Production and characterization of flame-retardant poly (butylene terephthalate) composites containing boron compounds

Within the scope of this work, flame retardant polybutylene terephthalate (PBT) was produced using boron compounds, namely, anhydrous borax (BX), colemanite (C), and zinc borate (ZnB) in three different concentrations of 40, 50, and 60 wt%. The thermal, flame retardant, and tensile properties of PBT composites were systematically investigated using thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical UL 94 test (UL-94V), mass loss calorimeter (MLC), and tensile tests. The thermal stability of PBT slightly enhanced with the use of BX, whereas the use of C and ZnB reduced the thermal stability. Improvement in LOI value, a reduction in peak heat release rate (pHRR), and total heat release (THR) values were observed with the use of all boron compounds. The improvement in UL-94V rating was observed only with the use C. The addition of all boron compounds deteriorates the tensile strength of the composites. In brief, the highest flame retardant performance with V0 rating (UL-94 V), 33.5% (LOI), and 48 Kw<middle dot>m(-2) (pHRR) was achieved with the use of C.