含水率及燃烧性能等级对中密度纤维板点燃行为及安全性能影响的研究

采用锥形量热仪,在不同辐射热流强度下,对三种燃烧性能等级(B级、C级和非阻燃)的中密度纤维板在不同相对湿度(0%、50%和98%)形成的含水率条件下进行了辐射引燃实验,测得点燃时间和热释放速率等参数。利用点燃理论中热厚型积分模型,推导了不同含水率不同燃烧性能等级(防火等级)纤维板的临界辐射热通量。通过对比发现,点燃时间随着板材含水率的增加而明显增大,而临界辐射热通量则几乎不受环境相对湿度(即含水率)的影响。添加阻燃剂可延长点燃时间,使板材临界辐射热通量增加,并能有效地降低纤维板材燃烧时的热释放速率。阻燃纤维板的临界辐射热通量要明显高于非阻燃纤维板,但是阻燃纤维板材之间相比,临界辐射热通量差别不大。因而,从本质安全的角度对材料的安全性进行评价,不能将临界辐射热通量作为单一的标准,必须综合多个参数进行全面评价。

An experimental study of effects of moisture content and fire retardant level on ignition and fire behavior of medium density fiberboard

This paper investigates the ignition time and heat release rate of medium density fiberboard (MDF) with different fire retardant levels by using cone calorimeter, with different moisture contents and incident heat fluxes. A thermally thick model of ignition is applied to determine the critical heat fluxes of the samples. The results show that the ignition time increases greatly with the increasing moisture content, while moisture content has no noticeable effect on the critical heat flux. The fire retardant treatment not only prolongs the ignition time and increases the critical heat flux, but also significantly reduces the heat release rate of fiberboard. However, there is no significant difference among the MDFs with different flame retardant levels in the critical heat flux. It is thus concluded that other parameters should be considered for better assessment of the fire hazard of fiberboard.