Synergistic flame retardant of APP/ADP on bamboo powder/polypropylene composites(PDF)
Synergistic flame retardant of APP/ADP on bamboo powder/polypropylene composites
ZHOU Xiaxing; YUAN Feng; WANG Jiahui; LIU Zijiang; QIN Xingfa
1. College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China;2. National Forestry and Grassland Administration Key Laboratory of Plant Fiber Functional Materials, Fuzhou 350002, China
bamboo powder (BP); wood plastic composites; flame retardancy; polypropylene (PP); ammonium polyphosphate (APP); aluminum diethylphosphinate (ADP); synergistic effect
S781.9;TB332
Bamboo powder(BP)/polypropylene (PP) composite is an environmentally friendly material with BP as the reinforcing phase and PP as the matrix. It takes full advantages of plenty bamboo resources in China and reduction of the waste pollution of plastics. However, both BP and PP are flammable, and the applications of the BP/PP composites are limited. In order to improve the flame resistance of BP/PP composites and thus broaden the composite application, the ammonium polyphosphate (APP) was used as a flame retardant, and the maleic anhydride grafted polypropylene (MAPP) was used as an interfacial compatibilizer to prepare the flame retardant composites. The effects of APP addition amounts on the mechanical properties and flame retardancy of the composites were studied. Based on the optimal addition amount of APP, the new phosphorous halogen��free environmental flame retardant of aluminum diethylphosphite (ADP) was used as the synergistic agent. The BP/PP composites with the addition of different mass ratios of APP and ADP were prepared by the hot��pressing, and the synergic effect of APP and ADP was further investigated. The results showed that, with the increase of APP addition amount, the modulus of rupture (MOR), modulus of elastic (MOE), and tensile strength of the composites were decreased, but the notched impact strength (NIS) was enhanced, and the limiting oxygen index (LOI) was increased. The APP addition amount had no significant effect on LOI, the growth rate of LOI was small and the flame retardant effect was not obvious. The optimal addition amount of APP was 10%, and LOI value increased from 17.1% to 21.4%, and the composite with 10% APP addition amount was still a flammable material. When the mass ratio of APP to ADP was 6∶1, the mechanical properties increased, and the MOR, MOE, tensile strength and NIS of the flame retardant composites were 41.47 MPa, 3 206.82 MPa, 18.91 MPa, and 7.25 kJ/m2, respectively, which were increased by 11.9%, 12.0%, 18.5% and 28.1%, respectively; the LOI continued to increase to 24.5%, with a growth rate of 43.3%, compared with the control sample. Cone calorimeter results showed that the heat release rate, peak heat release rate, total heat release and effective heat of combustion of APP/ADP flame retardant composites were reduced by 44.6%, 33.8%, 32.8% and 17.8%, respectively. The amount of generated CO was increased, the average mass loss rate was decreased, and the residue weight was increased to 66.9%, indicating that the carbon forming effect of the flame retardant composites was improved. The APP played a flame retardant role in the gas phase, while ADP had a synergistic effect in the condensed phase. However, after 400 s of combustion, the total smoke production of the flame retardant composites increased slightly, and the long��lasting smoke suppression property still need to be enhanced.