De Monte Cristina, Locritani Marina, Merlino Silvia, Ricci Lucia, Pistolesi Agnese, Bronco Simona
Istituto per i Processi Chimico-Fisici, Sede di Pisa, del Consiglio Nazionale delle Ricerche, (IPCF-CNR), Via G. Moruzzi 1, 56124 Pisa, Italy.
Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Roma, Italy.
Polymers (Basel). 2022 Mar 10;14(6):1111. doi: 10.3390/polym14061111.
In this paper, we present two novel experimental setups specifically designed to perform in situ long-term monitoring of the aging behaviour of commercial plastic granules (HDPE, PP, PLA and PBAT). The results of the first six months of a three year monitoring campaign are presented. The two experimental setups consist of: (i) special cages positioned close to the sea floor at a depth of about 10 m, and (ii) a box containing sand exposed to atmospheric agents to simulate the surface of a beach. Starting from March 2020, plastic granules were put into the cages and plunged in seawater and in a sandboxe. Chemical spectroscopic and thermal analyses (GPC, SEM, FTIR-ATR, DSC, TGA) were performed on the granules before and after exposure to natural elements for six months, in order to identify the physical-chemical modifications occurring in marine environmental conditions (both in seawater and in sandy coastal conditions). Changes in colour, surface morphology, chemical composition, thermal properties, molecular weight and polydispersity, showed the different influences of the environmental conditions. Photooxidative reaction pathways were prevalent in the sandbox. Abrasive phenomena acted specially in the sea environment. PLA and PBAT did not show significant degradation after six months, making the possible reduction of marine pollution due to this process negligible.
在本文中，我们展示了两种新颖的实验装置，这些装置是专门为对商业塑料颗粒（高密度聚乙烯、聚丙烯、聚乳酸和聚己二酸/对苯二甲酸丁二醇酯）的老化行为进行原位长期监测而设计的。本文展示了一项为期三年监测活动前六个月的结果。这两种实验装置包括：（i）放置在约10米深处靠近海底的特殊笼子，以及（ii）一个装有沙子并暴露于大气环境中的盒子，以模拟海滩表面。从2020年3月开始，将塑料颗粒放入笼子中并沉入海水和沙箱中。在颗粒暴露于自然环境六个月前后，对其进行了化学光谱和热分析（凝胶渗透色谱法、扫描电子显微镜、衰减全反射傅里叶变换红外光谱、差示扫描量热法、热重分析法），以确定在海洋环境条件下（海水和沙质海岸条件下）发生的物理化学变化。颜色、表面形态、化学成分、热性能、分子量和多分散性的变化表明了环境条件的不同影响。光氧化反应途径在沙箱中较为普遍。磨损现象在海洋环境中作用尤为明显。六个月后，聚乳酸和聚己二酸/对苯二甲酸丁二醇酯没有表现出明显的降解，因此该过程对海洋污染的可能减少可以忽略不计。
