Nomex has meta-phenylene groups, the amidegroups are attached to the phenyl ring at the 1 and3 positions.001N+一NHHIn Nomex the aromnatic groups are all linked into thebackbone chainthroughtheland3positions. Thisiscalledmeta-linkage
Nomex has meta-phenylene groups, the amide groups are attached to the phenyl ring at the 1 and 3 positions
StructureKevlar usually takes two different conformations.The one on the left is called the transconformation, and the one on the right is the cis-conformation.0Hatrns- amidea cis-amide
Structure Kevlar usually takes two different conformations. The one on the left is called the trans conformation, and the one on the right is the cisconformation
StructureWhen Kevlar tries to twist into the cisconformation. The cis - conformation puts thehydrogen just a little closer to each other thanthey want to be. So Kevlar stays nearly fully inthe trans- conformation. The phenyl rings ofadjacent chains stack on top of each other veryeasily and neatly, which makes the polymereven more crystalline, and the fibers evenstronger
Structure When Kevlar tries to twist into the cisconformation. The cis - conformation puts the hydrogen just a little closer to each other than they want to be. So Kevlar stays nearly fully in the trans- conformation. The phenyl rings of adjacent chains stack on top of each other very easily and neatly, which makes the polymer even more crystalline, and the fibers even stronger
StructureH0！HHHHHHAH1H0HHNHThere'snot enoughroomhereforthephenylhydroegensinthecis conformationOnlyinthefransconformationcanallthehydrogenshaveenoughHHroomnto breatheHKH0二0H0HHHHHi0H
Structure
Propertyand ApplicationKevlar is a very crystalline polymer. Itwouldn't dissolve in any solvent and wouldn'tmelt below 5oo C. So processing it is verydifficulty. Dissolv Kevlar in strong sulfuric acidand process the solution in a form of liguidcrystalline. Aramids are used in the form offibers which is much better than non-aromaticpolyamides, like nylon 6,6Kevlar is used to produce bulletproof vests andpuncture resistant bicycle tires. Blends ofNomexand Kevlar are usedto makefireproofclothing
Property and Application ◼ Kevlar is a very crystalline polymer. It wouldn't dissolve in any solvent and wouldn’t melt below 500 ℃. So processing it is very difficulty. Dissolv Kevlar in strong sulfuric acid and process the solution in a form of liquid crystalline. Aramids are used in the form of fibers which is much better than non-aromatic polyamides, like nylon 6,6. ◼ Kevlar is used to produce bulletproof vests and puncture resistant bicycle tires. Blends of Nomex and Kevlar are used to make fireproof clothing