Noguchi Miyuki, Yamasaki Akihiro
Department of Materials and Life Sciences, Seikei University, 3-3-1 Kichijoji-kitamachi, Musashino, Tokyo, 180-8633, Japan.
Heliyon. 2020 Mar 3;6(3):e03314. doi: 10.1016/j.heliyon.2020.e03314. eCollection 2020 Mar.
Emissions of volatile and semivolatile organic compounds from various kinds of polymer sheets during thermal degradation process were determined by the passive flux sampling method. The polymer sheets used were commercial products made of: polyethylene (PE), ethylene-vinyl acetate (EVA), polypropylene (PP), polyacetal (POM), polycarbonate (PC)), and polymer sheet samples: poly (methyl methacrylate) (PMMA), polyethylene terephthalate (PET), polystyrene (PS) and four types of poly vinyl chloride (PVC) with different contents of additives; (bis(2-ethylhexyl)phthalate (DEHP)), and triphenylphosphine (TPP)). The emission fluxes from the polymer sheets were measured for up to 30 days stored under a constant temperature (25-75 °C). Emission of various kinds of chemicals were observed from PVC sheets including and products of polymer degradation, while emission of hydrocarbons were dominant from PE, PP and EVA, and the emission of an additive (DEP) only was observed from PMMA, PET, POM and PC. The TVOC (total VOC) emission rates from PVC sheets with DEHP and TPP (soft PVCs) were in the range of 30-120 mg m at 50 °C, which were much higher than the TVOC emission rates from other polymers. The emission rates for these chemicals for the same sampling period increased dramatically as the temperature increased. The temperature-dependences of the emission rates from the soft PVC sheet for a given sampling period could be expressed using an Arrhenius-type equation, and the apparent emission activation energy , correlated well with the enthalpy of vaporization by the following empirical equation. We also found that the emission rates of chemicals changed with time with different changing characters, and the activation energy decreased with the progress of the polymer degradation.
采用被动通量采样法测定了各类聚合物片材在热降解过程中挥发性和半挥发性有机化合物的排放。所用聚合物片材为商业产品，包括：聚乙烯（PE）、乙烯-醋酸乙烯酯（EVA）、聚丙烯（PP）、聚甲醛（POM）、聚碳酸酯（PC），以及聚合物片材样品：聚甲基丙烯酸甲酯（PMMA）、聚对苯二甲酸乙二酯（PET）、聚苯乙烯（PS）和四种不同添加剂含量的聚氯乙烯（PVC）；（邻苯二甲酸二（2-乙基己基）酯（DEHP））和三苯基膦（TPP））。在恒温（25-75°C）下储存长达30天，测量聚合物片材的排放通量。从PVC片材中观察到各类化学物质的排放，包括聚合物降解产物，而PE、PP和EVA主要排放碳氢化合物，从PMMA、PET、POM和PC中仅观察到一种添加剂（DEP）的排放。在50°C时，含有DEHP和TPP的PVC片材（软质PVC）的总挥发性有机化合物（TVOC）排放速率在30-120mg/m²范围内，远高于其他聚合物的TVOC排放速率。在相同采样期间，这些化学物质的排放速率随温度升高而急剧增加。给定采样期间软质PVC片材排放速率的温度依赖性可用Arrhenius型方程表示，表观排放活化能与蒸发焓通过以下经验方程具有良好的相关性。我们还发现，化学物质的排放速率随时间变化，具有不同的变化特征，且活化能随聚合物降解进程而降低。
