Evaluating Weathering of Food Packaging Polyethylene-Nano-clay Composites: Release of Nanoparticles and their Impacts

Sep 1, 2026

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Nano-fillers are increasingly incorporated into polymer materials to enhance mechanical, barrier, and related properties in consumer and industrial nanocomposites. Over their life cycle, environmental exposure can drive degradation and release embedded nanomaterials into surrounding media. This study evaluates degradation and nanomaterial release from LDPE nano-clay food packaging films under accelerated UV irradiation or low ozone at 40 °C, tracking structural, surface, chemical, and physical changes. Nanoclay particle release accelerates after ~130 h irradiation and is linked to proportional exposure time, while toxicity assays show comparable levels to untreated cells.

LanguageEnglish

CategoryGeneral

FormatDOCX

Pages26

Reading Time9 min

AccessFree to download

Abstract

Accelerated weathering setup

Degradation and property changes

Nanoparticle release

Toxicity assessment

Evaluating Weathering of Food Packaging Polyethylene-Nano-clay Composites: Release of Nanoparticles and their Impacts Changseok Han1, Amy Zhao1, and Eunice Varughese2, E. Sahle-Demessie*1 1U.S. EPA, Office of Research and Development, National Risk Management Research Laboratory, 26 W. Martin Luther King Drive 2U.S. EPA, Office of Research and Development, National Exposure Research Laboratory, 26 W. Martin Luther King Drive * Corresponding author. Tel.: +1 (513) 569 7739; fax: +1 (513) 569 7677. Email address: HYPERLINK "mailto:sahle-demessie.endalkachew@epa.gov" sahle-demessie.endalkachew@epa.gov (E. Sahle-Demessie). November 15, 2016 Abstract Nano-fillers are increasingly incorporated into polymeric materials to improve the mechanical, barrier or other matrix properties of nanocomposites used for consumer and industrial applications. However, over the life cycle, these nanocomposites could degrade due to exposure to environmental conditions, resulting in the release of embedded nanomaterials from the polymer matrix into the environment. This paper presents a rigorous study on the degradation and the release of nanomaterials from food packaging composites. Films of nano-clay-loaded low-density polyethylene (LDPE) composite for food packaging applications were prepared with the spherilene technology and exposed to accelerated weathering of ultraviolet (UV) irradiation or low concentration of ozone at 40 oC. The changes in the structural, surface morphology, chemical and physical properties of the films during accelerated weathering were investigated. Qualitative and quantitative changes in properties of pristine and aged materials and the release of nano-clay proceeded slowly until 130 hr irradiation and then accelerated afterward resulting complete degradation. Although nano-clay increased the stability of LDPE and improved thermal and barrier properties, they accelerated the UV oxidation of LDPE. With increasing exposure to UV, the surface roughness, chemiluminescence index, and carbonyl index of the samples increased while decreasing the intensity of the wide-angle X-ray diffraction pattern. Nano-clay particles with sizes ranging from 2-8 nm were released from UV and ozone weathered composite. The concentrations of released nanoparticles were proportional to a time of the accelerated weathering process. Various toxicity tests, including reactive oxygen species generation and cell activity/viability were also performed on the released nano-clay and clay polymer. Toxicity levels for these compounds were found to be comparable to untreated cells. Our combined results demonstrate the degradation properties of LDPE clay nanoparticle composites and its reduced levels of toxicity, which will help with future risk based-formulations of exposure. Key Words: nanoclay, polymer composite, weathering, nanorelease, nanotoxicity Introduction Thermoplastic nanocomposites are playing a significant role in the fast growing area of nanotechnology. The volume and types of nanocomposites used for non-structural applications such as packaging are growing. As compared to the conventional micro and macro, or neat counterparts, low amounts of nano-fillers exhibit superior enhancement of properties of pristine plastics. Engineered nanoparticle (ENPs) are increasingly incorporated in a wide variety of polymeric materials with favorable matrix-filler interaction that resulted in improved physical, chemical, and electrical properties. Also, nanoparticles have other “smart” functions such as enzyme immobilization, antimicrobial activities, and recognition of biomolecules (Azeredo, 2009). At the same time, the mobility of the nano-fillers is much higher than conventional micro or macro composite fillers because of their comparable time scale of motion with polymer chains. Polyethylene (PE, (C2H4)n) is a semi-crystalline straight chain polymer and a non-degradable material that is commonly used for food packaging (Mark, 2004). However, requir

FAQs

What materials and weathering conditions were used to study degradation?

Low-density polyethylene (LDPE) films loaded with nano-clay were prepared and subjected to accelerated weathering via UV irradiation or low-concentration ozone at 40 °C.

How did nano-clay affect LDPE properties under UV exposure?

Nano-clay improved LDPE thermal and barrier properties but accelerated LDPE UV oxidation, increasing surface roughness and oxidation-related indices while reducing the wide-angle X-ray diffraction intensity.

When did nanoparticle release accelerate, and what governed released concentrations?

Nanoclay release proceeded slowly until about 130 hours of irradiation, then accelerated afterward; released nanoparticle concentrations were proportional to the accelerated weathering time.

Sep 1, 2026

Upload by Noah