Polyamide
Name polyamide gathers all the Polymère S containing of the groupings “amide” N-H-C-O. This grouping amide results from the reaction of a Acide and a amine.
In 1927, the american company Dupont constituted a research service for the study of the synthesis of polymers with long chains. The direction was entrusted by it to Wallace Hume Carothers.
Nylon 6.6 was discovered in 1938. At the same time in Germany one discovered Nylon 6.
At the beginning the Nylon was called NO RUN, which means “slips by not” in English (in connection with the silk stockings which slipped by), then it was called Nolen, Nolon and finally Nylon.
The name NYLON would come from initial from: Nancy Yvonne Louella Olivia Nina wives of the chemists of Bridge of Nemours, who collaborated in the discovery.
During the second world war, the significance of the word was deformed to make a joke in: Now You Lousy Old Japanese (“ With you maintaining, old disgusting Japanese! ”) or Now You' ve Japanese Lost Old (“ You now lost old Japanese ! ”). The polyamide (PA) was very quickly used in textile industry, in particular for the manufacture of the fabrics of parachute.
It is necessary today to speak about polyamide' in the plural so much the family is important.
General information
They are polymers most generally with semicrystalline structure, i.e. comprising an amorphous phase and a crystalline phase. They are generally used with loads or reinforcements.
The aliphatic polyamides are generally indicated by figures, relating to the number of carbon atoms contained in the reason for repetition of the polymère.
Ex: Pa 6, Pa 11, Pa 12 obtained by Polymerization of an amino-acid or a lactam with respectively 6,11 or 12 carbon atoms in the motif.
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Pa 6.6, Pa 4.6, Pa 6.10, Pa 6.12, obtained by Polycondensation of a diacid and a diamine. In this case, the first figure corresponds to the number of carbon atoms of diamine whereas the second corresponds to the number of carbon atoms of the diacide.
On the other hand the aromatic polyamides do not use a rule of precise designation. Ex: PAA (polyarylamide), PPP (polyphtalamide)
Characteristics
They are polymers presenting a very good compromise between the mechanical, thermal and chemical characteristics.
One of the principal differences between the various types of polyamides is the melting point, and consequently the thermal behavior.
The principal disadvantage of all polyamides is the important hydrophily of the grouping “amide” which involves an absorption of important water of material. The mechanical properties and dimensional are affected. New polyamides are in studies at the research center of Glasgow to decrease the absorption of water.
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