinforced recycled aggregate concrete (SFRAC) composite, confined with jute fiber-reinforced polymer (JFRP) tube (the structure was termed as JFRP-SFRAC) was assessed. A total of 36 cylindrical specimens were tested under uniaxial compression. Three major experimental variables were investigated: (1) the compressive strength of concrete core (i.

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Effects of Thermal Aging on the Adhesion Forces of Biopolymers of Wood Cell Walls.

Biomacromolecules

April 2022

Division of Organic and Wood-Based Materials, TU Braunschweig, Hopfengarten 20, 38102 Braunschweig, Germany.

Wood is the most important, industrially used renewable resource on the planet, but the aging mechanism of biopolymers on cell walls is poorly understood. Adhesion properties are of critical importance for wood and many other lignocellulosic materials. We used atomic force microscopy and defined the jump-off force ratio in the retract force-displacement curve to study the adhesion force phenomenon and the effects of heat treatments.

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The renewable resource, wood, is becoming increasingly popular as a feedstock material for additive manufacturing (AM). It can help make those processes more affordable and reduce their environmental impact. Individual layer fabrication (ILF) is a novel AM process conceived for structural applications.

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We have created a new architected material, which is both highly deformable and ultra-resistant to dynamic point loads. The bio-inspired metallic cellular structure (with an internal grid of large ceramic segments) is non-cuttable by an angle grinder and a power drill, and it has only 15% steel density. Our architecture derives its extreme hardness from the local resonance between the embedded ceramics in a flexible cellular matrix and the attacking tool, which produces high-frequency vibrations at the interface.

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In the field of polymer chemistry, tremendous efforts have been made over the lastdecade to replace petrochemical monomers with building blocks from renewable resources. In thisrespect, itaconic acid has been used as an alternative to acrylic acid or maleic acid in unsaturatedpolyesters for thermal or UV-curing applications. However, examples of poly(ester amide)s fromitaconic acid are scarce.

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We describe new hydrophobic functionalized linear polyurethane resins by combining N-alkyl maleimides via the Diels-Alder reaction with linear furan-modified polyurethanes. This procedure provides the opportunity for the post-polymerization-functionalizing of polyurethanes. Access to furan-bearing polyurethanes is achieved via the reaction of a furan-containing diol, polyethylenglycol (PEG), and different diisocyanates.

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In this study, ammonium polyphosphate (APP) and aluminum hydroxide (ALH) with different mass contents were used as fire retardants (FRs) on plant-based natural flax fabric-reinforced polymer (FFRP) composites. Thermogravimetric analysis (TGA), limited oxygen index (LOI), and the Underwriters Laboratories (UL)-94 horizontal and vertical tests were carried out for evaluating the effectiveness of these FR treatments. Flat-coupon tensile test was performed to evaluate the effects of FR treatment on the mechanical properties of the FFRP composites.

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Quality assessment of recycled wood with and without non-wooden materials from selected recycling companies in Europe.

Waste Manag

September 2018

Fraunhofer-Institut Für Holzforschung Wilhelm-Klauditz-Institut WKI, Bienroder Weg 54 E, 38108 Braunschweig, Germany. Electronic address:

Recycled wood is becoming an important material source for production of new materials and chemicals. Predominantly clean recycled wood should be used for the products with high added value. However, contamination of the recycled wood defines the potential end uses.

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Bio-based unsaturated polyester resins derived from itaconic acid can be an alternative to established resins of this type in the field of radical-curing resins. However, one of the challenges of these polyester itaconates is the somewhat more elaborate synthetic process, especially under polycondensation conditions used on an industrial scale. The α,β-unsaturated double bond of the itaconic acid is prone to side reactions that can lead to the gelation of the polyester resin under standard conditions.

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State-of-the-art of waste wood supply chain in Germany and selected European countries.

Waste Manag

December 2017

Fraunhofer-Institut für Holzforschung Wilhelm-Klauditz Institut WKI, Bienroder Weg 54 E, 38108 Brunswick, Germany. Electronic address:

According to the statistic office of the European Union (Eurostat), Germany is the main producer of waste wood in Europe followed by France, United Kingdom, Italy and Finland. Based on the characteristics of the waste wood, it can be classified in four (4) categories: A I, A II, A III and A IV. This paper focuses in the A I waste wood since is the only category able to be used directly for both material and energy purposes without a previously pre-treatment.

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Adhesion force mapping on wood by atomic force microscopy: influence of surface roughness and tip geometry.

R Soc Open Sci

October 2016

Organische Baustoffe und Holzwerkstoffe, TU Braunschweig, Hopfengarten 20, 38102 Braunschweig, Germany; Fraunhofer Wilhelm-Klauditz-Institut WKI, Bienroder Weg 54E, 38108 Braunschweig, Germany.

This study attempts to address the interpretation of atomic force microscopy (AFM) adhesion force measurements conducted on the heterogeneous rough surface of wood and natural fibre materials. The influences of wood surface roughness, tip geometry and wear on the adhesion force distribution are examined by cyclic measurements conducted on wood surface under dry inert conditions. It was found that both the variation of tip and surface roughness of wood can widen the distribution of adhesion forces, which are essential for data interpretation.

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Release of acetic acid and furfural from cork products.

Indoor Air

June 2000

Fraunhofer-Institut für Holzforschung, Wilhelm-Klauditz-Institut (WKI), Bienroder Weg 54 E, D-38108 Braunschweig, Germany.

Cork samples were exposed to different temperatures and volatile ingredients were analyzed using gas chromatography/mass spectrometry (GC/MS). Thermal treatment at 180 degrees C yielded considerable amounts of furfural and acetic acid. In accordance with previous investigations it was concluded that both compounds are produced under thermal stress from degradation of polyoses.

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