Take a piece of paper, and hold it next to a sycamore tree. If you do this a very obvious question should come to mind, and that question being how do you come from a massive, living object, to a slim piece of paper? The entire process is quite complex, and varies from manufacturer to manufacturer. In order to get a general feel for the production of paper the operation of the Ticonderoga Mill will be described ⁶.

The process can be broken down into four steps, which are in turn supported by three additional processes. The four steps directly involved with the production of paper are:

1) Raw material preparation - Wood yard

3) Chemical Recovery – Power and Recausticizing

4) Paper making – Paper mill and finishing operations

The three supporting cast members, to the steps directly involved with paper

manufacturing, are:

Paper manufacturing begins in the wood yard where wood chips are sorted for size, prepared for pulping, and subsequently moved along to the next step, which is bleaching and recausticizing in the pulp mill. Logs, in the wood yard, must first be debarked, chipped, and then sorted for size, just like the previous set of chips, and subsequently sent into the pulping operation. It should be noted that no part of the logs goes to waste in the production of paper. Up to this point the only part of the logs not utilized were bark, and other wood waste. This "waste," however, is redirected to the power boiler, as is shown in figure l, and utilized as a fuel source. Only 70% of the chips sent to the pulping operation came from logs. The remaining 30% of the woodchips came from wood waste from sawmills, and other sources. This 30% would have become waste if not for paper manufacturing. It can be seen that paper manufacturing, in part, takes seemingly useless wood waste, and produces a viable product ⁶.

The chips from the wood yard then enter the pulp mill. The chips must undergo two main changes before it becomes usable bleached pulp. The first change is dissolution of lignin (a form of glue). The dissolution is achieved by sending the wood chips into a continuous digester, which is in essence a very large pressure cooker, and mixing the chips with a white cooking liquor. By exposing the chips to the liquor, and steam, dissolution of lignin is achieved. Three main products come from the continuous digester, and they are:

1. Black cooking liquor (contains the lignin)
1. Knots of wood chips, and uncooked chips
1. Brown stock (unbleached pulp)

knots, and uncooked chips, are returned to the continuous digester for reprocessing. The second division of the pulp mill is the bleaching operation. The bleaching operation is where the brown stock is shipped to in order to make final preparations for the pulp.

The bleaching operation, in essence, is a five-stage operation that exposes the brown stock to the following chemicals:

1. Chlorine
1. Chlorine dioxide
1. Caustic
1. Oxygen
1. Hydrogen Peroxide

Judging by the extensive use of chemicals in this process it is very easy to understand how this step, in the paper manufacturing process, draws the most amount of criticism, and is the most detrimental step to the environment. While this step is a platform for critics against paper manufacturing it is also the step that has seen the most area of improvements. In fact it will later be shown that alternative methods now exist that bleach the pulp without such damaging chemicals as chlorine. It should also be realized that water and chemicals are conserved in the bleaching operation by having the wash water running in a counter-current manner.

The black liquor is used to produce more white cooking liquor via the Kraft chemical recovery cycle outlined in figure ll. The lignin in the black liquor actually has a high heating value if concentrated. Therefore the black liquor is concentrated by boiling off water via multiple effect evaporators to produce a 63% black liquor. This liquor is then fed into the recovery boiler where some of the heat is used to produce steam. The steam is sent to the continuous digester. During the burning, sodium and sulfur compounds are converted to usable forms and dissolved in water. This produces a green liquor which is sent to the recausticizing operation. The recausticizing operation adds lime to the green liquor from the recovery boiler to produce the white cooking liquor needed for the continuous digester.

The beauty of this system can be seen in the supporting steps of paper manufacturing. The process is run efficiently so as to maximize the value of all ingredients. Saw dust is not disposed of, but instead used as part of the wood chip mixture, black liquor is not dumped, but fed to the recovery boiler, and white cooking liquor is produced from the recovery cycle instead of being produced from raw materials. The manufacturing process is not perfect, but is run with the best interest of the environment, and business in mind.

The bleached pulp from the pulp mill is then sent to the paper mill where the finished product is produced. In the paper mill the dyes, fiber retention aids, and fillers are added to pulp in order to produce paper. The pulp is laid out on a screen at high speeds, and water is allowed to drain out. Heated rollers smooth out the paper, and remove additional water. The paper is then cut according to customer specification. Some of the paper, however, does not meet the quality specifications and is sent back to the pulping operation. It is important to realize that the sub-standard paper is not disposed of, but instead recycled.

As mentioned earlier the bleaching operation utilizes a tremendous amount of water, and chemicals. In fact the Ticonderoga Mill uses approximately seventeen million gallons of raw water from Lake Champlain everyday. ⁶ This water must of course be purified before it is sent back into the lake so as to avoid polluting Lake Champlain, and avoid environmental catastrophes. The water is collected, and run through primary clarifiers in order to remove solid waste. Most of the solid waste is in fact cellulose fibers lost during the manufacturing process. These fibers are not disposed, but rather sent back to the pulp mill and recycled. The remaining water is sent to an aeration basin for biological treatment, and then to secondary and tertiary clarifiers for final preparation, and then back to Lake Champlain. It should be noted that waste from the secondary, and tertiary clarifiers are not recyclable, and are disposed of in landfills. This is one of the few products of the paper manufacturing process that is not recycled, and becomes true unusable waste.

The aforementioned manufacturing process can be potentially dangerous if it is allowed to proceed in one-way consumption, and disposal. Paper manufacturing has a great deal of problems such as energy consumption, pollution of our air, and waterways, and poses a great burden on our natural resources. These problems, however, can be answered, in most part, by extensive use of recycling. While paper manufacturing is problematic, the more recycling is utilized in the process the less problematic it becomes.

The first boon of recycling is the fact you conserve natural resources, and decrease pollution. This is done by the fact that much of the manufacturing process is cut out because virgin raw materials are no longer being utilized. When paper is recycled the continuous digester is avoided since there is no lignin to dissolve, and much of the bleaching operation is avoided as well. Recycled materials have undergone the manufacturing process once, so much of it avoided when recycled materials are used in lieu of virgin raw materials.

Recycling paper also decreases energy consumption thereby reducing pollution and conserving fossil fuel. As stated previously, significant parts of the manufacturing process can be avoided if recycled paper is used instead of virgin raw materials. This saves on energy costs of running the continuous digester, and the recovery boiler, which produces white cooking liquor for the continuous digester. By recycling a ton of raw materials it is estimated that $187 worth of electricity is conserved, and that includes the cost of collecting, and transporting the paper.¹² The net benefit of recycling paper is not merely $187, because other costs are being neglected. For instance if the paper was not recycled then it would end up in our nations landfills, and there is a significant cost associated with that. For example in heavily populated areas such as New York, New Jersey, and Massachusetts the cost of placing a ton of paper in landfills were $96, $73, and $72 respectively ¹². This is a significant cost to add to the net benefits of recycled paper. There are also numerous benefits that a direct cost cannot be attached to at this point. For example by avoiding sections of the manufacturing process the amount of pollution in our air, and water is reduced. This in turn leads to fewer instances of cancer, and other health related problems. Thus recycling paper has a far extending hand that not only conserves energy, natural resources, and landfill space but improves the health, and the quality of life of the average American.

It is difficult to talk of paper manufacturing, and the benefits that recycling brings to it in general terms. Therefore it would be well worth it to analyze a specific segment of the paper industry, namely the catalog industry, to see how much of an impact recycling, and improving the paper manufacturing process can have.

The catalog industry utilizes a tremendous amount of paper per year. In fact in 1999 the catalog industry utilized 3.35 million tons of paper, which is approximately 12 percent of the printing and writing paper in the United States .¹⁸

To put this figure in perspective, understand that each person on hand receives sixty-four catalogs every year. Such overproduction of catalogs has very serious consequences. For instance producing 3.35 million tons of paper requires 105 million BTUs, which is enough to power one million households for an entire year. ¹⁸ In addition 9.8 million tons of greenhouse gases are emitted, 51 billion gallons of wastewater, and 3.7 million tons of solid waste are produced. ¹⁸ The obvious attack on the catalog industry is that it is wasteful, and a tightening of the belt is required to curtail paper production. It was shown in a recent study that of forty-two catalogs produced every year only eight allowed their customers to stop their receiving catalogs. This means that many of the catalogs being sent out to the public are not even wanted, and may be termed junk mail. In addition most catalogs are printed monthly, when being printed three or four times a year would result in the same outcome as printing monthly. E-commerce may also help decrease the amount of paper used, if catalog companies use web version of catalogs, instead of paper ones. At this time, however, no catalog company replaces electronic versions for paper versions. Instead the web is used to get the names and addresses of more potential customers, and so e-commerce has actually led to an increase in the paper catalog industry. What needs to be understood is that the United States by no means has a legitimate reason to produce 3.35 million tons of paper for catalogs. It is estimated that figure could easily be cut in half.

Another problem is that the public needs to demand that catalog companies utilize recycled paper. In the past recycled paper was not up to the standards of the glossy catalog paper, but that has changed. It is now possible to obtain glossy paper with ten percent postconsumer fiber (PCF). Some may argue that the extra cost of the recycled paper is what keeps catalog companies away from recycled paper, but the fact is 10 percent PCF costs exactly the same amount as paper produced from virgin raw materials. The only reason catalog companies have not made the switch is because of a lack of information, as well as an apathetic consumer group. It is not doubtable that if the public demanded that their catalogs use ten percent PCF that catalog companies, always aware of the almighty dollar, would make the switch. Experts also argue that the ten percent PCF mark could easily be surpassed if paper manufacturers saw a demand for the ten percent brand currently available. Recycled paper uses 33% less energy, produces 11% less sulfur dioxide, 23% less nitrogen oxides, 43% less net greenhouse gases, and 84% less hazardous air pollutants than paper manufactured from virgin raw materials does. The benefits of recycled paper is then obvious, and these gains can be achieved if only the consumer made certain demands.

Another major area for advancement is a cleaner manufacturing process. As was seen in the Ticonderoga Mill process a number of chemical were utilized in the pulp mill to remove lignin, and produce bleached pulp. By using elemental chlorine in the bleaching process it has been realized that dioxins (toxic chlorinated organic compounds) will form in the waterway used to supply the mill. Procedures exist now that substitute all of the elemental chlorine with chlorine dioxide. This procedure has been termed elemental chlorine free (ECF). ECF, however, only slightly improves the quality of the water released to the waterway by not allowing the formation of dioxins, but the water is still polluted. By removing more of the lignin before it is bleached less energy, and fewer chemicals are used in the bleaching process. This process of extended delignification reduces energy consumption by 30%, and reduces mill wastewater by 50%. Another process uses ozone as a brightening agent, and further improves the quality of the wastewater, and reduces quantity of wastewater by 70% to 90%, when compared to traditional ECF. The totally chlorine free process (TCF) uses only oxygen based compounds to bleach the pulp, and thereby removes all chlorine products from the pulp mill. This process, although expensive, virtually eliminates all wastewater because the wastewater is restored to it original condition. It is therefore abundantly obvious that the manufacturing process can come close to being problem free if only consumers demanded changes.

Paper is still of fundamental importance to the United States, as paper consumption has nearly doubled since 1960, and trends indicate that paper consumption will be on the rise for some time. ¹⁸ Paper is needed for newspapers, bags, writing material, and so on, but the harmful effects are now being minimized so that natural resources are conserved, water quality improves, air quality improves, and more waste is not sent to landfills. As long as consumers keep a vigil and make sure industry takes full advantage of recent advancements in paper technology, paper will be the safest choice available.

In today’s society, plastic is being used for many different applications because of its light weight and durability. It is being used in appliances, cars, packaging, toys and many other purposes. Plastic is even being recycled and used in secondary applications such as plastic "wood" and industrial fuel. Although plastics have many advantages, they are not perfect and cause numerous problems in the environment.

Plastic comes in many forms and is used in applications from bags to parts for household appliances to children’s toys. Since each of these products has very different properties, they require plastics with different qualities. The first thing that determines what type of traits a plastic will have is what monomer or monomers it is made from. A few of these monomers are styrene, ethylene (ethene), and propylene (propene). Each monomer yields a plastic resin with different characteristics.⁸ Styrene produces polymers that are mostly used for packaging, where ethylene makes polymers that have a wide range of properties depending upon the size of the molecules among other things. Using two or more monomers produces co-polymers with further property variations. Each resulting resin can be molded to make different plastic products with different applications. This variability allows compounds to be tailored to a specific design requirement. These plastic products have such properties as heat resistance, chemical resistance and impact strength. Some examples of products are chemical resistance packaging for bleach and impact strength in car bumpers.

Another important factor in what properties a polymer will have is the crystallinity within the molecule. Two major types of polyethylene are low-density polyethylene, which has low crystallinity, and high-density polyethylene, which contains high crystallinity. LDPE is in such things as films and packaging, where HDPE is used for containers and gas tanks.

When plastics come out of the reactor and they do not have the desired properties that are needed, that plastic is subject to further treatments with additives that are put in to give it specified properties. Most times additives are blended with plastics during the raw material processing into their finished product. These additives are incorporated to enhance their physical, mechanical or chemical properties. Some types of additives are:

· antioxidants: for outside applications

· colorants: for coloring plastic parts

· foaming agents: for styrofoam cups

· plasticizers: used in toys and food processing equipment⁸

Another important factor in the final properties of a plastic product is the method of processing to convert the resins into a finished product. Some of these include extrusion, injection molding, blow molding and rotational molding. All of these require the plastic to be in a molten form at some point during the process, but each has its own unique way of forming the plastic into the desired shape. Extrusion pushes the heated plastic through a small opening called a die, to a conveyor belt where it is cooled. Extrusion produces semi-finished goods such as piping that may need more processing later. Injection molding has the plastic being heated then forced into a closed mold and allowed to cool. During injection molding the plastic is put into a hopper, then fed into a heating chamber. Once in the heating chamber a plunger pushes the plastic through into a closed mold. Once the plastic cools, the mold opens and the finished product is ejected. This method produces moldings of high quality and great accuracy. Blow molding is used in conjunction with extrusion to produce more finished products. In this case compressed air is used to conform the material coming from the die to a chilled mold which clamps around the tube. In rotational molding, the plastic is put into a heated mold and rotated in 2 directions simultaneously to distribute the plastic into a uniform coating on the inside of the mold.⁸

Two other types of processing that are a little different from the four mentioned above are reaction injection molding and thermoforming. During reaction injection molding, the polymer is simultaneously synthesized and molded into the finished product. Disadvantages include the worker exposure to noxious, high vapor-pressure reagents that are used. In thermoforming, a plastic sheet is heated until it softens and then is formed to the shape of a mold preform by application of external air pressure or by pulling vacuum between the sheet and the mold.¹⁷

Plastics have many advantages over other raw materials. The first advantage that plastic has over paper and other raw materials is the number of applications that it can be used for. Where paper is mostly used for packaging and bags, plastic can be used in packaging, automobile parts, appliances, among many other things. Plastics are a much lighter weight than many other raw materials. A plastic peanut butter jar weighs 1.7 oz. compared to 10.2 oz. for a glass jar containing the same amount of peanut butter (18 oz.). On the next page are a couple of examples of the lightweight of plastics as compared to other raw materials.⁸

Not only does this lightweight save raw materials that make it, plastic leads to more efficient use of raw materials that are used to ship these goods as also can be seen above. Not only is plastic lightweight, it is also very durable and impermeable to many chemicals including air and water. This reduces spoilage and breakage during shipping. Plastic’s resistance to corrosion helps extend the useful life of major appliances.⁸ Plastic also reduces the number of individual parts that must be manufactured due to the ease of fabrication. Molten plastics are usually between 95 and 330 degrees Celsius. For molten metals temperatures can be anywhere upwards of 400 degrees Celsius. Not all plastics are durable in fact they can be used to make very delicate things such as pantyhose. Plastics are also good thermal and electrical insulators. They can keep heat out as in a refrigerator or cooler, and in as the insulation in your house and long underwear do. Electrical outlets and wiring covers are made from plastic polymeric materials. There are other materials that are secondary products that are made from recycled plastic that will be mentioned later.

Contrary to popular belief, plastic does not take up most of the space in landfills. The volume of all plastics – foam, film and rigid; toys, utensils and packages – amounted to between 20 and 24 percent of all garbage. When compacted along with everything else, the volume of plastics fell to only about 16 percent. Even though the number of individual plastic objects to be found in a deposit of garbage of a given size has increased considerably in the course of a decade and a half the proportion of landfill space taken up by those plastics has not changed.

Although today’s technologies can do many wonderful things with plastics, there are still a few problems with them. Many of the qualities that make plastic such a good raw material cause problems when their use is done. Plastics’ resistance to corrosion and impermeability to many chemicals make them last for a long time without changing much, even when released into the environment. They may change their shape but they cannot change their composition.¹⁴ When plastics are released into the ocean, they cause many problems with animals that depend on the ocean for food and habitat. A plastic bag looks like a jellyfish to a sea turtle and plastic pellets look like fish eggs to sea birds. These animals can choke, block the intestines, or cause infection in those animals that consume them. Even if these plastics do pass through the animals system, the plastics block the nutrients these animals need making them weak or even causing them to starve. The six pack ring can become a deadly noose for a bird or fish. Drifting nets can entangle birds, fish and mammals making it difficult or even impossible to move or eat. When metal, cloth or paper nets were used once lost they would either sink to the bottom or biodegrade quickly. Plastic remains floating on the surface, the same place food sources may lie and can remain there for 400 years.¹⁶ One would think that with the huge size of the ocean, contact between the relatively small amount of plastics that end up in the ocean and animals that rely on the ocean for food would be limited and small, dispersing the refuse. On the contrary, the ocean currents keep the floating trash traveling in "gyres" concentrating it in areas where currents meet. Consequently the ocean just isn’t big enough to avoid marine life encounters with plastic debris.

An example of how damaging plastics have been on the life forms that rely on the oceans is the decline in population of the northern fur seal. Since the 1970’s this seal population has declined by more than 50 percent.¹⁶ These curious and playful seals would often play with fragments of plastic netting or packing straps. The webbing then can get caught on their necks creating a harness, which restricts the seals’ movements, killing the seal through starvation, exhaustion, or infection from the deep wounds caused by the tightening material.

Finished products aren’t the only step in plastic making that can become pollutants to the environment. The raw material that is first processed to make plastics can be a source of environmental pollution. Oil can cause problems when it is released into the environment. By far, the most dangerous way oil can be released into the environment is from major spills. This accounts for 37 million gallons put into the ocean each year. Compared to other methods of oil entering the ocean, this is not much. Such things as natural seeps and oil going down the drain from homes release many more gallons for oil, but during the big spills the concentration of the oil in a small area creates the problem. Oil floats on top of water because it is less dense than water. Consequently when there is a big spill, oil covers the ocean water, blocking sun light from the plants and animals below. Birds that land on the surface get covered by oil, making it hard for the animals to fly out of the spill.

Some plastic products can release toxic chemicals into the air. Major sources of air pollution come from building materials and consumer products, many of them are plastics or are plastics related. These can emit chemicals into the air over a long period of time. Some of these include air fresheners, office materials such as pens, ink and carbonless paper, office machines and laundry products. Carpets, upholstery, and books rapidly absorb pollutants from the air and release them at a slower rate.

In mattresses numerous chemicals are added to the finished product and contain three potential risks: the foam, the cover, and the additives.¹⁵ The foam can cause shortness of breath due to the fact it is polymerized using TDI-toluene di iso cyanate, which is a potent asthma trigger. If the cover is made of PVC, off gassing of numerous harmful organic chemicals is possible. The additives can sometimes have toxic properties, especially to young children and infants. These mattresses can release chemicals into the air, causing toxic effects on the eyes, nose, throat and lungs. Dr. Jim Sprotts of New Zealand believes that PVC covers releasing toxic gases can cause sudden infant death syndrome in children while they are sleeping. The doctor’s book documents the reduction of SIDS’s in New Zealand after polyethylene barriers were used to keep those chemicals away from the babies.¹⁵

Some carpets do emit toxic fumes and can also act as a reservoir for dust mites and lead dust. Every time you put your foot down, a cloud 18 inches deep is produced containing dust mite fecal antigens that are associated with asthma and lead, which can be very toxic to the brain. This is especially dangerous for children who incidentally play in this zone.¹⁵

An alternative to putting plastics into a landfill or littering them into the ocean and environment, they can be recycled and used again in other plastic products. Most plastics can be recycled and reused including packaging, bottles, and even auto bumpers. These plastics can be reused for the same purpose as in soda-pop bottles or they can be transformed into another good such as plastic "wood" or carpets. Also plastics and paper can be used again in Processed Engineered Fuels (PEF). Some plastics can be depolymerized which means they are broken down into base components, then polymerized again and formed into other products. More and more plastic us recycled each year, but the percent of plastic that is recycled continues to fall and the amount of virgin plastic that is made increases rapidly.

Plastic "wood" is a relatively new and useful way to recycle plastic. It is made mainly from recycled high-density polyethylene. Plastic lumber also can be made with composites, recycled HDPE and wood fibers, fiberglass and other plastics.¹³ This lumber is finding many applications from home decks to railroad ties. The railroad tie market is huge since each tie requires 200 lb. of plastic.¹³ Plastic lumber has many good qualities that make it a good replacement for wood. It will not rot, crack, warp or splinter. It is denser than wood, long lasting, stain resistant, graffiti proof, waterproof, impervious to insects, and like many plastics affected by exposure to most substances. Plastic lumber also works with any deck fastener, requires no painting or sealing and is a good shock absorber. It holds nails 90 percent better than wood and screws 50 percent better than wood. Engineers estimate the workable life of plastic is anywhere from 15-20 years in under marine applications and over 50 years in construction applications. Plastic "wood" also has environmental benefits, besides the fact that 200 lb. of plastic is put in each railroad tie. It contains no hazardous chemicals and therefore cannot leak or contaminate soil as wood that is injected with chemicals to ward off insects. Since less wood is needed, fewer trees are cut down. Plastic lumber has not yet been approved for load-bearing applications, but testing is underway.

Another secondary use for plastics is for industrial fuels called Processed Engineered Fuel (PEF). Conventional PEF contains 70 to 90 percent paper and the remaining plastic. PEF is not a waste, but a marketable product that must meet strict end-user requirements. This is a high-energy resource that in many cases can be economically co-fired with coal and other fuels to reduce criteria pollutants greenhouse gas emissions.¹³ PEF is made from scrap plastic, wood, sawdust, and scrap paper stripped of all foreign materials. Then these are pelletized into dense cubes for easy transportation.

Some plastics such as polyolefins can be thermally depolymerized into a variety of smaller hydrocarbon intermediates and synthesis monomers. Depolymerization from polymer feed stock must be very efficient with very high yields of monomers and little waste to be viable. The resulting synthesis chemicals can then be used to make new plastics that are indistinguishable from the initial polymers. One problem with depolymerization processes is that hazardous wastes are produced that need to be dealt with to make sure of the safety to persons and the environment.¹³

The recycling of plastics is increasing yearly by millions of pounds, but the percentage of plastics recycled to that made and wasted is decreasing. Below is a table from 1997-98 that shows the increase in amount of plastic recycled.

Also the ratio of growth of production of virgin plastic to growth in recycling is huge from the years 1990 to 1996. For example, the amount ratio of PVC created to the amount recycled was 196 to 1 in those years. Polypropylene was a little better but still not good at 90 to 1. Capacity to process material and the market for recovered plastic resin exceed the amount of post-consumer bottles that are now recovered from the waste stream. There are some graphs that demonstrate this at the end of this report.

Plastic is a very good raw material, but it still has a few problems that need to be fixed. Still there are many possibilities for plastic in the future. Plastics are being incorporated more and more into large goods such as cars. Many raw materials used in a car can be possibly replaced with plastics. These include glazing, body seals and the interior. The instrument panel is the most expensive, complex assembly in the interior. Polypropylene compounds with improved energy absorption, scratch resistance, and dimensional stability are targeting the hard instrument panel.

Plastics are also finding use in the medical markets and will be used further because of the need for disposability of plastic. The design, flexibility, excellent performance and increased manufacturing and assembly efficiencies of plastics have made them a desirable choice to a broad range of medical products.

In conclusion, plastic is a raw material already with many applications and numerous future possibilities, provided the environmental problems it can cause are solved to some extent.

1. LPM Technologies-www.lpm.qc.ca
2. Paper Recycling Working Group – www.pwrg.com
3. Progress in Paper Recycling – Journal
4. Green Peace – www.greenpeaceusa.org
5. The Idaho Forest: Paper Recycling – www.IdahoForests.org
6. International Paper – www.internationalpaper.com
7. American Forest and Paper Association – www.afandpa.org
8. Plastics Resource – www.plasticsresource.com
9. Tellus Institute Packaging Study
10. GRN – www.grn.com
11. Technology of Recycling Plastics www.ctem.uwstout.edu/tec/chiodo/web/epilhomepage/html
12. Enviromental Defense – www.edf.org
13. Modern Plastics – www.modplas.com
14. The Indian Express – www.expressindia.com
15. Anderson Laboratories – www.andersonlaboratories.com
16. Farrell, Joe; Plastic Pollution In the Marine Environment: Boaters Can Help Control The Growing Population

17. Fried, Joel R; Polymer Science and Technology; Prentice Hall; pg. 272-285.