Photodegradation of polyolefin thin films in simulated freshwater conditions

Abstract

Polypropylene (PP) and polyethylene (PE) are commonly used polyolefins in a variety of applications, which have resulted in their accumulation in the environment. Once in the environment, these polymers undergo...

Quantification of Polymer Surface Degradation Using Fluorescence Spectroscopy

“…and PP in the correlation between fluorescence signatures and irradiation time. This variation is likely the result of varying degrees of degradation that are observed in these polymers under similar photon fluxes, 37 but this indicates a similar calibration curve could be established for PP as had been demonstrated for PE. Beyond PP, we also sought to test the applicability of the staining tool toward a substantially more hydrophilic polymer, PLLA.…”

“…As previously reported, there is an irradiation of approximately 2.5 Wm −2 for this lamp setup, 10 which forms markers of degradation on the polymer within 48 h, which are equivalent to 3−4 weeks of aging in summer sunlight. 37 PE was aged for 2, 4, 8, 12, 18, 24, and 48 h timepoints; PP was aged for 6 and 12 h time points. This intensity of light is not intended to directly mimic natural sunlight but instead is used to artificially degrade the plastic samples at an accelerated rate to test the applicability of this fluorescence staining to track degradation.…”

“…The products of aging in this manner are equivalent to those observed in aging with natural sunlight but occur at a much faster rate for convenience of research. 37 To ensure the photodegradation models did not induce special artifacts that would invalidate the technique to other modes of degradation, PE samples (30 μm thick) were degraded thermally by suspending plastics in an oven at 110 °C for 24, 48, 72, 192, 264, and 336 h. This temperature is relatively close to the melting point (∼120 °C), which allowed for accelerated aging while keeping the polymer film intact. The temperature chosen for aging is, again, not intended to directly mimic environmental factors but is instead meant to produce model-degraded plastics.…”

Exposure Order to Photoaging and Humic Acids Significantly Modifies the Aggregation and Transformation of Nanoplastics in Aqueous Solutions

“…NOM could bind with nanoplastics through diverse attractions such as electrostatic interaction, hydrophobic effect, and hydrogen bond. − It is well documented that photoaging is likely to increase oxygen-containing groups and surface charge density of nanoplastics and thus enhance the suspending ability. , Previous attempts to explore the NOM effect on the dispersion of photoaged nanoplastics were mainly based on the structural alterations of nanoplastics during photoaging and overlook the impact of sunlight-mediated reactions between NOM and nanoplastics. In fact, NOM-coated nanoplastics (or viewed as the NOM-nanoplastics assembly) might experience distinct transformation relative to nanoplastics themselves in the aging process owing to the photoactive nature of NOM. , A recent study observed that the attached NOM promoted the aging of microplastics under both dark and ultraviolet light conditions because the produced reactive oxygen species (ROS) contributed to the oxidation of microplastics . The photoaging of nanoplastics in the presence of NOM might be more complicated than we expected.…”

“…In fact, NOM-coated nanoplastics (or viewed as the NOM-nanoplastics assembly) might experience distinct transformation relative to nanoplastics themselves in the aging process owing to the photoactive nature of NOM. 17 microplastics under both dark and ultraviolet light conditions because the produced reactive oxygen species (ROS) contributed to the oxidation of microplastics. 19 The photoaging of nanoplastics in the presence of NOM might be more complicated than we expected.…”