Dynamic mechanical spectrometry of nylon‐12

The shear modulus and loss of ca. 30% crystalline nylon‐12 have been measured over the temperature range 100–440 K and frequency range 10−4−1 Hz. The effect of water and physical aging of the amorphous regions on the relaxation spectra have been investigated. Absorbed water decreases both the temperature and height of the γ‐relaxation peak, induces a β‐relaxation peak, and decreases the temperature of the α‐relaxation peak. These results are interpreted in terms of the hydrogen‐bonding effect of water on nylon‐12 monomer and polymer. The G″ spectrum of the polymer has a half‐width of ca. 6 decades of frequency, and neither the G″, nor G″, nor the tan ϕ spectra can be superposed by shifting along the frequency axis. The large half‐width is attributed to the random distribution of crystalline regions in the polymer. The results are further discussed in terms of hydrogen‐bonding, with or without H2O, and compared with the properties of other nylons.