COPOLYMER MODIFICATION OF NYLON-6,6 WITH 2-METHYLPENTAMETHYLENEDIAMINE

Polyamides were prepared in which part or all of the hexamethylenediam ine (HMD) in nylon-6,6 was replaced by its isomer, 2-methylpentamethyl enediamine (MPMD). The intermediate compositions are considered random copolymers between the two homopolymers (66 and MPMD-6). The crystall ine properties of these polymers were studied by differential scanning calorimetry, X-ray diffraction and optical microscopy; It was conclud ed that the two kinds of units, 66 and MPMD-6, do not co-crystallize. In copolymers containing large fractions of HMD, the MPMD units are ex cluded from the crystals. With appropriate thermal treatment, MPMD-6 c an crystallize with two different unit cells and a variety of spheruli tic morphologies. The two crystal forms can be distinguished by their crystallization, melting and optical properties. The crystallization k inetics of the copolymers are slower than those of the homopolymers, w hich is associated with the slower rate of nucleation formation rather than the transport ability. This is consistent with the dielectric re sults, which showed that the glass transition temperatures of the diff erent copolymers are similar. It was found that MPMD-6 can be quenched into an amorphous state. The properties of the amorphous portions wer e further investigated through dielectric relaxations. Although, the i ncorporation of MPMD tends to shift the dielectric gamma relaxation to wards higher temperatures, the total effects of variations on chemical structure were much smaller than those which pertain to the crystalli ne phase.