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What is the difference between uncured rubber and vulcanized rubber?
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Ludeman Eng
What is the difference between uncured rubber and vulcanized rubber?
I guess the story is about Mr. Goodyear spending his family wealth to research stiffening of rubber to utilize it as a load bearing wheel component. Luckily if you can call it, he found the correct chemical additive to crosslink or vulcanize soft rubber just as he was going bankrupt. Sulphur bonded the rubber molecules to eachother three dimensionally and significantly increased the stiffness and compressive strengtg of the material at the expense of its flexibility.
I guess the story is about Mr. Goodyear spending his family wealth to research stiffening of rubber to utilize it as a load bearing wheel component. Luckily if you can call it, he found the correct chemical additive to crosslink or vulcanize soft rubber just as he was going bankrupt. Sulphur bonded the rubber molecules to eachother three dimensionally and significantly increased the stiffness and compressive strengtg of the material at the expense of its flexibility.
Talking of vulcanizing rubber is incomplete without delving into some history. You will find it quite interesting.
The 'Olmecs' were the earliest known civilization in Mexico; they were known to have used the sap from a certain tree to make an elastic and waterproof material which they used for making clothing items 3000 years ago. It was brought to Europe by explorers, in the 18th century, and various chemists experimented with its properties - purely from a business point of view. It came to be known as 'rubber' because its only use in the beginning was to erase pencil writing off paper.
Charles Goodyear (1800-1860) - an American chemist, tried for years to use rubber in a variety of ways in his inventions, but was not successful in counteracting the poor thermal stability of the material - it degraded in heat and hardened in cold. Some others had tried ‘sun drying’ rubber treated with a sulphur solution - a process known as "solarisation" but without any success.
One day, the story goes, Goodyear accidentally dropped a sheet of rubber infused with sulphur and white-lead, onto a hot stove. He retrieved it, and was astonished to see that rather than melting, the fabric had hardened into a permanent flexible state. Further experimentation confirmed that it was far less affected by extremes of heat and cold than it had been earlier. The combined rubber and sulphur when placed in an oven under pressure, was 'cured' to form a stable material that had good mechanical properties. He immediately applied for a patent, and sent samples to England with a view to study the market over there.
But another chemist in Scotland - Charles Macintosh (1766-1843) - analyzed the samples and found out that sulphur was the key to the process, then quickly replicated and improved on Goodyear’s work, and took out a British patent immediately. It was Mackintosh who named the process “Vulcanisation” after Vulcan - the Roman god of Fire.
The natural latex (non vulcanized rubber) sap that is tapped from the tree contains many isoprene molecules, and as the latex dries out, the isoprene molecules crowd closer together until one molecule attacks the carbon-carbon double bond of an adjacent molecule; the double bond breaks and the electrons reform to create a bond between the two isoprene molecules, becoming a monomer. This process continues until many isoprene molecules have joined together, their inherent structure creating long strands or chains of monomers rather than homogeneous clusters; materials with these repeating chains of monomers are called polymers, of which natural rubber is one.
The aggregate of these monomer chains of isoprene is called polyisoprene, a formal polymer. The polyisoprene strands are stuck together by forming electrostatic bonds, which in turn allow the strands to move relative to each other when pulled, and return back to their original state when relaxed. So, rubber already has a degree of natural elasticity in its polyisoprene state.
What Goodyear had discovered was the effect that sulphur has under the right conditions of temperature and pressure, on the structure of the rubber. The chemistry that occurs under the conditions of vulcanization is such that the heat and pressure applied allows the sulphur atoms present to attack the double bonds of the carbon atoms in the isoprene strands and bind to them. Since sulphur atoms can also bond to themselves, these “disulphide” bonds start to link adjacent strands of isoprene together – the permanent state of cure known as “crosslinking”.
This crosslinking produces a netlike structure that gives a more stable elasticity to rubber than the purely electrostatic nature of the pre-vulcanisation bonds, and once created, this vulcanized material cannot easily be broken down.
This is what is known as “Thermoset”, which describes the permanent nature of the change in chemistry of the rubber. The amount of sulphur used determines the hardness of the cured product, and the addition of other chemicals and fillers can further enhance the eventual properties of the finished rubber item. The process of vulcanisation has now been extensively developed, and is the global science and industry that is rubber compounding.
The traditional sulphur cure system developed all those years ago by Goodyear was just the beginning of what has become a vast selection of different polymer families including synthetic materials, allied to a vast range of curatives, process aids and fillers. These can be combined in an infinite number of ways to deliver tailored and specific performance from the fascinating group of materials collectively known as rubber, yet it all goes back to the accidental discovery that Goodyear had that day in his laboratory, and his curiosity as to the unexpected change that had occurred.
Talking of vulcanizing rubber is incomplete without delving into some history. You will find it quite interesting.
The 'Olmecs' were the earliest known civilization in Mexico; they were known to have used the sap from a certain tree to make an elastic and waterproof material which they used for making clothing items 3000 years ago. It was brought to Europe by explorers, in the 18th century, and various chemists experimented with its properties - purely from a business point of view. It came to be known as 'rubber' because its only use in the beginning was to erase pencil writing off paper.
Charles Goodyear (1800-1860) - an American chemist, tried for years to use rubber in a variety of ways in his inventions, but was not successful in counteracting the poor thermal stability of the material - it degraded in heat and hardened in cold. Some others had tried ‘sun drying’ rubber treated with a sulphur solution - a process known as "solarisation" but without any success.
One day, the story goes, Goodyear accidentally dropped a sheet of rubber infused with sulphur and white-lead, onto a hot stove. He retrieved it, and was astonished to see that rather than melting, the fabric had hardened into a permanent flexible state. Further experimentation confirmed that it was far less affected by extremes of heat and cold than it had been earlier. The combined rubber and sulphur when placed in an oven under pressure, was 'cured' to form a stable material that had good mechanical properties. He immediately applied for a patent, and sent samples to England with a view to study the market over there.
But another chemist in Scotland - Charles Macintosh (1766-1843) - analyzed the samples and found out that sulphur was the key to the process, then quickly replicated and improved on Goodyear’s work, and took out a British patent immediately. It was Mackintosh who named the process “Vulcanisation” after Vulcan - the Roman god of Fire.
The natural latex (non vulcanized rubber) sap that is tapped from the tree contains many isoprene molecules, and as the latex dries out, the isoprene molecules crowd closer together until one molecule attacks the carbon-carbon double bond of an adjacent molecule; the double bond breaks and the electrons reform to create a bond between the two isoprene molecules, becoming a monomer. This process continues until many isoprene molecules have joined together, their inherent structure creating long strands or chains of monomers rather than homogeneous clusters; materials with these repeating chains of monomers are called polymers, of which natural rubber is one.
The aggregate of these monomer chains of isoprene is called polyisoprene, a formal polymer. The polyisoprene strands are stuck together by forming electrostatic bonds, which in turn allow the strands to move relative to each other when pulled, and return back to their original state when relaxed. So, rubber already has a degree of natural elasticity in its polyisoprene state.
What Goodyear had discovered was the effect that sulphur has under the right conditions of temperature and pressure, on the structure of the rubber. The chemistry that occurs under the conditions of vulcanization is such that the heat and pressure applied allows the sulphur atoms present to attack the double bonds of the carbon atoms in the isoprene strands and bind to them. Since sulphur atoms can also bond to themselves, these “disulphide” bonds start to link adjacent strands of isoprene together – the permanent state of cure known as “crosslinking”.
This crosslinking produces a netlike structure that gives a more stable elasticity to rubber than the purely electrostatic nature of the pre-vulcanisation bonds, and once created, this vulcanized material cannot easily be broken down.
This is what is known as “Thermoset”, which describes the permanent nature of the change in chemistry of the rubber. The amount of sulphur used determines the hardness of the cured product, and the addition of other chemicals and fillers can further enhance the eventual properties of the finished rubber item. The process of vulcanisation has now been extensively developed, and is the global science and industry that is rubber compounding.
The traditional sulphur cure system developed all those years ago by Goodyear was just the beginning of what has become a vast selection of different polymer families including synthetic materials, allied to a vast range of curatives, process aids and fillers. These can be combined in an infinite number of ways to deliver tailored and specific performance from the fascinating group of materials collectively known as rubber, yet it all goes back to the accidental discovery that Goodyear had that day in his laboratory, and his curiosity as to the unexpected change that had occurred.
I guess the story is about Mr. Goodyear spending his family wealth to research stiffening of rubber to utilize it as a load bearing wheel component. Luckily if you can call it, he found the correct chemical additive to crosslink or vulcanize soft rubber just as he was going bankrupt. Sulphur bonded the rubber molecules to eachother three dimensionally and significantly increased the stiffness and compressive strengtg of the material at the expense of its flexibility.
I guess the story is about Mr. Goodyear spending his family wealth to research stiffening of rubber to utilize it as a load bearing wheel component. Luckily if you can call it, he found the correct chemical additive to crosslink or vulcanize soft rubber just as he was going bankrupt. Sulphur bonded the rubber molecules to eachother three dimensionally and significantly increased the stiffness and compressive strengtg of the material at the expense of its flexibility.
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Talking of vulcanizing rubber is incomplete without delving into some history. You will find it quite interesting.
The 'Olmecs' were the earliest known civilization in Mexico; they were known to have used the sap from a certain tree to make an elastic and waterproof material which they used for making clothing items 3000 years ago. It was brought to Europe by explorers, in the 18th century, and various chemists experimented with its properties - purely from a business point of view. It came to be known as 'rubber' because its only use in the beginning was to erase pencil writing off paper.
The ancient Olmec Civilization
Charles Goodyear (1800-1860) - an American chemist, tried for years to use rubber in a variety of ways in his inventions, but was not successful in counteracting the poor thermal stability of the material - it degraded in heat and hardened in cold. Some others had tried ‘sun drying’ rubber treated with a sulphur solution - a process known as "solarisation" but without any success.
One day, the story goes, Goodyear accidentally dropped a sheet of rubber infused with sulphur and white-lead, onto a hot stove. He retrieved it, and was astonished to see that rather than melting, the fabric had hardened into a permanent flexible state. Further experimentation confirmed that it was far less affected by extremes of heat and cold than it had been earlier. The combined rubber and sulphur when placed in an oven under pressure, was 'cured' to form a stable material that had good mechanical properties. He immediately applied for a patent, and sent samples to England with a view to study the market over there.
But another chemist in Scotland - Charles Macintosh (1766-1843) - analyzed the samples and found out that sulphur was the key to the process, then quickly replicated and improved on Goodyear’s work, and took out a British patent immediately. It was Mackintosh who named the process “Vulcanisation” after Vulcan - the Roman god of Fire.
The chemistry and history. - Martin's Rubber Company
Now, the chemistry:
The natural latex (non vulcanized rubber) sap that is tapped from the tree contains many isoprene molecules, and as the latex dries out, the isoprene molecules crowd closer together until one molecule attacks the carbon-carbon double bond of an adjacent molecule; the double bond breaks and the electrons reform to create a bond between the two isoprene molecules, becoming a monomer. This process continues until many isoprene molecules have joined together, their inherent structure creating long strands or chains of monomers rather than homogeneous clusters; materials with these repeating chains of monomers are called polymers, of which natural rubber is one.
The aggregate of these monomer chains of isoprene is called polyisoprene, a formal polymer. The polyisoprene strands are stuck together by forming electrostatic bonds, which in turn allow the strands to move relative to each other when pulled, and return back to their original state when relaxed. So, rubber already has a degree of natural elasticity in its polyisoprene state.
What Goodyear had discovered was the effect that sulphur has under the right conditions of temperature and pressure, on the structure of the rubber. The chemistry that occurs under the conditions of vulcanization is such that the heat and pressure applied allows the sulphur atoms present to attack the double bonds of the carbon atoms in the isoprene strands and bind to them. Since sulphur atoms can also bond to themselves, these “disulphide” bonds start to link adjacent strands of isoprene together – the permanent state of cure known as “crosslinking”.
This crosslinking produces a netlike structure that gives a more stable elasticity to rubber than the purely electrostatic nature of the pre-vulcanisation bonds, and once created, this vulcanized material cannot easily be broken down.
This is what is known as “Thermoset”, which describes the permanent nature of the change in chemistry of the rubber. The amount of sulphur used determines the hardness of the cured product, and the addition of other chemicals and fillers can further enhance the eventual properties of the finished rubber item. The process of vulcanisation has now been extensively developed, and is the global science and industry that is rubber compounding.
The traditional sulphur cure system developed all those years ago by Goodyear was just the beginning of what has become a vast selection of different polymer families including synthetic materials, allied to a vast range of curatives, process aids and fillers. These can be combined in an infinite number of ways to deliver tailored and specific performance from the fascinating group of materials collectively known as rubber, yet it all goes back to the accidental discovery that Goodyear had that day in his laboratory, and his curiosity as to the unexpected change that had occurred.
Source: Rubber and Vulcanisation
Talking of vulcanizing rubber is incomplete without delving into some history. You will find it quite interesting.
The 'Olmecs' were the earliest known civilization in Mexico; they were known to have used the sap from a certain tree to make an elastic and waterproof material which they used for making clothing items 3000 years ago. It was brought to Europe by explorers, in the 18th century, and various chemists experimented with its properties - purely from a business point of view. It came to be known as 'rubber' because its only use in the beginning was to erase pencil writing off paper.
The ancient Olmec Civilization
Charles Goodyear (1800-1860) - an American chemist, tried for years to use rubber in a variety of ways in his inventions, but was not successful in counteracting the poor thermal stability of the material - it degraded in heat and hardened in cold. Some others had tried ‘sun drying’ rubber treated with a sulphur solution - a process known as "solarisation" but without any success.
One day, the story goes, Goodyear accidentally dropped a sheet of rubber infused with sulphur and white-lead, onto a hot stove. He retrieved it, and was astonished to see that rather than melting, the fabric had hardened into a permanent flexible state. Further experimentation confirmed that it was far less affected by extremes of heat and cold than it had been earlier. The combined rubber and sulphur when placed in an oven under pressure, was 'cured' to form a stable material that had good mechanical properties. He immediately applied for a patent, and sent samples to England with a view to study the market over there.
But another chemist in Scotland - Charles Macintosh (1766-1843) - analyzed the samples and found out that sulphur was the key to the process, then quickly replicated and improved on Goodyear’s work, and took out a British patent immediately. It was Mackintosh who named the process “Vulcanisation” after Vulcan - the Roman god of Fire.
The chemistry and history. - Martin's Rubber Company
Now, the chemistry:
The natural latex (non vulcanized rubber) sap that is tapped from the tree contains many isoprene molecules, and as the latex dries out, the isoprene molecules crowd closer together until one molecule attacks the carbon-carbon double bond of an adjacent molecule; the double bond breaks and the electrons reform to create a bond between the two isoprene molecules, becoming a monomer. This process continues until many isoprene molecules have joined together, their inherent structure creating long strands or chains of monomers rather than homogeneous clusters; materials with these repeating chains of monomers are called polymers, of which natural rubber is one.
The aggregate of these monomer chains of isoprene is called polyisoprene, a formal polymer. The polyisoprene strands are stuck together by forming electrostatic bonds, which in turn allow the strands to move relative to each other when pulled, and return back to their original state when relaxed. So, rubber already has a degree of natural elasticity in its polyisoprene state.
What Goodyear had discovered was the effect that sulphur has under the right conditions of temperature and pressure, on the structure of the rubber. The chemistry that occurs under the conditions of vulcanization is such that the heat and pressure applied allows the sulphur atoms present to attack the double bonds of the carbon atoms in the isoprene strands and bind to them. Since sulphur atoms can also bond to themselves, these “disulphide” bonds start to link adjacent strands of isoprene together – the permanent state of cure known as “crosslinking”.
This crosslinking produces a netlike structure that gives a more stable elasticity to rubber than the purely electrostatic nature of the pre-vulcanisation bonds, and once created, this vulcanized material cannot easily be broken down.
This is what is known as “Thermoset”, which describes the permanent nature of the change in chemistry of the rubber. The amount of sulphur used determines the hardness of the cured product, and the addition of other chemicals and fillers can further enhance the eventual properties of the finished rubber item. The process of vulcanisation has now been extensively developed, and is the global science and industry that is rubber compounding.
The traditional sulphur cure system developed all those years ago by Goodyear was just the beginning of what has become a vast selection of different polymer families including synthetic materials, allied to a vast range of curatives, process aids and fillers. These can be combined in an infinite number of ways to deliver tailored and specific performance from the fascinating group of materials collectively known as rubber, yet it all goes back to the accidental discovery that Goodyear had that day in his laboratory, and his curiosity as to the unexpected change that had occurred.
Source: Rubber and Vulcanisation
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