Influence of Ultrafine Zinc Borate on the Thermal Degradation Behavior of a(Low-Density Polyethylene)/ (Intumescent Flame Retardant) System

摘要

The thermal degradation behavior of low-density polyethylene (LDPE), LDPE treated with an intumescent flame retardant (LDPE/IFR), and LDPE treated with an intumescent flame retardant and ultrafine zinc borate (LDPE/IFR/UZB) was studied by (thermal gravimetric)-(differential thermal) analysis (TG-DTA) and cone calo-rimetry. The results of TG-DTA showed that the initial degradation temperature increased, thermal degradation rate decreased, and the residual char amount increased substantially during the Pyrolysis process when ultrafine zinc borate was introduced into the LDPE/IFR system. The mass-loss rate (MLR) curves and mass curves obtained by cone calorimetry showed that UZB could decrease the MLR and significantly enhance the residual char amount of LDPE/IFR during the combustion process. The results of Fourier transform infrared spectroscopy implied that a graphite-like char and aromatic structures containing P-O-P, P-O-C, and B-O-B bonds were formed when LDPE/IFR/UZB was heated at high temperature. Scanning electronic micrographs of residual chars showed that ultrafine zinc borate improved char quality. X-ray diffraction Studies implied that boron orthophosphate (BPO4) formed in the residual char may play an important role in improving the structural properties of the char and is responsible for its good quality.