Design for the Environment/Automobile Car Mats

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This study was performed for the Design for the Environment course.


The main aim of this article is to evaluate, quantify, and examine effects of production of car mats on the environment while identifying possible alternatives to the current baseline material, synthetic rubber. Car mats have long been used in motor vehicles to protect the underlying floor surface. They are almost always installed in the factory and meant to last the life of the vehicle. Initially, car mats were a piece of carpet cut to fit a defined area of the carpeted floor surface.[1] Over time, Velcro and other means of fastening have been used to secure the mats in place, eventually leading to current widely used rubber spikes and grooves (base) at the back of the mat (fibers).

The two alternatives are analyzed based on their energy requirements and environmental impact. The aim is to choose materials that require less energy to produce, involve less harmful manufacturing methods, and have the smallest footprint after their useful life (i.e. be readily recyclable). Furthermore, the car mats must be able to fulfill their basic functionality throughout the lifetime of the vehicle. The mats must prevent salt and water from reaching the floor, retain dirt and odor, withstand abrasion, and be easy to clean. The materials studied are being considered for use in Toyota’s future eco-friendly models as a response to a continually growing need for environmentally friendly vehicles. As such, it is necessary to study and determining better alternatives to the current baseline. In context of this report, the three sets of materials analyzed are as follows:

Baseline material: Synthetic rubber base with nylon fibers
Synthetic rubber is the predominant material used in car mats. 6,6 Nylon fibers are then attached to the rubber base using adhesive material.

Alternative 1: Polylactic acid (PLA) base and fibers
PLA is a carbon-neutral, nature-derived polymer. This material can be formed and used both as the base and fibers of the mat.

Alternative 2: Biodegradable rubber base with coir fibers
Biodegradable rubber is extracted mainly from the bark of rubber trees and will degrade completely. Coir fibers are extracted from the outer husks of coconuts. Both materials are readily available and environmentally friendly.


Highlights and Recommendations


  • Considering Functional analysis, all three groups of materials have the capability of carry out the intended task for the life of the product.
  • EIO-LCA suggests that PLA production has fewer greenhouse gas and toxic releases and requires less energy.
  • Based on SLCA, PLA has fewer negative impacts on the environment during its life cycle than the other two sets of materials with a score of 75 out of 100, whereas synthetic rubber achieved a score of 68.
  • Based on Cost analysis, synthetic rubber and nylon fibers are currently the cheapest materials. Biodegradable rubber and coir on the other hand are relatively more expensive, mainly due to small production amounts of these materials compared to synthetic rubber.
  • Societal impacts of car mats in general are insignificant and identical for all three materials.

Considering the results of each analysis and importance of each area, it can be concluded that Polylactic Acid (PLA) is the most suitable material for use in car mats and it is recommended out of the studied materials. For the decision making process, see recommendation.


Project Information[edit]

Section 1 Group A23 TA: Richard Mills

Name Responsibility
Poya Rahmati - (Rahmatip) Team Leader
Mohammed (Viquar) Zia - (Viquar1) Baseline: Synthetic rubber/Nylon fibers
Michael Li - (Unseenfire) Alternative 1: Polylactic Acid
Alizera Moeini Alternative 2: Biodegradable rubber/Coir fibers

Considered Materials[edit]

Baseline: Synthetic Rubber Base with Nylon Fibers[edit]

Structure of Styrene Butadiene

Rubber (Styrene Butadiene Rubber - SBR) is primarily made of styrene and butadiene, both by products of petroleum refining. The processes involved in making them are extensive heating and steam cracking. Nylon 6,6 is made of adipic acid and hexamethylene diamine. The processes involved in making them are hydrogenation and oxidation. The analysis is included in SLCA (section 4.1) below.


Alternative 1: Polylactic Acid Base and Fibers[edit]

Structure of Polylactic Acid

Polylactic Acid (PLA) is a semi-synthetic polymer created from renewable natural resources which impacts the environment less than the conventional polymers used in mats. The starchy plants necessary for synthesizing PLA can be harvested continually, guaranteeing a continual supply of raw material. The primary advantages of PLA are its recyclability and biodegradability. After it use in car mats, polylactic acid can be potentially be reused for other applications. If this is not possible, exposure to a suitable environment promotes degradation into it's constituent compounds.[2] As a final resort, PLA car mats can undergo combustion, releasing water and carbon dioxide back into the atmosphere and completing the carbon cycle without releasing sulfur, nitrogen, or volatile organic compounds.


Alternative 2: Biodegradable Rubber Base with Coir Fibers[edit]

Natural rubber is derived from liquid called latex, which is extracted mainly from the bark of rubber trees (Hevea brasiliensis) through a tapping process. Through vulcanization, rubber acquires qualities such as strength, elasticity, impermeability and resistance to abrasion and solvents.[3] Coir is the fiber extracted from the outer husks of coconuts.[4] Currently, all our coir comes from the state of Kerala, at India's south-west Malabar Coast.[5] Combination of Natural Rubber and Coir could be used as new materials in car mat production. Both materials are available and environmentally friendly.

Functional Analysis[edit]

Synthetic Rubber and Nylon[edit]

Automobile mats made of synthetic rubber base (referred as rubber henceforth) with nylon fibers are most widely used in automobile industry. Their properties such as impermeability to water (rubber); trapping dirt and dust (nylon carpet) contribute to their popularity among mat manufacturers. They both fulfill the requirements of providing all weather protection and aesthetic appeal.

Polylactic Acid[edit]

Polylactic acid exhibits multiple characteristics which satisfy the criteria for car mat materials. According to industry sources, it possesses good abrasion resistance, impact resistance and toughness.[6] These properties indicate that PLA car mats will be able to withstand the daily physical rigours of an automobile floor. Furthermore, PLA is grease and oil resistant as well, reducing the cleaning effort required when spills occur. Although PLA is generally biodegradable, it is rigid and non-degradable under life cycle conditions. [7]

Biodegradable Rubber and Coir[edit]

Biodegradable rubber is very similar to Polylactic acid in terms of durability, flexibility, and impermeable to water. Coir fibers have proven to be a good choice of material as fibers used in mats as they are used currently for their strong fiber for products such as welcome mats and regular carpets. Also, coir fibers are easy to clean using water and other detergents. Combination of these two materials can be used in car mat manufacturing.

Summary[edit]

All materials analyzed meet the functional requirements of a car mat.

Streamlined Life Cycle Assessment (SLCA)[edit]

Synthetic Rubber and Nylon[edit]

Streamlined Life Cycle Assessment Table

Material Choice Energy Use Solid Residues Liquid Residues Gaseous Residues Subtotal
Resource Extraction 1 2 3 4 3 13
Manufacturing 1 1 3 2 3 10
Product Delivery 4 3 4 4 3 18
Product Use 4 4 4 4 4 20
Disposal, Recycling 1 1 1 3 1 7
Total: 68


Resource Extraction

Styrene-butadiene rubber (SBR or rubber) is made from styrene and butadiene; both by-products of petroleum refining [8]. Nearly 3.5 gallons [9] of oil is needed to make a set of mats (assuming they weigh 4kg). Nylon 6,6 is made from organic compounds: adipic acid and Hexamethylene diamine. The processes involved consume a lot of heat. Significant environmental concerns are depletion of fossil fuels and thermal pollution.

Manufacturing

SBR is produced by the copolymerization of butadiene and styrene. Nylon 6,6 fibers are made by extruding molten nylon through spinnerets. The fibers then undergo processes such as weaving and dyeing to become a carpet. A lot of energy is used in resource extraction and manufacturing in terms of power generation and consumption has significant impact on global climate change.

Product Delivery

Packaging is usually done in plastic or cardboard. Delivery (truck) requires energy and releases gases harmful for the environment.

Product Use

Minimum maintenance required with no significant impact on the environment.

Disposal / Recycling

Rubber and Nylon generally end up at landfills and take 50-80 [10] and 50 [11] years respectively to decompose naturally. However both of them can be recycled in their respective ways. Incineration of rubber produces useful energy but causes pollution.

Polylactic Acid[edit]

Streamlined Life Cycle Assessment Table

Material Choice Energy Use Solid Residues Liquid Residues Gaseous Residues Subtotal
Resource Extraction 2 2 3 3 3 13
Manufacturing 2 2 2 2 2 10
Product Delivery 3 3 4 4 3 17
Product Use 4 4 4 4 4 20
Disposal, Recycling 3 3 2 4 3 15
Total: 75

Resource Extraction
Polylactic acid manufacture requires starch from plants - a renewable resource. .[12] Although this resource can be replenished, significant energy and effort is required to grow the crops. Additionally, the material drain on the environment is still present. Residues are present in this phase due to transport and similar tasks but they do not have a large impact.

Manufacturing
After harvesting, the starch in the corn is separated from the husk and waste material. The starch then undergoes a series of chemical reactions to convert the starch into the polylactic acid polymer.[12] PLA fibres and bulk material are then formed into automobile car mats. This process is material and energy intensive, producing residue from residual plant matter, waste water, and released gaseous agents.

Product Delivery
Upon manufacture of the car mats, the product is then packaged and shipped for sale. Energy is consumed from transportation and fossil fuel emissions are released as a by-product of gasoline engine use.

Product Use
During the use phase, polylactic acid car mats are inert, requiring few resources and energy. The weight added to the automobile is negligible and cleaning agents for maintainance have negligible effect. As such, there are negligible solid, liquid and gaseous residues as well.

Disposal/Recycling
The merits of PLA are especially apparent during the disposal phase. Polylactic acid can be recycled if it can be isolated from other compounds. if this is impossible, PLA based car mats can be disposed of via composting and incineration, returning the carbon dioxide and water initially absorbed by the corn plants back into the atmosphere and completing the carbon cycle.[12] Additionally, fewer toxic residues are released from PLA mats in comparison to petrochemical compounds although solid residues may initially remain before decomposition. The natural decomposition process requires little energy.

Biodegradable Rubber and Coir[edit]

Streamlined Life Cycle Assessment Table

Material Choice Energy Use Solid Residues Liquid Residues Gaseous Residues Subtotal
Resource Extraction 2 2 3 3 2 12
Manufacturing 3 2 3 3 2 13
Product Delivery 2 2 2 3 2 11
Product Use 4 4 4 4 4 20
Disposal, Recycling 4 3 3 4 3 17
Total: 73
Life Cycle Stages of Coir Fibers

Resource Extraction

Natural rubber mostly comes from Pará rubber trees (Rubber tree) that grows in tropical parts of the earth. Brown fibers used in mat production are extracted from the fibrous outer shell of a coconut. Energy must be expended to plant, grow, reap, and transport the plants used in manufacturers. Small amount of wastes are produced at this stage.

Manufacturing

Coir fibers are removed by hand and softened in sea water, so that they can be woven into a selection of designs. [13] Natural rubber is a polymer and needs to be treated with chemicals to enhance some of its properties. Emission of dust and fumes from rubber processing operations is concern of manufacturing processes.

Product Delivery

Plastic used for packaging car mats is harmful for environment and wastes from packaging process need to be recycled. Also, the delivery of the goods from manufacturers to distributers requires burning of fuels and as a result emission of GHG gases in the environment.

Product Use

The final material is a durable and environmentally friendly. No maintenance is needed throughout its life span from users other than cleaning. The design is easy to install and needs a little effort and energy.

Disposal, Recycling

Some of the methods used these days are as follow: Incineration, Reuse, and recycling. Thin rubber products will degrade naturally especially if they are subjected to natural sunlight. [14]

Summary[edit]

SLCA Results:

Material SLCA Score
Baseline Synthetic rubber / Nylon fibers 68
Alternative I Polylactic Acid 75
Alternative II Biodegradable rubber / Coir fibers 73

Based on the SLCA results shown above, Polylactic Acid is again favored as the better choice of material for use in car mats. However, Biodegradable rubber and coir fibers are also a good choice of materials. The short coming of Alternative II is mostly due to long distance shipping requirement of coir fibers, although this can be accounted for by local production of coconut trees or use of cheaper or less harmful method of shipping.

Economic Input Output Life Cycle Assessment (EIOLCA)[edit]

Synthetic Rubber and Nylon[edit]

Based on EIOLCA model - US Department of commerce 1997 Industry Benchmark, the mat (rubber with nylon carpet) was broken down into the following sectors: synthetic rubber manufacturing, industrial mold manufacturing, noncellulosic organic fiber manufacturing, carpet and rug mills and adhesive manufacturing. There are no sectors for recycling of the components. Therefore, recycling is not included in this analysis. The inputs used for analysis were: conventional air pollutants, greenhouse gases, energy and toxic releases.

Synthetic Rubber Manufacturing

Synthetic rubber is the primary material used in this product. Therefore, it will have a greater share in overall environmental impact.

Significant Impacts:

  • 1510 metric ton (mt) CO2. CO2 is the largest contributor to global warming potential (gwp) – 92% of the total.
  • 17.5 terra joules (TJ) of energy is produced from natural gas. Methane, released through leakage, is a green house gas (23 times stronger that same amount of CO2) 31% of indirect emissions come from release of methane.
  • Total toxic releases are 2190 kg. 28% of this are non-point air (not readily and specifically identifiable)[15]

Environment Concerns: Global climate change, ozone depletion, acid disposition and smog.

Industrial Mold Manufacturing

This sector does not have any significant impact. A brief summary is included in the consolidated table of environmental impacts below.

Noncellulosic Organic Fiber Manufacturing

This sector encompasses nylon fiber and polypropylene for the nylon carpet. Nylon carpet is a major component for this product.

Significant Impacts:

  • High levels of CO, SO2 and NOx are released – 6.42, 2.48 and 2.06 mt respectively. Emissions are comparable to those from synthetic rubber manufacturing sector.
  • 12.3 terra joules (TJ) of energy is produced from natural gas. Methane, released through leakage, is a green house gas (23 times stronger that same amount of CO2) 31% of indirect emissions come from release of methane.)[15]

Environment Concerns: Global climate change, Depletion of nonrenewable resources and smog

Carpet and Rug Mills

The nylon carpet and polypropylene from previous sector need to be brought together. This is accomplished in this sector. It is related to the noncellulosic manufacturing sector and there are overlaps. This is mainly the use of industrial machines to weave, cut and dye.

Significant Impacts: 2% of 1260 toxic releases go underground.

Environment Concerns: Threat to ground water and lost of arable land.

Adhesive Manufacturing

There is no doubt that adhesives manufacturing have an impact on the environment. However, adhesives do not meet the 5% rule of mass of product and does not pose any significant threat. For more information, please refer to consolidated table below. It should be noted that sectors are not scaled.

Sector (per 1 million of activity) Greenhouse gases GWP (MTCO2E) Energy Use (TJ) Toxic Releases (kg)
Synthetic Rubber Manufacturing 1750 26.6 2190
Industrial mold Manufacturing 482 5.72 654
Noncellulosic Organic Fiber Manufacturing 1670 22.9 2420
Carpet and Rug Manufacturing 1140 14.5 1260
Adhesive Manufacturing 1120 14.6 1110

[15]

Polylactic Acid[edit]

EIOLCA of polylactic acid car mats is complicated by the fact that its manufacture does not fit into any one specific industry sector. However, it is possible to divide the analysis into the harvesting, pre-processing, and fabrication stages and utilize intermediate values.

Crop Farming

Starchy crops are the primary raw material for PLA formation. In North America, corn presents itself as an excellent raw material. As a grain, its production corresponds to the Grain Farming sector in EIOLCA. For this sector, most of the air pollutants result from pesticide and fertizer use. The total Global Warming potential for $1 million of economic activity is 6310 MTCO2E of which 5300 MTCO2E come from the actual farming process. Additional significant contributors are fertilizer manufacturing (415 MTCO2E) and power generation (204 MTCO2E) likely used for powering machines which aid in farming and harvesting the crops.[15] The energy consumption and toxic releases share a similar emphasis on grain farming and fertilizer manufacturing.

Cellulosic Fibre Manufacturing

PLA fibre formation does not fully correspond to the Cellulosic Fibre Manufacturing sector since starch, not cellulose is utilized. However, both these compounds are glucose polymers and their manufacturing processes are comparable. For $1 million economic activity, the global warming potential for this stage is 3460 MTCO2E with the bulk of the emissions from the organic fiber manufacturing process and power generation and supply. These two sectors also contribute most to toxic releases and energy consumption.[15]

Carpet and Rug Mills

The final stage of mat formation involves the integration of the fibre into a mat form. The processes used are similar to those of the Carpet and Rug Mills sector in EIOLCA so the environmental effects are potentially comparable. The total GTP is 1140 MTCO2E with power generation and supply, fiber manufacturing, and carpet and rug mills as the leading pollutant and energy usage sectors.[15]

Total Environmental Effect of PLA Mats using EIOLAC $1 million economic activity

Total Output
Greenhouse Gases 2051.5 MTCO2E
Energy Use 26.9 TJ
Toxic Releases 4199 kg

[15]

Biodegradable Rubber and Coir[edit]

Since there is no specific values for some processes, numbers from the closest sector were used as an estimation.

Farming and Harvesting

Both natural rubber and coir come from forestry areas so we use Sector #1130: Forestry and logging from EIOLCA website. (Greenhouse Gases = 1308 MTCO2E, Energy Use = 17.351 TJ)[15]

Manufacturing and Processing

Manufacturing of cellulosic organic fibers can be used as estimation for coir fiber production. Rubber manufacturing sector can be used for natural rubber production. (Rubber Manufacturing: Greenhouse Gases = 548 MTCO2E, Energy Use = 22.552 TJ, Air Pollution = 2.086 mt)(Coir Fiber Manufacturing = Greenhouse Gases = 3460 MTCO2E, Energy Use = 61.9 TJ, Toxic Releases = 15800 kg)[15]

Car Mat Fabrication

Rug and Mills manufacturing sector can be used as estimation for car mat production. (Mat Fabrication: Greenhouse Gases = 866.1 MTCO2E, Energy Use = 11.2 TJ, Toxic Releases = 447 kg)[15]

Summary[edit]

Material GWP (MTCO2E) Energy Input (TJ) Toxic Releases (kg)
Baseline Synthetic rubber / Nylon fibers 6,182 84.32 7,634
Alternative I Polylactic Acid 2,051.5 26.90 4,199
Alternative II Biodegradable rubber / Coir fibers 6,182.1 113.00 16,247
EIOLCA analysis results

As is can be seen from the figures, Polylactic Acid is a better material choice based on the EIOLCA analysis.

Cost Analysis[edit]

Synthetic Rubber and Nylon[edit]

According to International rubber study group, cost of US export Synthetic rubber (type not specified) in 2008 was $2,012/tonne [16]. Cost of nylon carpet is $1.37/sqft [17]. A set (2 front and 2 rear) of mats weigh approximately 5 kg. Assuming 80% is made up of rubber and 2 sqft of nylon carpet is used, the material costs will be: $8.04 (rubber) + $2.76 (nylon carpet) = $10.80

Cost will include either sending it to the land fill or incinerating factory. Incineration have negative costs associated with as it is producing energy. So it can be a source of revenue rather than expense. Scrap rubber today costs ~$120/100 kg (Rs 5550/100 kg)[18]. This is approximately equal to $250/100kg 15 years from now taking into consideration time value of money. (Calculated at a compound interest rate of 5%)

Additional costs may be associated with the manufacture of this product. Workers involved in the production of rubber are known to face serious health hazards such as cancers, respiratory and dermatologic problems.[19] Adequate data is not available to have a cost estimate. Other costs include tackling environmental impacts such as global climate change, smog and ground pollution caused during the lifecycle of the mat.

Polylactic Acid[edit]

It is always a challenge to design eco-friendly products which can provide similar functional capabilities for a comparable cost. As with new technologies, polylactic acid was initially expensive and limited to biomedical applications.[12] Recently, it has become possible to manufacture this material at a lower cost, increasing the commercial viability of this technology. [20] This price results from an increase in accessibility to renewable resources like corn and a reduction in processing energy requirements. Due to a decrease in availability of fossil fuels, the price of hydrocarbon-based polymer rubber will tend to increase in the long run. At this time, it will be more economically feasible to use mats created from renewable resources. For now, however, polylactic acid car mats provide environmental benefits at a slightly higher price than mainstream rubber mats. [20]

Biodegradable Rubber and Coir[edit]

The current world consumption of rubber, totaling around 18 million tons per year, consists of 48% natural rubber (NR).[21] Taking the price of natural rubber as 110 Rs per Kg (2.65 Canadian dollars per Kg) gives us:

1 ton of Natural Rubber = 2.65 x 1000 = $ 2650 (According to latest prices) Globally, around 500,000 tons of coir is produced every year. The value of coir production has been put at around $100 million annually.[22] We now can estimate the price of 1 ton of coir about $2000.

Addition to shipping costs, burning fuels by delivery vehicles creates emissions that are harmful to the environment such as greenhouse gases.

Disposal costs of out materials can range from $0.02 - $0.05 per pound, depending on your State or region.[23]

Summary[edit]

Although synthetic rubber production currently cost much less than Polylactic acid or coir fibers, the disposal and recycling costs related to synthetic rubber are high. Some of these costs are not easily quantifiable and so they have been ignored for many years. Considering these costs when comparing synthetic rubber to Alternativ I or II shows that polylactic acid or coir fibers, although more expensive in production are a viable replacement materials for synthetic rubber.

Societal Analysis[edit]

Considering the small scale of environmental impacts associated with car mats, the impact of car mats on the society is relatively insignificant compared to the effect of the car that it is going to be used in. Car mats are relatively cheap and can be acquired by any person who owns a vehicle. Also the main users of car mats are restricted to very few people including the driver, hence car mats do not have significant effect on society as a whole. Although it is more likely that car mats will be seen as a small step towards environmental sustainability. As such the public will view the mats as another product to promote environmental responsibility and may not be as motivated to expend the extra effort to purchase product made of environmentally friendly materials. In light of these circumstances, it will be more beneficial to have automobile manufacturers using environmentally friendly car mats in new cars to immediately reap the benefits on a large scale. Along with other “environmentally friendly” features, this could promote the automobiles to a society which is becoming increasingly interested in eco-friendly products.

Recommendation[edit]

Below is a weighted matrix which is used to identify the most feasible set of material. Each set of material is given a score out of 5 for each analysis totaling to a score out of 20. The material with highest score is then chosen.

Material Functional Analysis EIOLCA SLCA Cost Analysis Total
Baseline Synthetic rubber / Nylon fibers 5 3 1 4 13
Alternative I Polylactic Acid 5 5 5 3 18
Alternative II Biodegradable rubber / Coir fibers 5 2 4 3 14

In conclusion, as shown in Table 7.3, polylactic acid base and fibers (Alternative I) is the most feasible replacement for current baseline, synthetic rubber base and nylon fibers. Therefore, out of the three sets of materials tested, we would recommend polylactic acid to be used in future models.


See also[edit]

References[edit]

  1. FreePatents Online. Available: http://www.freepatentsonline.com/6381806.html
  2. Nature, “Plastic Promises”, Nature, vol. 446 pp. 715 April 2007
  3. Article: Commodity Atlas Natural Rubber, Page 35.
  4. Coirmats.com Article, “Information on coir”,Available: http://www.coirmats.com/coir.html
  5. Article, “From Coir to Mat”, Available: http://www.onevillage.org/coirsociety.htm
  6. iDES, “Polylactic Acid (PLA) Features an Uses.”, Available: http://www.ides.com/generics/PLA/PLA_features.htm
  7. Toray Industries(America) Inc., “BCF Yarn for Car Mats.” (2006), Available: http://www.tory-auto.us/products/fibers_carmat.html
  8. Rubber Types – Trelleborg HTTP: <http://www.trelleborg.com/en/The-Group/Career/The-Polymer-School/Rubber-Types/>
  9. Rubber FAQs – Rubber Manufacturers Association HTTP: <http://www.rma.org/about_rma/rubber_faqs/>
  10. Recycling of Rubber – Review reports, Volume 9 Number 3 [Manuel & Dierkes, 1997] HTTP: <http://books.google.ca/books?id=XCuBK4c9ZeYC&pg=PA27&lpg=PA27&dq=cost+of+disposing+rubber&source=bl&ots=sRsht_W-YY&sig=gJxV0uJG1qWr3Ou1RvMSuc4Y-Qk&hl=en&ei=4NzKSYKmEJjsnQev8KHpCQ&sa=X&oi=book_result&resnum=6&ct=result#PPA26,M>
  11. Recycling Carpet – How stuff works video center, HTTP: <http://videos.howstuffworks.com/planet-green/27666-g-word-recycling-carpet-video.htm?sort=most_watched&page=2>
  12. 12.0 12.1 12.2 12.3 D. W. Farrington, J. Lunt, S. Davies, R. S. Blackburn, “Poly(lactic) fibers” (2009), Natureworks, 2009
  13. Greenspec UK, Coir Fibers. Available: http://www.greenspec.co.uk/html/product-pages/AltFloorCoir.php
  14. Article: Commodity Atlas Natural Rubber, Page 35
  15. 15.0 15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 15.9 Carnegie Mellon University Green Design Institute, “Economic Input-Output Life Cycle Assessment (EIOLCA),” (2006) Available: http://www.eiolca.net
  16. History of synthetic rubber industry – Chemical Industry News and Intelligence HTTP: <http://www.icis.com/Articles/2008/05/12/9122056/history-of-the-synthetic-rubber-industry.html>
  17. Wholesale carpets - Own a Carpet Inc. <http://www.owencarpet.com/carpetswholesale.htm>
  18. Weekly Rubber Price – Rubber Board of India. HTTP: <http://rubberboard.org.in/weeklyrubberprice.asp>
  19. Hazards Review – Rubber products manufacturing industry [1993]. Available: <http://www.cdc.gov/niosh/rubberhr.html
  20. 20.0 20.1 Alexander H. Tullo, “Growing Plastics,” Chemical and Engineering News, vol. 86 no. 39 pp. 31-35. September 2008
  21. Presented by A.F.S. Budiman, Secretary-General, International Rubber Study Group Article, “Recent Developments in Natural Rubber Prices”, 2006, Available: http://www.fao.org/DOCREP/006/Y4344E/y4344e0d.htm
  22. International fiber Article, “Natural Fiber (Coir), 2009, Available: http://www.naturalfibres2009.org/en/fibres/coir.html
  23. Presentation at University of Philadelphia on “Material Reclaim”, 2007