Study On Preparation And Performance Of EG/APP IFR Flame Retarding ABS-based WPC

In this article, EG/APP intumescent flame retardant, which is halogen-free, and friendly to environment and nontoxic, was employed to enhance the flame retardancy of WPC. Sodium silicate which was used to cure wood flour was taken into account. The WPC was prepared by a torque rheometer. Limited oxygen index (LOI), UL-94test, thermogravimetric analysis (TGA), cone calorimeter (CONE), scanning electron microscopy and mechanical testing machine were employed to characterize the flame retardancy, thermal stability, combustion behavior and the morphology of the residue after LOI test.The results of EG/APP flame-retarded WPC containing40%raw wood flour showed that the LOI reached the highest value and the UL-94test passed V-0level with20wt%flame retardant when EG/APP=12.5:7.5. But the LOI of the one that contained20wt%APP and20wt%EG alone were only24.5%and30.5%, respectively. The result indicated that there is synergistic effect between APP and EG which improved the flame retardant efficient. The addition of flame retardant could increase the residue under high temperature and enhance the thermal stability. The cone showed that the combustion behavior of WPC was better improved by greatly decreasing heat release rate (HRR), total heat release (THR) and smoke production release (SPR) by the addition of flame retardant. Thus the potential danger during the fire hazard was lowered. The SEM micrographs of the residue after the LOI test showed that the char formed by WPC/APP was more compact than that of WPC containing no flame retardant. At the same time, the inflated char residue of WPC/EG/APP2was also more compact than that of WPC/EG, it was mainly due to the polyphosphoric acid-like product produced by APP during high temperature. The higher magnification of the two samples showed that the surface of wormlike inflated char of WPC/EG/APP2was covered with granular crystalline material but the one of WPC/EG was smooth. The mechanic properties of WPC was worsen by flame retardant, but little difference among the effect of flame retardant with different ratio EG and APP on the mechanic properties of WPC was demonstrated.ABS-based WPC filled with sodium silicate-cured wood flour (SSWF) was also investigated. The results showed that the thermal degradation behavior of sodium silicate-cured wood flour (SSWF) was different from that of raw wood flour. The SSWF greatly improved the residue with high stability under750℃. ABS filled with SSWF (SSWPC) had higher LOI than WPC at the same content level. The LOI of SSWPC reached23.4%which was4%higher than that of WPC when the loading was40%. EG/APP intumescent flame retardancy was also employed to improve the flame retardancy of SSWPC. The LOI of SSWPC could reach33.5%when EG:APP=12.5:7.5at20%total content. But the LOI of that with20%EG or APP was only30.0%and25.0%, respectively. TG results showed that EG/APP could improved the amount of residue under750℃. The SEM micrographs of SSWPC/APP had less holes than SSWPC, thus SSWPC/APP had higher LOI. The char produced by SSWPC/EG/APP2was more compact than that produced by SSWPC/EG. The surface of char in SSWPC/EG was smooth, not so that in SSWPC/EG/APP2. The surface of char of SSWPC/EG/APP2was covered with granular crystalline material produced by APP which could compactly bind the worm-like char together, thus resulted in higher LOI. Comparing the SEM micrograph of WPC/EG/APP2with that of SSWPC/EG/APP2, one may find that denser granular crystalline material in the char surface of WPC/EG/APP2was found than that of SSWPC/EG/APP2. It proved why SSWPC/EG/APP2had lower LOI than WPC/EG/APP2based on the fact that the bubble-shaped particle consumed part of phosphoric acid produced by APP, thus the amount of phosphoric acid used to join the worm-like char was reduced and the compaction rate of the char was lowered behaved as decreasing LOI. The mechanic properties of SSWPC were similar to those of WPC at the same loading but worsen by the addition of flame retardant. And the effect of flame retardant with different ratio EG and APP on the mechanic properties of SSWPC was little.