3. Properties

3.1 General

Some twenty producers worldwide market over a thousand different grades made from the twenty or so types of polyamide industrially available, out of some 65 currently known PA types. Every year, around a hundred new grades replace the older ones to meet the needs of industry.

Hydrogen bonds, electrostatic interactions between a hydrogen atom bonded to a strongly electronegative atom (N) and a polar group containing a strongly electronegative atom (O), are highly energetic because they involve large dipole moments with very small interpolar distances due to the small size of the atoms involved.