Department of Energy and Environmental Engineering, Catholic University, 43 Jibong-ro, Bucheon-si, 14662, Republic of Korea.
Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea.
Chemosphere. 2022 Sep;302:134813. doi: 10.1016/j.chemosphere.2022.134813. Epub 2022 May 5.
The goal of this study was to evaluate the impact of thermal and chemical aging processes on high-density polyethylene (HDPE), low-density polyethylene (LDPE), unplasticized polyvinyl chloride (U-PVC), and high-impact polyvinyl chloride (Hi-PVC) pipes. The materials were exposed to 1-10 ppm chemical disinfectants [chlorine dioxide (ClO) and hypochlorite (HOCl)] at 40-80 °C for 1200 h. The diffusion properties of the materials were systematically analyzed based on the change in their sorption characteristics and activation energies according to the Arrhenius model. Moreover, the structural changes were analyzed with scanning electron microscopy (SEM), Fourier transform infrared (FTIR) radiation, and thermogravimetric analysis (TGA). The results show that the materials have Fickian characteristics in the aging environment. Specifically, the water sorption rates of HDPE and LDPE increase first and then decrease after reaching saturation (Ms); those of U-PVC and Hi-PVC its increasing continuously with different rate. This behavior of materials was prominent for ClO at high temperature and disinfectant dose because of polymeric chains crosslinking and rearrangement, extraction of monomers, and stable compounds removal during aging under exposed conditions. The deleterious effects decreased the activation energies of the materials and increased the concentrations of carbonyl groups [CO] via the formation of ketones, aldehydes, and carboxylic acids. The decomposition temperature increased with the changes in the material morphology and elemental contents under the investigated conditions. Moreover, LDPE and Hi-PVC were more severely affected in the thermal aging process with 10 mg.L ClO at 80 °C.
本研究旨在评估热和化学老化过程对高密度聚乙烯（HDPE）、低密度聚乙烯（LDPE）、未增塑聚氯乙烯（U-PVC）和高抗冲聚氯乙烯（Hi-PVC）管材的影响。将材料暴露于 40-80°C 的 1-10 ppm 化学消毒剂[二氧化氯（ClO）和次氯酸盐（HOCl）]中 1200 小时。根据 Arrhenius 模型，通过材料吸附特性和活化能的变化，系统分析了材料的扩散特性。此外，通过扫描电子显微镜（SEM）、傅里叶变换红外（FTIR）辐射和热重分析（TGA）分析了结构变化。结果表明，材料在老化环境中具有菲克特征。具体来说，HDPE 和 LDPE 的吸水率在达到饱和（Ms）后先增加后减少；U-PVC 和 Hi-PVC 的吸水率则以不同的速率持续增加。在高温和高消毒剂剂量下，由于聚合链交联和重排、单体提取以及老化过程中暴露条件下稳定化合物的去除，ClO 导致了材料这种行为。老化的有害影响降低了材料的活化能，并通过形成酮、醛和羧酸增加了羰基[CO]的浓度。在研究条件下，材料形态和元素含量的变化导致分解温度升高。此外，在 80°C 下，10mg.L ClO 的热老化过程对 LDPE 和 Hi-PVC 的影响更为严重。
