Investigation on Thermal Degradation of Poly(1,4-butylene terephthalate) Filled with Aluminum Hypophosphite and Trimer by Thermogravimetric Analysis–Fourier Transform Infrared Spectroscopy and Thermogravimetric Analysis–Mass Spectrometry

Flame-retarded poly(1,4-butylene terephthalate) (PBT) has been prepared using aluminum hypophosphite (AHP) and tri(1-oxo-2,6,7-trioxa-1-phosphabicyclo[2,2,2]octane-methyl)phosphate (Trimer). The combustion properties of flame-retarded PBT were evaluated using limiting oxygen index, UL-94, and cone calorimetry. The cone calorimeter data indicated that the presence of PBT/AHP/Trimer imparted a significant smoke-suppressing effect. The thermal degradation properties of flame-retarded PBT were investigated using thermogravimetric analysis–Fourier transform infrared and thermogravimetric analysis–mass spectrometry. For the samples of PBT, PBT/25% AHP, and PBT/AHP/Trimer, the main gas pyrolysis products were CO2 and butadiene; the sample of PBT/AHP/Trimer generated less CO2 and butadiene and consequently retained more carbon in the matrix. The amount of phosphorus–oxygen radicals of PBT/25% AHP was 1.3 times that of PBT/AHP/Trimer, which indicated that AHP alone showed slightly stronger gaseous phase effect tha...