Synthetic Applications Of Nylon 6-6 Fibre
Nylon 6-6, also referred to as nylon 6,6, is a type of nylon. Nylon comes in many types, and the two most common for textile and plastics industries are nylon 6 and nylon 6,6.
Ny Nylon 6,6
Nylons are one of the most common polymers used as a fiber. Nylon is found in clothing all the time, but also in other places, in the form of a thermoplastic.
Nylon's first real success came with it's use in women's stockings, in about 1940. They were a big hit, but they became hard to get, because the next year the United States entered World War II, and nylon was needed to make war materials, like parachutes and ropes. But before stockings or parachutes, the very first nylon product was a toothbrush with nylon bristles.
Nylons are also called polyamides, because of the characteristic amide groups in the backbone chain. Proteins, such as the silk nylon was made to replace, are also polyamides. These amide groups are very polar, and can hydrogen bond with each other. Because of this, and because the nylon backbone is so regular and symmetrical, nylons are often crystalline, and make very good fibers.
The nylon in the pictures on this page is called nylon 6,6, because each repeat unit of the polymer chain has two stretches of carbon atoms, each being six carbon atoms long. Other nylons can have different numbers of carbon atoms in these stretches.
* Formation In Laboratory
Nylons can be made from diacid chlorides and diamines. Nylon 6,6 is made from the monomers adipoyl chloride and hexamethylene diamine.
This is one way of making nylon 6,6 in the laboratory. But in a nylon plant, it's usually made by reacting adipic acid with hexamethylene diamine.
Formation at industrial scale
Nylon 6-6 can be made from diacids and diamines. Nylon 6,6 is made from the monomers adipic acid and hexamethylene diamine.
* Mechanism Of Synthesis Of Nylon 6-6
Nylon is made by a reaction which is a step-growth polymerization, and a condensation polymerization. Nylons are made from diacids and diamines. Step 1:
To make nylon 6,6 one doesn't need a catalyst, but acids do catalyze the reaction, one of the monomers is itself an acid. A little reaction happens between two adipic acid molecules. One will donate a proton to a the carbonyl oxygen of another.
When this oxygen is protonated the carbonyl oxygen becomes much more vulnerable to attack by the nitrogen of our diamine. This happens because our protonated oxygen bears a positive charge. Oxygen does not like to have a positive charge. So it pulls the electrons it shares with the carbonyl toward itself. This leaves the carbonyl carbon lacking electrons, and ready for the amine nitrogen to donate a pair to it:
Then the electrons play musical chairs. One of the electron pairs form the carbonyl double bond shifts entirely to the oxygen, taking care of the problem of the positive charge at that atom, but now our nitrogen has a positive charge.
The electrons from the hydrogen oxygen bond go back to the oxygen, freeing the proton, regenerating the acid catalyst. Then the carbonyl oxygen shares its newly regained electrons with the carbon atoms, regenerating the carbonyl double bond.
The oxygen of the hydroxyl group decides to do a little bit of electron shuffling of its own. It takes the pair it shares with the carbon and hogs them to itself, severing the bond between it and the carbon. It then donates a pair of electrons to a hydrogen connected to the nitrogen. Step 4:
As it now shares a pair of electrons with the oxygen, it sees no need to keep the pair it shares with the nitrogen, so it lets go of that pair, giving it over to the nitrogen. This shift of electrons breaks the bond between the hydrogen and the nitrogen, and gets rid of the...
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