Influence of polymer swelling and dissolution into food simulants on the release of graphene nanoplates and carbon nanotubes from poly(lactic) acid and polypropylene composite films

Abstract

The study compared the effects of swelling and dissolution of a matrix polymer by food simulants on the release of graphene nanoplates (GNPs) and multiwall carbon nanotubes (MWCNTs) from poly(lactic) acid (PLA) and polypropylene (PP) composite films. The total migration was determined gravimetrically in the ethanol and acetic acid food simulants at different time and temperature conditions, while migrants were detected by laser diffraction analysis and transmission electron microscopy. Swelling, thermal analysis, and scanning electron microscopy were applied to characterize the degradation of polymer films at the migration conditions. The release of nanoparticles was found in a high‐temperature migration test of 4 h at 90 °C. The hydrolytic dissolution of the PLA polymer in the food simulants caused a migration of GNPs (>100 nm) from the PLA/GNP/MWCNT films into the simulant solvents, while the entangled MWCNTs formed a network on the film surface, preventing their migration from the PLA composite films. In contrast, the PP polymer slightly swells in ethanol solvents, allowing some short carbon nanotubes to be released from the surface and cut edges of the PP/MWCNT film into food simulants. Mathematical modeling of diffusion was applied that accounts for type of polymer, time–temperature conditions, and solvent concentration; model parameters were validated with experimental results. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45469.

PLA/Graphene/MWCNT Composites with Improved Electrical and Thermal Properties Suitable for FDM 3D Printing Applications

“…Thermal conductivity and diffusivity of GNP nanocomposites were improved by the addition of graphene nanoplatelets by 181% and 214%, respectively. Thermal transport in obtained PLA/GNP composites is a thriving area of research thanks to graphene's extraordinary heat conductivity properties and its In our previous studies [50][51][52] it was found that the PLA is still biodegradable and, only if there is a burning of composites (T < 850 • C), residual ash contains an amount of graphite and carbon nanotubes, creating concerns about environmental pollution and damage. A quantitative and qualitative risk assessment has been carried out in two cases-so-called "bad practices" (not in compliance with safety measures) and "good practices" (subject to modern safety measures).…”

Biodegradable and Water Resistant Poly(vinyl) Alcohol (PVA)/Starch (ST)/Glycerol (GL)/Halloysite Nanotube (HNT) Nanocomposite Films for Sustainable Food Packaging

“…The overall migration rate and migration rate of nanofillers are studied widely for packaging materials based on petro-based nanocomposites such as low density polyethylene (LDPE) nanocomposites with different types of nanofillers like nanosilver (Hannon et al, 2016), nanocarbon black (Bott et al, 2014b), nanoclays (Echegoyen et al, 2016), and nanotitanium nitride (Bott et al, 2014a). PLA nanocomposites are also of a particular concern in migration studies of bionanocomposite systems reinforced with different nanofillers such as sliver-based modified MMT nanoclays (Busolo et al, 2010), Cloisite nanoclays (Schmidt et al, 2009), CNCs (Fortunati et al, 2012), multiwalled CNTs (Velichkova et al, 2017). But very limited migration studies have been investigated based on other biopolymers like PVA and ST for potential material packaging applications.…”

Release of Graphene and Carbon Nanotubes from Biodegradable Poly(Lactic Acid) Films during Degradation and Combustion: Risk Associated with the End-of-Life of Nanocomposite Food Packaging Materials

“…The characterization of such release provides critical information for environmental nanoobject exposure from biodegradable nanocomposites. In our previous studies [19][20][21], we have investigated the release of GNP and MWCNTs from the composite film GNP/MWCNT/PLA in alcoholic and acid food simulants, high temperature migration conditions, such as: (i) strong static migration test (with heating at 90 o C for 4 hours); and (ii) ultra-strong dynamic migration test (heating at 90 o C for 4 hours followed by subsequent storage for 10 days at 40°C, including dynamic treatment for 1 min daily). The strong static and ultra-strong dynamic migration conditions were set accordingly with the prescription in EU Regulation 10/2011 (EU 2011) [28] and literature sources [29,30] for migration of polymer films in food simulants.…”

“…At the strong static migration test [19,20], we have observed that large graphene nanoplatelets (GNP) of about 100-1000 nm in length and a few nanometers in thickness indeed migrate from the poly(lactic) composite film, GNP/MWCNT/PLA, into food simulants. We have assumed that heating above the glass transition temperature enhance the dynamics of polymer molecules and facilitate the diffusion of graphene nanoplatelets from PLA film into food simulant.…”

“…Release during service life of MWCNT-based composites is projected to be quite low and composed of polydisperse fragments with only a small fraction of free MWCNTs [15][16][17]. Studies for the release of graphene from food packaging materials into food are very scare [19][20][21].…”