Synthesis of poly(diethylenetriamine terephthalamide) and its application as a flame retardant for ABS

Abstract

A novel aliphatic–aromatic polyamide poly(diethylenetriamine terephthalamide) (PDTA) was synthesized by using terephthaloyl chloride (TPC) and diethylenetriamine (DETA). A ammonium polyphosphate (APP)/PDTA mixture was prepared for use as an intumescent flame retardant (IFR) for acrylonitrile–butadiene–styrene terpolymer (ABS). The structure of PDTA was characterized by Fourier transform infrared spectroscopy (FTIR) and 1H NMR. The thermal properties and thermal decomposition model were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The flame-retardant effect, thermal degradation behavior, and mechanism of IFR–ABS were investigated by limiting oxygen index (LOI), vertical burning test (UL-94), microscale combustion calorimetry test (MCC), TG, FTIR, and scanning electron microscopy (SEM). The results showed that PDTA was synthesized as expected and was stable below 200 °C. The results also showed that when the loadings of ABS, APP, and PDTA were 70, 22.5, and 7.5 %, respectively, the LOI value reached 31 % and the UL-94 vertical burning test was V-0. What is more, even when the addition of IFR was decreased to 25 %, the LOI value of the ABS/APP/PDTA (75/18.75/6.25) system was 28 %, indicating compounding APP and PDTA could improve the flame-retardant performance of ABS. The FTIR indicated there was a chemical reaction between APP and PDTA to form a heat-resistant triazine ring, and SEM indicated the ABS/APP/PDTA systems had a denser char structure than that of pure ABS.