Investigations into the Potential Abrasive Release of Nanomaterials due to Material Stress Conditions—Part B: Silver, Titanium Nitride, and Laponite Nanoparticles in Plastic Composites

Johannes Bott,Roland Franz

doi:10.3390/app9020221

Abstract

Three plastic nanocomposites containing the nanomaterials silver, titanium nitride, and laponite were investigated on the potential to release nanoparticulates under stress conditions into food simulants. Nanocomposites were exposed to thermal, chemical, and mechanical stress followed by mechanical abrasion of their surface. Particle sensitive asymmetric flow field-flow fractionation (AF4) with multi-angle laser light scattering (MALLS) as well as inductively coupled plasma mass spectrometry (ICP-MS) detection was used to detect and quantify the respective nanoparticulates. The results of this study demonstrate that even under dynamic stress conditions nanoparticulates are not released from the nanocomposites into food.

Highlights

This article is the second in a series of two dealing with the potential release of nanomaterials after intense mechanical, thermal, and chemically-induced stress conditions
In our previous works, based on comprehensive migration testing using plastics nanocomposites with incorporated silver nanoparticles (Ag-NPs) [1], nanotitanium nitride (TiN) [2], and nanolaponite [3], we could not find any detectable migration and together with theoretical considerations we concluded that migration of nanoparticles from plastic food packaging materials in general is not possible according to Fickian Law of diffusion as long as the particles are larger than 3-4 nm or 1–2 nm in diameter [4] and when the nanomaterial is fully covered with polymer
Even under the assumption that the detected signals in abrasion tests after additional preceding heating, swelling or stretching of the nanocomposites were solely caused by release of TiN, the released amount of TiN onto the abrasive food simulant would be less than 1 μg/kg

Summary

Introduction

This article is the second in a series of two dealing with the potential release of nanomaterials after intense mechanical-, thermal-, and chemically-induced stress conditions. In our previous works, based on comprehensive migration testing using plastics nanocomposites with incorporated silver nanoparticles (Ag-NPs) [1], nanotitanium nitride (TiN) [2], and nanolaponite [3], we could not find any detectable migration and together with theoretical considerations we concluded that migration of nanoparticles from plastic food packaging materials in general is not possible according to Fickian Law of diffusion as long as the particles are larger than 3-4 nm (in case of polyolefins) or 1–2 nm (for PET and similar polymers) in diameter [4] and when the nanomaterial is fully covered with polymer (i.e., does not stick out of the polymer). A closer view into these publications revealed that the migration tests were done using cut strips or pieces of polymer films or articles or using very aggressive food simulants which destroyed the polymer [5]

Objectives

Methods

Results

Discussion

Conclusion