Effect of stabilizer and pigment on photodegradation of polypropylene as revealed by macromolecule scission and crosslinking measurements

Novel Hybrid Polymer Composites Based on Anthraquinone and Eco-Friendly Dyes with Potential for Use in Intelligent Packaging Materials

This study aimed to present the influence of bio-based and anthraquinone dyes and their combinations on the optical properties of ethylene-propylene (EPM) composites after thermo-oxidative and climatic aging. Therefore, the chosen polymer was filled with a natural, plant-origin flavonoid—quercetin, and with two commercial anthraquinone dyes (C.I. Solvent Yellow 163 and C.I. Solvent Red 207). The manufactured polymer composites were subjected to accelerated aging tests: weathering and thermo-oxidation, respectively. Examination of the materials’ properties indicated that the combination of synthetic and natural dyes can result in better resistance to oxidizing agents and higher thermal stability of ethylene-propylene products. Moreover, color change of quercetin-containing samples due to exposure to simulated atmospheric conditions could be a promising solution for use as aging indicators in intelligent packaging materials that will inform about the ongoing degradation process. Another interesting finding is that these samples exhibited good fungistatic activity against Candida albicans yeast and Aspergillus niger mold. Overall, this novel solution based on hybrid polymer composites containing natural and commercial dyes is a more environmentally friendly alternative to traditional materials used in the plastic packaging industry with better and more desirable properties.

Disposable masks release microplastics to the aqueous environment with exacerbation by natural weathering

The COVID-19 pandemic has driven explosive growth in the use of masks has resulted in many issues related to the disposal and management of waste masks. As improperly disposed masks enter the ocean, the risk to the marine ecological system is further aggravated, especially in the shoreline environment. The objective of this study is to explore the changing characteristics and environmental behaviors of disposable masks when exposed to the shoreline environment. The transformation of chain structure and chemical composition of masks as well as the decreased mechanical strength of masks after UV weathering were observed. The melt-blown cloth in the middle layer of masks was found to be particularly sensitive to UV irradiation. A single weathered mask can release more than 1.5 million microplastics to the aqueous environment. The physical abrasion caused by sand further exacerbated the release of microplastic particles from masks, with more than 16 million particles released from just one weathered mask in the presence of sand. The study results indicate that shorelines are not only the main receptor of discarded masks from oceans and lands, but also play host to further transformation of masks to plastic particles.

Visible light photocatalytic degradation of polypropylene microplastics in a continuous water flow system

Microplastic pollution of water and ecosystem is attracting continued attention worldwide. Due to their small sizes (≤5 mm) microplastic particles can be discharged to the environment from treated wastewater effluents. As microplastics have polluted most of our aquatic ecosystems, often finding its way into drinking water, there is urgent need to find new solutions for tackling the menace of microplastic pollution. In this work, sustainable green photocatalytic removal of microplastics from water activated by visible light is proposed as a tool for the removal of microplastics from water. We propose a novel strategy for the elimination of microplastics using glass fiber substrates to trap low density microplastic particles such as polypropylene (PP) which in parallel support the photocatalyst material. Photocatalytic degradation of PP microplastics spherical particles suspended in water by visible light irradiation of zinc oxide nanorods (ZnO NRs) immobilized onto glass fibers substrates in a flow through system is demonstrated. Upon irradiation of PP microplastics for two weeks under visible light reduced led to a reduction of the average particle volume by 65%. The major photodegradation by-products were identified using GC/MS and found to be molecules that are considered to be mostly nontoxic in the literature.

Investigation of polymer-based composites by laser desorption/ionization study of their photo-oxidative aging

RATIONALE

Polybutadiene (PB) is one of the most widely used polymers. Its aging occurs by reaction with oxygen under illumination and may modify its mechanical and/or aesthetic properties. To modify its properties, organic and/or inorganic compounds are generally added to PB. The aging of such composite materials is poorly known.

METHODS

PB and its mixtures with TiO₂ and/or the Orange 13 pigment are subjected to an accelerated photo-oxidative aging step for one week. The analysis of PB and its composites with regard to their composition and the aging time is carried out by 266 nm and/or 355 nm laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (LDI-FTICR-MS).

RESULTS

Both PB and its degradation products are detected by (+) LDI-FTICR-MS. The oxidation mechanism of PB is not significantly affected by the used organic or inorganic fillers, which results from the cleavage of the polymer chain and the formation of carbonyl compounds. The crosslinking of PB is significantly reduced by the two investigated fillers. Analysis in negative mode [(-) LDI-FTICR-MS] ensures the specific detection of the Orange 13 pigment.

CONCLUSIONS

LDI-FTICR-MS has demonstrated its ability to provide relevant information on the degradation of polymer-based composites. The main advantages of this approach are its ability to probe the surface, which is specifically affected by photo-oxidation aging processes, and to access the insoluble degradation compounds.