Polymer and Composite

Unfortunately the majority of this plastic ends up in landfills. When plastic is dumped into landfills the decomposition process can take anywhere from 10 to 30 years.

Recycling has therefore become a reasonable solution to the landfill problem.

There are five factors that are necessary in order for the recycling of plastic to be a successful process. First, the supply of used plastic has to be of a large quantity. This large quantity of plastic is collected at certain areas, which is the second step. Once the plastic is collected, the sorting and separating process begins; this is the third step in the process. The sorting and separating process depends upon the type of polymers that make up the plastic. Plastic products are given codes to help the sorting and separating process. The fourth step in plastic recycling is reprocessing. The reprocessing of polymers includes the melting process, the melting process can be accomplished if the polymers have not been widely cross-linked with any synthetics. If the cross-linking of polymers contain too many synthetics, the polymers will be difficult to stretch and less pliable. The final step is the manufacturing of the melted plastic into new products.

The codes on plastic recyclable containers are what help most in the sorting and separating process. The six categories of plastics are separated into two areas: polyethelyne plastics and polymer plastics. The polyethelyne plastics are labeled HDPE, for high density polyethelyne; or LDPE, for low density polyethelyne. The four polymer plastics that are recycled include polyvinyl chloride, labeled V; polystyrene, labeled PS; polypropylene, labeled PP; and polyethylene terephthalate, labeled PETE. These names and labels can seem confusing, but they are a necessity in the recycling process.

There are four types of recycling processes that usually occur: primary, secondary, tertiary, and quaternary. The primary recycling process is recycling materials and products that contain similar features of the original product. This process is only feasible with semi-clean industrial scrap plastics, therefore this process is not widely used. Secondary recycling allows for a higher mixture of combination levels in plastics. When the secondary process of recycling is used it creates products such as fenceposts and any products that can be used in the substitution of wood, concrete, and metal. The low mechanical properties of these types of plastics are the reason why the above products are created. Tertiary recycling is occurring more and more today because of the need to adapt to the high levels of waste contamination. The actual process involves producing basic chemicals and fuels from plastic. The last form of recycling is the quarternary process. This quarternary process uses the energy from plastic by burning. This process is the most common and widely used in recycling. The reason this process is widely used is because of the high heat content of most plastics. Most incinerators used in the process can reach temperatures as high as 900 to 1000 degrees Celsius. For the sake of the environment the new techniques being used with the incinerators have decreased the amount of air pollutants being released.

The use of incineration in the quarternary process is most beneficial because through the high temperature heating process the incoming waste is reduced by 80% in weight and 90% in volume. The materials left over form this process are then placed in landfills.

A current promotional program sponsored by the plastics industry emphasizes the positive contributions that plastics make.
And claims listed in those advertisements are accurate.

But as shown in the article on the preceding page, the largest single use for plastics is packaging. Because packaging has a short lifespan, it makes up a large portion of the plastics waste stream. But where does that “waste stream” lead?

In general, the Environmental Protection Agency says that in the early 1990s about 80 percent of all municipal solid waste was sent to landfills, 10 percent was incinerated and 10 percent was recycled. While more and more plastic is being recycled, the EPA estimates that plastics make up about 20 percent of the solid waste that is landfilled.

Most consumers think that the slow degradation of plastics is the primary reason that plastics should be recycled. However, research has shown that other waste, such as paper, wood and food wastes, also degrade very slowly in landfills.

The more serious problem with plastic waste concerns the additives contained in plastics. These additives include colorants, stabilizers and plasticizers that may include toxic components such as lead and cadmium. Studies indicate that plastics contribute 28 percent of all cadmium in municipal solid waste and about 2 percent of all lead. Researchers don’t know whether these and other plastic additives contribute significantly to products leached from municipal landfills.

How toxic are plastics that are burned? Researchers don’t know that, either. Plastics that contain heavy-metal-based additives may also contribute to the metal content of incinerator ash. The EPA is looking for substitutes for lead- and cadmium-based additives.

One additional concern relates to use of petroleum products. All plastics began their lives as petroleum. By increasing plastics recycling, scientists and engineers are able to reduce dependence on petroleum.

PVC is used for packaging and other short-life consumer products, furnishings and long-life goods, mostly construction material such as window frames and pipes. Short-life products, disposed of within a few years, have caused serious PVC waste problems, especially when incinerated. The average life span of the long life products is around 34 years. Long-life PVC goods produced and sold since the 1960s are now just starting to enter the waste stream. We are now only seeing the first stages of an impending PVC waste mountain.

There are currently over 150 million tonnes of long-life PVC materials in existence globally, used mostly in the construction sector, which will constitute this waste mountain in coming decades. Taking into account the ongoing growth in production, by the year 2005 this amount will double and the world will have to deal with approximately 300 million tonnes of PVC starting to enter the waste stream. The amount of PVC waste arising in industrialised countries is already expected to grow faster than PVC production. Of even more concern is the fact that the PVC industry is rapidly expanding in Latin America and Asia, so that eventually a growing waste mountain will be generated in these parts of the world.

In the late 1980s, PVC recycling was promoted by the vinyl industry in order to make PVC more acceptable to the public and to prevent government action to limit PVC production and use. As a result, the general public and decision-makers are now accepting recycling as a technical solution to the environmental problems associated with PVC. This is especially the case in countries with advanced recycling policies, like Denmark, Germany, the Netherlands and the USA.

Independent research shows that by the year 2005, it will only be possible to mechanically recycle 15-30% of PVC consumed, and at a very high cost. It is virtually impossible to separate, collect and recycle the remaining 70-85%. Thus for 70-85% of PVC waste, recycling is not even an option for the mid- to long-term. A major problem in the recycling of PVC is its high chlorine content of raw PVC - 56% of the polymer’s weight - and the high levels of hazardous additives added to the polymer to achieve the desired material quality. Additives may comprise up to 60% of a PVC product’s weight. Of all plastics, PVC uses the highest proportion of additives.

As a result, PVC requires separation from other plastics and sorting before mechanical recycling. PVC recycling is particularly problematic because of high separation and collection costs, loss of material quality after recycling, the low market price of PVC recyclate compared to virgin PVC and, therefore, the limited potential of recyclate in the existing PVC market. Feedstock recycling of PVC is hardly feasible at present, from an economic or an environmental perspective, and it is doubtful whether it will ever play a significant role in PVC waste management. The PVC industry seems to acknowledge that PVC recycling is no solution for PVC waste and it therefore is not surprising that industry is now lobbying for PVC incineration as a recovery option (for energy, hydrochloric acid and/or salt) in Western Europe and Japan and for landfilling in the USA and Australia. This forces local authorities to shoulder the burden of pollution and costs from PVC consumption.

Incineration is not a sustainable option for dealing with waste. Less energy is generated from burning the plastic than was used to make it, and incineration also means that the carbon contained within it is emitted as CO2 - a greenhouse gas. Toxic substances are also emitted, and large amounts of solid wastes are produced as slag, ash, filter residues and neutralisation salt residues. Part of this needs to be disposed of as hazardous waste.

Despite these concerns, PVC production is still increasing, especially in developing economies where PVC consumption is being encouraged. PVC waste is exported from the USA, Europe and Australia to developing countries, often for recycling into lower quality products such as shoes and low quality pipes, or ‘downcycling’. According to the Indonesian Environment Minister, up to 40% of the plastic waste imported into Indonesia is not recycled but directly disposed of, partly as hazardous waste. Downcycled products will eventually be dumped or burned since downcycling simply delays the inevitable need to dispose of PVC plastic waste. In light of the large volume of long-life PVC products due to become waste in the coming decades, and the projected increase in PVC production, it becomes apparent that an international PVC phase-out is urgently required. Only this will put a halt to a growing, dangerous and intractable waste problem.

Political frameworks for PVC phase-outs already exist. The North Sea Ministers Conference agreed in 1995 to stop environmental emissions of hazardous substances within one generation. According to the Swedish Chemical Committee, PVC has no place in a sustainable society and should be phased out for all uses by the year 2007. Denmark has proposed restrictions on the use of softeners, lead and other additives used in PVC plastic and is questioning the recycling potential claimed by the PVC industry. The Czech Republic agreed to phase-out production, imports and use of PVC packaging from 2001 onwards and Switzerland has banned PVC drinking bottles in 1991.

POLYETHYLENE TEREPHTHALATE

Polyethylene terephthalate (PET), or polyethylene terephthalic ester (PETE), is a condensation polymer produced from the monomers ethylene glycol, HOCH₂CH₂OH, a dialcohol, and dimethyl terephthalate, CH₃O₂C–C₆H₄–CO₂CH₃, a diester. By the process of transesterification, these monomers form ester linkages between them, yielding a polyester. PETE fibers are manufactured under the trade names of Dacron and Fortrel. Pleats and creases can be permanently heat set in fabrics containing polyester fibers, so-called permanent press fabrics. PETE can also be formed into transparent sheets and castings. Mylar is a trade name for a PETE film. Transparent 2-liter carbonated beverage bottles are made from PETE. (The opaque base on some bottles is generally made of HDPE.) One form of PETE is the hardest known polymer and is used in eyeglass lenses.

POLYETHYLENE

Polyethylene is perhaps the simplest polymer, composed of chains of repeating –CH₂– units. It is produced by the addition polymerization of ethylene, CH₂=CH₂ (ethene). The properties of polyethylene depend on the manner in which ethylene is polymerized. When catalyzed by organometallic com pounds at moderate pressure (15 to 30 atm), the product is high density polyethylene, HDPE. Under these conditions, the polymer chains grow to very great length, and molar masses average many hundred thousands. HDPE is hard, tough, and resilient. Most HDPE is used in the manufacture of containers, such as milk bottles and laundry detergent jugs. When ethylene is polymerized at high pressure (1000–2000 atm), elevated temperatures (190–210°C), and catalyzed by peroxides, the product is low density polyethylene, LDPE. This form of polyethylene has molar masses of 20,000 to 40,000 grams. LDPE is relatively soft, and most of it is used in the production of plastic films, such as those used in sandwich bags.

POLYVINYL CHLORIDE

Polymerization of vinyl chloride, CH₂=CHCl (chloroethene), produces a polymer similar to polyethylene, but having chlorine atoms at alternate carbon atoms on the chain. Polyvinyl chloride (PVC) is rigid and somewhat brittle. About two-thirds of the PVC produced annually is used in the manufacture of pipe. It is also used in the production of “vinyl” siding for houses and clear plastic bottles. When it is blended with a plasticizer such as a phthalate ester, PVC becomes pliable and is used to form flexible articles such as raincoats and shower curtains.

POLYPROPYLENE

This polymer is produced by the addition polymerization of propylene, CH₂=CHCH₃ (propene). Its molecular structure is similar to that of polyethylene, but has a methyl group (–CH₃) on alternate carbon atoms of the chain. Its molar masses falls in the range 50,000 to 200,000 grams. Polypropylene (PP) is slightly more brittle than polyethylene, but softens at a temperature about 40°C higher. Polypropylene is used extensively in the automotive industry for interior trim, such as instrument panels, and in food packaging, such as yogurt containers. It is formed into fibers of very low absorbance and high stain resistance, used in clothing and home furnishings, especially carpeting.

POLYSTYRENE

Styrene, CH₂=CH–C₆H₅, polymerizes readily to form polystyrene (PS), a hard, highly transparent polymer. The molecular structure is similar to that of polypropylene, but with the methyl groups of polypropylene replaced by phenyl groups (–C₆H₅). A large portion of production goes into packaging. The thin, rigid, transparent containers in which fresh foods, such as salads, are packaged are made from polystyrene. Polystyrene is readily foamed or formed into beads. These foams and beads are excellent thermal insulators and are used to produce home insulation and containers for hot foods. Styrofoam is a trade name for foamed polystyrene. When rubber is dissolved in styrene before it is polymerized, the polystyrene produced is much more impact resistant. This type of polystyrene is used extensively in home appliances, such as the interior of refrigerators and air conditioner housing. [For more information about this polymer, see Chemical Demonstrations: A Handbook for Teachers of Chemistry, by Bassam Z. Shakhashiri, Volume 1 (1983), page 241.]

POLYTETRAFLUOROETHYLENE

Teflon is a trade name of polytetrafluoroethylene, PTFE. It is formed by the addition polymerization of tetrafluoroethylene, CF₂=CF₂ (tetrafluoroethene). PTFE is distinguished by its complete resistance to attack by virtually all chemicals and by its slippery surface. It maintains its physical properties over a large temperature range, -270° to 385°C. These properties make it especially useful for components that must operate under harsh chemical conditions and at temperature extremes. Its most familiar household use is as a coating on cooking utensils.

POLYURETHANE

This important class of polymers is formed by the addition polymerization of an diisocyanate (whose molecules contain two –NCO groups) and a dialcohol (two –OH groups). The polymer chain is linked by urethane groups (–O–CO–NH–). The –NH– portion of the urethane group can react similarly to an –OH group, producing cross-linking between polymer chains. Polyurethane is spun into elastic fibers, called spandex, and sold under the trade name Lycra. Polyurethane can also be foamed. Soft polyurethane foams are used in upholstery, and hard foams are used structurally in light aircraft wings and sail boards. The formation of some polyurethane (and polystyrene) foams exploits the exothermic nature of the polymerization reaction. A liquid with a low boiling point, called a blowing agent, is added to the monomers before the polymerization starts. As the polymerization proceeds, it releases enough heat to boil the liquid. The boiling liquid produces bubbles that create a foam. In the past, the most commonly used low-boiling liquids were chlorofluorocarbons. However, the damaging effect of chlorofluorocarbons on the stratospheric ozone layer has eliminated their use. Other low-boiling liquids have other disadvantages, such as flammability. Therefore, most polyurethane and polystyrene foams are manufactured by forcing a pressurized gas, such as nitrogen or carbon dioxide, into the polymerizing mixture. [For more information about this polymer, see Ibid., Volume 1, page 216.]

POLYAMIDE

Polyamides are a group of condensation polymers commonly known as nylon. Nylon is made from two monomers, one a dichloride and the other a diamine. One particular nylon is made from 1,6-diaminohexane, NH₂(CH₂)₆NH₂ and sebacoyl chloride, ClCO(CH₂)₈COCl. When these polymerize, the resulting molecules contain repeating units of –NH(CH₂)₆NH–CO(CH₂)₈CO–. Molecules of HCl are released during the polymerization. This particular polymer is called nylon 6-10 because it contains alternating chains of 6 and 10 carbon atoms between nitrogen atoms. Nylon can be readily formed into fibers that are strong and long wearing, making them well suited for use in carpeting, upholstery fabric, tire cords, brushes, and turf for athletic fields. Nylon is also formed into rods, bars, and sheets that are easily formed and machined. In this form, nylon is used for gears and for automobile fuel tanks. [For more information about this polymer, see Ibid., Volume 1, page 213.]

POLYACRYLAMIDE

Polyacrylamide is a condensation polymer with an unusual and useful property. The structure of polyacrylamide is similar to that of polyethylene, but having a hydrogen on every other carbon replace by an amide group, –CONH₂. The molecule is composed of repeating –CH₂–CH(CONH₂)– units. The amide groups allow for linking between polymer strands. The –CONH₂ group from one molecule can react with the same group of another molecule, forming a link between them with the structure –CONHCO–. This produces a network of polymer chains, rather like a tiny sponge. The free, unlinked amide groups, because they contain –NH₂ groups, can form hydrogen bonds with water. This gives the tiny cross linked sponges a great affinity for water. Polyacrylamide can absorb many times its mass in water. This property is useful in a variety of applications, such as in diapers and in potting soil. The polyacrylamide will release the absorbed water if a substance that interferes with hydrogen bonding is added. Ionic substances, such as salt, cause polyacrylamide to release its absorbed water. [For more information about this polymer, see Ibid., Volume 3 (1989), page 368.]

& .

General Rules

1. Remove and discard all lids or caps.
2. Rinse all containers.
3. Remove and discard sprayer tops.
4. CRUSH all plastic bottles to save space.
5. No 5 gallon pails.
6. No containers with metal handles.

What can be Recycled?

Plastic Code Number

Recyclable Containers

Soda Bottles
Water Bottles
Juice Bottles
Cooking Oil Bottles
Soap/Detergent Bottles
Shampoo Bottles
Clear Liquor Bottles
Food Jars (Peanut Butter etc.)

Plastic Code Number
Recyclable Containers

Milk Bottles
Water Bottles
Juice Bottles
Cooking Oil Containers
Windshield Washer Fluid Bottles
Shampoo Bottles
Butter/Margarine Tubs
Cottage Cheese Containers
Ice Cream Containers Without Metal Handles
Baby Wipe Containers

Do NOT Recycle This Plastic

• Motor Oil Bottles
• Anti-Freeze Containers
• Gasoline and Oil Additive Bottles

3. All Containers Marked With The Following Codes:

Uncoded Plastics

Plastic consumer goods not identified by code numbers are not usually collected. Plastic tarps, pipes, toys, computer keyboards, and a multitude of other products simply do not fit into the numbering system that identifies plastics used in consumer containers. There are actually thousands of different varieties of plastic resins or mixtures of resins. These are developed to suit the needs of particular products. There is limited recycling of some of these specific plastic products in truckload quantities from industrial sources. No one has entered the business of collecting a variety of these plastics in small quantities.

POLYETHYLENE TEREPHTHALATE

Polyethylene terephthalate (PET), or polyethylene terephthalic ester (PETE), is a condensation polymer produced from the monomers ethylene glycol, HOCH₂CH₂OH, a dialcohol, and dimethyl terephthalate, CH₃O₂C–C₆H₄–CO₂CH₃, a diester. By the process of transesterification, these monomers form ester linkages between them, yielding a polyester. PETE fibers are manufactured under the trade names of Dacron and Fortrel. Pleats and creases can be permanently heat set in fabrics containing polyester fibers, so-called permanent press fabrics. PETE can also be formed into transparent sheets and castings. Mylar is a trade name for a PETE film. Transparent 2-liter carbonated beverage bottles are made from PETE. (The opaque base on some bottles is generally made of HDPE.) One form of PETE is the hardest known polymer and is used in eyeglass lenses.

POLYETHYLENE

Polyethylene is perhaps the simplest polymer, composed of chains of repeating –CH₂– units. It is produced by the addition polymerization of ethylene, CH₂=CH₂ (ethene). The properties of polyethylene depend on the manner in which ethylene is polymerized. When catalyzed by organometallic com pounds at moderate pressure (15 to 30 atm), the product is high density polyethylene, HDPE. Under these conditions, the polymer chains grow to very great length, and molar masses average many hundred thousands. HDPE is hard, tough, and resilient. Most HDPE is used in the manufacture of containers, such as milk bottles and laundry detergent jugs. When ethylene is polymerized at high pressure (1000–2000 atm), elevated temperatures (190–210°C), and catalyzed by peroxides, the product is low density polyethylene, LDPE. This form of polyethylene has molar masses of 20,000 to 40,000 grams. LDPE is relatively soft, and most of it is used in the production of plastic films, such as those used in sandwich bags.

POLYVINYL CHLORIDE

Polymerization of vinyl chloride, CH₂=CHCl (chloroethene), produces a polymer similar to polyethylene, but having chlorine atoms at alternate carbon atoms on the chain. Polyvinyl chloride (PVC) is rigid and somewhat brittle. About two-thirds of the PVC produced annually is used in the manufacture of pipe. It is also used in the production of “vinyl” siding for houses and clear plastic bottles. When it is blended with a plasticizer such as a phthalate ester, PVC becomes pliable and is used to form flexible articles such as raincoats and shower curtains.

POLYPROPYLENE

This polymer is produced by the addition polymerization of propylene, CH₂=CHCH₃ (propene). Its molecular structure is similar to that of polyethylene, but has a methyl group (–CH₃) on alternate carbon atoms of the chain. Its molar masses falls in the range 50,000 to 200,000 grams. Polypropylene (PP) is slightly more brittle than polyethylene, but softens at a temperature about 40°C higher. Polypropylene is used extensively in the automotive industry for interior trim, such as instrument panels, and in food packaging, such as yogurt containers. It is formed into fibers of very low absorbance and high stain resistance, used in clothing and home furnishings, especially carpeting.

POLYSTYRENE

Styrene, CH₂=CH–C₆H₅, polymerizes readily to form polystyrene (PS), a hard, highly transparent polymer. The molecular structure is similar to that of polypropylene, but with the methyl groups of polypropylene replaced by phenyl groups (–C₆H₅). A large portion of production goes into packaging. The thin, rigid, transparent containers in which fresh foods, such as salads, are packaged are made from polystyrene. Polystyrene is readily foamed or formed into beads. These foams and beads are excellent thermal insulators and are used to produce home insulation and containers for hot foods. Styrofoam is a trade name for foamed polystyrene. When rubber is dissolved in styrene before it is polymerized, the polystyrene produced is much more impact resistant. This type of polystyrene is used extensively in home appliances, such as the interior of refrigerators and air conditioner housing. [For more information about this polymer, see Chemical Demonstrations: A Handbook for Teachers of Chemistry, by Bassam Z. Shakhashiri, Volume 1 (1983), page 241.]

POLYTETRAFLUOROETHYLENE

Teflon is a trade name of polytetrafluoroethylene, PTFE. It is formed by the addition polymerization of tetrafluoroethylene, CF₂=CF₂ (tetrafluoroethene). PTFE is distinguished by its complete resistance to attack by virtually all chemicals and by its slippery surface. It maintains its physical properties over a large temperature range, -270° to 385°C. These properties make it especially useful for components that must operate under harsh chemical conditions and at temperature extremes. Its most familiar household use is as a coating on cooking utensils.

POLYURETHANE

This important class of polymers is formed by the addition polymerization of an diisocyanate (whose molecules contain two –NCO groups) and a dialcohol (two –OH groups). The polymer chain is linked by urethane groups (–O–CO–NH–). The –NH– portion of the urethane group can react similarly to an –OH group, producing cross-linking between polymer chains. Polyurethane is spun into elastic fibers, called spandex, and sold under the trade name Lycra. Polyurethane can also be foamed. Soft polyurethane foams are used in upholstery, and hard foams are used structurally in light aircraft wings and sail boards. The formation of some polyurethane (and polystyrene) foams exploits the exothermic nature of the polymerization reaction. A liquid with a low boiling point, called a blowing agent, is added to the monomers before the polymerization starts. As the polymerization proceeds, it releases enough heat to boil the liquid. The boiling liquid produces bubbles that create a foam. In the past, the most commonly used low-boiling liquids were chlorofluorocarbons. However, the damaging effect of chlorofluorocarbons on the stratospheric ozone layer has eliminated their use. Other low-boiling liquids have other disadvantages, such as flammability. Therefore, most polyurethane and polystyrene foams are manufactured by forcing a pressurized gas, such as nitrogen or carbon dioxide, into the polymerizing mixture. [For more information about this polymer, see Ibid., Volume 1, page 216.]

POLYAMIDE

Polyamides are a group of condensation polymers commonly known as nylon. Nylon is made from two monomers, one a dichloride and the other a diamine. One particular nylon is made from 1,6-diaminohexane, NH₂(CH₂)₆NH₂ and sebacoyl chloride, ClCO(CH₂)₈COCl. When these polymerize, the resulting molecules contain repeating units of –NH(CH₂)₆NH–CO(CH₂)₈CO–. Molecules of HCl are released during the polymerization. This particular polymer is called nylon 6-10 because it contains alternating chains of 6 and 10 carbon atoms between nitrogen atoms. Nylon can be readily formed into fibers that are strong and long wearing, making them well suited for use in carpeting, upholstery fabric, tire cords, brushes, and turf for athletic fields. Nylon is also formed into rods, bars, and sheets that are easily formed and machined. In this form, nylon is used for gears and for automobile fuel tanks. [For more information about this polymer, see Ibid., Volume 1, page 213.]

POLYACRYLAMIDE

Polyacrylamide is a condensation polymer with an unusual and useful property. The structure of polyacrylamide is similar to that of polyethylene, but having a hydrogen on every other carbon replace by an amide group, –CONH₂. The molecule is composed of repeating –CH₂–CH(CONH₂)– units. The amide groups allow for linking between polymer strands. The –CONH₂ group from one molecule can react with the same group of another molecule, forming a link between them with the structure –CONHCO–. This produces a network of polymer chains, rather like a tiny sponge. The free, unlinked amide groups, because they contain –NH₂ groups, can form hydrogen bonds with water. This gives the tiny cross linked sponges a great affinity for water. Polyacrylamide can absorb many times its mass in water. This property is useful in a variety of applications, such as in diapers and in potting soil. The polyacrylamide will release the absorbed water if a substance that interferes with hydrogen bonding is added. Ionic substances, such as salt, cause polyacrylamide to release its absorbed water. [For more information about this polymer, see Ibid., Volume 3 (1989), page 368.]

& .

General Rules

1. Remove and discard all lids or caps.
2. Rinse all containers.
3. Remove and discard sprayer tops.
4. CRUSH all plastic bottles to save space.
5. No 5 gallon pails.
6. No containers with metal handles.

What can be Recycled?

Plastic Code Number

Recyclable Containers

Soda Bottles
Water Bottles
Juice Bottles
Cooking Oil Bottles
Soap/Detergent Bottles
Shampoo Bottles
Clear Liquor Bottles
Food Jars (Peanut Butter etc.)

Plastic Code Number
Recyclable Containers

Milk Bottles
Water Bottles
Juice Bottles
Cooking Oil Containers
Windshield Washer Fluid Bottles
Shampoo Bottles
Butter/Margarine Tubs
Cottage Cheese Containers
Ice Cream Containers Without Metal Handles
Baby Wipe Containers

Do NOT Recycle This Plastic

• Motor Oil Bottles
• Anti-Freeze Containers
• Gasoline and Oil Additive Bottles

3. All Containers Marked With The Following Codes:

POLYETHYLENE TEREPHTHALATE

Polyethylene terephthalate (PET), or polyethylene terephthalic ester (PETE), is a condensation polymer produced from the monomers ethylene glycol, HOCH₂CH₂OH, a dialcohol, and dimethyl terephthalate, CH₃O₂C–C₆H₄–CO₂CH₃, a diester. By the process of transesterification, these monomers form ester linkages between them, yielding a polyester. PETE fibers are manufactured under the trade names of Dacron and Fortrel. Pleats and creases can be permanently heat set in fabrics containing polyester fibers, so-called permanent press fabrics. PETE can also be formed into transparent sheets and castings. Mylar is a trade name for a PETE film. Transparent 2-liter carbonated beverage bottles are made from PETE. (The opaque base on some bottles is generally made of HDPE.) One form of PETE is the hardest known polymer and is used in eyeglass lenses.

POLYETHYLENE

Polyethylene is perhaps the simplest polymer, composed of chains of repeating –CH₂– units. It is produced by the addition polymerization of ethylene, CH₂=CH₂ (ethene). The properties of polyethylene depend on the manner in which ethylene is polymerized. When catalyzed by organometallic com pounds at moderate pressure (15 to 30 atm), the product is high density polyethylene, HDPE. Under these conditions, the polymer chains grow to very great length, and molar masses average many hundred thousands. HDPE is hard, tough, and resilient. Most HDPE is used in the manufacture of containers, such as milk bottles and laundry detergent jugs. When ethylene is polymerized at high pressure (1000–2000 atm), elevated temperatures (190–210°C), and catalyzed by peroxides, the product is low density polyethylene, LDPE. This form of polyethylene has molar masses of 20,000 to 40,000 grams. LDPE is relatively soft, and most of it is used in the production of plastic films, such as those used in sandwich bags.

POLYVINYL CHLORIDE

Polymerization of vinyl chloride, CH₂=CHCl (chloroethene), produces a polymer similar to polyethylene, but having chlorine atoms at alternate carbon atoms on the chain. Polyvinyl chloride (PVC) is rigid and somewhat brittle. About two-thirds of the PVC produced annually is used in the manufacture of pipe. It is also used in the production of “vinyl” siding for houses and clear plastic bottles. When it is blended with a plasticizer such as a phthalate ester, PVC becomes pliable and is used to form flexible articles such as raincoats and shower curtains.

POLYPROPYLENE

This polymer is produced by the addition polymerization of propylene, CH₂=CHCH₃ (propene). Its molecular structure is similar to that of polyethylene, but has a methyl group (–CH₃) on alternate carbon atoms of the chain. Its molar masses falls in the range 50,000 to 200,000 grams. Polypropylene (PP) is slightly more brittle than polyethylene, but softens at a temperature about 40°C higher. Polypropylene is used extensively in the automotive industry for interior trim, such as instrument panels, and in food packaging, such as yogurt containers. It is formed into fibers of very low absorbance and high stain resistance, used in clothing and home furnishings, especially carpeting.

POLYSTYRENE

Styrene, CH₂=CH–C₆H₅, polymerizes readily to form polystyrene (PS), a hard, highly transparent polymer. The molecular structure is similar to that of polypropylene, but with the methyl groups of polypropylene replaced by phenyl groups (–C₆H₅). A large portion of production goes into packaging. The thin, rigid, transparent containers in which fresh foods, such as salads, are packaged are made from polystyrene. Polystyrene is readily foamed or formed into beads. These foams and beads are excellent thermal insulators and are used to produce home insulation and containers for hot foods. Styrofoam is a trade name for foamed polystyrene. When rubber is dissolved in styrene before it is polymerized, the polystyrene produced is much more impact resistant. This type of polystyrene is used extensively in home appliances, such as the interior of refrigerators and air conditioner housing. [For more information about this polymer, see Chemical Demonstrations: A Handbook for Teachers of Chemistry, by Bassam Z. Shakhashiri, Volume 1 (1983), page 241.]

POLYTETRAFLUOROETHYLENE

Teflon is a trade name of polytetrafluoroethylene, PTFE. It is formed by the addition polymerization of tetrafluoroethylene, CF₂=CF₂ (tetrafluoroethene). PTFE is distinguished by its complete resistance to attack by virtually all chemicals and by its slippery surface. It maintains its physical properties over a large temperature range, -270° to 385°C. These properties make it especially useful for components that must operate under harsh chemical conditions and at temperature extremes. Its most familiar household use is as a coating on cooking utensils.

POLYURETHANE

This important class of polymers is formed by the addition polymerization of an diisocyanate (whose molecules contain two –NCO groups) and a dialcohol (two –OH groups). The polymer chain is linked by urethane groups (–O–CO–NH–). The –NH– portion of the urethane group can react similarly to an –OH group, producing cross-linking between polymer chains. Polyurethane is spun into elastic fibers, called spandex, and sold under the trade name Lycra. Polyurethane can also be foamed. Soft polyurethane foams are used in upholstery, and hard foams are used structurally in light aircraft wings and sail boards. The formation of some polyurethane (and polystyrene) foams exploits the exothermic nature of the polymerization reaction. A liquid with a low boiling point, called a blowing agent, is added to the monomers before the polymerization starts. As the polymerization proceeds, it releases enough heat to boil the liquid. The boiling liquid produces bubbles that create a foam. In the past, the most commonly used low-boiling liquids were chlorofluorocarbons. However, the damaging effect of chlorofluorocarbons on the stratospheric ozone layer has eliminated their use. Other low-boiling liquids have other disadvantages, such as flammability. Therefore, most polyurethane and polystyrene foams are manufactured by forcing a pressurized gas, such as nitrogen or carbon dioxide, into the polymerizing mixture. [For more information about this polymer, see Ibid., Volume 1, page 216.]

POLYAMIDE

Polyamides are a group of condensation polymers commonly known as nylon. Nylon is made from two monomers, one a dichloride and the other a diamine. One particular nylon is made from 1,6-diaminohexane, NH₂(CH₂)₆NH₂ and sebacoyl chloride, ClCO(CH₂)₈COCl. When these polymerize, the resulting molecules contain repeating units of –NH(CH₂)₆NH–CO(CH₂)₈CO–. Molecules of HCl are released during the polymerization. This particular polymer is called nylon 6-10 because it contains alternating chains of 6 and 10 carbon atoms between nitrogen atoms. Nylon can be readily formed into fibers that are strong and long wearing, making them well suited for use in carpeting, upholstery fabric, tire cords, brushes, and turf for athletic fields. Nylon is also formed into rods, bars, and sheets that are easily formed and machined. In this form, nylon is used for gears and for automobile fuel tanks. [For more information about this polymer, see Ibid., Volume 1, page 213.]

POLYACRYLAMIDE

Polyacrylamide is a condensation polymer with an unusual and useful property. The structure of polyacrylamide is similar to that of polyethylene, but having a hydrogen on every other carbon replace by an amide group, –CONH₂. The molecule is composed of repeating –CH₂–CH(CONH₂)– units. The amide groups allow for linking between polymer strands. The –CONH₂ group from one molecule can react with the same group of another molecule, forming a link between them with the structure –CONHCO–. This produces a network of polymer chains, rather like a tiny sponge. The free, unlinked amide groups, because they contain –NH₂ groups, can form hydrogen bonds with water. This gives the tiny cross linked sponges a great affinity for water. Polyacrylamide can absorb many times its mass in water. This property is useful in a variety of applications, such as in diapers and in potting soil. The polyacrylamide will release the absorbed water if a substance that interferes with hydrogen bonding is added. Ionic substances, such as salt, cause polyacrylamide to release its absorbed water. [For more information about this polymer, see Ibid., Volume 3 (1989), page 368.]

Over the past few decades, the use of polymers in disposable consumer goods has grown tremendously. This growth is proving to be taxing on the waste disposal system, consuming a large fraction of available landfill space. Furthermore, the raw materials for these polymers are obtained from petroleum, a limited, non-renewable resource. To reduce the demand for landfill space and the consumption of limited petroleum reserves, the recycling of polymers has become a subject of concern. One of the problems faced in recycling polymers is the great variety of polymers in use. To help sort wastes by type of polymer, most disposable polymeric goods are labeled with a recycling code: three arrows around a number above the polymer's acronym. These are intended to help consumers separate the waste polymers according to type before disposing of them. In the city of Madison, currently only type 1 (PETE) and type 2 (HDPE) polymers are being recycled – see below. The recycling of polymers is not a closed loop, where a material is reformed into new products repeatedly, such as in the case with aluminum. Most polymeric materials are recycled only once, and the product made of recycled polymer is discarded after use. To obtain the maximum benefit from recycled polymer, the products made from it generally are intended to have a relatively long useful life. Recycled polymers are used in products such as cafeteria trays, large plastic toys, impact absorbing highway pylons, and carpeting. Some recycled PETE is now used in 2-liter soft-drink containers. In general, products made from recycled polymers are more expensive than those made from virgin plastic. This is the case because current manufacturing facilities are geared to production from new materials. As more factories capable of using recycled plastics are constricted, the costs of using recycled polymers will decline; however, more factories will be built only if we are willing to pay "up front" the costs of recycling (as higher prices of consumer goods),rather than delaying costs of disposal (in the form of increased taxes)

& .

General Rules

1. Remove and discard all lids or caps.
2. Rinse all containers.
3. Remove and discard sprayer tops.
4. CRUSH all plastic bottles to save space.
5. No 5 gallon pails.
6. No containers with metal handles.

What can be Recycled?

Plastic Code Number

Recyclable Containers

Soda Bottles
Water Bottles
Juice Bottles
Cooking Oil Bottles
Soap/Detergent Bottles
Shampoo Bottles
Clear Liquor Bottles
Food Jars (Peanut Butter etc.)

Plastic Code Number
Recyclable Containers

Milk Bottles
Water Bottles
Juice Bottles
Cooking Oil Containers
Windshield Washer Fluid Bottles
Shampoo Bottles
Butter/Margarine Tubs
Cottage Cheese Containers
Ice Cream Containers Without Metal Handles
Baby Wipe Containers

Do NOT Recycle This Plastic

• Motor Oil Bottles
• Anti-Freeze Containers
• Gasoline and Oil Additive Bottles

3. All Containers Marked With The Following Codes: