The 3D printing process allows complex structures to be obtained with low environmental impact using biodegradable materials. This work aims to develop and acoustically characterize 3D-printed panels using three types of materials, each manufactured at five infill densities (20%, 40%, 60%, 80% and 100%) with three internal configurations based on circular, triangular, and corrugated profiles. The highest absorption coefficient values (α = 0.93) were obtained from the acoustic tests for the polylactic acid material with ground birch wood particles in the triangular configuration with an infill density of 40%. The triangular profile showed the best acoustic performance for the three types of materials analysed and, from the point of view of the mechanical tests, it was highlighted that the same triangular configuration presented the highest resistance both to compression (40 MPa) and to three-point bending (50 MPa). The 40% and 60% infill density gave the highest absorption coefficient values regardless of the material analyzed. The mechanical tests for compression and three-point bending showed higher strength values for samples manufactured from simple polylactic acid filament compared to samples manufactured from ground wood particles. The standard defects of 3D printing and the failure modes of the interior configurations of the 3D-printed samples could be observed from the microscopic analysis of the panels. Based on the acoustic results and the determined mechanical properties, one application area for these types of 3D-printed panels could be the automotive and aerospace industries.

Purpose. This paper focuses on detailed studies regarding the analysis of occupational risk factors on health and occupational disease, namely the influence of noise, hand-arm vibration (HAV), Wet Bulb Globe Temperature index (WBGT) and exposure to particulates. Methods. In this study were measured: the equivalent acoustic level LAeq (dB(A)), A(8) (m/s²), WBGT index (°C), particulate concentration in the respirable area of the worker (mg/m³). The inferential analysis consisted in the application of specific statistical methods: probability plot with 95% confidence interval, Anderson-Darling statistic and the 87²⁰⁸ percentile estimation. A sample of 107 chainsaw operators was medically evaluated, out of which 30 workers’ were suspected of having professional pathologies and hospitalized in the university clinic. Results. The measurements highlight: exceeding the legal limit for noise exposure, 13% of cases exceed the limit of 2.5 m/s² for HAV, dust exposure is generally within legal limits, and WBGT shows the thermal stress of the workers. Following the medical evaluation, osteo-musculoskeletal disorders (25.23%), Raynaud's Syndrome (0.93%) and bilateral hearing loss (3.74%) were identified. Conclusions. The analysis of the levels of exposure to the risk factors, the typology and the incidence of occupational diseases require the need to adopt new preventive measures.

The paper aims to investigate the influence of the characteristics of the strands on the properties of oriented strand boards (OSB). To solve this objective, some global synthetic characteristics of the strands (the slenderness ratio, the characteristics of thinness, and the specific surface) of four wood species currently used in this technology (spruce and pine for softwood, and poplar and willow for hardwood) were first studied. The characteristics of the OSB obtained from each species separately were also determined, and finally the correlations analysis was made between the characteristics of the strands and those of the corresponding OSB boards. The working methodology used the European tests regarding the physical and mechanical properties of the boards, but also algorithms for forecasting and evaluating the quality of the strands and boards. The conclusions regarding the characteristics of the strands have highlighted the role of the specific surface of the strand and the characteristics of the thickness; respectively, the conclusions regarding the characteristics of the boards showed that the fast-growing species of willow and poplar lead to obtaining higher quality OSB boards. The general conclusion of the paper is that the characteristics of the strands have a significant influence on the physical–mechanical properties of the OSB board.

Large amounts lignocellulosic biomass in the form of straw is leftover after wheat harvesting that could be utilized for beneficial purposes. The latter has led to the emergence of new technologies to make use of this resource. One such technology currently in use turns wheat straw into briquettes. In the present study, we have prepared and evaluated the physical, mechanical and calorific properties of two types of briquettes made of wheat straw. The two types of briquettes prepared were (i) hollow briquettes and (ii) solid briquettes. The densities of these briquettes obtained on a mechanical device with a crank mechanism were 1.169 kg/m³, irrespective of whether the briquettes were hollow or solid. The briquette densities are consistent with European standards. The calorific value of wheat straw was 17.69 MJ/kg. Although the calorific value was somewhat lower than the beech wood briquettes (18.38 MJ/kg), it is adequate for their combustion in both stoves and thermal power plants. The ash content of wheat straw was 9.1% (~10-fold higher than that of beech wood). The briquettes showed a compressive mechanical strength of 1.15–2.17 N/mm² and splitting mechanical strength of 0.17–0.39 N/mm² suggesting that the straw briquettes were well compacted and can be stable during transport and/or other manipulations. In conclusion, wheat straw briquettes have similar physical, mechanical and calorific properties to those prepared from beech wood biomass and are a viable solution to replace beech wood briquettes with similar efficiency.

Sustainable building materials with excellent thermal stability and sound insulation are crucial for eco-friendly construction. This study investigates biocomposites made from cellulose pulp reinforced with beeswax, fir resin, and natural fillers like horsetail, rice flour, and fir needles. Eight formulations were obtained, and their thermal resistance, oxidation temperature, and acoustic properties were evaluated. Biocomposites exhibited significant improvements compared to conventional materials. Oxidation temperature onset increased by 60–70 °C compared to polyurethane foam or recycled textiles, reaching 280–290 °C. Sound absorption coefficients ranged from 0.15 to 0.78, with some formulations exceeding 0.5 across mid-frequencies, indicating good sound-dampening potential. These findings demonstrate the promise of these biocomposites for sustainable construction, offering a balance of thermal and acoustic performance alongside environmental and health benefits.

The paper aims to compare the oriented strand boards (OSBs) made in the laboratory from a mixture of softwood species to those made from hardwood species, followed by their comparison to European and industry standards. In this regard, the main properties of the panels made in the laboratory were determined, including density, absorption, and swelling in thickness, modulus of elasticity, modulus of rupture, and internal bond. The analysis of the properties of swelling (24 h) and absorption (24 h) revealed that the mixture of softwood species was slightly better thanthe hardwood one. It was also shown that the panels manufactured from the mixture of hardwood species had better mechanical properties than those made of the softwood mixture (modulus of rupture (MOR) = 43.48 N/mm², modulus of elasticity (MOE) = 7253 N/mm, and internal bond (IB) = 1.57 N/mm²). Additionally, the comparative analysis of properties indicates that the density is highly significant in determining the MOE values of the OSBs. This will allow softwood speciestobe replaced with other species of soft and fast-growing deciduous trees such as willow, birch, and poplar in the manufacture of oriented strand boards.