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Combined impact of ultraviolet and chemical fluids on high-density polyethylene packaging material
(2012)
To investigate the ageing behaviour of filled plastic containers outdoors, square cuts of the wall of two high-density polyethylene (HDPE) types were exposed to ultraviolet (UV) radiation at their front side and to specific liquid chemicals (de-ionized water, surfactant or White Spirit) at their back. The UV radiant exposure at the front side was 80 MJ/m².
To compare the actions of the different exposures, separate dark backside fluid exposures were performed, in parallel. Besides, UV weathering was carried out until a UV radiant exposure of 325 MJ/m², being roughly comparable to outdoor exposure of one year in Northern Australia.
An unpigmented HDPE included in the investigation gave no sufficient protection for the White Spirit. In addition, it showed clear degradation after several of these exposures. In combination with the White Spirit, an increase of carbonyl bonds was measured, presumably assignable to degradation products of the White Spirit.
For a pigmented HDPE material, with the implemented combined exposures, no relevant damage was observed, within applied the exposure period.
Scrap tyres are widely reused in the form of granules as infill materials or component of sub-base layers in construction of sporting grounds such as synthetic turf areas and athletic track surfaces. The recycled rubber may contain organic and inorganic pollutants due to the presence of vulcanisation catalysts, stabilisers and other additives which can be released into soil and groundwater in the case of outdoor sports facilities. In order to evaluate the amount of potentially mobile pollutants, leaching tests can be employed. This study aimed particularly at the investigation of the feasibility of column tests using complete synthetic surface flooring or turf system assemblies. The release of zinc and polycyclic aromatic hydrocarbons (PAH) leached from components of sports surfaces containing recycled rubber granules was considered. Additionally, batch tests on coated and uncoated styrene butadiene rubber (SBR) granules aged by artificial weathering were performed to indicate its possible influence on the leaching behaviour of zinc and PAH. The chosen approach of column tests simulating typical complete synthetic sports surface installations has been proven to be feasible and robust. The time-dependent leaching behaviour and interactions between single components can be evaluated by column tests. Zinc was the most relevant contaminant in the eluates and its leachability was enhanced after accelerated ageing by artificial weathering. Leachable PAH were found in relatively low but well detectable amounts which increase by ageing as well.
Jerrycans made from three different types of high-density polyethylene (HDPE) were exposed outdoors, for one Berlin summer season. They were filled with a 55 percent nitric acid solution (HN03), pure water, or air, and half of them were protected from sunlight by an UV absorbing canvas. Thus, the separate effects of UV radiation and nitric acid could be compared to the combined impact. Combined impact was mainly affected by decomposition of nitric acid, resulting in presence of reactive nitrogen oxides, increased oxygen partial pressure, and UV radiation energy, simultaneously in vapour phase.
To investigate the degradation effects after the outdoor exposure, jerrycans were exposed to a so called hydraulic internal pressure test, similar to an approval test for dangerous goods packaging. After combined impact of UV radiation and nitric acid, internal pressure tests showed very fast failures, whereas after separate impacts no remarkable deteriorations were observed, compared to unaged jerrycans.