Cover photo: PETE (or PET) is one of the most commonly recycled plastic containers.

Copyright @ 1993, Institute of Scrap Recycling Industries, Inc., 1325 G Street, N. W., Suite 1000, Washington, DC 20005-3104, telephone (202) 466-4050.

Recycled Paper

Plastics Primer It often seems that we cannot live without plastics, yet people did until about 100 years ago when we note the earliest uses for this common material with the introduction of bakelite. Today plastics appear to be everywhere, a circumstance that is not always viewed as positive, given the ever- increasing challenge of what to do with plastic products when we no longer need or want them. Recycling is an emerging and reasonable response to this challenge, but before we can understand what is involved in recycling plastics, we need to understand exactly what plastics are.

Plastics are synthetic materials consisting of molecules called polymers. The polymers that make up plastics are derived from petrochemicals, as compared to natural polymers such as cellulose, starch, and natural rubber. The synthetic polymer that constitutes plastics is a large molecule consisting of a long chain of chemically linked subunits called monomers. All plastics are made of polymers.

Plastics consist of two main classes: thermo- plastics and thermosets. While both classes are fluid enough to be formed and molded during their production stages, once hardened, thermo- sets, unlike thermoplastics, cannot be restored to their fluid state again even with subsequent heating. Thermosets comprise approximately 20 percent of all plastic products manufactured today and are used in many durable goods applications, including automotive. Common examples are reaction injection molded (RIM) polyurethane bumpers and unsaturated polyester (SMC) fenders.

plastics and sell them to fabricating companies that form plastic products in diverse shapes. Polymers are shipped to the fabricators in pelletized, granulated, powdered, film, sheet, or liquid form and are called resins at this stage. Small unpigmented pellets are the predominant resin form for thermoplastics.

Chemical companies produce both classes of

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Although plastics have been around for about a century, the remarkable growth of these useful materials has actually occurred during the past four decades. Today's plastics industry offers myriad complex and sophisticated polymers used in household products as well as many com- mercial applications, including the aerospace industry. On a cost-performance basis, because plastics are relatively inexpensive to produce and offer extreme versatility, they are well suited to meeting many of the needs of industry and consumers alike.

Recycling Scrap Plastics While plastics provide many valuable uses, when they become obsolete or unwanted their presence in the waste stream poses a significant resource recovery challenge. Discarded plastic products account for 20 percent by volume and 8 percent by weight of the municipal solid waste stream, compared with yard waste-10 percent by volume and 18 percent by weight; paper and paper- board-34 percent by volume and 40 percent by weight; and food wastes-3 percent by volume and 7 percent by weight. Nevertheless, the rapid disappearance of landfill space, an expanding consciousness about environmental protection, and a growing recognition of the inherent value of recycling have prompted widespread interest in recycling plastics.

But all plastics are not equally recyclable. Because thermosets, once formed and hardened, do not melt or even soften significantly when heated, they resist remolding and therefore are not considered as well suited to recycling as thermoplastics, which can be recycled by heating and reforming and by chemical processes such as depolymerization back to monomer or other petrochemical feedstocks. When thermosets are recycled, they are most frequently ground to a form that can be used as a filler in new plastics- both thermosets and thermoplastics.

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Th Once the commitment is made to recycle a plastic product, such as a post-consumer plastic container, numerous steps must be taken to complete the recycling loop. These include:

Collection Handling (Separation and Densification) Reclamation End Use or Consumption

~~~~~~t~~~ Collection refers to municipal residential curbside programs where plastic containers are often commingled (mixed) with aluminum and steel cans and glass containers, community drop-off sites, buy-back and deposit redemption.centers, or source-separated office collection programs.

Plastics for recycling are collected from many sources, including municipal residential curbside programs, commercial enterprises such as restaurants and stores, and manufacturing and other industrial operations.

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Commercial enterprises such as restaurants, stores, theaters and stadiums, and similar businesses constitute additional collection sources.

Collection also refers to industrial sources of plastic scrap, which may come from manufac- turers of plastic products that have scrap resulting from the manufacturing processes, such as trimmings from thermoformers and similar leftover materials. Examples include PVC-coated fabric scrap from the manufacture of upholstery and scrap resulting from the manufacture of numerous flexible and rigid containers used by the packaging industry, such as broken or imperfect bottles. The plastics industry refers to this as process scrap. Industrial and commercial plastic scrap can also result from plastic products that have been used by business and industry but are no longer needed. Examples might include plastic pails and buckets, shipping containers, signs, pallets, and wraps.

Handling or Separation and Densification Separation and densification by scrap plastics handlers involve taking collected scrap plastics into a sorting facility where initial processing for recycling begins. This may include inspecting the materials for contaminants, sorting them by generic plastic type, and baling them for shipment to a reclaimer. Baling requires pressing together or densifying large amounts of a particular type of sorted plastic, such as milk jugs, into a large bundle or bale. Sometimes, at this stage, the sorted plastic might be granulated or processed into flakes rather than baled.

Reclamation After receiving the incoming bales and inspecting them, the reclaimer chops, washes, and dries the scrap plastic into flakes, melts or grinds them, and then may pelletize them. The reclaimed plastic is now ready to be sold to a compounder, fabricator, or molder in the same form in which the virgin feedstock might be sold.

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End Use or C ~ n $ u ~ ~ t ~ Q n The end user is any manufacturer who uses the reprocessed plastic as a feedstock. Plastic pellets can be mixed with virgin resin to create a finished product or be used alone, thus completing the recycling loop. It is only when a product manufactured from recycled materials is purchased in the marketplace that true recycling actually occurs. Until this happens, only collection and processing of the recyclable material have taken place. Thus, to expand plastics recycling, it is essential to develop new markets for recycled plastic products.

Identifying Scrap Plastics To help ensure that successful commercial plastics recycling occurs, buyers and sellers of scrap plastics are currently developing a common language to identify the scrap correctly. The Institute of Scrap Recycling Industries, Inc. (ISRI) and the Society of the Plastics Industry (SPI), through its American Plastics Council (APC), have published commercial guidelines for sorting plastic scrap bottles. These guidelines, though only a beginning, are structured to provide for the potential recycling of all scrap plastics. They identify the following material attributes of the scrap:

Type of resin Contamination Product Hazardous materials Product category Moisture

Storage Source General Bale properties

Type

To facilitate the identification of individual bottles and other types of rigid plastic containers for recycling, the plastics industry has also introduced a voluntary numerical coding system. The codes generally are molded into or imprinted on the base of containers and feature an easy-to-read number inside a triangle formed by three arrows. Although the coding system is voluntary, at least 36 states have passed laws that require coding of plastic bottles 16 ounces or larger and plastic containers 8 ounces or larger.

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While this coding system can facilitate plastics recycling, it is important to understand that the presence of a code on any plastic container does not mean that a market exists for the recycled material or even that the product is being or will be recycled. Like all other scrap commodities, the demand for scrap plastics is totally dependent on the market’s interest in purchasing and using the material to manufacture new products. If any scrap material, including plastics, is not returned to the marketplace in the form of a new product, recycling does not occur.

A voluntary numerical coding system molded into or Imprinted on the base of plastic containers is a recent attempt to facilitate recycling of rigid plastic containers.

Plastics Coding System Code Plastic Container Type

6 PETE (or PET)

6 HDPE

6 V (vinyl/polyvinyl chloride) (PVC)

PETE

HDPE

V

LDPE LDPE

6 PP PP

&3 PS PO a Other

OTHER

Source: The Society of the Plastics Industry, Inc.

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Plastic Containers PETE or PET (Polyethylene Tere~h~halate) PETE, a commonly recycled household plastic material, represents approximately 30 percent of the plastic bottle market and is used to package a wide variety of food and beverage products such as soft drinks, juices, edible oils, liquor, and peanut butter. PETE is valued for its clarity, toughness, and ability to resist permeation by carbon dioxide.

Products made from recycled PETE include carpets, insulating material in garments and sleeping bags (fiberfill), strapping, bottles and containers, scouring pads, auto parts, paint brushes, geotextiles such as landfill liners, and industrial paints.

HDPE and LDPE ( P o l y e ~ ~ y ~ e n e ) Polyethylene, the most widely used household plastic, is a family name that includes such specific plastics as HDPE (High Density Polyethylene) and LDPE (Low Density Polyethylene).

ease of forming, and resistance to breakage. It is used to bottle milk, water, juices, bleach, detergents, and motor oil. It is also used to make margarine tubs and grocery sacks.

Recycled products made from HDPE include detergent and engine oil bottles, trash cans, recycling bins, soft drink bottle base cups, drainage pipes, animal pens, drums and pails, matting, milk bottle carriers, industrial pallets, bathroom stalls, plastic lumber, traffic barrier cones, flower pots, golf bag liners, kitchen drain boards, and hair combs.

LDPE is widely used in applications requiring clarity and processing ease. Its most common use is as film for sacks, shrink wrap, stretch wrap, and trash bags.

When recycled, LDPE can be used to make most of the products made from virgin LDPE.

HDPE is characterized by its rigidity, low cost,

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Vinyl or PVC (Polyvinyl Chloride) Because of its blending capability, polyvinyl chloride-commonly called either vinyl or PVC- can be used to manufacture commercial products including heavy-walled pressure pipes, windows, doors, as well as crystal-clear food packaging, particularly bottles for cooking oils, water, household chemicals, food wraps, and health and beauty aids. Its properties include good clarity and chemical resistance.

make drainage pipes, fencing, handrails, house siding, tiles, sewer pipe, traffic cones, garden hoses, and drains.

Recycled polyvinyl chloride can be used to

PP (Polypropylene) Polypropylene or PP is resistant to chemicals, heat, and fatigue. Consequently, it is widely used in many applications ranging from the manufacture of fibers and films to food packaging such as screw-on caps and lids, some yogurt and margarine tubs, juice bottles which can be filled hot, and drinking straws. Polypropylene has long been used as the primary material for the manufacture of automotive battery cases because it is lightweight, durable, and cost-effective.

Products made from recycled PP, as well as . potential markets for it, include auto parts, new automotive battery cases, bird feeders, furniture, pails, water meter boxes, bag dispensers, golf equipment, carpets, refuse and recycling containers, grocery cart handles, and industrial fibers.

Polystyrene (PS) Polystyrene is a versatile resin with a range of physical properties that include thermoforming- an ability to form and foam-and relative ease of processing. While it is one of the least-used plastics for household packaging, it is used in some yogurt cups, egg cartons, and meat trays. In its high- impact form, it is commonly used for thermo- formed signs and is foamed for fast-food packaging and institufional dining products such as hot and cold drinking cups, plates, and boxes.

Products made from recycled polystyrene include insulation board, office and desk accessories, household products, license plate frames, packing "peanuts," waste baskets, videotape cassettes, and reusable cafeteria trays.

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Products that can be made from recycled plastics include paint brushes, carpets and mats, film wraps, scouring pads, and automotive components.

Other Plastics The category referred to as "other" plastics consists of high performance plastics, frequently in the form of composites, that are used in automotive and other durable goods applications. They are called composites because the plastic resin is combined with fiber reinforcements and/or fillers. These plastics represent a significant recycling challenge because products made from the recycled mixed material tend to have poor physical properties; they are often brittle because most polymers are incompatible and do not chemically adhere to each other. Generally, the greater the number of plastic components in a blend, the poorer are its properties.

Few products are currently being manufactured from recycled multi-material plastics, although limited ways do exist to improve the mechanical properties of products made from mixed plastics.

While recycling of composite plastics is currently extremely limited, when recycled, such plastics might be used to make landscaping lumber, farm animal pens, roadside posts, industrial pallets, marine pilings, benches, and picnic tables. The lack of any significant recycling of this material reflects the current need to subsidize such activity to be cost-effective.

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Other Plastic Resins In addition to the commodity-grade thermo- plastics described above, other thermoplastics, termed intermediate, engineering, and advanced resins, exhibit unique characteristics and may be found in a myriad of products from computer housings to automobile bumpers and dashboards. For example, polycarbonate, an engineering thermoplastic, is being recycled and can be melt- processed using all the traditional methods for thermoplastics, such as injection molding, extrusion, and blow molding.

What Is the Institute of Scrap Recycling Industries? The Institute of Scrap Recycling Industries, Inc. (ISRI), the trade association of the private recycling industry, represents 1,800 member companies that process, broker, and consume scrap commodities including ferrous and nonferrous metals, paper, plastics, glass, rubber, and textiles. Suppliers of equipment and services to this industry complete ISRI's membership.

Many ISRI member companies are family- owned businesses, some in continuous operation for 100 years or more. Thus, ISRI members are often described as The Original RecyclersTM. Other members are large publicly traded or privately held corporations. All are experts in the handling, processing, shipping and/ or ultimate recycling of scrap commodities and can assist communities and organizations in the planning, establishment, and implementation of recycling activities. Because they are experts in resource recovery, their experience and handling capabilities can save countless public and private hours and dollars in developing effective approaches to resource recovery.

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Bale. A large bundle, usually rectangular, of compressed or densified recyclable materials such as plastic beverage bottles.

Buyback Centers. Locations where consumers can drop off recyclables and receive payment for them.

Commercial Scrap. Recyclables that result from business sources such as restaurants, stores, theaters, stadiums, airlines, trains, demolition companies, and similar enterprises.

Curbside Recycling. A process of collection in which separated or commingled recyclables are set out in containers at residents' curbsides for pickup.

Densification. The process of packing recyclables closely together, such as in a bale, to facilitate shipping and processing.

Drop-off Centers. Locations where discards can be left for recycling.

End User or Consumer. An industrial plant or other facility where recyclables are used as feedstock for the manufacture of new products.

Handler. A'company that performs at least one of the following processes on plastics collected for recycling: sorting, baling, shredding, or granulating.

Industrial Scrap. Recyclables generated by manufacturing processes, such as trimmings and other leftover materials, or recyclable products that have been used by industry but are no longer needed, such as buckets, shipping containers, signs, pallets, and wraps.

Municipal Solid Waste. The combined residential and commercial waste material generated in a given municipal area.

Process Scrap. Residues from plastics manufactur- ing processes, such as trimmings, etc., that are reused in manufacturing; also called home scrap.

Reclaimer. A company that performs at least one of the following processes on plastics collected for recycling: washing/ cleaning, pelletizing, or manufacturing a new product.

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Recycling. The practice of collecting, separating, and processing scrap materials diverted or removed from the solid waste stream to be used as feedstock for new products that otherwise would have been produced using virgin materials.

Sanitary Landfill. An area where waste is dumped, then buried beneath a layer of earth. Landfills are usually equipped with a liner to reduce soil and water pollution from contami- nating seepage.

Source Separation. Any method that separates recyclables from waste at the point at which they are generated. Such methods include curbside collection, buyback programs, and drop-off programs.

Virgin Materials. Any basic materials for industrial processing that have not been previously used, such as petroleum for plastics manufacture, iron ore for steel manufacture, wood pulp for paper manufacture, or bauxite ore for aluminum manufacture.

Waste Stream. The total waste material output of a community, region, facility, private residence, etc.

For additional information on scrap processing and recycling, send this coupon, together with a self-addressed business-size envelope, to: Public Relations Dept., Institute of Scrap Recycling Industries, Inc. 1325 G Street, N.W., Suite 1000 Washington, DC 20005-3104

Check the box of each publication you would like to receive.

0 Recycling Scrap Iron and Steel 0 Recycling Nonferrous Scrap Metals 0 'Recycling Paper

Design for Recycling@ What Is Recycling? Why Do Community Recycling Programs Sometimes Fail?

0 Recycling Scrap Materials Contributes to a Better Environment

0 Recycling: The Economic and Environmentally Intelligent Alternative to Landfilling and Incineration

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