Preparation and characterization of dimer acid-based polyamide nylon copolymer modified by adipic acid

A series of dimer acid-based polyamide nylon copolymers modified by adipic acid were prepared from nylon salt and adipic acid by melt phase polycondensation method. The effects of short-chain adipic acid on the state of aggregation and thermal properties of them were investigated by means of Infrared spectra, UV-Vis absorption spectra, differential scanning calorimetric analysis, and thermo gravimetric analysis, etc. The addition of adipic acid led to the change of phase structure from γ to α, β crystal forms, and increased the degree of crystalline of the copolymers, and favored the activation of amide groups. These are advantageous for the decrease of thermal degradation temperature, and thus deteriorate the thermal stability of copolymers.