Flame retardancy and thermal degradation properties of polypropylene/wood flour composite modified with aluminum hypophosphite/melamine cyanurate
In this study, aluminum hypophosphite (AP) and melamine cyanurate (MCA) were used as flame retardant in polypropylene (PP)/wood flour (WF) composite. The flammability of the PP/WF composites was examined by the limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter test. When the PP/WF composite was loaded with 20% AP/MCA (the mass ratio of AP and MCA was 5: 1), the UL-94 achieved V-0 rating and the LOI was increased to 29.5%. In addition, the flexural strength was increased by about 11.0%. The results of cone calorimeter test revealed that the heat release rate and heat release rate peak of the PP/WF composite with AP/MCA were significantly reduced. The thermal degradation mechanism of PP/WF composites was investigated by thermo-gravimetric analysis, Fourier transform infrared spectrometry, energy-dispersive X-ray spectroscopy and scanning electron microscopy. The results indicate that AP/MCA had the effect of gas-phase and condensed-phase flame retardancy during the combustion and degradation of PP/WF composite. Consequently, a thermal property reinforcing mechanism of the PP/WF composite with AP/MCA was presented.
KeywordsAluminum phosphate Melamine cyanurate Wood flour Flame retardance
This work was financially supported by the National Natural Science Foundation of China (31570572 and 31670516) and Heilongjiang Key Project Technologies R&D Programme (GA15A101).
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