| Polypropylene (PP) is one of the most commonly used polymers in today's society. It is extensively used in many fields, such as household goods, building, transportation and electric & electrical devices and so on, due to its excellent performance. However, PP is one of easily inflammable polymeric materials, and its limiting oxygen index (LOI) is only 17-18%. Because of, flammability,the application of PP is restricted. Therefore, achieving good flame retardancy is one of important research aspects that researchers have been paying attention to. The use of intumescent fire retardant additives is a promising technique, particularly in the area of non-halogen flame retardant Polypropylene.In this paper, ammonium polyphosphate was surface modified with SMA, The results show that when ammonium polyphosphate was surface modified with 0.5% SMA in APP, modification time was 5 min, dried at 150℃for 2h. The experimental results demonstrate modified ammoniumpolyphosphate gave a smaller solubility in water, it's solubility is 0.2224g/100mL,it's core-shell activation is 94.46%.New intumescent flame retardants (IFRs) consisted of SMAPP or APP, CFA and other additives was used for flame-retardant PP. The effects of different acid source was studied on IFR-PP composites. The results demonstrate the IFR-PP with SMAPP shows the excellent general properties,when PP systems with 22% loading of IFR, M-SiO2 as an intumescent flame retardant promoter was added to the mixtures of CFA/SMAPP, it had the better disperse in PP system, the flame retardancy of IFR-PP passed UL94V-0 rating,and it's LOI value reached 36.8%. After hot water treatment, the flame retardancy of IFR-PP passed UL94V-1 rating,and it's LOI value reached 32.5%, weightlessness is 2.92%.The synergistic effects of polysiloxane and M-SiO2 on the properties of intumescent flame retardant polypropylene (IFR-PP) have been studied. The results demonstrate that both polysiloxane and M-SiO2 could effectively enhance the flame retardancy of the IFR-PP, despite only 20wt% loading of IFRs. Remarkably, the IFR-PP with polysiloxane shows the excellent general properties,the flame retardancy of IFR-PP passed UL94V-0 rating,and it's LOI value reached 36.3%.It can yet pass UL94 V-0 rating, weightlessness is 18.9%, and its LOI remains over 34.9% after the water treatment.Thermal degradation and combustion behavior of IFR-PP without synergistic agent, IFR-PP with 5.5wt% polysiloxane and IFR-PP with 5.5wt% M-SiO2were tested by TGA and CONE. The results proved that the thermal degradation behavior and combustion behavior of PP had been changed due to the addition of IFR-PP with polysiloxane, and could make HRR,THR,MLR,COP and SPR of IFR-PP with polysiloxane, composites decreased largely. The research also found that the polysiloxane synergistic agent, could more effectively accelerate the degradation of the systems, enhance the char formation in high temperature, enhance the thermal stability of the IFR-PP at high temperature furthermore, thereby a better flame retardancy is obtained.The dispersion of IFR in PP and the structure of char layer after burning of intumescent flame retardant PP have been investigated by means of SEM. Combination of the results of TGA and CONE, There are many crevasses and holes on the surface of char residue without synergistie agent, and the IFR-PP with synergistic agent after burning can form more compact and stabile char layer, which like large leaves,the compact and intact surface of the char layers (the polysilicone system) may effectively stop the transfer of oxygen, heat and flammable volatiles, leading to good flame retardancy. the experimental results demonstrated that the dispersion of IFR in PP were better, while burning for IFR-PP with polysiloxane, the dispersion of IFR in PP were best. |
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