Curtzwiler, Greg

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gregc@iastate.edu
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Curtzwiler
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Greg

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Global plastic waste recycling and extended producer responsibility laws

2023-12-15 , Tumu, Khairun , Vorst, Keith , Curtzwiler, Greg , Food Science and Human Nutrition

In the USA, 8.66% of municipal solid waste (MSW) plastic was recycled and 75.9% landfilled (2018). Some critical challenges in widespread adoption of post-consumer recycled (PCR) plastic include high collection costs, sortation complexity, inconsistent feedstock properties, and unknown contamination leading to safety considerations. The objective of this review is to discuss global Extended Producer Responsibility (EPR) policies/regulations and their ability to facilitate coordination of domestic/international policies and business to overcome critical recycling complications. Global EPR and recycling laws were examined to compare and contrast initiatives to increase recycling and avoid plastic waste generation. EPR laws increase producers’ liability towards product generation, marketing, and disposal by applying fees and taxes on products depending on product recyclability and volume generation. Countries with established plastic EPR regulations and landfill bans often possess higher recycling rates. The results of this research can facilitate development of local regulatory mandates to increase recycling rates.

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Ion Selective Electrode (ISE) Method for Determination of Total Fluorine and Total Organic Fluorine in Packaging Substrates

2023-01-18 , Ignacio, Ma Cristine C D , Curtzwiler, Greg , Early, Mark R , Updegraff, Katie M , Vorst, Keith L , Food Science and Human Nutrition

Various testing methods and techniques have been used to identify and quantify per- and polyfluoroalkyl substances (PFAS) in food packaging. A common indirect measurement of PFAS is total fluorine (TF) and total organic fluorine (TOF). These methods are critical in rapidly screening food packaging materials for the >9000 PFAS and are often globally used for regulatory limits. However, this destructive approach requires careful sample preparation, combustion, and the analysis of the solution by a fluoride-specific electrode. The method described herein is a cost-effective, rapid, quantitative, and externally validated initial screening of packaging materials for fluoro-chemistry. This study presents validated protocols for measuring TF and TOF in packaging substrates using oxygen combustion sample preparation coupled with fluoride ion-selective electrode (F-ISE); the materials and required equipment are provided, and the step-by-step procedure from sample preparation to the analysis are described, including critical steps to minimize contamination and interferences during sample preparation.

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A Study on Recycled Polymers Recovered from Multilayer Plastic Packaging Films by Solvent-Targeted Recovery and Precipitation (STRAP)

2022-08-14 , Cecon, Victor S. , Curtzwiler, Greg , Vorst, Keith , Food Science and Human Nutrition

Multilayer plastic film use increased in multiple packaging applications due to its versatility and overall increased performance over monolayer structures. However, the performance gains from multiple layers also make recycling difficult because they contain multiple polymers that can be immiscible and burdensome to traditional mechanical recycling operations. A possible solution is the solvent-targeted recovery and precipitation (STRAP) process, but the effect on the retrieved polymer is still unknown. The STRAP process is applied to two different multilayer films and samples of recovered polymers are evaluated for physical, molecular, and thermal properties. Changes in the molecular weight are not significant, but differences in thermal properties are reported along with the coprecipitation of different polymers. Solvent retention in the polymer matrix from STRAP reduced the glass transition temperature of samples, but enhanced drying recovered it. Heavy metals, such as Cd, Cr, and Pb are not detected, indicating regulatory compliance for different applications.

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Sustainable Composites Using Landfill Bound Materials

2022-02-17 , Mort, Rebecca , Cecon, Victor S. , Mort, Paul , McInturff, Kelsey , Jiang, Shan , Vorst, Keith , Curtzwiler, Greg , Materials Science and Engineering , Food Science and Human Nutrition

The demand for new methods of diverting materials from waste streams has grown as sustainability and landfill reduction goals continue to be set. Municipal solid waste combustion and waste-to-energy (WTE) facilities reduce landfill waste accumulation but ash material by-products are commonly sent to landfills. In this work, we evaluate the potential for fly ash to be used as an inert filler in post-consumer recycled polyethylene to maximize landfill diversion of high-volume materials. Using fly ash from solid waste combustion as a filler increases landfill diversion, reduces associated costs, and offsets the cost of the recycling for post-consumer plastics by blending with a low cost filler. Characterization of the fly ash revealed high variability in ash particle composition and size, which was expected due to the municipal solid waste source. A series of composites were compounded incorporating fly ash into recycled linear low-density polyethylene utilizing various compatibilizers. The composites were characterized for molecular interactions, thermal properties, mechanical properties and changes in melt processing via infrared spectroscopy, differential scanning calorimetry, electromechanical testing, and oscillatory melt rheology, respectively. Mechanical testing of the fly ash composites indicated that the fly ash did not significantly change the Young’s modulus or yield stress and the addition of various compatibilizer additives increased impact strength. The impact strength of the neat polymer decreased drastically from ∼55 kJ/m2 to ∼20 kJ/m2 at 5 wt. % fly ash. However, the addition of PGME compatibilizer at 0.75 wt. % increased the composite’s impact strength to roughly the same value as the neat polymer. Thus, the addition of a compatibilizer could be used to alter the fly ash filler composite’s resistance to flexural shock. These results indicate that fly ash can be added to recycled linear low-density polyethylene up to 10% while maintaining physical properties.

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Low-Isocyanate Polyurethane Foams with Improved Stability and Compression Modulus Prepared from Biosourced and Landfill-Diverted Materials

2023-08-09 , Mort, Rebecca , Peters, Erin , Griffin, Elizabeth , Curtzwiler, Greg , Vorst, Keith , Jiang, Shan , Materials Science and Engineering , Food Science and Human Nutrition

Polyurethane foams are widely used in a variety of applications that impact everyday life, including single-use packaging and durable furniture. Currently, the industry depends primarily on petroleum-based reactants, such as polyols and isocyanates. Isocyanates are particularly troublesome due to their harmful effects on human health but are also crucial for achieving foam properties, such as rigidity. In this study, we demonstrate that cost-competitive, scalable, and more sustainable foams can be attained using biobased polyol substitutes along with landfill-diverted biofillers (rice hulls and coffee chaff) at a lower ratio of isocyanate. To avoid the common collapsing issue, we designed a prepolymerization step that can consistently produce high-quality foam with zero volume loss after expansion. The addition of biofiller increased the foam compression modulus drastically up to 400% at the same isocyanate concentration. Therefore, the incorporation of the biofiller provided a mechanism to enhance the mechanical properties without increasing the amount of isocyanates. Additionally, the reproducibility and foam properties can be further improved through grinding and sieving. The finer particles can be loaded at even higher levels without negatively impacting the mechanical properties. The same approach can be expanded to other types of biobased cellulosic biofillers. The results put forward a scalable, economical, and more sustainable route to improve foam performance while reducing isocyanate usage by incorporating biobased content.

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Correction: Expanding plastics recycling technologies: chemical aspects, technology status and challenges

2023 , Li, Houiqian , Bai, Xianglan , Brown, Jessica , Brown, Robert , Cecon, Victor , Curtzwiler, Greg , Olafasakin, Olumide O. , Radhakrishnan, Harish , Tumu, Khairun N. , Vorst, Keith L. , Wright, Mark M. , et al. , Mechanical Engineering , Agricultural and Biosystems Engineering , Chemical and Biological Engineering , Bioeconomy Institute , Food Science and Human Nutrition

Correction for ‘Expanding plastics recycling technologies: chemical aspects, technology status and challenges’ by Houqian Li et al., Green Chem., 2022, 24, 8899–9002, https://doi.org/10.1039/D2GC02588D.

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Publication

Waterborne Polyurethane/Acrylic Adhesive Blends from Physaria fendleri Oil for Food Packaging Applications

2022-07-15 , Mort, Rebecca , Olson, Emily , Thurber, Henry , Jiang, Shan , Vorst, Keith , Curtzwiler, Greg , Materials Science and Engineering , Food Science and Human Nutrition , Industrial and Manufacturing Systems Engineering , Ames Laboratory

Environmental concerns and the diminishing acceptability of using petrochemical polymers require innovative synthetic approaches to materials for essential polymeric technologies such as adhesives. Biobased plant oils have been suggested as replacements for petrochemical monomers in polyurethane formulations. A variety of seed oil extracts from plants contain naturally occurring functional groups such as hydroxyl and glycidyl ether, which can be utilized in polyurethane synthesis. Most studies of bioderived polyurethane adhesives occur in solventborne systems and with chemically modified oils. However, rising concerns and manufacturing limitations of volatile organic compounds in solventborne systems warrant investigation into more sustainable and alternatives that are easier to handle. In this work, we synthesized waterborne polyurethanes comprised of oil derived from Physaria fendleri seed (naturally occurring hydroxyl functionality), hexamethylene diisocyanate, toluene diisocyanate, and dimethyl propionic acid. Acrylate copolymers were synthesized via emulsion polymerization comprised of different butyl and methylmethacrylate monomer ratios. These polymers were formulated into waterborne polyurethane/acrylic adhesive blends. The resulting formulations possess a commercially comparable peel strength of >6 N and are suggested for use in resealable food packaging applications. This study demonstrates the utility of oil derived from Physaria fendleri seeds in waterborne adhesive applications, adding value with bioderived materials and increasing sustainability of polyurethane adhesives.

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Endocrine modulating chemicals in food packaging: A review of phthalates and bisphenols

2023-02-15 , Tumu, Khairun , Vorst, Keith , Curtzwiler, Greg , Food Science and Human Nutrition

Phthalates and bisphenol chemicals have been widely used globally in packaging materials and consumer products for several decades. These highly functional chemicals have become a concern due to their toxicity (i.e., endocrine/hormone modulators) and ability to migrate from food contact materials (FCMs) into food matrices and the environment resulting in human and environmental health risks. FCMs, composed of postconsumer materials, are particularly high risk for containing these compounds. The evaluation of postconsumer recycled feedstocks in FCMs is compulsory and selection of an appropriate detection method to comply with applicable regulations is necessary to evaluate human and environmental safety. Numerous regulations have been proposed and passed globally for both compound classes that are recognized as priority pollutants by the United States Environmental Protection Agency and the European Union. Several brand owners and retailers have also released their own “restricted substance lists” due to the mounting consumer and regulatory concerns. This review article has two goals: (1) discuss the utilization, toxicology, human exposure routes, and occurrence levels of phthalates and bisphenols in FCMs and associated legislation in various countries and (2) discuss critical understanding and updates for detection/quantification techniques. Current techniques discussed include extraction and sample preparation methods (solid-phase microextraction [SPME], headspace SPME, Soxhlet procedure, ultrasound-assisted extraction), chromatographic techniques (gas, liquid, detectors), and environmental/blank considerations for quantification. This review complements a previous review of phthalates in foods from 2009 by discussing phthalate and bisphenol characteristics, analytical methods of determining concentrations in packaging materials, and their influence on the migration potential into food.

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Machine-Learning-Based Predictions of Polymer and Postconsumer Recycled Polymer Properties: A Comprehensive Review

2022-09-14 , Andraju, Nagababu , Curtzwiler, Greg , Ji, Yun , Kozliak, Evguenii , Ranganathan, Prakash , Food Science and Human Nutrition

There has been a tremendous increase in demand for virgin and postconsumer recycled (PCR) polymers due to their wide range of chemical and physical characteristics. Despite the numerous potential benefits of using a data-driven approach to polymer design, major hurdles exist in the development of polymer informatics due to the complicated hierarchical polymer structures. In this review, a brief introduction on virgin polymer structure, PCR polymers, compatibilization of polymers to be recycled, and their characterization using sensor array technologies as well as factors affecting the polymer properties are provided. Machine-learning (ML) algorithms are gaining attention as cost-effective scalable solutions to exploit the physical and chemical structures of polymers. The basic steps for applying ML in polymer science such as fingerprinting, algorithms, open-source databases, representations, and polymer design are detailed in this review. Further, a state-of-the-art review of the prediction of various polymer material properties using ML is reviewed. Finally, we discuss open-ended research questions on ML application to PCR polymers as well as potential challenges in the prediction of their properties using artificial intelligence for more efficient and targeted PCR polymer discovery and development.

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Biofillers Improved Compression Modulus of Extruded PLA Foams

2022-05-05 , Mort, Rebecca , Peters, Erin , Curtzwiler, Greg , Jiang, Shan , Vorst, Keith , Materials Science and Engineering , Food Science and Human Nutrition

Foams produced with biobased materials, such as poly(lactic acid) (PLA), cellulose, starch, and plant oil-based polyurethanes, have become more and more important in the circular economy. However, there are still significant challenges, including inferior performance and higher cost. The use of low-cost filler material has the potential to reduce the cost and alter the composite properties of biobased foams. By selecting biofillers derived from plant material, we can reduce the cost without sacrificing the compostability. This study explored the impact of landfill-diverted biofiller material, ground coffee chaff and rice hulls on the physical properties of biobased foams. Both biofillers were extrusion compounded with PLA, then extruded into rigid foams using a physical blowing agent. A filler concentration up to 10 weight % rice hull or 5 weight % coffee chaff could be incorporated without a significant increase in density, in comparison to the regular PLA foam. The thermal conductivity was similarly unaffected by biofiller loading, with values ranging between 71.5 and 76.2 mW/m-K. Surprisingly, the filler composite foams possessed impressive mechanical properties with all compressive moduli above 300 MPa. Only 5 weight % loading resulted in the doubling of compressive modulus, compared to the regular PLA foam. These results indicate that landfill-diverted fillers can strengthen foam mechanical properties without impacting thermal insulation performance, by forming reinforcing networks within the cell walls.

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