Recycled Plastics in Infrastructure: Current Practices, Understanding, and Opportunities (2023)

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Appendix J Overview of Plastics by Resin Identification Code (RIC) RIC 1: POLYETHYLENE TEREPHTHALATE (PET OR PETE) • Properties:   Tough and strong.  Clear and good barrier properties. Can make optically smooth bottle sidewalls.  High melting point (>225°C to 255°C). Products usually crystalline.  Relatively high service temperature (150°C/302°F when crys- tallized) (glass transition temperature 73°C/163°F).  At room temperature, good chemical resistance.  Sinks in water. • Uses:  About two-thirds used for filament and staple fiber for apparel, carpet, and furnishing.  About one-third used for food and non-food bottles, cups, and thermoforms.  Also used for films (including Mylar films), strapping, and rope. • Recycle:  2018 U.S. post-consumer recycling rate for PET bottles and jars was 29.1 percent.  18.5 percent recycling rate overall for all PET (PET carpet sometimes recycled). 367

368 RECYCLED PLASTICS IN INFRASTRUCTURE  Recycled PET used for food and non-food containers, carpet, apparel, strapping. • Production volume, consumed in the United States:   Per the U.S. Environmental Protection Agency (USEPA), 5.290 million tons, 14.8 percent of all plastics.  • Comments:   Of the first six polymer types, this is the only condensation polymer.  Can be quantitatively depolymerized to monomers.  Recycle can be repolymerized as a solid (no need to melt).  Bottle PET actually a copolymer. Other copolymers often not PET.  In spite of name, not chemically related to polyethylene.  Hygroscopic and must be desiccant-dried before melting or PET degrades.  Recycled PET widely included in food and beverage packaging, which is mandated in several state laws (California, Washing- ton, New Jersey) RIC 2: HIGH-DENSITY POLYETHYLENE (HDPE)  • Properties:   Tough and strong.  White (non-clear) and good water barrier properties, fair gas barrier properties.  Modest melting point (131°C/268°F). Crystalline.  Modest service temperature (71°C/160°F).  At room temperature, good chemical resistance.  Floats in water. • Uses:  Bottles, caps, bags, pipe, geomembrane, toys, house wrap. • Recycle:  2018 U.S. post-consumer recycling rate for HDPE packaging was 14.8 percent, 8.9 percent recycling rate overall for all HDPE.  Recycled HDPE packaging used for pipe and new bottles. • Production volume, consumed in the United States:   Per USEPA, 6,380 million tons, 17.7 percent of all plastics.  • Comments:   An addition polymer, not chemically related to PET. An olefinic polymer.  Can be depolymerized by pyrolysis to small chemicals.

APPENDIX J 369  Recycled pellets cannot be repolymerized.  Bottle HDPE either natural (no copolymer) or copolymer (usu- ally colored), natural and copolymer are interchangeable.  Need not be desiccant-dried before melting.  Subject to state mandates for recycled content in packaging. Limited approvals by U.S. Food and Drug Administration (FDA) for recycled HDPE in food contact. RIC 3: POLYVINYL CHLORIDE (PVC) • Properties:   Neat PVC is brittle, toughened and made flexible by plasticiz- ers and other additives, often to levels of 40 percent.  Can be clear and fair barrier properties.  Always amorphous, no fixed melting point.  Processing temperature 140°C/284°F to 185°C/365°F  Relatively low service temperature (60°C/140°F).  At room temperature, excellent chemical resistance.  Sinks in water.  Does not support flames. • Uses:  Windows and siding, conduit, pipe, gutters, furniture, bottles, flooring, toys, wire insulation, and health care. • Recycle:  2018 U.S. post-consumer recycling rate for PVC was negligible. • Production volume, consumed in the United States:   Per USEPA, 0.84 million tons, 2.4 percent of all plastics.  • Comments:   An addition polymer.  Presence of corrosive chlorine makes unwelcome for pyroly- sis.  Recycled pellets cannot be repolymerized.  PVC needs stabilizers; lead was used, which makes old PVC unwanted for recycling.  Need not be desiccant-dried before melting.  Subject to state mandates for recycled content in packaging. No approvals by FDA for recycled PVC in food contact.  Globally, third most produced plastic after polyethylene and polypropylene.

370 RECYCLED PLASTICS IN INFRASTRUCTURE RIC 4: LOW-DENSITY POLYETHYLENE (LDPE) AND LINEAR LOW- DENSITY POLYETHYLENE (LLDPE) • Properties:   Almost always a flexible film. Stretchable, unlike crystalline HDPE films.  Clear, good water barrier properties, and fair gas barrier properties.  Modest processing temperature (160°C/320°F to 220°C/428°F).  Amorphous.  Modest service temperature (71°C/160°F).  At room temperature, good chemical resistance except for halogenated hydrocarbons, such as chloroform.  Floats in water. • Uses:  Films, stretch wrap, flex pipe, bags, cable covering, pouches, lids, and laminates. • Recycle:  2018 U.S. post-consumer recycling rate for LLDPE/LDPE packaging was 9.9 percent, 4.3 percent recycling rate overall for all LLDPE/LDPE. • Production volume, consumed in the United States:   Per USEPA, 8,590 million tons, 24 percent of all plastics.  • Comments:   An addition polymer, not chemically related to PET. An olefinic polymer.   Different in structure than HDPE.   Can be depolymerized by pyrolysis to small chemicals, includ- ing ethylene.   Recycled pellets cannot be repolymerized. Small-chemical eth- ylene can be repolymerized.  Lacks collection infrastructure for collection from public for recycling.  Need not be desiccant-dried before melting.  Subject to state mandates for recycled content in packaging. Very limited approvals by FDA for recycled LDPE in food contact. RIC 5: POLYPROPYLENE (PP) • Properties:   Tough and strong. Resists fatigue failure (“living hinge”).

APPENDIX J 371  Clear and good water barrier properties, fair gas barrier properties.  High melting point (164°C/327°F). Can be crystalline or amorphous.  Robust service temperature (can be 82°C/180°F).  At room temperature, good chemical resistance.  Floats in water. • Uses:  Injection moldings (toys, caps, containers) and extrusions (bot- tles, films [both oriented and unoriented], labels, filaments, and non-wovens, carpet). • Recycle:  2018 U.S. post-consumer recycling rate for PP packaging was 2.7 percent, 0.6 percent recycling rate overall for all PP. • Production volume, consumed in the United States:   Per USEPA, 8,150 million tons, 22.8 percent of all plastics.  • Comments:   An addition polymer. An olefinic polymer.  A highly versatile plastic that can be used as a replacement for other plastics for many applications.  Not the most inexpensive plastic or the most chemically stable without additives.  Can be depolymerized by pyrolysis to small chemicals.  Recycled pellets cannot be repolymerized. Small-chemical pro- pylene can be repolymerized.  Need not be desiccant-dried before melting.  Subject to state mandates for recycled content in packaging. Limited approvals by FDA for recycled PP in food contact. RIC 6: POLYSTYRENE (PS) • Properties:  Clear, hard, and stiff. Brittle unless modified.  White (non-clear) and poor water and gas barrier properties.  Modestly high melting point (185°C/365°F to 240°C/464°F). Usually amorphous.  Modest service temperature (100°C/212°F).  Dissolves in many non-aqueous solvents.  Sinks in water. • Uses:  Packing dunnage, foams, containers, lids, bottles, trays, tum- blers, and disposable cutlery.

372 RECYCLED PLASTICS IN INFRASTRUCTURE • Recycle:  2018 U.S. post-consumer recycling rate for PS packaging was 3.6 percent, 0.9 percent recycling rate overall for all PS. • Production volume, consumed in the United States:   Per USEPA, 2,260 million tons, 6.3 percent of all plastics.  • Comments:   An addition polymer.  Can be depolymerized by pyrolysis to small chemicals, includ- ing styrene.   Recycled pellets cannot be repolymerized. Styrene from pyroly- sis can be repolymerized to PS.  Need not be desiccant-dried before melting.  Subject to state mandates for recycled content in packaging. Limited approvals by FDA for recycled PS in food contact. RIC 7: OTHER RESINS This resin category refers to other polymers, a blend of plastics, or multi- layers of materials.  • Properties:   Variable • Uses:  Variable • Recycle:  2018 U.S. post-consumer recycling rate for “Other resins” was 26.7 percent. (USEPA does not specify the plastics.) • Production volume, consumed in the United States:   Per USEPA, 4.160 million tons, 14.8 percent of all plastics.  • Comments:   Can include nylons, ABS, polyurethanes, and others.