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(In Free radical polymerization), Why when the initiator [I] concentration increases, the yield ratio increases, and the average molecular weight (Mw) and the number of units (Mn) decreased? Please, I want explain the reason.
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+ Free radicals
+ Polymerization
+ Chemistry
+ Organic chemistry
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Mian Muhammad
(In Free radical polymerization), Why when the initiator [I] concentration increases, the yield ratio increases, and the average molecular weight (Mw) and the number of units (Mn) decreased? Please, I want explain the reason.
Unsaturated fatty acids are reactive and especially sensitive to oxygen because of the carbon-carbon double bonds they contain. This is especially true of polyunsaturated fatty acids. When exposed to free radicals such as those produced by oxygen, one those bonds open. Once that happens, the bond can re-close itself or it can form a new bond with a neighboring unsaturated fatty acid. Thus, the two fatty acid chains are bound together in a larger molecule. When this happens repeatedly, large aggregates of fatty acid chains are formed. This is what polymeric fats are.
Have you ever noticed how the bottles of cooking oils, especially those oh so healthy oils that contain polyunsaturated FAs, seem to grow a thick, sticky coating that you can’t wash off, even with soap? Fatty acid polymers at work. My insides are very sensitive to rancid oils, which contain polymers of FAs. I don’t know if it’s the rancid compounds (another product of the reaction of unsaturated FAs and air), or the polymers that does it. I can’t imagine how that waxy stuff could be friendly to your GI tract, but I don’t know the details.
The polymerization of fats can be useful. Oil-based paints ‘dry’ because the pigments in them are dispersed in an oil that polymerizes rapidly on contact with air. Linseed oil (aka flax seed oil) is the one I know. Spread a layer of linseed oil paint on a canvas or the sides of a house and let it sit for several hours and it becomes hard and insoluble in water. Don’t they tell you to store your oh-so-healthy flax seed oil in the ‘fridge? That’s why.
Unsaturated fatty acids are reactive and especially sensitive to oxygen because of the carbon-carbon double bonds they contain. This is especially true of polyunsaturated fatty acids. When exposed to free radicals such as those produced by oxygen, one those bonds open. Once that happens, the bond can re-close itself or it can form a new bond with a neighboring unsaturated fatty acid. Thus, the two fatty acid chains are bound together in a larger molecule. When this happens repeatedly, large aggregates of fatty acid chains are formed. This is what polymeric fats are.
Have you ever noticed how the bottles of cooking oils, especially those oh so healthy oils that contain polyunsaturated FAs, seem to grow a thick, sticky coating that you can’t wash off, even with soap? Fatty acid polymers at work. My insides are very sensitive to rancid oils, which contain polymers of FAs. I don’t know if it’s the rancid compounds (another product of the reaction of unsaturated FAs and air), or the polymers that does it. I can’t imagine how that waxy stuff could be friendly to your GI tract, but I don’t know the details.
The polymerization of fats can be useful. Oil-based paints ‘dry’ because the pigments in them are dispersed in an oil that polymerizes rapidly on contact with air. Linseed oil (aka flax seed oil) is the one I know. Spread a layer of linseed oil paint on a canvas or the sides of a house and let it sit for several hours and it becomes hard and insoluble in water. Don’t they tell you to store your oh-so-healthy flax seed oil in the ‘fridge? That’s why.
In a free radical polymerization the initiator starts it by reacting with a single monomer, activating it to seek another monomer. It reacts with the new monomer to elongate the chain by one, and the end of the chain is now active, seeking the next monomer. The chain elongation can stop when an impurity is encountered, or when two expanding chains meet, each terminating the other. Therefore the higher the concentration of initiator, the more chains are in the mix the chance of termination goes up, then chain length and consequent MW are both reduced.
The only reason yield would increase would be if polymerization stopped before all substrate was consumed. The extra initiator would help get it all reacted.
In a free radical polymerization the initiator starts it by reacting with a single monomer, activating it to seek another monomer. It reacts with the new monomer to elongate the chain by one, and the end of the chain is now active, seeking the next monomer. The chain elongation can stop when an impurity is encountered, or when two expanding chains meet, each terminating the other. Therefore the higher the concentration of initiator, the more chains are in the mix the chance of termination goes up, then chain length and consequent MW are both reduced.
The only reason yield would increase would be if polymerization stopped before all substrate was consumed. The extra initiator would help get it all reacted.
Unsaturated fatty acids are reactive and especially sensitive to oxygen because of the carbon-carbon double bonds they contain. This is especially true of polyunsaturated fatty acids. When exposed to free radicals such as those produced by oxygen, one those bonds open. Once that happens, the bond can re-close itself or it can form a new bond with a neighboring unsaturated fatty acid. Thus, the two fatty acid chains are bound together in a larger molecule. When this happens repeatedly, large aggregates of fatty acid chains are formed. This is what polymeric fats are.
Have you ever noticed how the bottles of cooking oils, especially those oh so healthy oils that contain polyunsaturated FAs, seem to grow a thick, sticky coating that you can’t wash off, even with soap? Fatty acid polymers at work. My insides are very sensitive to rancid oils, which contain polymers of FAs. I don’t know if it’s the rancid compounds (another product of the reaction of unsaturated FAs and air), or the polymers that does it. I can’t imagine how that waxy stuff could be friendly to your GI tract, but I don’t know the details.
The polymerization of fats can be useful. Oil-based paints ‘dry’ because the pigments in them are dispersed in an oil that polymerizes rapidly on contact with air. Linseed oil (aka flax seed oil) is the one I know. Spread a layer of linseed oil paint on a canvas or the sides of a house and let it sit for several hours and it becomes hard and insoluble in water. Don’t they tell you to store your oh-so-healthy flax seed oil in the ‘fridge? That’s why.
Unsaturated fatty acids are reactive and especially sensitive to oxygen because of the carbon-carbon double bonds they contain. This is especially true of polyunsaturated fatty acids. When exposed to free radicals such as those produced by oxygen, one those bonds open. Once that happens, the bond can re-close itself or it can form a new bond with a neighboring unsaturated fatty acid. Thus, the two fatty acid chains are bound together in a larger molecule. When this happens repeatedly, large aggregates of fatty acid chains are formed. This is what polymeric fats are.
Have you ever noticed how the bottles of cooking oils, especially those oh so healthy oils that contain polyunsaturated FAs, seem to grow a thick, sticky coating that you can’t wash off, even with soap? Fatty acid polymers at work. My insides are very sensitive to rancid oils, which contain polymers of FAs. I don’t know if it’s the rancid compounds (another product of the reaction of unsaturated FAs and air), or the polymers that does it. I can’t imagine how that waxy stuff could be friendly to your GI tract, but I don’t know the details.
The polymerization of fats can be useful. Oil-based paints ‘dry’ because the pigments in them are dispersed in an oil that polymerizes rapidly on contact with air. Linseed oil (aka flax seed oil) is the one I know. Spread a layer of linseed oil paint on a canvas or the sides of a house and let it sit for several hours and it becomes hard and insoluble in water. Don’t they tell you to store your oh-so-healthy flax seed oil in the ‘fridge? That’s why.
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In a free radical polymerization the initiator starts it by reacting with a single monomer, activating it to seek another monomer. It reacts with the new monomer to elongate the chain by one, and the end of the chain is now active, seeking the next monomer. The chain elongation can stop when an impurity is encountered, or when two expanding chains meet, each terminating the other. Therefore the higher the concentration of initiator, the more chains are in the mix the chance of termination goes up, then chain length and consequent MW are both reduced.
The only reason yield would increase would be if polymerization stopped before all substrate was consumed. The extra initiator would help get it all reacted.
In a free radical polymerization the initiator starts it by reacting with a single monomer, activating it to seek another monomer. It reacts with the new monomer to elongate the chain by one, and the end of the chain is now active, seeking the next monomer. The chain elongation can stop when an impurity is encountered, or when two expanding chains meet, each terminating the other. Therefore the higher the concentration of initiator, the more chains are in the mix the chance of termination goes up, then chain length and consequent MW are both reduced.
The only reason yield would increase would be if polymerization stopped before all substrate was consumed. The extra initiator would help get it all reacted.
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