Polymer and eWaste Recycling
Polymers and electronics are infused into every part of our lives—from the cars we drive, to the design and packaging of products, to the devices we use for communication and entertainment. As polymer and electronics use increases, the volume of polymer waste and e-waste also increases. In response to this reality, there is a growing commitment by consumers, industries, and governments around the world to better understand the potential impact that polymer and electronic waste has on the environment and human health.
The response that is emerging from that commitment is to advance the circular economy. Instead of perpetuating a linear economy that begins with raw materials and ends with waste disposal, the circular economy focuses on strategies and designs that keep materials in use and out of the disposal bin. In the polymers and electronics industries, the focus is on improving plastics recycling technologies, reclaiming and reusing rare earth elements from electronics, and developing new bio-based materials and processes.
Analytical testing plays a major role in helping support these recycling, reuse, and development efforts, and in helping companies meet regulations surrounding their efforts. Some of the important analytical technologies for the polymers and electronics recycling industry are discussed here, including FT-IR, Thermal Analysis, GC, ICP-MS, and ICP-OES.
Polymer Recycling Technologies
Mechanical recycling is the primary plastics recycling method used today. Mechanical recycling involves chopping, shredding, or grinding the waste plastics to provide shreds or flakes to polymer compounders and converters. The shreds/flakes recyclates must be tested for several parameters so the compounders and converters can determine if the recyclate will meet their and their customers’ specifications.1
FT-IR
Different polymers tend to be mutually immiscible, thus it is important that a recyclate batch said to be polyethylene terephthalate (PET) or polyethylene (PE) really be that polymer and not polycarbonate (PC) or polystyrene (PS). Fourier Transform Infrared (FT-IR) spectroscopy is an ideal technology to identify the chemical makeup of the recyclate as it provides a fast and accurate way to identify the specific chemical or chemicals within a polymer recyclate.
Thermal Analysis
Thermal analysis is used to determine the thermal and/or oxidative stabilities of materials as well as their compositional properties. Measurements obtained with TGA technology provide valuable information that can be used to select materials for certain end-use applications, predict product performance, and improve product quality. The technology is particularly useful for the following types of measurements.
- Decomposition kinetics: Decomposition data can be used to predict the useful product lifetimes of some recyclates the coatings for electrical or telecommunication cables.
- Moisture and volatiles content: many polymer applications are sensitive to the occurrence of low-level volatilization. A high performance TGA instrument provides the high degree of sensitivity and stability needed to make these long-term measurements in recyclates.
- Compositional analysis of multi-component recyclates: One of the most important applications of TGA is the assessment of the compositional analysis of recyclate blends.
- Characterization of the differences between two or more recyclates: a high performance TGA allows for the detection of subtle, but potentially important, differences between recyclate batches.
- Filler content: One major application of TGA is the assessment of the fillers (glass fibers, calcium carbonate, talc, and others) in recyclates. Filler levels can significantly impact the end use properties (thermal expansion, stiffness, and damping) of the final product.
Gas Chromatography
GC is an important and versatile technology that is readily hyphenated with other techniques to identify organic chemicals in plastics recyclates. The data can be used to evaluate the appropriateness of a recyclate for specific end uses. For example, GC can be used to determine phthalate content, the presence of residual monomers, the presence of styrene butadiene, volatile organics emissions, the presence of alkylphenols, and other end-use parameters or concerns.
ICP-MS
For nearly 30 years, ICP-MS has been gaining favor with laboratories around the world as the instrument of choice for performing trace metal analysis. ICP-MS technology achieves detection limits at or below the single part per trillion (ppt) level for much of the periodic table. Its analytical working range is nine orders of magnitude, and isotopic analysis can be readily achieved.
ICP-OES
Lead and other metals that may be present in certain polymers must be quantified at increasingly lower concentrations. ICP-OES is the approved certifying tool for identifying a wide variety of metals in polymers and their recyclates. ICP-OES can reliably quantify lead at the newer, more stringent 90 mg/kg detection limit.2
Technologies and Trends on the Horizon
New recycling needs and technologies are under development, including recovery of certain metals from e-wastes, chemical recycling of polymers, and bio-based polymers and recycling. The COVID-19 pandemic has also created a new trend in plastic packaging and recycling.
Recovery of Rare Earth Elements from eWaste
The 17 rare earth elements (REE) are used in numerous high-tech applications such as cellular telephones, computer memory and hard drives, and flat-screen monitors and televisions.3,4 Most REE are abundant in the earth’s crust but at low concentrations and in combination with other elements. Extracting them in sufficient quantity is difficult and expensive.3 Given the increasing abundance of consumer electronics, recovering REE from these devices could be more simple and cost effective than mining raw material.
Two sample preparation techniques that are well-suited for media containing REE are hot block open digestion and microwave closed digestion. The complete digestion provided by these methods results in high-quality samples for quantitative analysis.
Two quantitative analytical techniques that are relied upon for REE analysis are ICP-OES and ICP-MS. ICP-OES is a multi-element analytical technique used for the accurate determination of different elements at major, minor, and trace concentration levels in a variety of materials. ICP-MS is equally suitable for REE analysis based on its multi-element capability, extremely low detection limits, small sample size needs, accuracy, isotopic detection capability, and ease of operation.2
Chemical Recycling of Plastics
Chemical recycling of plastics is an emerging technology that breaks down polymers to the original raw materials, such as monomers and additives. The recyclates can then be reused by resin producers and polymer compounders.1 This will reduce the amount of new raw materials required for polymer production.
The reclaimed raw materials will require the same scrutiny as shred/flake recyclates before being used for new polymer production. Analysis will be required of each material’s chemical identification, characterization, physical and chemical properties, residuals content, and other specifications.
Bio-based Polymers and Processes
Biologically-based materials and processes are being investigated by many companies and institutions around the world. New bioplastics are under development using natural materials such as starch, cellulose, plant proteins, and plant oils. The goals of development include materials that are readily biodegradable while still retaining their functional and unique properties.5 New bioplastics will require confirmatory analysis of their chemical, thermal, mechanical, and other properties, as well as end-use specifications.
Another bio-based technology being developed is the use of microbes to break down traditional plastics into their raw materials. As with the products of chemical recycling, microbially recycled products need to undergo analysis for chemical identification, characterization, physical and chemical properties, residuals content, and other specifications.
COVID-19 Impacts on Plastics
Finally, the COVID-19 pandemic has impacted the thinking and practices of consumers, plastics producers, and recyclers.
Consumers are shopping online more frequently, resulting in increased use of plastic packaging. Consumer use of personal protective equipment (PPE), such as face masks and gloves, has also greatly increased during the pandemic. In the U.S. during the first six months of the year, consumers spent $347.26 billion online. That is a 30.1% increase compared to the same period in 2019.6
Restaurants and other service industries are using more single-use plastics such as utensils and beverage containers, takeout boxes, menus, and PPE. One example of the magnitude of the increase comes from Singapore. During the country’s eight-week lockdown in April and May, Singapore residents discarded an additional 1,470 tons of plastic waste from takeout packaging and food delivery.7
Medical facilities are using more single-use items such as testing kits, masks, gloves, gowns. The resulting volume of medical waste has been measured at 6 to 10 times higher in cities worldwide.8,9
In response, plastics production has increased to meet the growing demand. Recycling, however, has decreased in many countries and cities due to concerns about potential exposure of workers to COVID-19 contaminated materials. Thus, new plastics are primarily produced from virgin raw materials as the availability of recyclates has decreased.8
These changes have become a challenge for companies that have dedicated recycling programs and/or commitments to using recycled plastic. Thus, emerging bioplastics technologies will play an even more important role in the future of plastics.
A Final Word
The world of polymer and electronics recycling continues to evolve in response to consumer and business demands and growing commitments to sustainability. As evidenced in this article, advanced analytical technologies are an integral part of today’s recycling efforts and are equally crucial to development of the advanced biotechnology materials and processes of the future.
About the Author
Gerlinde Wita is the global market leader for materials, energy, & petrochem at PerkinElmer.
Tiffany Kang is the director for greater China market segment team at PerkinElmer.
References
1. Polymer Lifecycle Challenges for the Betterment of Society and the Environment. https://www.perkinelmer.com/libraries/WHT_PolymerLifecycleChallengesFinal
2. Lead and Other Toxic Metals in Toys Using XRF Screening and ICP-OES Quantitative Analysis. https://www.perkinelmer.com/searchresult?searchName=ICP-OES&_csrf=fa246b6c-9a9e-4feb-8226-99c55ee6655f
3. The American Geosciences Institute. What are rare earth elements, and why are they important? https://www.americangeosciences.org/critical-issues/faq/what-are-rare-earth-elements-and-why-are-they-important. Accessed on September 24, 2020.
4. Balaram, V. 2019. Rare earth elements: A review of applications, occurrence, exploration, analysis, recycling, and environmental impact. Geoscience Frontiers, Volume 10, Issue 4, July, Pages 1285-1303. https://doi.org/10.1016/j.gsf.2018.12.005
5. Mohan, Sneha et al. 2016. Recent Advances in Biopolymers: Biopolymers – Application in Nanoscience and Nanotechnology. March 9. DOI: 10.5772/62225; https://www.intechopen.com/books/recent-advances-in-biopolymers/biopolymers-application-in-nanoscience-and-nanotechnology
6. Ali, Fareeha. 2020. Charts: How the coronavirus is changing ecommerce. August 25. https://www.digitalcommerce360.com/2020/08/25/ecommerce-during-coronavirus-pandemic-in-charts/
7. United Nations. 2020. Growing plastic pollution in wake of COVID-19: how trade policy can help. July 27. https://unctad.org/en/pages/newsdetails.aspx?OriginalVersionID=2440
8. Zambrano-Monserrate, M. A., Ruano, M. A., & Sanchez-Alcalde, L. 2020. Indirect effects of COVID-19 on the environment. The Science of the total environment, 728, 138813. https://doi.org/10.1016/j.scitotenv.2020.138813
9. H.A. Abu-Qdais, M.A. Al-Ghazo, & E.M. Al-Ghazo. 2020. Statistical analysis and characteristics of hospital medical waste under novel Coronavirus outbreak. Global J. Environ. Sci. Manage. 6(SI): 21-30, Autumn Special Issue.