聚合物燃烧过程中熔化特性研究

通过试验和模拟研究了大量聚合物包括热塑性和热固性聚合物在燃烧过程中的熔化特性。研究发现，在火灾情况下，有些热塑性聚合物如PP，LDPE，EVA-18和PA6等与PMMA相比熔化得较快，并且熔化物很快汽化，很少有熔化物遗留。相反，有些热固性树脂一般不熔化或者只是轻度熔化，如酚醛树脂和环氧树脂。在热塑性聚合物研究中，其熔化特性在温度燃烧阶段影响了质量损失速率。那些快速熔化的热塑性聚合物与PMMA相比，质量损失塑料较低，这跟单个聚合物高温分解机理有关。一般说来，热分解过程杂乱无序的聚合物更容易造成快速熔化。发生热聚作用的聚合物会导致快速挥发，因此熔化较少。开发了一个聚合物燃烧数学模型，能够模拟聚合物燃烧过程中的溶化特性。结果表明，考虑熔化特性的模型模拟结果与锥形量热仪测试结果的相符性比不考虑熔化特性的模型模拟结果的要好。

Study on melting behavior of polymers during burning

The melting behavior of a number of polymers during burning, including thermoplasticand thermosetting polymers was studied by experiment and modeling. It was found that in a fire situation some thermoplastic polymers such as PP, LDPE, EVA-18 and PA6 melted significantly compared to PMMA for which the resulting melt vaporized rapidly and as a consequence there was little melt observed. On the other hand, some thermosetting resins generally did not melt or melted slightly, such as phenolic resin and epoxy resin. For the thermoplastics studied, the melting behavior affected the mass loss rates during the steady burning stage. The thermoplastics that melted significantly experienced much lower mass loss rates compared with the PMMA. This has been related to the pyrolysis mechanism of individual polymers. Generally, the polymers with a random pyrolysis process were more likely to lead to significant melting. The polymers undergoing depolymerization will lead to a rapid volatilization and therefore experienced much less melting. A numerical model for polymer burning was developed to include the melting behavior during burning. It was shown that the simulated results for the model considering melting behavior fitted in better with the cone calorimeter test results when compared to the model without considering the melting behavior.