The technology enhancement of any population is connected to the materials available. Therefore scientists have developed new materials to cope with the development of human civilisation. With the use of organic chemistry, new material is producing commonly synthetic polymers. Due to the versatility of these polymers it allows creation and fabrication of materials that cannot be attain from materials such as wood, metals and ceramics. The raw materials of polymer derived from petroleum and with the advance technology the synthesis of raw material became cheap and useful.
2. Step Growth or Condensation Polymerizations
Step Growth polymerization is a polymerization ...view middle of the document...
Then he concentrates to reactions of dicarboxylic acids and diamines to form polyamides and 1934 synthesized nylon 6, 6 is made which is a purely synthetic fibres. Nylon 6, 6 is synthesized from two different monomers, each containing six carbon atoms.
The conditions that is suitable to form nylon 6,6 is the Tm has to be between 250-260C and the molecular weight is in the range of 10,000-20,000 g/mol.
The first step of fiber production, crude nylon is melted, spun into fibers and cooled. The melt-spun fibers are cold drawn (drawn at room temperature) to about four times their original length to increase their degree of crystallinity. Next, individual polymer molecules become orientated in the fiber axis, and hydrogen bond form between carbonyl oxygen of one chain and amide hydrogen of another chain. The physical properties of the fiber from polyamide are impressive because both tensile strength and stiffness increase due to the effects of orientation of polyamide molecules.
The existing raw material base for the production of nylon 6, 6 is benzene which arises from catalytic cracking and reforming of petroleum. A mixture of cyclohexanol and cyclohexanone is produce when benzene is catalyzed to cyclohexane by catalytic reduction and then followed by catalyzed air oxidation. Oxidation of this mixture by nitric acid will gives adipic acid. n
Adipic acid is the starting material for synthesis of hexamethylenediamine. Reaction od adipic acida and ammonia give ammoniums salt, which when heated will give adipiamide. If adipic acid is catalytic reduce it will give hexamethylenediamine. Hence the formation of nylon 6, 6 are completely from petroleum which is sadly unrenewable.
Nylon can be categories as polymers, the members of which have tactfully different properties that suits them to one use or another. Nylon 6,6 and nylon 6 are the most popular polymers. Nylon 6 is so named because it is synthesized from caprolactam a six carbon monomer. In the synthesis of nylon 6, caprolactam is partially hydrolyzed to 6-aminohexanoic acid and then it is heated to 250C to start the polymerization. Nylon 6 is fabricated into fibers. Brush bristle, ropes, high impact molding and tire cords.
Based on extensive research of the relationship between molecular structure and bulk physical properties, scientist at Dupont reasoned that polyamide containing aromatic ring will become stiffer and stronger than either nylon 6 or nylon 6, 6. From there Kevlar where produce, a polyaromatic amide fiber synthesized from tetraphthalic acid and p-phenylenediamine. The amazing features of Kevlar are that it is light weighted and strong even if it is compared with other material that have the same strength. Kevlar is used as anchor cables for offshore drilling rigs and reinforcement fibres for automobiles tires. Because of its remarkable feature it is also woven into fabric such as bulletproof vest, jackets and raincoats.