Rubber Wrist Bands
If you have not noticed, rubber wrist bands have become very popular over the past two years. Thousands of people are wearing these wrist bands as a way of showing their pride for something, or simply as a fashion statement. There are so many different colors and style being worn by people from all over the world that it can sometimes be very difficult to figure out what is what.
If you see somebody with a rubber wrist band on, the thing that you need to look for is the color. Each color represents something different. But if this was not complicated enough, there are also companies that make custom rubber wristbands for anybody that wants to order them. This means that anybody can order a rubber wristband to read whatever they want and in whatever color they want.
But as a basic rule of thumb, there are certain colors that represent certain things. The colors are as follows:
Pink Bracelets are usually worn as a cancer awareness band. Often times, you will also notice that the pink wristbands also have words on them such as “Find a cure.” These are meant to spread the word about how dangerous cancer can be.
If you see somebody that is wearing a rainbow bracelet, this usually means that they are trying to demonstrate gay pride. These are some of the more common custom wristbands that are around.
Red bracelets are often times worn by people that are trying to spread AIDS or heart disease awareness. In addition, red is also the color that is worn by military families. If you are having a hard time deciphering between the two you will want to look at the words that are imprinted on the band.
Red, white, and blue bands are pretty self explanatory; they show patriotism and love for the United States.
Yellow bracelets are among the most popular in the world thanks to Lance Armstrong. These wristbands are meant to raise cancer awareness and have the words “Live Strong” imprinted on them. Millions of these bracelets have been sold all over the world, and sales are still soaring.
If you are looking to buy a wristband, you should be aware that they come in a number of different materials. The two most popular are rubber and silicon wristbands. If you are placing an order with a specialty company, make sure that you specify the material that you want. Custom silicon wristbands are not as common as rubber, so if you want these you will need to ask for them.
Overall, rubber wrist bands are very popular all over the world. Regardless of where you are at, you are sure to see at least a few people that are sporting these bands.
วันอังคารที่ 7 ตุลาคม พ.ศ. 2551
Rubber band
Rubber band
Five rubber bands
A rubber band (in some regions known as a binder, elastic band, lackey band, "laggy band" or gumband) is a short length of rubber and latex formed in the shape of a loop. Such bands are typically used to hold multiple objects together. Some are used as weapons. The rubber band was patented in Australia
Rubber Band
Background
Rubber bands are one of the most convenient products of the twentieth century, used by numerous individuals and industries for a wide variety of purposes. The largest consumer of rubber bands in the world is the U.S. Post Office, which orders millions of pounds a year to use in sorting and delivering piles of mail. The newspaper industry also uses massive quantities of rubber bands to keep individual newspapers rolled or folded together before home delivery. Yet another large consumer is the agricultural products industry. The flower industry buys rubber bands to hold together bouquets or uses delicate bands around the petals of flowers (especially tulips) to keep them from opening in transit. Vegetables such as celery are frequently bunched together with rubber bands, and the plastic coverings over berries, broccoli, and cauliflower are often secured with rubber bands. All in all, more than 30 million pounds of rubber bands are sold in the United States alone each year.
Manufacturing
The manufacturing process is a complicated one which involves extruding the rubber into a long tube to provide its general shape, putting the tubes on mandrels and curing the rubber with heat, and then slicing it along the width of the tube into little bands.[1][2] While other rubber products may use synthetic rubber, rubber bands are still primarily manufactured using natural rubber because of its superior elasticity.
Processing the natural latex
1 The initial stage of manufacturing the harvested latex usually takes place on the rubber plantation, prior to packing and shipping. The first step in processing the latex is purification, which entails straining it to remove the other constituent elements apart from rubber and to filter out impurities such as tree sap and debris.
2 The purified rubber is now collected in large vats. Combined with acetic or formic acid, the rubber particles cling together to form slabs.
3 Next, the slabs are squeezed between rollers to remove excess water and pressed into bales or blocks, usually 2 or 3 square feet (.6 or .9 square meter), ready for shipping to factories. The size of the blocks depends on what the individual plantation can accommodate.
Mixing and milling
4 The rubber is then shipped to a rubber factory. Here, the slabs are machine cut (or chopped) into small pieces. Next, many manufacturers use a Banbury Mixer, invented in 1916 by Femely H. Banbury. This machine mixes the rubber with other ingredients—sulfur to vulcanize it, pigments to color it, and other chemicals to increase or diminish the elasticity of the resulting rubber bands. Although some companies don't add these ingredients until the next stage (milling), the Banbury machine integrates them more thoroughly, producing a more uniform product.
5 Milling, the next phase of production, entails heating the rubber (a blended mass if it has been mixed, discrete pieces if it has not) and squeezing it flat in a milling machine.
Extrusion
6 After the heated, flattened rubber leaves the milling machine, it is cut into strips. Still hot from the milling, the strips are then fed into an extruding machine which forces the rubber out in long, hollow tubes (much as a meat grinder produces long strings of meat). Excess rubber regularly builds up around the head of each extruding machine, and this rubber is cut off, collected, and placed back with the rubber going into the milling machine.
Curing
7 The tubes of rubber are then forced over aluminum poles called mandrels, which have been covered with talcum powder to keep the rubber from sticking. Although the rubber has already been vulcanized, it's rather brittle at this point, and needs to be "cured" before it is elastic and usable. To accomplish this, the poles are loaded onto racks that are steamed and heated in large machines.
8 Removed from the poles and washed to remove the talcum powder, the tubes of rubber are fed into another machine that slices them into finished rubber bands. Rubber bands are sold by weight, and, because they tend to clump together, only small quantities can be weighed accurately by machines. Generally, any package over 5 pounds (2.2 kilograms) can be loaded by machine but will still require manual weighing and adjusting.
Five rubber bands
A rubber band (in some regions known as a binder, elastic band, lackey band, "laggy band" or gumband) is a short length of rubber and latex formed in the shape of a loop. Such bands are typically used to hold multiple objects together. Some are used as weapons. The rubber band was patented in Australia
Rubber Band
Background
Rubber bands are one of the most convenient products of the twentieth century, used by numerous individuals and industries for a wide variety of purposes. The largest consumer of rubber bands in the world is the U.S. Post Office, which orders millions of pounds a year to use in sorting and delivering piles of mail. The newspaper industry also uses massive quantities of rubber bands to keep individual newspapers rolled or folded together before home delivery. Yet another large consumer is the agricultural products industry. The flower industry buys rubber bands to hold together bouquets or uses delicate bands around the petals of flowers (especially tulips) to keep them from opening in transit. Vegetables such as celery are frequently bunched together with rubber bands, and the plastic coverings over berries, broccoli, and cauliflower are often secured with rubber bands. All in all, more than 30 million pounds of rubber bands are sold in the United States alone each year.
Manufacturing
The manufacturing process is a complicated one which involves extruding the rubber into a long tube to provide its general shape, putting the tubes on mandrels and curing the rubber with heat, and then slicing it along the width of the tube into little bands.[1][2] While other rubber products may use synthetic rubber, rubber bands are still primarily manufactured using natural rubber because of its superior elasticity.
Processing the natural latex
1 The initial stage of manufacturing the harvested latex usually takes place on the rubber plantation, prior to packing and shipping. The first step in processing the latex is purification, which entails straining it to remove the other constituent elements apart from rubber and to filter out impurities such as tree sap and debris.
2 The purified rubber is now collected in large vats. Combined with acetic or formic acid, the rubber particles cling together to form slabs.
3 Next, the slabs are squeezed between rollers to remove excess water and pressed into bales or blocks, usually 2 or 3 square feet (.6 or .9 square meter), ready for shipping to factories. The size of the blocks depends on what the individual plantation can accommodate.
Mixing and milling
4 The rubber is then shipped to a rubber factory. Here, the slabs are machine cut (or chopped) into small pieces. Next, many manufacturers use a Banbury Mixer, invented in 1916 by Femely H. Banbury. This machine mixes the rubber with other ingredients—sulfur to vulcanize it, pigments to color it, and other chemicals to increase or diminish the elasticity of the resulting rubber bands. Although some companies don't add these ingredients until the next stage (milling), the Banbury machine integrates them more thoroughly, producing a more uniform product.
5 Milling, the next phase of production, entails heating the rubber (a blended mass if it has been mixed, discrete pieces if it has not) and squeezing it flat in a milling machine.
Extrusion
6 After the heated, flattened rubber leaves the milling machine, it is cut into strips. Still hot from the milling, the strips are then fed into an extruding machine which forces the rubber out in long, hollow tubes (much as a meat grinder produces long strings of meat). Excess rubber regularly builds up around the head of each extruding machine, and this rubber is cut off, collected, and placed back with the rubber going into the milling machine.
Curing
7 The tubes of rubber are then forced over aluminum poles called mandrels, which have been covered with talcum powder to keep the rubber from sticking. Although the rubber has already been vulcanized, it's rather brittle at this point, and needs to be "cured" before it is elastic and usable. To accomplish this, the poles are loaded onto racks that are steamed and heated in large machines.
8 Removed from the poles and washed to remove the talcum powder, the tubes of rubber are fed into another machine that slices them into finished rubber bands. Rubber bands are sold by weight, and, because they tend to clump together, only small quantities can be weighed accurately by machines. Generally, any package over 5 pounds (2.2 kilograms) can be loaded by machine but will still require manual weighing and adjusting.
วันพุธที่ 1 ตุลาคม พ.ศ. 2551
EPDM rubber
EPDM rubber
(ethylene propylene diene M-class rubber) is an elastomer which is characterized by wide range of applications.The E refers to Ethylene, P to Propylene, D to diene and M refers to its classification in ASTM standard D-1418. The “M” class includes rubbers having a saturated chain of the polymethylene type. The diene(s) currently used in the manufacture of EPDM rubbers are DCPD (dicyclopentadiene), ENB (ethylidene norbornene) and VNB (vinyl norbornene).
The ethylene content is around 45% to 75%. The higher the ethylene content the higher the loading possibilities of the polymer, better mixing and extrusion. During peroxide curing these polymers give a higher crosslink density compared with their amorphous counterpart. The amorphous polymer are also excellent in processing. This is very much influenced by their molecular structure. The diene content can vary between 2.5wt% up to 12wt%.
EPDM rubber is used in vibrators and seals; glass-run channel; radiator, garden and appliance hose; tubing; washers; belts; electrical insulation, and speaker cone surrounds. It is also used as a medium for water resistance in high-voltage polymeric cable jointing installations, roofing membrane, geomembranes, rubber mechanical goods, plastic impact modification, thermoplastic, vulcanizates, as a motor oil additive, pond liner, electrical cable-jointing, RV roofs, and chainmail applications.
EPDM exhibits satisfactory compatibility with fireproof hydraulic fluids, ketones, hot and cold water, and alkalis, and unsatisfactory compatibility with most oils, gasoline, kerosene, aromatic and aliphatic hydrocarbons, halogenated solvents, and concentrated acids.
The main properties of EPDM are its outstanding heat, ozone and weather resistance. The resistance to polar substances and steam are also good. It has excellent electrical properties. It has the ability to retain light colour.
(ethylene propylene diene M-class rubber) is an elastomer which is characterized by wide range of applications.The E refers to Ethylene, P to Propylene, D to diene and M refers to its classification in ASTM standard D-1418. The “M” class includes rubbers having a saturated chain of the polymethylene type. The diene(s) currently used in the manufacture of EPDM rubbers are DCPD (dicyclopentadiene), ENB (ethylidene norbornene) and VNB (vinyl norbornene).
The ethylene content is around 45% to 75%. The higher the ethylene content the higher the loading possibilities of the polymer, better mixing and extrusion. During peroxide curing these polymers give a higher crosslink density compared with their amorphous counterpart. The amorphous polymer are also excellent in processing. This is very much influenced by their molecular structure. The diene content can vary between 2.5wt% up to 12wt%.
EPDM rubber is used in vibrators and seals; glass-run channel; radiator, garden and appliance hose; tubing; washers; belts; electrical insulation, and speaker cone surrounds. It is also used as a medium for water resistance in high-voltage polymeric cable jointing installations, roofing membrane, geomembranes, rubber mechanical goods, plastic impact modification, thermoplastic, vulcanizates, as a motor oil additive, pond liner, electrical cable-jointing, RV roofs, and chainmail applications.
EPDM exhibits satisfactory compatibility with fireproof hydraulic fluids, ketones, hot and cold water, and alkalis, and unsatisfactory compatibility with most oils, gasoline, kerosene, aromatic and aliphatic hydrocarbons, halogenated solvents, and concentrated acids.
The main properties of EPDM are its outstanding heat, ozone and weather resistance. The resistance to polar substances and steam are also good. It has excellent electrical properties. It has the ability to retain light colour.
Butyl rubber (IIR)
BUTYL RUBBER
Properties and Applications
Butyl rubber (IIR) is the copolymer of isobutylene and a small amount of isoprene. First commercialized in 1943, the primary attributes of butyl rubber are excellent impermeability/air retention and good flex properties, resulting from low levels of unsaturation between long polyisobutylene segments. Tire innertubes were the first major use of butyl rubber, and this continues to be a significant market today.
The development of halogenated butyl rubber (halobutyl) in the 1950's and 1960's greatly extended the usefulness of butyl by providing much higher curing rates and enabling co-vulcanization with general purpose rubbers such as natural rubber and styrene-butadiene rubber (SBR). These properties permitted development of more durable tubeless tires with the air retaining innerliner chemically bonded to the body of the tire. Tire innerliners are by far the largest application for halobutyl today. Both chlorinated (chlorobutyl) and brominated (bromobutyl) versions of halobutyl are commercially available. In addition to tire applications, butyl and halobutyl rubbers' good impermeability, weathering resistance, ozone resistance, vibration dampening, and stability make them good materials for pharmaceutical stoppers, construction sealants, hoses, and mechanical goods. The total annual demand for Butyl Polymers is ~650,000 Metric Tons.
Photomicrograph of Tire Innerliner
Innerliner
Chemistry and Manufacturing Process
Butyl Rubber typically contains about 98% polyisobutylene with 2% isoprene distributed randomly in the polymer chain. To achieve high molecular weight, the reaction must be controlled at low temperatures (-90 to -100 degC). The reaction is highly exothermic. The most commonly used polymerization process uses methyl chloride as the reaction diluent and boiling liquid ethylene to remove the heat of reaction and maintain the needed temperature. It is also possible to polymerize butyl in alkane solutions and in bulk reaction. A variety of Lewis acids
1
can be used to initiate the polymerization. The molecular weight of butyl is set primarily by controlling the initiation and chain transfer rates.
C
In the most widely used manufacturing process, a slurry of fine particles of butyl rubber (dispersed in methyl chloride) is formed in the reactor. The methyl chloride and unreacted monomers are flashed and stripped overhead by addition of steam and hot water, and then they are dried and purified in preparation for recycle to the reactor. Slurry aid (zinc or calcium stearate) and antioxidant are introduced to the hot water/polymer slurry to stabilize the polymer and prevent agglomeration. Then the polymer is screened from the hot water slurry and dried in a series of extrusion dewatering and drying steps. Fluid bed conveyors and/or airvey systems are used to cool the product to acceptable packaging temperature. The resultant dried product is in the form of small "crumbs", which are subsequently weighed and compressed into 75 lb. bales for wrapping in PE film and packaging.
Butyl Molecule
Commercial Butyl Slurry Polymerization Process
2
The polymerization process for halobutyl is exactly the same as for non-halogenated butyl. Prior to halogenation, the butyl must be dissolved in a suitable solvent (hexane, pentane, etc...) and all unreacted monomer removed. Several different processes are currently used to prepare butyl solution for halogenation. Either reactor effluent polymer, in-process rubber crumb, or butyl product bales may be dissolved in solvent in preparation for halogenation.
Bromine liquid or chlorine vapor is added to the butyl solution in highly agitated reaction vessels. One mole of hydrobromic or hydrochloric acid is released for every mole of halogen that reacts, therefore the reaction solution must be neutralized with caustic (NaOH). The solvent is then flashed and stripped by steam/hot water, with calcium stearate added to prevent polymer agglomeration. The resultant polymer/water slurry is screened, dried, cooled, and packaged in a process similar to that of unhalogenated butyl.
BrBr
Cl
Minor Halobutyl Isomers
Most Abundant Halobutyl Isomer
Processing and Vulcanization
Like other rubbers, for most applications, butyl rubber must be compounded and vulcanized (chemically cross-linked) to yield useful, durable end use products. Grades of Butyl have been developed to meet specific processing and property needs, and a range of molecular weights, unsaturation, and cure rates are commercially available. Both the end use attributes and the processing equipment are important in determining the right grade of Butyl to use in a specific application. The selection and ratios of the proper fillers, processing aids, stabilizers, and curatives also play critical roles in both how the compound will process and how the end product will behave.
Care must be taken when processing Halobutyl that premature dehydrohalogenation does not occur due to high temperature. Stabilizers (calcium stearate alone for chlorobutyl, supplemented with an epoxy compound such as epoxidized soybean oil in the case of bromobutyl) are required to prevent dehydrohalogenation during processing.
Elemental sulfur and organic accelerators are widely used to cross-link butyl rubber for many applications. The low level of unsaturation requires aggressive accelerators such as thiuram or thiocarbamates. The vulcanization proceeds at the isoprene site with the polysulfidic cross links attached at the allylic positions, displacing the allylic hydrogen. The number of sulfur atoms per cross-link is between one and four or more. Cure rate and cure state (modulus) both increase if the diolefin content is increased (higher unsaturation). Sulfur cross-links have limited stability at sustained high temperature. Resin cure systems (commonly using alkyl phenol-formaldehyde derivatives) provide for carbon-carbon cross-links and more stable compounds.
3
In halobutyl, the allylic halogen allows easier cross-linking than does allylic hydrogen alone, because halogen is a better leaving group in nucleophilic substitution reactions. Zinc oxide is commonly used to cross-link halobutyl rubber, forming very stable carbon-carbon bonds by alkylation through dehydrohalogenation, with zinc chloride byproduct. Bromobutyl is faster curing than chlorobutyl and has better adhesion to high unsaturation rubbers. As a result, its volume growth rate has exceeded that of chlorobutyl in recent decades as tire plants have driven to higher productivity operation.
Br
Crosslinked Halobutyl Rubber
Conclusion
Butyl (and its primary derivative, halobutyl) is and will continue to be a high value polymer particularly well suited for its primary application of air retention in tires. Its unique combination of properties (excellent impermeability, good flex, good weatherability, co-vulcanization with high unsaturation rubbers, in the case of halobutyl) make it a preferred material for this application. As miles driven, tire size, and market sensitivity to pressure retention are all increasing, the demand for butyl rubber (specifically halobutyl) will continue to grow.
4
All of the material here is either paraphrased or verbatim from thepublic sources:
1. Encyclopedia of Polymer Science and Engineering (Vol 8)
2. The R. T. Vanderbilt Rubber Handbook (13th Edition)
3. Kirk-Othmer Encyclopedia of Chemical Technology (4th Ed, Vol No. 8)
5
Properties and Applications
Butyl rubber (IIR) is the copolymer of isobutylene and a small amount of isoprene. First commercialized in 1943, the primary attributes of butyl rubber are excellent impermeability/air retention and good flex properties, resulting from low levels of unsaturation between long polyisobutylene segments. Tire innertubes were the first major use of butyl rubber, and this continues to be a significant market today.
The development of halogenated butyl rubber (halobutyl) in the 1950's and 1960's greatly extended the usefulness of butyl by providing much higher curing rates and enabling co-vulcanization with general purpose rubbers such as natural rubber and styrene-butadiene rubber (SBR). These properties permitted development of more durable tubeless tires with the air retaining innerliner chemically bonded to the body of the tire. Tire innerliners are by far the largest application for halobutyl today. Both chlorinated (chlorobutyl) and brominated (bromobutyl) versions of halobutyl are commercially available. In addition to tire applications, butyl and halobutyl rubbers' good impermeability, weathering resistance, ozone resistance, vibration dampening, and stability make them good materials for pharmaceutical stoppers, construction sealants, hoses, and mechanical goods. The total annual demand for Butyl Polymers is ~650,000 Metric Tons.
Photomicrograph of Tire Innerliner
Innerliner
Chemistry and Manufacturing Process
Butyl Rubber typically contains about 98% polyisobutylene with 2% isoprene distributed randomly in the polymer chain. To achieve high molecular weight, the reaction must be controlled at low temperatures (-90 to -100 degC). The reaction is highly exothermic. The most commonly used polymerization process uses methyl chloride as the reaction diluent and boiling liquid ethylene to remove the heat of reaction and maintain the needed temperature. It is also possible to polymerize butyl in alkane solutions and in bulk reaction. A variety of Lewis acids
1
can be used to initiate the polymerization. The molecular weight of butyl is set primarily by controlling the initiation and chain transfer rates.
C
In the most widely used manufacturing process, a slurry of fine particles of butyl rubber (dispersed in methyl chloride) is formed in the reactor. The methyl chloride and unreacted monomers are flashed and stripped overhead by addition of steam and hot water, and then they are dried and purified in preparation for recycle to the reactor. Slurry aid (zinc or calcium stearate) and antioxidant are introduced to the hot water/polymer slurry to stabilize the polymer and prevent agglomeration. Then the polymer is screened from the hot water slurry and dried in a series of extrusion dewatering and drying steps. Fluid bed conveyors and/or airvey systems are used to cool the product to acceptable packaging temperature. The resultant dried product is in the form of small "crumbs", which are subsequently weighed and compressed into 75 lb. bales for wrapping in PE film and packaging.
Butyl Molecule
Commercial Butyl Slurry Polymerization Process
2
The polymerization process for halobutyl is exactly the same as for non-halogenated butyl. Prior to halogenation, the butyl must be dissolved in a suitable solvent (hexane, pentane, etc...) and all unreacted monomer removed. Several different processes are currently used to prepare butyl solution for halogenation. Either reactor effluent polymer, in-process rubber crumb, or butyl product bales may be dissolved in solvent in preparation for halogenation.
Bromine liquid or chlorine vapor is added to the butyl solution in highly agitated reaction vessels. One mole of hydrobromic or hydrochloric acid is released for every mole of halogen that reacts, therefore the reaction solution must be neutralized with caustic (NaOH). The solvent is then flashed and stripped by steam/hot water, with calcium stearate added to prevent polymer agglomeration. The resultant polymer/water slurry is screened, dried, cooled, and packaged in a process similar to that of unhalogenated butyl.
BrBr
Cl
Minor Halobutyl Isomers
Most Abundant Halobutyl Isomer
Processing and Vulcanization
Like other rubbers, for most applications, butyl rubber must be compounded and vulcanized (chemically cross-linked) to yield useful, durable end use products. Grades of Butyl have been developed to meet specific processing and property needs, and a range of molecular weights, unsaturation, and cure rates are commercially available. Both the end use attributes and the processing equipment are important in determining the right grade of Butyl to use in a specific application. The selection and ratios of the proper fillers, processing aids, stabilizers, and curatives also play critical roles in both how the compound will process and how the end product will behave.
Care must be taken when processing Halobutyl that premature dehydrohalogenation does not occur due to high temperature. Stabilizers (calcium stearate alone for chlorobutyl, supplemented with an epoxy compound such as epoxidized soybean oil in the case of bromobutyl) are required to prevent dehydrohalogenation during processing.
Elemental sulfur and organic accelerators are widely used to cross-link butyl rubber for many applications. The low level of unsaturation requires aggressive accelerators such as thiuram or thiocarbamates. The vulcanization proceeds at the isoprene site with the polysulfidic cross links attached at the allylic positions, displacing the allylic hydrogen. The number of sulfur atoms per cross-link is between one and four or more. Cure rate and cure state (modulus) both increase if the diolefin content is increased (higher unsaturation). Sulfur cross-links have limited stability at sustained high temperature. Resin cure systems (commonly using alkyl phenol-formaldehyde derivatives) provide for carbon-carbon cross-links and more stable compounds.
3
In halobutyl, the allylic halogen allows easier cross-linking than does allylic hydrogen alone, because halogen is a better leaving group in nucleophilic substitution reactions. Zinc oxide is commonly used to cross-link halobutyl rubber, forming very stable carbon-carbon bonds by alkylation through dehydrohalogenation, with zinc chloride byproduct. Bromobutyl is faster curing than chlorobutyl and has better adhesion to high unsaturation rubbers. As a result, its volume growth rate has exceeded that of chlorobutyl in recent decades as tire plants have driven to higher productivity operation.
Br
Crosslinked Halobutyl Rubber
Conclusion
Butyl (and its primary derivative, halobutyl) is and will continue to be a high value polymer particularly well suited for its primary application of air retention in tires. Its unique combination of properties (excellent impermeability, good flex, good weatherability, co-vulcanization with high unsaturation rubbers, in the case of halobutyl) make it a preferred material for this application. As miles driven, tire size, and market sensitivity to pressure retention are all increasing, the demand for butyl rubber (specifically halobutyl) will continue to grow.
4
All of the material here is either paraphrased or verbatim from thepublic sources:
1. Encyclopedia of Polymer Science and Engineering (Vol 8)
2. The R. T. Vanderbilt Rubber Handbook (13th Edition)
3. Kirk-Othmer Encyclopedia of Chemical Technology (4th Ed, Vol No. 8)
5
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