The mass loss kinetics of thermally modified wood species was analyzed as a time–temperature function. European beech (Fagus sylvatica L.), English oak (Quercus robur L.), Norwegian spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) wood specimens of dimensions 20 × 20 × 10 mm³ were thermally modified at 140 °C, 160 °C, 180 °C, 200 °C and 220 °C for 1–6 h using atmospheric pressure and superheated steam environment. The process intensity was determined by mass loss (M_L), based on oven-dry mass before and after the thermal modification. Furthermore, the equilibrium moisture content (EMC) was determined before and after thermal modification to analyze the effect of mass loss on the sorption properties. Measured mass loss data were compared with the three-dimensional analytical function and its applicability to mass loss prediction was verified. For the studied wood species, the M_L was found to be less than 1–1.5% when temperature of 140 °C and 160 °C was applied. Differences between studied species were more significant at temperatures higher than 160 °C. With the highest tested temperature (220 °C), mass loss reached 13.5% (beech), 18.8% (oak), 6.7% (spruce) and 13.5% (pine). According to the results, hardwoods have been shown to be more sensitive to the thermal degradation than softwoods as demonstrated by the higher mass loss recorded for the same modification time and temperature. The three-dimensional analytical function was confirmed as valid for all the species studied (R² = 0.89–0.99) and relevant for the mass loss prediction using fitted parameters. The EMC was reduced after thermal modification within the range of 4–48%, 0.4–47%, 1–32% and 0.7–40% for beech, oak, spruce and pine, respectively. Further, the EMC correlates exponentially (R² = 0.91–0.95) with the decrease in the specimens’ mass depending on the wood species used and modification temperature applied. However, the EMC seems to be almost stabilized beyond a limit value of approximately 10–12% of mass loss. The results provide a better insight into the mass loss and EMC kinetics of thermally modified wood species and can be used as a tool for prediction of mass loss values and required material properties (EMC) for designed wooden products.

分析了热改性木材的质量损失动力学，作为时间-温度函数。对欧洲山毛榉（Fagus sylvatica L.），英国橡木（Quercus robur L.），挪威云杉（Picea abies L.Karst。）和苏格兰松（Pinus sylvestris L.）尺寸为20×20×10 mm ^3的木材进行热加工。使用大气压和过热蒸汽环境在140°C，160°C，180°C，200°C和220°C下改性1–6小时。过程强度由质量损失（_ML），基于热改性前后的烘箱干燥质量。此外，在热改性前后确定平衡水分含量（EMC），以分析质量损失对吸附性能的影响。将测得的质量损失数据与三维分析函数进行比较，并验证了其在质量损失预测中的适用性。对于研究的木材种类，_ML当使用140°C和160°C的温度时，发现其含量低于1-1.5％。在高于160°C的温度下，研究物种之间的差异更为显着。在最高测试温度（220°C）下，质量损失达到13.5％（山毛榉），18.8％（橡木），6.7％（云杉）和13.5％（松树）。根据结果​​，硬木比软木对热降解更敏感，这是在相同的改性时间和温度下记录的较高质量损失所证明的。三维分析函数对所有研究的物种均有效（R ² = 0.89–0.99），并且与使用拟合参数进行的质量损失预测相关。热改性后，山毛榉，橡木，云杉和松木的EMC分别降低了4-48％，0.4-47％，1-32％和0.7-40％。此外，EMC与 样品质量的减少呈指数相关（R ² = 0.91-0.95），具体取决于所用木材种类和所施加的改性温度。但是，EMC几乎稳定在超过质量损失的10％至12％的极限值附近。结果提供了对热改性木材物种的质量损失和EMC动力学的更好的洞察力，并且可以用作预测质量损失值和设计的木制产品所需的材料特性（EMC）的工具。