Insights into the mechanism of plastics’ fragmentation under abrasive mechanical forces: An implication for agricultural soil health

Abstract

The application of agricultural plastic products such as mulch, greenhouse covers, and silage films is increasing due to their economic benefits in providing an early and better‐quality harvest. However, mechanical abrasion of these plastic materials by soil particles could result in generation of microplastic (MP) pollutants that could harm soil organisms and impact food safety. This study aims to better understand the physicochemical mechanisms resulting in the fragmentation of low‐density polyethylene (LDPE). Herein, we used pellets and films to study the impacts of abrasive wear forces on their surface morphology variations and fragmentation behavior. An innovative laboratory approach was developed to abrade the plastic surface under controlled normal loadings and abrasion durations. The investigation of the plastics’ surface morphology variations due to the abrasion process revealed microcutting as the dominant process at low normal force (4 N). However, a combination of microploughing and microcutting occurred for new LDPE films by increasing the normal force to 8 N. Despite the significant surface morphology variations of the new LDPE film due to the abrasion process; the water contact angle did not alter. Furthermore, the fragmentation behavior of photodegraded LDPE pellets and films was compared to the new plastics. The extent of MPs (3 µm < dp < 162 µm) generation due to fragmentation was studied using fluorescence microscopy imaging. The localized stress and strains at the contact sites of plastic and sand particles resulted in abrasion of the plastic surface. According to the results, the normal loadings and duration of abrasion played a significant role in the degree of fragmentation of plastics. Increasing the normal loading applied during the abrasion process from 2 to 8 N linearly increased the number of generated plastic fragments by more than five times for pellets and more than three times for film. Photodegradation significantly enhanced the extent of MPs fragmentation. Moreover, the limitations of this study and the implications for agricultural soil health were discussed.

Nanoscale Abrasive Wear of Polyethylene: A Novel Approach To Probe Nanoplastic Release at the Single Asperity Level

“…Plowing wear led to little direct debris release but the ridges could be removed by subsequent sliding. 26 Indeed, our results reveal that NP release by sand abrasion is a two-step process, including plastic deformation and wear debris release. By quantitatively analyzing the topography of the abraded area, we could first reveal the volume of deformed material, and their wear mechanism could inform the likelihood of the deformed material release as NPs.…”

A systematic review on microplastic contamination in marine Crustacea and Mollusca of Asia: Current scenario, concentration, characterization, polymeric risk assessment, and future Prospectives

“…This fragmentation gives rise to a spectrum of MPs sizes, encompassing large fragments to smaller particles and fibers. Natural mechanical processes, such as abrasion against rocks and surfaces, further contribute to breaking down larger plastic items into a variety of MP sizes (Battacharjee & Jazaei, 2023), resulting in diverse size distributions. Organisms may unintentionally ingest MPs of different sizes while feeding, and the sizes of MPs found in various species can be influenced by their feeding behavior and the size ranges of particles they are capable of ingesting (Gouin, 2020).…”

Improvement of Age-Resistance of LDPE-Based Nanocomposite Films by Addition of a Modified Layered Double Hydroxide with an Anionic UV Screener

“…PBS-LDH showed a much better thermal stability than PBS because the UV absorber in PE + PBS films could be partially degraded during the casting process and the sunscreen activity is enhanced in the encapsulated form. In this regard, the addition of PBS-LDH showed improved age-resistance and is a suitable option for outdoors applications such as fabrication of greenhouses [34], pipe coatings [35], or insulation [36].…”