火灾中典型热塑性聚合物的熔体性质及对燃烧过程的影响研究

发布时间：2018-03-24 03:37

本文选题：热塑性聚合物　切入点：熔融　出处：《青岛科技大学》2017年硕士论文

【摘要】：热塑性聚合物被广泛应用于室内装修、建筑外墙保温等领域。但由于其具有受热软化、熔融、流淌等特性,给火灾的防治带来了许多新的问题。本文研究了几种典型热塑性聚合物材料的燃烧过程及熔体流动行为,并进一步分析了熔体的性质及对燃烧过程的影响。首先采用锥形量热仪研究了几种热塑性聚合物的燃烧行为、熔体运动现象及熔体热性质的演化对燃烧的影响。发现聚合物的裂解机理与其熔融现象和燃烧行为相关,解聚为主的聚合物的熔体基本不流淌且燃烧速率较稳定或只有一个增长阶段,随机裂解的聚合物的部分熔体可流淌且燃烧速率曲线有两个增长阶段。随着燃烧的进行聚乙烯(PE)和聚丙烯(PP)熔体的热稳定性不断降低,分解热(Hd)逐渐减小,燃烧热(Hc)逐渐增大;而聚甲醛(POM)、聚甲基丙烯酸甲酯(PMMA)和高抗冲聚苯乙烯(HIPS)的热稳定性和Hc几乎不变。其次研究了熔体流滴行为及熔体性质,发现25kW/m2辐射热流条件下,水平燃烧时聚合物产生可流动熔体的比例从大到小为:聚酰胺PA6(0.79)PE(0.65-0.70)PP(0.39-0.46)HIPS(0.21)POM(0.13)PMMA(0.04),熔融指数越大的聚乙烯样品所产生的流动熔体的量越多。熔体的耐点燃性和燃烧热值均高于原聚合物的,但零剪切粘度和粘流活化能显著低于原料的。垂直燃烧时PP流滴速率最大,PA6流滴速率最小。最后研究了熔体流动对点燃和燃烧过程的影响,结果表明,熔体向下流动可延长水平样品的着火时间。熔体流淌受限时燃烧较稳定,熔体可流淌时燃烧速率具有非线性特点,且因燃烧面积扩大导致平均燃烧速率是流淌受限时的1.2-2.0倍。
[Abstract]:Thermoplastic polymers are widely used in interior decoration, building exterior wall insulation and other fields. However, due to its heat softening, melting, flowing and other characteristics, This paper studies the combustion process and melt flow behavior of several typical thermoplastic polymer materials. The properties of the melt and its influence on the combustion process were further analyzed. Firstly, the combustion behavior of several thermoplastic polymers was studied by means of a cone calorimeter. The effects of melt motion and the evolution of melt thermal properties on combustion. It is found that the cracking mechanism of polymer is related to its melting phenomenon and combustion behavior. The melt of the depolymerized polymer is basically non-flowing and the combustion rate is stable or has only one growth stage. The partial melt of the randomly cracked polymer can flow and the combustion rate curve has two growth stages. The thermal stability of the melt decreases, the decomposition heat decreases gradually, and the combustion heat increases with the combustion of polyethylene (PE) and PP (PP) melts. However, the thermal stability and HC of POM, PMMA and HIPSs were almost unchanged. Secondly, the droplet behavior and melt properties of 25kW/m2 were studied, and it was found that under the radiation heat flux of 25kW/m2, the droplet behavior and melt properties were studied. During horizontal combustion, the ratio of flowing melt produced by polymer is from large to small: polyamide PA6, 0.79, PEI, 0.65-0.70, PPU, 0.39-0.46, HIPSU 0.21, POM0.13, PMMA-0.04, the larger the melting index, the larger the amount of flowing melt, the higher the ignition resistance and combustion calorific value of the melt are, the higher the ignition resistance and combustion calorific value of the melt are compared with those of the original polymer. However, the zero shear viscosity and viscous flow activation energy were significantly lower than those of raw materials. The maximum droplet rate of PP and PA6 droplet rate in vertical combustion was the lowest. Finally, the effect of melt flow on ignition and combustion process was studied. The melt flow down can prolong the ignition time of the horizontal sample, the combustion rate of the melt is stable when the melt flow is limited, and the combustion rate is nonlinear when the melt can flow, and the average combustion rate is 1.2-2.0 times higher than that under the limited flow due to the expansion of the combustion area.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ317;TQ038

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