Less than 10% of the plastics generated globally are recycled, while the rest are incinerated, accumulated in landfills, or leach into the environment. New technologies are emerging to chemically recycle...

Food safety authorities and the food industry are focused on uses of perfluoroalkyl substances (PFAS) in various foodcontact packaging applications. Not widely known until recently, certain PFAS occur in paper-based packaging materials typically at parts-per-billion to parts-per-million concentrations. These substances are nonintentionally added substances (NIAS) and are attributed to residues from recycled fiber and paperboard used in the manufacture of new food packaging products. Low concentration PFAS detection has generated debate in the food industry and among scientific and governmental organizations about understanding their significance in food-contact products because certain PFAS are intentionally added to some food packaging materials. Distinguishing between both sources of PFAS in food packaging is essential for regulatory compliance purposes. In this paper, we describe ongoing research using contact angle measurement analysis to determine limits of performance (LOP) for perfluorocarboxylic acids (PFCAs) (C4, C6, C8, and C10) on the surface of recycled paper packaging materials. We find that the LOP concentrations for PFCAs ranged from 37 ppm (C10) to higher than 1238 ppm (C4). Because there is no economic justification for the presence of PFAS that do not provide functional performance, these LOP concentrations can reliably be considered as NIAS thresholds. This analytical method and the resulting test data are able to differentiate the source of PFAS in food packaging. Future research will broaden the test method to include measurements of fluorotelomer, sulfonamide, and fluoropolymer substances to develop a more comprehensive understanding of PFAS performance and NIAS concentration thresholds.

A waterborne, UV-blocking, and visually transparent nanocomposite coating was formulated with ZnO nanoparticles and 2-hydroxyethyl cellulose (HEC). The coating is highly effective (< 5% UV and ~ 65% visible transmittance) and the film thickness (0.2-2.5 μm) is ~100 times thinner than the conventional coatings of similar UV-blocking performance. The superior properties are due to the fractal structures of ZnO nanoparticles assembled within the HEC matrix, revealed by scanning electron microscopy (SEM) and smallangle x-ray scattering (SAXS). Changing the binder to 2-hydroxyethyl starch (HES) diminishes the UVblocking performance, as ZnO nanoparticles form dense globular aggregates, with an aggregation number measured by SAXS three orders of magnitude larger than the HEC coating. Since HEC and HES share the same same chemical compositionrepeating glucose unit in the polymer backbone, it suggests that the conformational characteristics of the binder polymer have a strong influence on the nanoparticle aggregation, which plays a key role in determining the optical performance. Similar structures were achieved with TiO2 nanoparticles. This study not only offers a cost-effective and readily scalable method to fabricate transparent UV-blocking coating, but also demonstrates that the unique fractal aggregation structures in a nanocomposite material can provide high performance and functionality without fully dispersing the nanoparticles.

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Sixty (60) polyethylene terephthalate (PET) sheets containing 0-100% recycled-PET (RPET) bottle flake were produced using industrial extruders. The PET/RPET sheets were characterized using differential scanning calorimetry, ultravioletvisible spectroscopy, mechanical testing, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The absorbance at 350 nm, %crystallinity, crystallization temperature, and crystallization peak offset were found to be both unaffected by a silicone mold release coating and reasonably valid indicators of %RPET. Mechanical testing determined that incorporating recycled content into virgin resin will significantly alter the composite mechanical properties; analysis indicated that there was approximately a 2-, 3-, and 30-MPa increase in stress at the proportional limit, stress at yield, and Young's modulus, respectively, in the machine direction at 40% RPET concentration when compared to virgin resin.

This review outlines the progress in biobased foams with a focus on low thermal conductivity. It introduces materials selection and processing, compares performance, examines modelling of physical properties, and discusses challenges in applying models to real systems.