Facile Synthesis of Processable Semiaromatic Polyamides Containing Thioether Units

Abstract

Semiaromatic polyamides containing thioether units were synthesized through the reaction of 4,4′-thiodibenzoyl chloride (TDC) and diamine by the method of interfacial polycondensation. The inherent viscosities of the resultant polyamides prepared with optimum synthesis conditions were 1.08–1.26 dL/g. These polyamides had excellent thermal properties with glass transition temperatures (Tg) of 119.8–190.1 °C, melting temperatures (Tm) of 281.4–355.5 °C, and initial degradation temperatures (Td) of 433.5–466 °C. They had wider processing windows than traditional semiaromatic polyamides. At the same time, they had better tensile strengths of 62.1–86.5 MPa, better low-temperature mechanical properties, lower water absorption, lower dielectric constants of 3.16–3.81 at 100 kHz, and better melt flowability properties. The results suggest that these semiaromatic polyamides containing thioether units [poly(hexanelene 4,4′-thiodibenzoamide) (PA-6), poly(octanelene 4,4′-thiodibenzoamide) (PA-8), and poly(decanelene 4,4′-thiodibenzoamide) (PA-10)] represent a promising type of heat-resistant and processable engineering plastic.