Influence of isotacticity and its distribution on degradation behavior of polypropylene

An investigation into the aging of disposable face masks in landfill leachate

Due to the excessive use of disposable face masks during the COVID-19 pandemic, their accumulation has posed a great threat to the environment. In this study, we explored the fate of masks after being disposed in landfill. We simulated the possible process that masks would experience, including the exposure to sunlight before being covered and the contact with landfill leachate. After exposure to UV radiation, all three mask layers exhibited abrasions and fractures on the surface and became unstable with the increased UV radiation duration showed aging process. The alterations in chemical groups of masks as well as the lower mechanical strength of masks after UV weathering were detected to prove the happened aging process. Then it was found that the aging of masks in landfill leachate was further accelerated compared to these processes occurring in deionized water. Furthermore, the carbonyl index and isotacticity of the mask samples after aging for 30 days in leachate were higher than those of pristine materials, especially for those endured longer UV radiation. Similarly, the weight and tensile strength of the aged masks were also found lower than the original samples. Masks were likely to release more microparticles and high concentration of metal elements into leachate than deionized water after UV radiation and aging. After being exposed to UV radiation for 48 h, the concentration of released particles in leachate was 39.45 μL/L after 1 day and then grew to 309.45 μL/L after 30 days of aging. Seven elements (Al, Cr, Cu, Zn, Cd, Sb and Pb) were detected in leachate and the concentration of this metal elements increased with the longer aging time. The findings of this study can advance our understanding of the fate of disposable masks in the landfill and develop the strategy to address this challenge in waste management.

Role of Structural Morphology of Commodity Polymers in Microplastics and Nanoplastics Formation: Fragmentation, Effects and Associated Toxicity in the Aquatic Environment

With the continued growth in plastic production, its ubiquitous use and insufficient waste management and disposal, the increased levels of plastics in the environment have led to growing ecological concerns. The breakdown of these plastic macromolecules to smaller micro and nanosized particles and their detection in the aerial, aquatic, marine and terrestrial environments has been reviewed extensively, especially for thermoplastics. However, the formation of micro and nanoplastics has typically been explained as a physical abrasion process, largely overlooking the underlying chemical structure-morphology correlations to the degradation mechanisms of the plastics. This is particularly true for the common commodity thermosets. This review focuses on the degradation pathways for the most widely produced commodity thermoplastics and thermosets into microplastics (MP)s and nanoplastics (NP)s, as well as their behaviour and associated toxicity. Special emphasis is placed on NPs, which are associated with greater risks for toxicity compared to MPs, due to their higher surface area to volume ratios. This review also assesses the current state of standardized detection and quantification methods as well as comprehensive regulations for these fragments in the aquatic environment.

Evaluation of polypropylene plastic degradation and microplastic identification in sediments at Tambak Lorok coastal area, Semarang, Indonesia

This study aims to determine the degradation of plastic polypropylene (PP) and identify the presence of microplastic in sediments and seawater along the Tambak Lorok coastal area. The study was conducted by collecting samples from the sea surface area, at 50 cm and 170 cm depths, while seawater and sediments were collected from six stations. The results showed an early stage of degradation because of abiotic factors. The surface morphology of plastic changed, indicating the disorientation of the plastic. Furthermore, the results demonstrated that organic carbon decreased by 3.15%, 6.67%, and 16.76% for the PP applied on surface water, at 50 cm depth and at 170 cm depth, respectively. From six stations, PP microplastic was the dominant type, where microplastic in sediment was bio-fouled fiber ranging in size from 255.23 to 1245.71 μm; however, in seawater, it was 7-111 particles/10 mL and ranged from 270.27 to 1279.12 μm in size.

Effect of different degradation types on properties of plastic waste obtained from espresso coffee capsules

In terms of large use of plastic products, a necessity exists to minimize effects of the waste produced on environment by recycling, reuse and application in new products. In Brazil, the espresso coffee capsules are an emerging plastic waste, representing 0.9% of the coffee consumed in 2017. Therefore, Nescafé Dolce Gusto espresso coffee capsules were chosen in order to understand the polypropylene stabilization and degradation initiators with the purpose of recycling by applying in a composite material, as home composting product. In this context, the plastic capsule wastes were exposed to chemical, thermal, accelerated weathering (ultraviolet radiation + humidity) and natural weathering in order to analyze the influence of exposure and possibilities of a real application in a composting environment. Masses of the samples were monitored before and during the weathering conditions. Thermal (TGA and DSC) and chemical (FTIR) analysis were carried out before and after exposure. No changes in thermal stability were observed, however, samples conditioned in acid solution presented thermal degradation event beginning at 131 °C. In addition, all samples presented a similar behavior of melting and crystallization points, which did not change with exposure. FTIR analysis showed a disappearance of CC and CO bonds on samples exposed to natural weathering and basic solution conditioning. It also showed formation of chromophores groups on samples exposed to accelerated weathering. The visual analysis showed huge differences in samples exposed to accelerated weathering and acid solution, which were the most damaged. On the other hand, samples exposed to natural weathering, thermal and basic conditioning did not presented significantly changes supported by the TGA and FTIR results.