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The impregnability of Portuguese maritime pine (Pinus pinaster Ait.) subjected to microwave (MW) drying was tested, and the hydrophobicity, anti-swelling efficiency (ASE), and water repellence efficiency (WRE) were evaluated. Small wood heartwood samples of Portuguese maritime pine and two distinct MW treatment settings were employed. The levels of ASE and WRE of the wood elements were evaluated throughout four cycles of drying in an oven and soaking in water. Because of MW applied energy, the wood pine samples were satisfactorily impregnated with the preservative product. Regarding the absolutely dry densities of the samples, very subtle reductions were measured, and they were statistically equivalent to the average density of the non-MW-treated group. Slight improvements were identified in the WRE values of wood samples dried in the microwave. In terms of ASE, both MW-treated groups had a statistically significant increase. The MW treatment decreased the volumetric swelling of the maritime pine wood specimens. Hence, this study raises new insights and previously unexplored paths that can contribute to the expansion and greater application of MW technology in maritime pine and other species.

Microwave (MW) pretreatment was used to increase the impregnability of Oriental spruce sapwood (Picea orientalis (L.) Link.). Wood samples with moisture contents of 55% and 83% were subjected to different MW energy treatments (1156 MJ/m3 and 1542 MJ/m3). Additionally, the mechanical properties of the treated wood samples were tested to determine the degradation caused by exposure to the MW radiation. According to the test results, the average preservative material retention rates increased by 47.5% and 70% for the samples with initial moisture contents of 55% and 83%, respectively, compared to the reference samples. The mechanical properties of the MW pretreated wood samples decreased within the range of 1.7% to 2.9% in the case of the compression strength; changed within the range of (+)1.9% to (-)6.1% in case of the bending strength; and changed within the range of (+)0.9% to (-)6.2% in case of the modulus of elasticity (MOE). The application of MW energy at different power settings on the samples with similar moisture levels was determined to have no impact on the mechanical properties of treated wood.

The impregnability of Portuguese maritime pine (Pinus pinaster Ait.) subjected to microwave (MW) drying was tested, and the hydrophobicity, anti-swelling efficiency (ASE), and water repellence efficiency (WRE) were evaluated. Small wood heartwood samples of Portuguese maritime pine and two distinct MW treatment settings were employed. The levels of ASE and WRE of the wood elements were evaluated throughout four cycles of drying in an oven and soaking in water. Because of MW applied energy, the wood pine samples were satisfactorily impregnated with the preservative product. Regarding the absolutely dry densities of the samples, very subtle reductions were measured, and they were statistically equivalent to the average density of the non-MW-treated group. Slight improvements were identified in the WRE values of wood samples dried in the microwave. In terms of ASE, both MW-treated groups had a statistically significant increase. The MW treatment decreased the volumetric swelling of the maritime pine wood specimens. Hence, this study raises new insights and previously unexplored paths that can contribute to the expansion and greater application of MW technology in maritime pine and other species.

Microwave (MW) drying of wood has gained popularity in the field of wood modification. The rise in temperature during MW drying leads to increased steam pressure, enhancing wood permeability but potentially decreasing mechanical properties. Understanding temperature and moisture behaviors during MW drying is crucial for its industrial application in wood drying. Therefore, this study aimed to characterize the temperature and moisture behaviors during MW drying of small Portuguese maritime pine (Pinus pinaster Aiton.) wood samples to support a wider use of this technology. The effects on water uptake and the compressive strength parallel to the grain were also investigated. The results indicated three distinct phases in the MW drying rates, with an average of 0.085% of water removed per second. Moreover, the temperature underwent three distinct stages: an initial rapid increase, a period of constant temperature, and a slight decrease until drying was complete. At the beginning of MW drying, the temperatures were below 100 °C, with average temperatures ranging from 126 to 145 °C. Specimens with lower initial moisture content had higher temperatures, and a positive correlation was found between initial moisture content and drying time. In contrast, negative correlations were found between the initial moisture content and average temperature, as well as average temperature and MW drying time. Additionally, the operating condition parameters used in MW drying of pine samples enhanced water impregnability by 65%, generating a slight reduction of 11% in compressive strength. It was also noticed that the initial moisture content did not impact MW-dried samples’ water uptake or compressive strength. Finally, although small clear wood samples of maritime pine were utilized, the temperature and moisture patterns observed closely matched real-scale specimens. Thus, the findings corroborate a wide utilization of MW technology for wood drying, mainly demonstrating positive possibilities for structural-sized wood specimens.

The possibility of increasing the anhydride epoxy bonding agent impregnability of glass fabric, made from aluminum borosilicate glass, by introducing adhesives into the serially produced lubricant 4s is studied. A wide range of wetting agents, produced by different global manufacturers for fiber and organosilicon coupling agents, was tested by determining the bonding agent impregnability over the height in a capillary. The impregnability of reinforcing glass fabric was increased considerably by improving the lubricant as well as counter-modification of the bonding agent.