Browsing by Author "Yu, Jianfang"

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    Analysis of Deformation Fixation of Thermally Compressed Scots Pine (Pinus sylvestris L.)
    Li, Lili; Shan, Xiaofei; Luo, Zhiying; Liu, Wenwen; Liu, Jianxia; Yu, Jianfang; Chen, Zhangjing; Wang, Ximing (MDPI, 2024-05-11)
    Heat treatment effectively inhibits the water absorption recovery of compressed wood. To elucidate this phenomenon, we prepared compressed pine and thermally compressed pine (heartwood and sapwood) using the hot pressing method at 160 °C, 180 °C, 200 °C, and 220 °C. The effects of chemical components, swelling stresses, and monosaccharides on modified wood recovery were investigated using regression analyses. Notably, the recovery of both compressed heartwood and sapwood during water absorption declined from 18.89% to 2.66% and from 58.40% to 1.60%, respectively, after heat treatment. Similarly, the swelling stresses of the compressed heartwood and sapwood at 220 °C, respectively, ranged from 0.693 MPa to 0.275 MPa and from 0.783 MPa to 0.330 MPa. These were close to the values of untreated heartwood (0.175 MPa) and sapwood (0.225 MPa). Regression functions indicated that the recovery of compressed wood is chemically dependent on hemicellulose and mechanically related to swelling stress. For monosaccharides, regression functions indicated that modified heartwood recovery primarily relied on mannose, whereas modified sapwood recovery was remarkably affected by mannose and xylose. This confirmed that the pyrolytic monosaccharides in hemicellulose promoted stress relaxation, which induced the deformation fixation of thermally compressed wood.
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    Study of VOCs release during drying of plantation-grown Pinus sylvestris and naturally grown Russian Pinus sylvestris
    Shen, Yulin; Zhang, Xiaotao; He, Qin; Wang, Xia; Wang, Zhe; Yang, Junli; Chen, Zhangjing; Yu, Jianfang; Duo, Huaqiong; Wang, Ximing (2020-05-12)
    A study was carried out to investigate the release of volatile organic compounds (VOCs) during drying of plantation Pinus sylvestris grown in China and naturally grown Pinus sylvestris from Russia. Our purpose was to provide basic information that can help wood processing mills set their VOCs emission limits and control the exhaust gas within such limits. During conventional drying of the plantation Pinus sylvestris, a total of 22 chemical compounds were detected in the exhaust gas: 9 aldehydes including formaldehyde, 8 terpenes including α-pinene, and 3 additional compounds including alkane, and propylbenzene. The VOCs released during both conventional drying and high-temperature drying were the same. However, large amounts of benzene were detected during the high-temperature drying process. During conventional drying of the Russian Pinus sylvestris material, a total of 17 chemical compounds were detected: 7 aldehydes including formaldehyde, 6 terpenes including α-pinene, and 2 additional compounds. The VOCs released during conventional drying and high-temperature drying were the same. However, large amounts of camphene were detected during high-temperature drying. For plantation Pinus sylvestris, the release of VOCs primarily took place at the later stage of conventional drying, and at the earlier stage of high-temperature drying. For Russian Pinus sylvestris, the amount and the release rate of VOCs during conventional drying were extremely low, and the VOCs during high-temperature drying were primarily released at the later stage. The total amount of VOCs released during drying was much higher from the plantation Pinus sylvestris than from Russian Pinus sylvestris material.
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    Wood for Application in Electrochemical Energy Storage Devices
    Shan, Xiaofei; Wu, Jing; Zhang, Xiaotao; Wang, Li; Yang, Junli; Chen, Zhangjing; Yu, Jianfang; Wang, Ximing (Elsevier, 2021-12-22)
    Nowadays, achieving powerful electrochemical energy conversion and storage devices is a major challenge of our society. Wood is a biodegradable and renewable material that naturally has a hierarchical porous structure, excellent mechanical performance, and versatile physicochemical properties. Wood-based materials and its derivatives are endowed with great potential as resources to fabricate advanced materials for energy storage, flexible electronics, and clean energy. Herein, we comprehensively overview the methodologies applied for the synthesis of various electrochemical energy storage systems and devices (e.g., supercapacitor, battery, catalytic hydrogen evolution, etc.), the strategies for tailoring the structures and conductivity, as well as their impact on electrochemical performance (energy and power density and long-term durability). Finally, an outlook of future opportunities and prospects in the synthesis and application of electrochemical energy storage is also presented.