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自然老化时间对古建筑松木理化性能和燃烧特性的影响

The effect of natural aging time on the physicochemical properties and combustion characteristics of pine wood

  • 摘要: 为了探究古建筑松木自然老化过程中的性能演变机制和劣化机理,以明、清、现代松木为研究对象,通过扫描电镜、傅里叶红外光谱、拉伸试验机、锥形量热仪等分析自然老化松木理化性能和燃烧特性的演化规律。结果表明:自然老化作用会促进木材的细胞开裂和木质素及半纤维素等有机成分降解,造成明代松木的纤维素结晶度比现代松木增加了3.6%;木材有机成分的降解会导致湿润性增加,致使明代松木的表面接触角比现代松木降低了31.9°;自然老化作用使松木的拉伸和抗弯强度下降,且松木抗拉强度和抗弯强度与自然老化时间呈线性关系;自然老化作用会破坏木材细胞壁微观结构,导致松木有机质减少、孔径增大,进而影响热释放效率,明代松木峰值热释放速率和总释放热相比现代松木分别降低了34.1%和34.7%。

     

    Abstract: The study took Ming, Qing and modern pine as research objects to reveal the degradation mechanisms of ancient architectural pine in the process of natural aging, and analyzed the evolution law of physicochemical properties and combustion characteristics of natural aging pine by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), mechanical tensile testing and cone calorimetry. The results showed that natural aging could promote cell wall cracking and degradation of organic components in wood, resulting in a 3.6% increase in cellulose crystallinity of Ming Dynasty pine compared with modern pine. The degradation of organic components led to an increase in wettability, surface contact angle decreased by 31.9° in Ming Dynasty pine. Natural aging also reduced mechanical strength of pine wood, the tensile and bending strength of pine are linearly related to natural aging time. Furthermore, natural aging decreased the organic matter and increased the pore size of pine wood, and then showed lower peak heat release rate(PHRR) and total heat release(THR) during combustion. Compared with modern pine, PHRR and THR of pine wood in Ming Dynasty decreased by 34.1% and 34.7%.

     

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