Materials Science Forum Vol. 1071

Abstract: Preparation of titanium alloy coating on the low carbon steel surface is an effective way to ensure the service performance of steel in marine environment. In this work, the effect of Cu interlayer thickness on the microstructure and properties of the titanium alloy coating was systematically studied. The results showed that a thin Cu interlayer cannot inhibit the diffusion of iron, and the Fe-Ti intermetallic compound (IMC) layer at the coating/substrate interface weakens the bonding property of the coating. And iron compounds on the surface of the coating surface are negative for corrosion resistance. The thickening of Cu interlayer inhibits the diffusion of iron and increases the shear strength of the coating by 40%～60%. When the iron compound is not present on the coating surface, the optimal electrochemical properties of the titanium alloy coating were achieved. However, the excessive thickness of the Cu interlayer will accelerate the heat loss of the molten pool and lead to the fusion defect in the initial cladding stage. In this study, the optimum thickness range of Cu interlayer (290μm ~ 375μm) was obtained. When the interlayer was in this range, titanium alloy coatings with excellent comprehensive properties could be prepared.

Abstract: The corrosion behavior of 3Cr steel in simulated oilfield CO₂ and formation water environment at different temperature and partial pressure of CO₂ were investigated using dynamic immersion tests, scanning electron microscopy inspection and X-ray diffraction analysis. The result demonstrated that with an increasing of temperature, the corrosion rate of 3Cr steel decreased, and reached the maximum corrosion rate when the partial pressure of CO₂ was 0.5MPa. The high content of Ca²⁺ in the formation water had also played an important role in the corrosion behavior of the 3Cr steel for it can lead to a deposition of the CaCO₃ on the surface of the specimen.

Abstract: Kraft cooking of juniper wood with NaOH/Na2S aqueous solution has been used in the study for partial delignification at the temperature of 165°C for different residence time (0-40 min) following by thermal compression for densification under a pressure of 5 MPa at 100°C for 24 hours. The densified and natural juniper wood samples were characterized by chemical composition and mechanical properties. The results show that the density of densified juniper wood was increased by 96-127% reaching the value of 1170 kg/m³ that is similar to conventional bone implants (1090 kg/m³). Modulus of rupture and modulus of elasticity of densified juniper wood were increased by 85% and 621%, respectively, demonstrating a high potential of the material to be used as bone implants.

Abstract: The growing global request to make green materials nowadays expresses in reducing environmental problems and obtaining biomaterials with high-performed properties. Aside from being carbon neutral, the use of biomass for obtaining green materials contributes to energy security and climate change mitigation. The aim of the work was to fabricate and study a recycled polypropylene-based composite filled with recycled waste paper obtained by the acid hydrolysis of de-inked newsprint. It has been found that, with increasing the content of the recycled paper microparticles in the bio-composite, its mechanical and wetting properties deteriorated. The presence of maleic anhydride grafted polypropylene as a compatibilizer increased the homogeneity of the structure of the bio-composite, which improved its mechanical properties and decreased its ability to be wetted with water.

Abstract: Article summarizes investigation results of rheological, thermal and some mechanical properties of industrially prepared wood plastic composites (WPCs), based on virgin and recycled polypropylenes (vPP, rPP) and birch plywood production waste product-plywood sanding dust (PSD). Investigated WPCs contain 40 and 50 wt. % PSD different another modifier, such as functional lubricant Struktol TWP-113, antioxidant 1010, thermal stabilizer 168, UV stabilizer 770 and different color pigments. According to our studies, we can conclude that rheological properties studied by capillary rheometry method depends on WPCs composition and experimental parameters: shear stress, shear deformation rate and temperature. The curves of the fluidity indicate to the character of typical pseudo-plasticity of all polymer melts of which viscosity not only depends on temperature, but also decreases with an increase of shear stress and shear deformation rate Pseudo-plastic properties confirm also the signed values of fluidity index (n) which for pseudo-plastic liquids always are smaller than one. TGA measurements showed that all systems have the high thermal stability and the weight losses after dynamic heating up to processing temperature 215°C are not more than 5.53 %, but during isothermal heating (1 h) at 215°C only 4.51%. Differential scanning calorimetry (DSC) showed a small changes of melting temperatures, but the beginning of thermal destruction temperature fluctuates between 256.96 and 188.5°C. Density of all composites changes in limits 1.02-1.09 g/cm³, temperatures by Vika 154.4-158.7°C, microhardness 125.1-151.8 MPa and impact strength 7.81-15.39 kJ/m²

Abstract: Plastic waste is an ever-growing concern, causing harm to many ecological and human health aspects, one of the major contributors to this problem being packaging. Mycelium composites (MC) are ecologically safe materials, well suited for the short-life usage as packaging materials. In our study we made MC using fine and coarse granulometry hemp shives applying them in 3 substrate variants – with added bran, with added bran and birch bark, and as the sole substrate. We assessed material's water absorption and mechanical properties, chemical decomposition, biodegradability, mold resistance and fungal biomass. Granulometric effect was observed only when using shives as the sole substrate, where larger particle size gave poorer results. Bran did not significantly improve mechanical properties or water uptake. Bark reduced water uptake by ~200 %, but lowered mechanical properties, and provided no benefits to mold resistance which was low for all specimens. Overall, hemp MC showed complete biodegradability after 12 weeks, mechanical properties up to 0,235 MPa, compatible with expanded polystyrene, but very high water uptake of up to 1000 %. Future studies are needed to reduce water absorption and improve mold resistance, as well as invent consensus methodology for better cross-study comparison.

Abstract: Some industrial crops residuals like wheat straw, buckwheat husks and reeds were used in the study as raw lignocellulosic materials to evaluate their potential as thermal insulation material. Steam explosion (SE) pre-treatment was used to disrupt and convert the raw material smooth shape to foamy fibrous shape. Two level Factorial design was used to evaluate the impact of raw material fraction size (10-20-30 mm), moisture content (10-30-50%), SE temperature (200-215-230 °C) and duration (00-30-60 s) on bulk density and thermal conductivity of the obtained loose-fill materials. The results show that all selected raw materials could be characterized as thermal insulation materials as the determined thermal conductivity was in the range of 0.042–0.058 W (m K)^-1 including neat samples. In spite of effective fibrillation of raw materials SE pre-treatment did not improve their thermal conductivity. The determined bulk density of loose-fill crops varied in range of 23–184 kg m^-3 depending on all variables; the SE pre-treatment showed the most significant effect on its reduction. Based on the study results the most suitable crops residues for bio-based thermal insulation purposes are suggested wheat straw and reeds demonstrating the lowest values of bulk density and thermal conductivity.

Abstract: The aim of this study was to characterize and evaluate the performance of two wood species, pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) used for wooden furniture in outdoor coated with a water based ecological paint and subjected to artificial weathering. Another task of this research was to investigate the potential of the application of paint using dipping method in alternative to traditional brush or spraying coating application methods, since, if wood samples are grouped in stacks, the processing time can be reduced, compared to samples painted singularly. From the analysis of the dipping parameters, such as time and paint concentrations, more practical and specific knowledge was obtained regarding this painting method.From the characterization of the painted samples and from the measurements of color changes during artificial weathering it was observed that coated wood surfaces have similar optical properties also in case of different dipping times, although the type of wood could affect the performance of final product during artificial weathering test as in case of spruce wood samples, specifically those prepared with the shortest dipping time: for these samples a lower resistance to weathering and higher color changes were observed.

Abstract: The scientometrics study of the publications set devoted to biorefinery allows to characterize the research field, its dynamics, most relevant countries, institutions, and authors, cooperation, thematic structure, and publishing praxis. The permanent and fast increase of biorefinery publications started in 2001 and will be approximated by the power function, which allows predicting a further increase in the number of biorefinery publications. The leading producers of publications are European Union countries, European Economic Area countries and Switzerland together, the USA, PR China, Brazil, and India, but the output of 76 countries have been at least 10 publications since 1981. The proportion of internationally coauthored publications was 33.0% during 2018-2021, and six clusters of more close cooperating countries are recognized. The keywords cooccurrence analysis allows recognition of 4 subfields of research: biorefinery itself and biofuels, wood chemistry, algae and biotechnology, and alcohol production. The citation characteristics of biorefinery publications are substantially higher than the values of the corresponding research fields, and the top journals are preferred for the dissemination of research results.

Abstract: Global sustainability challenges prompt the world to modify their strategies and shift from a fossil-fuel-based economy to a bio-resources-based one and to the production of renewable biomass-based chemicals. Different processes exist that allow the transformation of raw biomass into desirable bio-based products and/or energy. Depolymerized suberinic acids (SA) can be considered as an alternative resource to different feedstocks for value-added product obtaining, for example to develop bio-polyols that can be further used in polymeric material production. Birch outer bark was used as a raw material for obtaining SA and was extracted with ethanol to remove extractives. Further extracted birch outer bark was depolymerized with potassium hydroxide ethanol/methanol/n-butanol/2-propanol solutions. Obtained SA suspension was dried by performing lyophilization or by drying at 100 °C. As a result, we obtained 8 SA samples, which were characterized using chemical (total phenolics content, solubility in DMSO, acid number, hydroxyl number, and saponification number) and instrumental analytical methods (GC-MS, SEC-RID, FTIR). The most suitable SA for obtaining value-added product, such as bio-polyol, were obtained by using ethanol as a solvent for depolymerization process. The corresponding SA had the best results in terms of dry matter content, yield, solubility in DMSO, epoxy groups, acid number and ash content. After GC-MS results it was concluded that the amount of diacids, hydroxyacids and extractives are dependent of the used alkanol for SA depolymerization as well as the drying method.