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The analysis of microplastics is mainly performed using Fourier transformation infrared spectroscopy/microscopy (FTIR/ μFTIR). However, in contrast to most aspects of the analysis process, for example, sampling, sample preparation, and measurement, there is less known about data evaluation. This particularly critical step becomes more and more important if a large number of samples has to be handled. In this context, it is concerning that the commonly used library searching is not suitable to identify microplastics from real environmental samples automatically. Therefore, many spectra have to be rechecked by the operator manually, which is very time-consuming. In this study, a new fully automated robust microplastics identification method is presented that assigns over 98% of microplastics correctly. The main concept of this new method is to detect and numerically describe the individual vibrational bands within an FTIR absorbance spectrum by curve fitting, which leads to a very compact and highly characteristic peak list. This list allows very accurate and robust library searching. The developed approach is based on the already published microplastics identification algorithm (μIDENT) and extends and improves the field of application to μFTIR data with a special focus on relevant broad, overlapped, or complex vibrational bands.

The objective of this study is to evaluate and compare the mechanical and water-related properties of WPC containing two types of recovered wood particles. These particles were obtained by thermo-hydro-mechanical and sole mechanical (milling) disintegration and compared to virgin wood fibres. The respective composites were produced with and without maleic anhydride-grafted polypropylene (MAPP) as a coupling agent. The results clearly show that both types of particles, which derive from end-of-life MDF are a suitable resource to produce WPC. The physico-mechanical characteristics of the WPC containing particles from thermo-hydro-mechanical disintegration were statistically better than those containing mechanically produced particles.

In recent years, awareness regarding sustainability and the responsible usage of natural resources has become more important in our modern society. As a result, wood as a building material experiences a renaissance. However, depending on the use case, protective measures may be necessary to increase wood’s durability and prolong its service life. The chemical vapor deposition (CVD) of parylene-N layers offers an interesting alternative to solvent-based and potentially environmentally harmful coating processes. The CVD process utilized in this study generated transparent, uniform barrier layers and can be applied on an extensive range of substrates without the involvement of any solvents. In this study, European beech wood samples (Fagus sylvatica L.) were coated with parylene-N using the CVD process, with paracyclophane as a precursor. The aim of the study was to analyze the water absorption of beech wood, in relation to the different layer thicknesses of parylene-N. Therefore, four different coating thicknesses from 0.5 to 40 μm were deposited, depending on the initial amount of precursor used. The deposited layers were analyzed by reflection interference spectroscopy and scanning electron microscopy, and their chemical structures and compositions were investigated by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Due to the chemical structure of parylene-N, the deposited layers led to a significantly increased water contact angle and reduced the water uptake by 25–34% compared to the uncoated reference samples. A linear correlation between layer thickness and water absorption was observed. The coating of wood with parylene-N provides a promising water barrier, even with thin layers.

Wood-plastic composite (WPC) based on a polylactic acid (PLA) matrix is a promising material since it is biobased, degradable, sustainable, and 3D printable. However, due to its coloring, visible layers after 3D-printing, and small build volumes of these printers, a coating or gluing of parts might be required. This study investigates the influence of a dielectric barrier discharge (DBD) plasma treatment of PLA-based WPC to activate the surface and improve, e.g., coating capabilities. X-ray photoelectron spectroscopy (XPS) measurements showed the oxidation of the surface due to the formation of carbonyl and carboxyl groups. Laser scanning microscopy revealed a surface roughening after the treatment. Contact angles of water and diiodomethane decreased significantly after the plasma treatment and the consecutively calculated surface free energy increased. Finally, two practical adhesion tests revealed an improvement of the applied acrylic dispersion coating&rsquo, s adhesion to the WPC surface: The assigned cross-cut class improved, and the pull-off strength increased from 1.4 to 2.3 N/mm2.

Outdoor and indoor exposed wooden structures are prone to the hazard of fire. Thisr is often inevitable and hardly avoidable by factors such as the design. However, wood is widely used as a structural element in buildings, it is present all-over public places and the main source for indoor furniture. Thus, and due to recent incidents, the demand for an effective and leaching-resistant fire protection is rising. In addition, fire protection technologies are desired, which survive mechanical processing. Considering the latter, protective surface coatings show a high fire protection, while on opposite they are very sensitive to mechanical damages. Therefore, various approaches based on a full impregnation of timber with fire retardants have been studied. In the past aluminum, boron, halogens (e.g. bromine) and more recently phosphorus and nitrogen, were shown to be effective fire retardants in wood. Nowadays, most conventional fire retardant systems are halogen-free, while boron is still used. However, boron shows a low resistance to leaching and is classified as a SVHC candidate, which brings up health and environmental issues. The same is true for formaldehyde. Concerning environmental issues, nitrogen and phosphorus were found to be promising alternatives and highly effective fire retardants. Leaching in service was slightly reduced compared to boron but a decrease in strength properties was detected after treatment of wood with those compounds. In general, an increased hygroscopicity of wood was found after any of the listed treatments, together with a leaching of the flame-retardant chemical which was still too high to guarantee a long-term fire protection in wood exposed outside. The overall aim of this study is to (1) give an overview about the past developments and most established fire retardant chemicals and (2) review recent findings and developments in terms of permanent fire retardant treatments of wood.

In contrast to conventional coating processes such as varnishing, plasma powder deposition by means of an atmospheric pressure plasma jet on wood is not yet widely used. A key advantage of this process is that volatile organic compounds and organic solvents are avoided. In the present work, European beech (Fagus sylvatica L.) and pine sapwood (Pinus sylvestris L.) were coated with polymer (polyester), metal (aluminum coated silver) or metal oxide (bismuth oxide) particles. Furthermore, a layer system consisting of polyester and metal or metal oxide was investigated. The layer thickness and topography were analyzed with a laser scanning microscope and scanning electron microscope, revealing thicknesses of 2&ndash, 22 &micro, m depending on the coating material. In general, the chemical composition of the layers was determined using X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy measurements. The coatings consisting of metal and metal oxide showed a band gap and plasmon resonance in the range of 540 and 450 nm. Through this absorption, the wood may be protected against ultraviolet (UV) radiation. In the water uptake and release tests, the polyester layers exhibited a reduction of water vapor absorption after 24 h in 100% relative humidity (RH) by 53%&ndash, 66%, whereas the pure metal oxide layers indicated the best desorption performance. The combination of metal oxide and polyester in the one-layer system combines the protection properties of the single coatings against water vapor and UV radiation.

In this study, polyester powder based on iso- and teraphthalic acid was deposited with an atmospheric plasma jet. The powder was fed into the effluent plasma zone and deposited on European beech wood (Fagus sylvatica L.), Grand fir (Abies grandis Lindl.) and medium density fiberboard (MDF). The substrates were annealed subsequent to the coating process. To exclude decomposition of the polyester layers by the plasma treatment, the surface chemistry of the layers has been examined by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) and compared with the polyester powder reference. Furthermore, topographical investigations were carried out using laser scanning microscopy (LSM). Adhesive strength of the layers was evaluated by dolly test and gloss measurements with a goniophotometer. The deposited layers showed no chemical changes compared to the reference. The adhesive strength of the layer met practical requirements of >1 MPa. It was demonstrated that the deposition of a macroscopic layer is possible without a pretreatment or the usage of additives. Therefore this coating process by atmospheric pressure plasma for wood and wood based materials could represent an environmental-friendly alternative to conventional coating methods.