`
`oif,
`I
`Ps
`
`.- ——
`HANSER
`
`Yita v. MacNeil IP, IPR2020-01139, Page 1
`
`MacNeil Exhibit 2154
`
`MacNeil Exhibit 2154
`Yita v. MacNeil IP, IPR2020-01139, Page 1
`
`

`

`Rudolph / Kiesel / Aumnate
`Understanding Plastics Recycling
`
`MacNeil Exhibit 2154
`Yita v. MacNeil IP, IPR2020-01139, Page 2
`
`

`

`Natalie Rudolph
`Raphael Kiesel
`Chuanchom Aumnate
`
`Understanding
`Plastics Recycling
`
`Economic, Ecological, and Technical
`Aspects of Plastic Waste Handling
`
`Hanser Publishers, Munich Hanser Publications, Cincinnati
`
`MacNeil Exhibit 2154
`Yita v. MacNeil IP, IPR2020-01139, Page 3
`
`

`

`The Authors:
`
`Prof. Dr.-Ing. Natalie Rudolph, Polymer Engineering Center, Dept. of Mechanical Engineering, University of
` Wisconsin-Madison, WI, U.S.A.
`
`Raphael Kiesel, M.Sc., Fraunhofer Institute for Production Technology (IPT), Aachen, Germany
`Chuanchom Aumnate, Ph.D., Polymer Engineering Center, Dept. of Mechanical Engineering, University of
` Wisconsin-Madison, WI, U.S.A.
`
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`
`© Carl Hanser Verlag, Munich 2017
`Editors: Mark Smith, Anne Vinnicombe
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`
`ISBN: 978-1-56990-676-7
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`
`MacNeil Exhibit 2154
`Yita v. MacNeil IP, IPR2020-01139, Page 4
`
`

`

`Acknowledgments
`
`We would like to thank Prof. Tim A. Osswald for inspiring the publication of our
`work in this book. We would also like to acknowledge the support of the students
`at the Polymer Engineering Center at the University of Wisconsin-Madison for
`their help and support, especially Claudia Spicker, who worked with us on the to-
`pic of degradation during multiple reprocessing cycles, and Jirapa Kliewer, who
`supported the research on waste handling strategies.
`Prof. Natalie Rudolph would like to thank her parents, Ewald and Gabriele, for
`their lifelong unwavering support, as well as her brother, Michael, who not only
`encourages her in her work, but lends his technical expertise in a variety of ques-
`tions. Special thanks are due to her husband, Christian Wolf, who patiently sup-
`ported many days and evenings on this book.
`Raphael Kiesel would like to thank his family, including his parents Susanne and
`Harald, as well as his siblings Alissa and Fabian for supporting him in every stage
`of his life.
`Further, he would like to thank his office colleagues and friends Tobias Bandemer,
`Carsten Koch, and Franz Rustige for the many rounds of table tennis while writing
`the book, which freed his mind for new ideas. Particular thanks are to his partner
`Johanna Sckaer for supporting this project in countless ways.
`Chuanchom Aumnate would like to thank her mother, Boonma, as well as her sib-
`lings, Pornpimol and Phumintr, for their unflagging love and unconditional sup-
`port throughout her life. Particular thanks goes to her friend, Anchittha, who has
`always been available to support her in many ways. She would like to thank the
`Royal Thai Government (OCSC) for her financial support to continue her studies in
`the U.S. that allowed her to participate in writing this book.
`
`MacNeil Exhibit 2154
`Yita v. MacNeil IP, IPR2020-01139, Page 5
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`

`

`Preface
`
`Thank you for taking the time to read this book on plastic recycling. We hope you
`benefit from reading our summary and research regarding this topic. With differ-
`ent backgrounds and states in our scientific careers, we are united by the interest
`in using our knowledge to educate and make the world a little better—one topic and
`one word at a time.
`It all began when I had started as an assistant professor at the University of Wis-
`consin-Madison and a new potential graduate student was sitting in front of me to
`discuss our collaboration. With many topics in my head and finally a position
`where I could explore topics close to my heart, Chuanchom Aumnate wanted to
`work on recycling of plastics. I thought to myself that I should probably still wait
`some more years with such a topic, get more established first, and then start work-
`ing on it.
`But in reality, I could not resist and we started formulating a project. Our aim was
`to focus on a topic that would make an impact and could solve problems around the
`globe. We decided to start with plastic packaging, due to its huge worldwide mar-
`ket share, and wanted to investigate the necessity of sorting, a process which is
`still immature for typical packaging materials and therefore limits the amount of
`recycled plastic.
`Thus we worked on blending of typical packaging materials like polypropylene and
`polyethylene as an alternative for the sorting process to increase the amount of
`recycled plastic waste. We used scientific as well as industrial tests to analyze the
`resulting material properties. Our goal was to identify promising combinations as
`well as practical test methods for their analysis.
`Very early on we realized that in addition to our technical study, we needed to un-
`derstand the cost benefit of eliminating the sorting process and compare it to both
`conventional recycling and other waste management strategies. We could expand
`our work when Raphael Kiesel, on a scholarship from Germany, came to UW-Mad-
`ison and decided to work on this topic. He combines the solid technical and busi-
`ness background needed to look at all of those aspects in combination. Soon after
`Raphael started on the topic, we realized that all of us were driven by understand-
`
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`

`

`VIII
`
`Preface
`
`ing recycling holistically—including the technical, economic, and ecological advan-
`tages and disadvantages.
`The idea for the book was born from my colleague and mentor, Prof. Tim A. Osswald,
`when he attended Raphael’s Master defense and suggested that we should publish
`our very interesting analysis in a book to reach a broader audience. And this is
`what we did.
`We compiled our own analysis results together with data from other research
`groups and summarized it in the present book.
`The book starts with a general overview of waste handling strategies and their
`shares of the U.S. market are presented (Chapters 1 and 2). In Chapter 3 special
`focus is placed on the technical aspects of recycling for various applications and
`specific polymers.
`In separate chapters their economic (Chapter 4) and ecological value and costs
`(Chapter 5) are evaluated and compared. The analysis shows the advantages of
`plastic recycling as well as the necessary boundary conditions for future growth.
`In Chapter 6 different scenarios to increase the profitability of recycling are ana-
`lyzed and blending of plastic materials is identified as a suitable strategy.
`Last but not least, the findings for the U.S. are put into context to the worldwide
`potential for waste handling and in particular plastic recycling using Europe and
`China as examples in Chapter 7. All the data and calculations presented in the
`book and summarized in the tables in the Appendix in Chapter 8 can be down-
`loaded as spreadsheets for the reader’s own analysis and updates in a fast chang-
`ing economy.
`Thus, the book is an entry level book for decision makers in the plastics industry
`as well as students, researchers, and industry experts new to the field of plastic
`recycling.
`True to our mission, this book is printed on recycled paper. We hope you enjoy
`reading it.
`
`Madison, March 2017
`
`Natalie Rudolph
`
`MacNeil Exhibit 2154
`Yita v. MacNeil IP, IPR2020-01139, Page 7
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`

`

`Contents
`
`Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`
`V
`
`Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VII
`
`Acronyms and Other Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XIII
`
`1 All About the Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`1.1 Municipal Solid Waste—A Daily Companion . . . . . . . . . . . . . . . . . . . . . . . .
`1.2 Management Methods for Municipal Solid Waste . . . . . . . . . . . . . . . . . . .
`1.2.1 Landfilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`1.2.2
`Incineration with Energy Recovery (Waste-to-Energy) . . . . . . . . .
`1.2.3 Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`
`2 Plastics—Increasing Value, Decreasing Lifetime . . . . . . . . . . . . . .
`
`3 Plastics Recycling—Conservation of Valuable Resources . . . . . .
`3.1 Plastics Recycling Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.1.1 Mechanical Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.1.2 Chemical Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.2 Recycling Different Types of Plastic Waste . . . . . . . . . . . . . . . . . . . . . . . . .
`3.2.1 Preconsumer Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.2.1.1 Manufacturing Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.2.1.2 Dilution Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.2.2 Postconsumer Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.2.2.1 Packaging Plastic Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.2.2.2 Building and Construction Plastic Waste . . . . . . . . . . . . . .
`3.2.2.3 Automotive Plastic Waste . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.2.2.4 Agricultural Plastic Waste . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.2.2.5 Waste from Electrical and Electronic Equipment (WEEE)
`
`1
`1
`3
`4
`5
`7
`
`9
`
`13
`14
`14
`15
`15
`15
`15
`15
`17
`19
`20
`21
`21
`22
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`

`X
`
`Contents
`
`3.3 Sorting Processes for Plastic Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.3.1 Manual Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.3.2 Automated Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.3.2.1 Float-and-Sink Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.3.2.2 Froth-Flotation Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.3.2.3 Near-Infrared Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.3.2.4 X-Ray Fluorescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.3.2.5 Laser-Aided Identification . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.3.2.6 Marker Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.4 Plastic Degradation Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.4.1 Mechanical Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.4.2 Thermal Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.4.3 Thermal Oxidative Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.4.4 Effect of Degradation on Processing and Service-Life Properties
`3.5 Contaminants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`3.6 Conclusion: Technical Feasibility of Plastics Recycling . . . . . . . . . . . . . .
`
`23
`23
`23
`23
`24
`24
`24
`24
`24
`25
`26
`26
`27
`27
`35
`35
`
`4 Economic Analysis of Plastic Waste Handling . . . . . . . . . . . . . . . . 39
`4.1 Fundamentals of Economic Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`39
`4.1.1 Economic Efficiency Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . .
`39
`4.1.2 Static Economic Efficiency Calculation . . . . . . . . . . . . . . . . . . . . . .
`40
`4.1.3 Profit Comparison Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`40
`4.2 Economic Analysis of Landfilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`41
`4.3 Economic Analysis of Incineration with Energy Recovery
`(Waste-to-Energy Facilities) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`4.4 Economic Analysis of Plastics Recycling . . . . . . . . . . . . . . . . . . . . . . . . . .
`4.4.1 Materials Recovery Facility Costs . . . . . . . . . . . . . . . . . . . . . . . . . . .
`4.4.2 Plastic Reprocessing Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`4.4.3 Revenues from Selling Recycled Plastic . . . . . . . . . . . . . . . . . . . . . .
`4.4.4 Profitability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`4.4.5 Oil Price as a Factor in Profitability of Plastics Recycling . . . . . .
`4.5 Conclusion: Economical Feasibility of Plastics Recycling . . . . . . . . . . . .
`
`46
`50
`51
`55
`58
`59
`59
`62
`
`5 Environmental Analysis of Plastic Waste Handling . . . . . . . . . . . 67
`5.1 Environmental Analysis of Landfilling . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`67
`5.2 Environmental Analysis of Incineration with Energy Recovery
`(Waste-to-Energy Facilities) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`5.3 Environmental Analysis of Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`5.4 Conclusion: Environmental Necessity of Plastics Recycling . . . . . . . . . . .
`
`69
`70
`72
`
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`

`

`Contents
`
`XI
`
`6 Optimization of Plastics Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . .
`6.1 Optimization I: Reduction of Sorting Processes . . . . . . . . . . . . . . . . . . . . .
`6.2 Optimization II: Upcycling of Plastic Waste by Blending . . . . . . . . . . . . .
`6.2.1 Additional Costs of LDPE–PP Recycling . . . . . . . . . . . . . . . . . . . . .
`6.2.2 Additional Revenues of LDPE–PP Recycling . . . . . . . . . . . . . . . . . .
`6.2.3 Total Profit of Optimization II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`6.3 Optimization III: Increasing the Recycling Rate . . . . . . . . . . . . . . . . . . . . .
`
`75
`75
`78
`81
`83
`83
`85
`
`7 Plastic Waste of the World: Increasing Potential of Recycling 87
`7.1 Plastic Waste Handling in Europe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`90
`7.2 Plastic Waste Handling in China . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`95
`7.3 Plastic Waste in the Future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
`
`8 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
`8.1 Economic Analysis of Landfilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
`8.2 Economic Analysis of WTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
`8.3 Economic Analysis of Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
`8.4 Optimization I: Reduction of Sorting Processes . . . . . . . . . . . . . . . . . . . . . 112
`8.5 Optimization II: Upcycling of Plastic Waste by Blending . . . . . . . . . . . . . 113
`
`Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
`
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`

`

`Acronyms and Other
`Abbreviations
`
`Abbreviation
`ABS
`ARR
`ASTM
`CCM
`CLF
`DSC
`EPA
`EPS
`GHG
`HDPE
`HIPS
`LDPE
`LFG
`LLDPE
`MFI
`MFR
`MRF
`MSW
`OCC
`PA
`PBT
`PC
`PCM
`PE
`PEEK
`PET
`PLA
`PMMA
`POM
`
`Description
`acrylonitrile butadiene styrene
`average rate of return
`American Society for Testing and Materials
`cost comparison method
`closed loop fund
`differential scanning calorimetry
`U. S. Environmental Protection Agency
`expanded polystyrene
`greenhouse gas
`high-density polyethylene
`high-impact polystyrene
`low-density polyethylene
`landfill gas
`linear low-density polyethylene
`melt flow index
`melt flow rate
`materials recovery facility
`municipal solid waste
`old corrugated cardboard
`polyamide
`polybutylene terephthalate
`polycarbonate
`profit comparison method
`polyethylene
`polyether ether ketone (or polyarylether etherketone)
`polyethylene terephthalate
`polylactide
`polymethyl methacrylate
`polyoxymethylene (polyacetals)
`
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`

`

`XIV
`
`Acronyms and Other Abbreviations
`
`Abbreviation
`PP
`PPE
`PPP
`PRF
`PS
`PTFE
`PU
`PVC
`QA/QC
`RCRA
`rLDPE
`RoM
`rPP
`SAN
`SNCR
`SPP
`UV
`WARM
`WTE
`XPS
`
`Description
`polypropylene
`polyphenylene ether
`purchasing power parity
`plastics recycling facility
`polystyrene
`polytetrafluoroethylene
`polyurethane
`polyvinyl chloride
`quality assurance/quality control
`Resource Conservation and Recovery Act
`recycled low-density polyethylene
`rule of mixtures
`recycled polypropylene
`styrene acrylonitrile
`selective noncatalytic reduction
`static payback period
`ultraviolet
`EPA Waste Reduction Model
`waste-to-energy
`extruded polystyrene
`
`MacNeil Exhibit 2154
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`

`

`3 Plastics Recycling—
`
`Conservation of Valuable
`Resources
`
`Plastics recycling is the term used for reprocessing postconsumer and preconsumer
`plastic waste (manufacturing scrap) into useable products. The idea behind recyc-
`ling is to break down finished products into their component materials and then
`use those materials as feedstock to manufacture new products. Based on the plas-
`tics waste source, the recycling process and the finished product differ. In general,
`plastics can only be reused a limited number of times before they are too degraded
`for further use. Currently, all preconsumer plastic waste is fed back into the plastic
`production stream, but only a little portion of postconsumer plastic waste is re-
`claimed for its original use. However, every bit of plastic that is recycled reduces
`the need for new plastic feedstock and thus decreases the amount of resources and
`energy used for its production.
`Recycling of plastics for use in creating new high-quality plastic products requires
`that the recycled materials are clean and consist of only a single type of plastic. In
`such cases, the recycled plastic substitutes for virgin plastic. The big challenge in
`recycling postconsumer plastics, especially those from mixed (co-mingled and/or
`single) stream collection is that they are often contaminated. Recycling of mixed
`plastics is much more complicated. If the recycled plastics are contaminated and/
`or are a mixture of different types of plastic, the quality of the recycled plastic is
`lower; for example, the plastic may have lower strength. The challenge in manag-
`ing the recycling of large quantities of a mixture of miscellaneous types of contam-
`inated plastics needs to be considered using an integrated approach to source re-
`duction, reuse, and recycling. [1]
`Plastics recycling is more complex than metal or glass recycling because of the
`many different types of plastic. Thus, recyclability and environmental compatibil-
`ity need to be criteria considered at the beginning of the design process of plastic
`products instead of as an afterthought, particularly in many products where sev-
`eral kinds of plastic and sometimes non-plastic components are integrated. The
`separation, recovery, and purification of the plastic components in such a product
`require several steps, which consume additional energy. Unfortunately, the recyc-
`ling rate, the amount of any type of plastic that is recycled in a period of time, is
`
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`

`14
`
`3„Plastics Recycling—Conservation of Valuable Resources
`
`directly related to the price of virgin resins for that type of plastic, which is related
`to the price of oil (see Section 4.4.5). Low oil prices result in low costs for the virgin
`resins. In these times, recycled resins are too expensive to be used by comparison,
`and the recycling rates drop. Therefore, the goal of any sustainable growth in re-
`cyc ling should be the maximization of efficiency of energy utilization in every step
`of the process, from the initial production of plastic goods to the disposal or re-
`covery of plastic wastes. [2]
`
`3.1„Plastics Recycling Methods
`
`There are three common methods for plastics recycling: mechanical recycling (pri-
`mary and secondary recycling) and chemical recycling (tertiary recycling). Based
`on the degree of contamination of the plastics (Section 3.5) with organic or inor-
`ganic substances (other polymers or impurities), one of these three recycling
`methods is chosen. The molecular structure of the plastics as well as existing
`cross-links, such as in thermosets or rubbers, also influence the decision process.
`[3, 4]
`
`3.1.1„Mechanical Recycling
`
`Amongst the recycling methods, mechanical recycling is the most desirable ap-
`proach because of its low cost and high reliability. In general, mechanical recycling
`keeps the molecular structure of the polymer molecule basically intact. After
`grinding of the plastics waste material, the main processing step is remelting of
`the regrind material, which limits the use of mechanical recycling to thermoplastic
`polymers. Since remelting causes a degradation of the polymer chain, virgin mate-
`rial is often mixed with recycled material to reduce the effects of degradation on
`the product properties. The mixing leads to a dilution of the virgin material, which
`is described in Section 3.2.1.2. [5]
`Mechanical recycling is divided into primary and secondary mechanical recycling,
`depending on whether the source of the waste is preconsumer or postconsumer,
`respectively. Preconsumer manufacturing scrap plastic is usually clean and of a
`single type or at least of a known composition and requires no further treatment,
`whereas postconsumer waste is highly contaminated and requires additional steps
`like collecting, sorting, and cleaning.
`
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`3.2 Recycling Different Types of Plastic Waste
`
`15
`
`3.1.2„Chemical Recycling
`
`Chemical recycling is used for cross-linked polymers or for thermoplastic polymers if
`no sufficient quality can be achieved using mechanical recycling. Chemical pro-
`cesses are used to convert the polymer chains to low molecular weight compounds
`or, in some cases, the original plastic monomer (feedstock). The monomers can
`be used for polymerization to generate the original polymer again, whereas the
`low molecular weight compounds are used as feedstock for the petrochemical in-
`dustry. Common processes for this recycling method are hydrolysis, hydrocrack-
`ing, and depolymerization. Because of the large amounts of energy and chemicals
`consumed by these processes, chemical recycling is only economically and eco-
`logically reasonable for a very limited number of polymers such as polymethyl
`methacrylate (PMMA) and polyether ether ketone (PEEK). Chemical recycling of
`polyethylene terephthalate (PET) has been successfully developed. However, it is
`hindered by the processing cost. Furthermore, the chemical processing has been
`proven to be technically possible for polyolefins but is still in the laboratory stage
`of development. [3, 4, 6, 7, 8]
`
`„„ 3.2„ Recycling Different Types of
`Plastic Waste
`
`As mentioned before, plastic waste can be divided into preconsumer waste (manu-
`facturing scrap) and postconsumer waste (recovered waste). These different plastic
`waste types are recycled differently.
`
`3.2.1„Preconsumer Waste
`
`3.2.1.1„Manufacturing Scrap
`Preconsumer waste, such as runners, gates, sprues, and trimming, is normally
` recycled using primary mechanical recycling. It is ground and remelted in-house.
`
`3.2.1.2„Dilution Effect
`Manufacturing scrap is often mixed into virgin material to reduce material cost
`while at the same time minimizing the effects of degradation on part performance.
`Depending on the mixing ratio, either the virgin material is diluted with regrind or
`the regrind is refreshed with virgin material. By using a constant mixing ratio
`during continuous processing, the regrind waste itself is diluted by material that
`
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`16
`
`3„Plastics Recycling—Conservation of Valuable Resources
`
`has been reprocessed once, twice, three times, etc. The composition of a material
`with a proportion of recyclate q after n processing cycles can be calculated using
`Equation (3.1).
`
`
`
`(3.1)
`
`For small proportions of recyclate, the regrind material contains only minimal
`amounts of material that has passed through a large number of processing cycles
`and therefore is highly degraded.
`Figure 3.1 shows the composition of material with different mixing ratios of recy-
`cled and virgin material. The first column shows 30 % recycled and 70 % virgin
`material. Under these conditions, the regrind material contains less than 0.8 % of
`material that has been reprocessed five times or more. Seventy percent of the ma-
`terial is virgin material, 21 % has been processed once, 6.3 % twice, and 1.9 % three
`times. As proportions of material smaller than 1 % do not have a significant in-
`fluence on the material properties and can be neglected [9], the properties will be
`dominated by fractions that have been processed four times or less. Thus, it can be
`concluded that the properties of a material with small amounts of recyclate will not
`fall below a certain level. [10]
`
`Figure 3.1 Composition of recycled plastics material after n reprocessing steps for 30 %, 50 %,
`and 70 % recycled material
`
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`3.2 Recycling Different Types of Plastic Waste
`
`17
`
`However, regrind material with high proportions of recyclate contains significant
`amounts of highly degraded material, as can be seen in the right column in Fig-
`ure 3.1, in which 70 % of the regrind is recycled and 30 % is virgin material. This
`regrind material contains 5.0 % material that has been reprocessed five times, as
`well as 30 % that is virgin material, 21 % that has been processed once, 14.7 % twice,
`10.3 % three times, and 7.2 % four times. After nine processing cycles, the material
`still contains 1.2 % of the initial material. Although this mix contains significant
`portions of highly degraded material, after 10 reprocessing cycles the material
`reaches a steady state in which performance properties are not affected any fur-
`ther by further processing. Therefore, this mixing ratio is used quite frequently for
`packaging products.
`
`3.2.2„Postconsumer Waste
`
`Consumer plastics are largely made from six different polymer resins, which are
`indicated by a number, or resin code, from 1 to 7 molded or embossed onto the sur-
`face of the plastic product. The number 7 indicates any polymer other than those
`numbered 1 to 6. Table 3.1 lists the polymer resins, their resin codes, and the gen-
`eral applications for virgin and recycled plastics made from these resins. The per-
`centages of the different types of postconsumer plastic waste in municipal solid
`waste (MSW) in the United States in 2013 are given in Table 2.1. [11]
`
`Table 3.1 Plastic Types and Products from Virgin and Recycled Materials
`
`Resin Symbol and Plastic
`Type
`
`Products Created from
`Virgin Plastics
`Bottles for water, soft drinks,
`salad dressing, peanut butter, and
`vegetable oil
`
`Products Created from
` Recycled Plastics
`Egg cartons, carpet, and fabric for
`T-shirts, fleeces, tote bags, etc.
`
`Polyethylene terephthalate
`
`High-density polyethylene
`
`Polyvinyl chloride
`
`Milk and juice cartons, detergent
`containers, shower gel bottles,
`and shipping containers
`
`Toys, pails, drums, traffic barrier
`cones, fencing, and trash cans
`
`Packaging materials, plastic
`pipes, decking, wire and cable
`products, blood bags, and medi-
`cal tubing
`
`Shoe soles, construction material,
`and boating and docking bumpers
`
`
`
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`18
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`3„Plastics Recycling—Conservation of Valuable Resources
`
`Table 3.1 Plastic Types and Products from Virgin and Recycled Materials (continued)
`
`Resin Symbol and Plastic
`Type
`
`Products Created from
`Virgin Plastics
`Disposable diaper liners, cable
`sheathing, shrink-wrap, and film
`
`Products Created from
` Recycled Plastics
`Timbers, trash can liners, shop-
`ping envelopes, lumber, and floor
`tiles
`
`Low-density polyethylene
`
`Polypropylene
`
`Polystyrene
`
`All other resins or mixtures
`of resins
`
`Medicine bottles, drinking straws,
`yogurt containers, butter and
`margarine tubs, automotive parts,
`and carpeting
`
`Signal lights, bicycle racks, trays,
`battery cables, and ice scrapers
`
`Egg cartons, cups, food contai-
`ners, plastic forks, and foam
`packaging
`
`Egg cartons, foam packing, and
`light-switch plates
`
`Mixed plastics or multilayer plas-
`tics packaging
`
`—
`
`The chemical composition and function of each resin controls where the resin can
`be recycled as well as the recycling rate. The latter is attributed to the difficulty of
`separating mixed plastic during the recycling process. For example, PET, or resin
`code 1, only accounts for 14.39 % of the total plastic waste but it has the highest
`recycling rate of all resins. Because of its widespread use in transparent drinking
`bottles, PET is easy to identify and sort by transmission detectors.
`Some resins are not compatible with others, because their molecular structures
`repel each other if mixed. This leads to deterioration of the mechanical per form-
`ance of plastic products made from them if they are not engineered properly. Most
`plastics have additives incorporated to achieve certain additional properties such
`as flame retardancy, flexibility, or resistance to ultraviolet (UV) damage. This
`makes it nearly impossible to obtain a homogeneous plastic mixture with uniform
`behavior. Therefore, it is important that the sorting process is well regulated to
`ensure the integrity and overall performance of recycled plastic products.
`Depending on their properties, different plastics are used for different applica-
`tions. Currently, packaging, consumer and institutional products, and building and
`construction materials are the top three uses for plastics. The share of U. S. plastics
`demand by use in 2015 is shown in Figure 3.2. These different applications are
`again represented in the plastic waste. [12]
`
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`3.2 Recycling Different Types of Plastic Waste
`
`19
`
`Figure 3.2 United States plastics demand by use in 2015 [11]
`
`3.2.2.1„Packaging Plastic Waste
`As a result of the demand for plastics, a large share of MSW plastics consists of
`packaging items in which high-density polyethylene (HDPE, 17.16 %), low-density
`polyethylene (LDPE, 22.94 %), and polypropylene (PP, 22.76 %) together account for
`about 63 % of the waste (see Table 2.1). The continuing increase in the use of dis-
`posable packaging has led to increasing amounts of plastics ending up in the waste
`stream. In Europe, where the proportion of plastic waste in the waste stream is
`similar to that in the United States, packaging waste amounts to nearly two