Chemistry and Materials Science

Abstract: The Iulia Felix is a 2nd century AD Roman wreck discovered on the seabed off Grado in 1986. After being recovered, the hull was dismantled and its components were treated with PEG 4000 at high concentrations and temperatures. The treatment and drying pro-cess were completed in 2003. While awaiting exhibition, the wreck elements were stored in a stockroom, where they were preserved for over 20 years. However, this prolonged storage has introduced new variables. In particular, salt efflorescence has appeared on the surfac-es of some elements, raising concerns about potential further degradation. This made in-vestigating this efflorescence and studying how environmental conditions may affect the state of the treated wood particularly pertinent. The efflorescence was analysed using mi-croanalysis performed with a scanning electron microscope equipped with an energy dis-persive spectroscopy probe (EDS), X-ray powder diffraction (XRPD), and Fourier transform infrared (FTIR) spectroscopy. To verify the effect of climate on the treated material, some samples were exposed to severe but realistic humidity levels of 35% and 85% for an ex-tended period until equilibrium was reached. Analysis of the efflorescence revealed the presence of iron- and sulphur-based com-pounds, namely hydrated ferrous sulphates, calcium sulphate and hydrated iron oxides. This indicates that the ship’s elements had been affected by a corrosion process typically associated with the degradation of metal components. This process begins in a maritime environment and is completed in a humid, oxidative environment following artefact re-covery. Moreover, the presence of PEG in the efflorescence indicates that the artefact un-derwent unforeseen conditions after treatment that caused PEG to migrate to the surface over time. Environmental tests showed that using PEG 4000 for treatment significantly slowed down hygrometric exchange with the environment. However, exposure to a dry climate resulted in limited deformation due to minimal mass change (less than 1% for both mass and surface area), whereas prolonged exposure to a humid environment caused an 11% mass increase (due to water vapour absorption), resulting in a ca. 5% increase in sur-face area. This phenomenon was accompanied by the onset of minor cracks. In some cases, however, the samples fractured. Overall, this work contributes to the ongoing under-standing of the preservation challenges faced by underwater archaeological finds, partic-ularly with regard to treatment with high molecular weight PEG. It highlights the need for continuous monitoring to address degradation and its impact on the structural integrity of the wrecks, and provides a basis for future conservation strategies in museums.

Abstract: The alkaline oxidation of pine wood powder (Pinus sylvestris) by oxygen to produce vanillin and cellulose has been studied. The influence of temperature and catalyst (CuO) on the yield of vanillin, other monophenols and lignocellulosic residue (LCR) has been studied over a wide temperature range (120-220 °C). The highest vanillin yield obtained (49 wt.%) surpasses previously reported values. This can be attributed to the high oxidation rate, intense mass transfer, and optimal temperature conditions (12-15 minutes; stirring speed 1200 rpm; 180 °C). Within the temperature range of 120-180 °C, the use of a catalyst slightly increased the maximum vanillin yield (approximately 10% relative). The cellulose yield in the process attained 28-45% based on its initial content in wood. The highest vanillin yield was attained under harder conditions compared to those for cellulose production. Catalyst use accelerated the process, but this effect decreased to zero as temperature increased to 160 °C. The decrease in apperent activation energy as temperature increases can be explained by the transition of the process from a kinetic mode at lower temperatures (120-140 °C) to a diffusion-controlled regime under the conditions of maximum vanillin yield. The structure of native lignin in softwood is discussed.

Abstract: Accurate paper fiber identification is crucial for cultural heritage conservation. To address the destructive nature of traditional staining and the “black-box” limitations of macroscopic AI models, this study explores the feasibility of a non-destructive testing paradigm using micro-hyperspectral imaging (Micro-HSI). Three traditional Japanese pure bast fibers (Kozo, Mitsumata, and Gampi) were analyzed as standard samples. Raw relative reflectance spectra from microscopic regions of the fibers were extracted via Micro-HSI. Dynamic normalization and Savitzky–Golay first-derivative filtering were applied to suppress scattering and baseline drift. Principal component analysis (PCA) and linear discriminant analysis (LDA) were subsequently employed for dimensionality reduction and supervised classification. The results showed that while unsupervised PCA suffered from inter-class overlap due to shared cellulose-dominated structures, supervised LDA amplified weak chemical fingerprint differences, achieving complete class separation of the highly similar fibers. Analysis of the feature loadings confirmed that the classification relies on the visible-range reflectance baseline, lignin π→π∗ transition absorption (400–450 nm), and near-infrared O-H and C-H overtone vibrations (~835 nm). This proof-of-concept study demonstrates that combining Micro-HSI with chemometrics enables high-precision, non-destructive fiber separation while retaining rigorous physicochemical interpretability, thereby providing an optical reference baseline for future historical paper analysis.

Abstract: This study investigates the valorization of post-consumer and post-industrial recycled cotton fibers from textile waste into porous fiber-based insulation composites using a lowenergy cold-pressing process and a water-borne hybrid binder based on polyvinyl acetate (PVAc) and modified cornstarch. Insulation boards were produced with target densities ranging from 300 to 340 kg·m⁻³, achieved by systematically adjusting the percentage weight fractions of recycled cotton fibers and binder components. The influence of board density on microstructure, inter-fiber bonding, and structure-property relationships was evaluated. The resulting boards exhibited thermal conductivity values between 0.0710 and 0.0739 W·m⁻¹·K⁻¹. Compressive strength measured at 10% relative deformation of the specimen thickness ranged from 46 to 162 kPa, while internal bond strength varied between 2 and 6 kPa. Water absorption decreased by approximately 18% with increasing density, indicating improved binder distribution and reduced open porosity. The PVAc–starch binder system enabled effective inter-fiber bonding without formaldehyde-based resins or energy-intensive curing, supporting a low-energy and circular processing concept for textile waste valorization. Overall, the results demonstrate that recycled cotton fibers represent a viable feedstock for porous insulation composites combining balanced thermal, mechanical, and moisture-related performance with reduced environmental impact.

Abstract: The unique visual characteristics of wood can evoke and regulate affect. This study quantitatively investigates the affective responses to the visual characteristics of wood radial sections based on the dimensions of valence and arousal. First, the visual characteristics of radial sections were quantified, proposing the wood color characteristic parameter (c) and density characteristic parameter (d), and defining their respective ranges. Subsequently, by controlling these visual characteristics, the study explored their influence patterns on affective valence and arousal, thereby constructing an affective response model. Finally, the model was evaluated through an eye-tracking experiment, and prediction results were correlated with eye-tracking metrics. Results indicate that the visual characteristic parameters of radial sections range within 20 < c < 80 (dark brown to light yellow) and 5 < d < 25 (dense to sparse). Lighter wood color (higher c values) and denser grain (lower d values) evoked higher valence and lower arousal, indicating emotions tending toward pleasant relaxation. The proposed model effectively predicted the correlation between sections and affects, achieving a Mean Absolute Error (MAE) of 0.2. Predicted valence and arousal values showed high correlation with pupil data, further validating the model's reliability from a physiological perspective.

Abstract: This work deals with the impact of surface acoustic treatment (holes and grooves) and primary material (plywood, MDF, solid wood panel) of acoustic panels on its fire characteristics. Fire characteristics were determined based on the cone calorimeter method, single-flame source test, and smoke generation assessment. In general, birch plywood demonstrated the highest values for heat release rate (HRR), maximum average rate of heat emission (MARHE), and effective heat of combustion (EHC), indicating its higher flammability compared to the other tested materials. MDF generally exhibited the lowest values for heat release rate (HRR) and maximum average rate of heat emission (MARHE), yet under certain perforated configurations, it generated the highest amount of smoke. Solid wood panels exhibited the lowest heat release rate (HRR) but developed the largest charred areas during the single-flame source test. Among the surface treatments, the 16/8 mm treatment resulted in the highest values of effective heat of combustion (EHC) and maximum average rate of heat emission (MARHE), while the 8/1.5–15T treatment exhibited the most rapid increase in heat release rate (HRR), attributed to the swift degradation of its thin surface layer and high void fraction. The presence of holes and grooves increased smoke production, which was most evident in MDF and plywood panels.

Abstract: Reversible thermochromic materials change color in response to temperature variations and hold significant potential in smart textiles. Their reversible color-changing property not only offers temperature indication and enhances textile performance, but also pro-motes smart textile development. This is achieved by improving the intelligence, mul-tifunctionality, and environmental adaptability of textiles. This review summarizes the characteristics and recent advancements of reversible thermochromic materials, including organic, liquid crystal (LC), inorganic, and photonic crystal (PC) types. It emphasizes recent progress in integrating these materials into textiles through techniques such as microencapsulation, printing and dyeing, and fiber fabrication. Furthermore, the review systematically examines applications of reversible thermochromic materials in smart textiles, covering areas such as anti-counterfeiting, temperature-sensitive regulation, and aesthetic enhancement. Current challenges, including limited stability, inadequate wash durability, and low color sensitivity, are also addressed, alongside potential development directions. The aim of this review is to provide a theoretical foundation and technical guidance for designing and developing reversible thermochromic smart textiles.

Abstract: The fiberboard industry remains heavily reliant on synthetic, formaldehyde-based adhesives, which, despite their cost-effectiveness and strong bonding performance, present significant environmental and human health concerns due to volatile organic compound (VOC) emissions. In response to growing sustainability imperatives and regulatory pressures, the development of non-toxic, renewable, and high-performance bio-based adhesives has emerged as a critical research frontier. This review, conducted through both narrative and systematic approaches, synthesizes current advances in green adhesive technologies with emphasis on lignin, tannin, starch, protein, and hybrid formulations, alongside innovative synthetic alternatives designed to eliminate formaldehyde. The Evidence for Policy and Practice Information and Coordinating Centre (EPPI) framework was applied to ensure a rigorous, transparent, and reproducible methodology, encompassing the identification of research questions, systematic searching, keywording, mapping, data extraction, and in-depth analysis. Results reveal that while bio-based adhesives are increasingly capable of approaching or matching the mechanical strength and durability of urea-formaldehyde adhesives, challenges persist in terms of water re-sistance, scalability, cost, and process compatibility. Hybrid systems and novel cross-linking strategies demonstrate particular promise in overcoming these limitations, paving the way toward industrial viability. The review also identifies critical research gaps, including the need for standardized testing protocols, techno-economic analysis, and life cycle assessment to ensure the sustainable implementation of these solutions. By integrating environmental, economic, and technological perspectives, this work high-lights the transformative potential of green adhesives in transitioning the fiberboard sector toward a low-toxicity, carbon-conscious future. It provides a roadmap for research, policy, and industrial innovation.

Abstract:

The objective of this study was to investigate the chlorine-related challenges in Automotive Shredder Residue (ASR) by developing a de-chlorination strategy and formulating Solid Recovered Fuel (SRF) pellets with improved environmental and fuel quality. A ternary blending approach was employed using Fe–Ca-based inorganic dechlorinating agents and thorny bamboo biomass as co-materials with ASR. The de-chlorination efficiency, calorific value, and ash content of the resulting SRF were evaluated. Results indicated that the optimal dechlorinating formulation reduced the chlorine content of PVC from 43.26 wt% to 0.59 wt%, achieving a de-chlorination efficiency of 97.23%. A second-order polynomial regression model（η_DeCl = –1.5277x² + 2.5519x – 0.0225，R² = 0.9347）was developed to predict the de-chlorination performance based on the blending ratio of dechlorinating agent to ASR, demonstrating behavior consistent with first-order reaction kinetics observed in pyrolytic de-chlorination. The final ternary formulation—comprising 55% thorny bamboo, 37.5% ASR, and 7.5% dechlorinating agent—produced SRF pellets with improved overall quality, demonstrating effective chlorine control, reasonable ash content, and enhanced thermal properties suitable for regulatory compliance and practical application. Such findings meet the criteria set by EN ISO 21640:2021 (Class 2), JIS Z7311 (Grade A), and forthcoming Taiwanese SRF regulations. Based on the findings in this work it can be stated that the high de-chlorination potential of Fe–Ca-based additives for chlorine-rich waste and introduces a predictive formulation model that supports both resource circularity and clean fuel production.

Abstract: Phosphorus tailings are solid waste generated from phosphate ore processing, and their prolonged accumulation consumes significant land area and poses a substantial risk to soil and groundwater quality. This study innovatively converts phosphorus tailings into gypsum fiber for papermaking, thereby addressing the issue of excessive accumulation of phosphorus-rich tailings. Experiments were conducted to investigate the effects of slurry concentration, stirring speed, and reaction temperature on the length of gypsum fibers; and the prepared fibers were used as paper fillers for papermaking to investigate the effects of gypsum fiber lengths, mixing ratio, and retention amount on the performance of paper. The findings indicated that at a slurry concentration of 9%, a stirring speed of 50 rpm, and a reaction temperature of 55℃, the resultant gypsum fibers exhibited increased length, elevated aspect ratio. The 100 μm homogeneous gypsum fiber incorporated into paper exhibits superior mechanical strength compared to shorter or irregular gypsum fibers. The research findings present a novel method for the effective and valuable utilization of phosphorus tailings, resulting in solid waste reduction and pollution abatement, while providing a more environmentally friendly source of functional fillers for the paper industry, thereby generating both ecological benefits and potential economic gains.

Abstract: While most efforts are aimed at preventing the surface roughening and colour change of wood due to weathering, some, mainly for decorative reasons, want wooden objects and elements to give the impression that they have been weathered for a long time. In this study, the simulated weathering of numerous softwoods as well as ring-porous and diffuse-porous woods by sandblasting and greying with iron sulphate was investigated. Calculations of the correlations between wood density, orientation, mass loss and thickness reduction by sandblasting, the difference between the hardness of late and early wood and the surface profile parameter Pt showed that the surface profiles correlates strongly with the mass loss, especially in the tangential orientation. Softwoods appeared to be the most promising for simulated profiling, especially spruce and larch with tangential surfaces. Among the ring-porous woods, oak and sweet chestnut also delivered good results.

Abstract: The aim of the study was to develop an optimum method for investigating the change in the content of selected metals in biomass before and after pretreatment by steam explosion. The study included testing the metal content using an X-ray fluorescence spectrometer (XRF) of metals such as chromium, manganese, iron, nickel, copper and zinc. These metals are considered inhibitors of biological processes occurring during biofuel production such as enzymatic hydrolysis, alcoholic fermentation. In this study, a steam explosion process was carried out on poplar wood biomass at selected temperatures in the range 140°C -205°C. The study found the greatest increase in metal content for materials after SE at 175°C. The significant increase in the accuracy of the determination of metals in the material is influenced by the transfer of the raw material to the liquid state.

Abstract: Fast-growing hardwoods like poplar often lack natural durability in outdoor use and require homogeneous impregnation with protective agents, though achieving homogeneity remains a known challenge. Various anatomical structures influence fluid transport in wood. This study compares characteristics of pits in libriform fibres, between ray–vessel interfaces, and between vessel-to-vessel connections in normal wood and tension wood of a hybrid poplar genotype (Populus × canadensis, ‘Gelrica’), including both impregnated (with an aqueos, dye-containing solution) and non-impregnated regions, to identify anatomical barriers to impregnation. Light and scanning electron microscopy revealed significant differences in pit morphology and frequency in libriform fibres between normal wood and tension wood. In non-impregnated regions, pits were often encrusted. Vessel-ray pits did not differ between normal wood and tension wood but showed distinct differences between impregnated and non-impregnated regions: in the latter, pits were occluded by tylose-forming layers. Intervessel pits differed in border and aperture size between earlywood and latewood in both normal wood and tension wood. Hence, fluid transport is strongly impeded by occluded vessel-ray pits and, to a lesser extent, by encrusted fibre pits.

Abstract: A key discovery of this study is the strong correlation (r = 0.96) between excitation and emission maxima across chemically distinct clusteroluminogens. All 157 evaluated peaks fall along a single regression line (Ex = 0.844 Em -12 nm), a pattern that was not valid for conventional fluorophores. This suggests a general principle of clusteroluminescence. We show that in lignocellulosic materials, peak positions reflect chemical interactions: isolated lignin and cellulose showed short excitation and emission wavelengths, while native wood exhibited longer wavelengths. Fungal or photoinduced degradation led to a further red-shift. These effects are attributed to increased molecular heterogeneity, reducing the effective energy gap within the lignocellulosic complex. We conclude that the spectral position reflects the degree of molecular interaction rather than the chemical structure of individual molecules. It may serve as a novel analytical parameter for assessing purity and degradation in a wide range of polymers.

Abstract: Global climate crisis shifts the building industry towards ecological use of materials, often based on renewable sources. Properties of such materials, as well as their behavior in structures, need to be constantly verified both theoretically and experimentally. The article focuses on vapor retarder influence on moisture content of timber log peripheral wall structures with sheep wool insulation. Moisture content was verified experimentally during the period of over 2 years via monitoring sensors and insulation samples weighing. Results show vapor retarder has got a positive and statistically significant impact on moisture content of sheep wool insulation and log structure. This case study can help further the knowledge of log structure design and provide insight into hygrothermal properties of sandwich structures.

Abstract: This study investigates the impact of multilayers and drying strategies on the barrier properties of high-speed starch/bentonite-coated paperboard. The machine speed was 400 m/min. The hypotheses were that thin multilayer coatings reduce oxygen permea-bility more effectively than thick single or double coatings and that gentle infrared (IR) drying is required to engender this effect. The experiments involved coating paperboard up to six times with dry coat weights between 0.5 and 1.5 g/m² in each layer. The IR dryer power ranged from 207 kW to 829 kW, and different IR element positions were tested. The results indicated that thin multilayer coatings resulted in fewer pinholes, lower oxygen transmission rates and improved grease resistance compared with one or two thick layers. However, the effectiveness of the multilayer-coated paperboard was in-fluenced by the employed drying strategy. Specifically, gentle IR drying reduced pin-holes, lowered oxygen transmission rates and enhanced grease resistance.

Abstract: Acid hydrolysis can be more efficient than water hydrolysis, particularly in breaking down cured adhesives found in waste panels within a shorter reaction time that could benefit large-scale industrial processes. This study evaluates the effects of various acid hydrolysis conditions on the thermal, physical, and chemical properties of recycled particles intended for particleboard production. Particleboards were recycled using oxalic acid and ammonium chloride at different concentrations and reaction times at 122 °C. The thermal stability of the particles was determined by thermogravimetric analysis. Particle size distribution, particle morphology, nitrogen content, pH and acid/base buffer capacity were analyzed. The effect of the recycled particles on the urea-formaldehyde (UF) curing was assessed using differential scanning calorimetry and the gel time method. The recycled particles exhibited a higher thermal degradation beyond 200 °C, indicating their thermal stability for manufacturing new panels. The acid treatments did not damage the anatomical structure of the particles. The nitrogen content of recycled particles decreased by up to 90% when oxalic acid was used, compared to raw board particles. Recycled particles had a lower pH, a lower acid buffer capacity, and a higher base buffer capacity than those of raw board particles. The recycled particles did not significantly affect the peak polymerization temperature of the UF adhesive. However, some treatments affected the gel time of the adhesive. The results indicate that particleboards can be effectively recycled through acid hydrolysis, mainly with oxalic acid, which gives better results than hydrolysis using water alone. Oxalic acid showed increased selectivity in eliminating the cured UF adhesive, resulting in recycled particles suitable for manufacturing new panels.

Abstract: This study aimed to develop a mathematical model describing the thermal dissipation kinetics during the post-processing cooling phase of flat-pressed wood–polymer composites (FPWPC). The model elucidates the relationship between the composite's cooling time and the spatiotemporal temperature distribution across its thickness, as influenced by wood particle content, initial surface temperature, and bulk density. Analysis of the thermal profile in the core layer revealed three distinct phases: an initial temperature increase, a thermal peak, and a convective cooling phase. The results demonstrate that both the wood particle content and the initial surface temperature significantly affect the thermal dissipation rate. Higher initial surface temperatures (e.g., 200 °C) led to an initially accelerated cooling rate, followed by a deceleration phase. Composites with higher wood particle content (60%) exhibited slower cooling rates, which is attributed to the lower thermal conductivity of wood relative to the thermoplastic polymer matrix, resulting in greater thermal retention. Bulk density was also found to play a critical role in thermal management by influencing the composite’s specific heat capacity, thermal conductivity, and convective heat transfer efficiency. The proposed mathematical model offers potential for optimizing FPWPC manufacturing processes by enabling more precise control over cooling dynamics.

Abstract: The pine cone is an important forest product for the Portuguese economy. However, it is associated with environmental impacts, such as the generation of waste and the increased risk of forest fires. The objective of this research is to valorise waste from the production of Pinus pinaster Aiton in the form of natural dyes. The pine cone extracts were characterised in different alkaline solutions (1%, 5% and 10% NaOH) in order to evaluate the dyeing process on cotton knitwear, using the CIELab coordinates. The dyed samples were also subjected to light and water fastness tests. The extracts showed an increase in solids content with increasing alkalinity and a reduction in antioxidant content. The phenol content increased in the extract with 5% but decreased with the 10% concentration. All the dyes expressed a pink colour, but with different shades. About the L* coordinate (luminosity), the colours became lighter as the NaOH increased. n the a* coordinate, all the samples had a reddish colour and, in the b* coordinate, all the samples had a yellowish colour. About light and water fastness, all the samples lost colour, but in the water test it was not noticeable.

Abstract: This paper discusses how to make a diaper made with biodegradable materials. With the population increasing, pollution has become more prevalent in our current society, especially with waste that cannot be broken down and composted. Other companies that make diapers do not make use of environmentally friendly materials. Instead, they use gels and cloths that are not able to decompose. We used kapok fiber and bamboo cloth to tackle this problem and create environmentally safe and fully biodegradable diapers. We tested the diaper prototype dubbed the “Kaboo Diaper” using the rewet and absorbency test. The absorbency test showed that the diaper absorbed 323g of simulated urine. The rewet test showed that the diaper picked up 24g of water over time, passing industry standards. Showing the diapers to mothers contacted by the Health and Sanitation unit of Brgy. Oranbo deemed the prototype ready to use.