Combined impact of UV radiation and nitric acid on HDPE containers during outdoor exposure

Abstract

Unpigmented HDPE jerrycans filled with nitric acid (55 wt.-%) and water respectively had been exposed to outdoor conditions for one Berlin summer season. As both liquids underwent equal temperature progression, exposure effects of UV radiation and nitric acid as well as of the combination of both can be separated and compared. On the basis of various property changes after these exposures, synergistic action is evaluated and compared to a damaged Intermediate Bulk Container (IBC) from a transport accident. It is found that carbonyl formation accompanies lightness increase in color measurement due to microcracking and with a worsening in mechanical behavior, all of them showing the synergistic effects of UV and nitric acid exposure. By contrast, embedding nitrogen compounds accompanies yellowing of the material but cannot be correlated to oxidation. The reason for intensified damaging is the decomposition of the 55-percent nitric acid and the formation of nitrogen oxides even at ambient temperatures, caused by UV radiation. Thus, damaging effects become similar to those caused by fuming nitric acid exposure at temperatures above 60 °C, resulting in strong oxidative degradation of the polyethylene. By contrast, exclusive exposure to the 55 wt.-% nitric acid at 40 °C does not cause any failure. It can therefore be assumed that the damaged IBC too had been exposed to both UV radiation and nitric acid, probably outdoors.

Physicochemical and biological ageing processes of (micro)plastics in the environment: a multi-tiered study on polyethylene

“…2). This behavior is possibly due to the embrittlement of PE induced by acidic conditions, regardless of the surface oxidation (Geburtig et al 2018). Acidic conditions, in fact, are also observed to negatively affect the tensile strength of PE films (Wang et al 2021).…”

Combined impact of UV radiation and nitric acid on high‐density polyethylene containers as a laboratory test

“…1.6 e, it can be used as a standard liquid for verifying the chemical compatibility testing of polyethylene packaging, for all substances having an oxidizing effect on PE. However, it was shown 2 for several transparent HDPE jerrycans that a simple storage of the 55% nitric acid (HNO 3 -55%) does not necessarily lead to oxidation. Instead, it was found that the UV radiation transmitted through the HDPE can decompose the filling good 3 and then the resulting decomposition products damage the HDPE (secondary damage).…”

“…Nitrogen dioxide NO 2 is a free radical that can act as an autoxidation initiator 4 in HDPE, leading to strong oxidation of the polyethylene (PE) molecules through the formation of carbonyl groups. 5 Outdoor exposures, as in Geburtig et al, 2 have a bad reproducibility as well as several safety challenges. Especially because of the strong temporal variability of the weather, they are not suited for extensive systematic further investigations.…”

“…However, it was shown 2 for several transparent HDPE jerrycans that a simple storage of the 55% nitric acid (HNO 3 ‐55%) does not necessarily lead to oxidation. Instead, it was found that the UV radiation transmitted through the HDPE can decompose the filling good 3 and then the resulting decomposition products damage the HDPE (secondary damage).…”

“…In outdoor exposure tests, 2 it was found that a damaging action of the HNO 3 ‐55% only occurs in combination with its decomposition, caused by UV radiation. The dissolved HNO 3 decomposes into gaseous nitrogen oxides (4 HNO 3 ↔ 2 H 2 O + 4 NO 2 + O 2 ).…”