Study Of Non-halogen Flame Retardant ABS Based On Novolac/MRP

With the development of non-halogen flame retardant, carbonaceous forming flameretardant system for ABS have made a significance achievement. As a high carbon residuerate resin, with low smoke, low toxicity and low cost, Novolac is one of an economic andefficient carbonizing agents. Microencapsulate red phosphorus (MRP) overcome the defectsof hygroscopic, easy oxidation and has a perfect flame retardant ability. At present, there is noreport based on Novolac/MRP flame retardant ABS. Therefore, it is significance to prepare anexcellent flame retardant ABS based on synergistic effect of Novolac and MRP.Firstly, non-halogen flame retardant ABS was prepared by using Novolac and MRP. Theeffect of components contents and ratios on flame retardant performance of ABS, andsynergistic effect between Novolac and MRP were studied. The results showed when the massratio of Novolac and MRP among3:2~2:3and total content was15.0wt%, UL-94V-0levelflame retardant ABS was prepared. However, with the optimal ratio of3:2, the LOI of flameretardant ABS can reach26.70%, and the surface of carbonaceous layer was much smootherand denser than other formulas after vertical burning. A cross-linked reinforced char formedby the reacting between phosphoric acid generated from MRP at a high temperature and rich–OH of Novolac, slowed down the decomposition ofABS.Secondly, aluminum hydroxide (ATH), zinc borate (ZB) and magnesium sulfate whisker(MHSH) was cooperate with Novolac/MRP system to retardant ABS, respectively. The resultsshowed when the mass ratio of Novolac and MRP was1:1and total content reduce to12.0wt%, the LOI of flame retardant ABS was23.50%and vertical burning only reach UL-94V-1level. However, a UL-94V-0level with LOI increased12.30%flame retardant ABS can beobtained by adding3.0wt%of ATH, ZB and MHSH, respectively. Due to a special structure,MHSH has a better compatibility with ABS matrix compared to ATH and ZB. With3.0wt%of MHSH, the tensile strength of flame retardant ABS was39.60MPa, and impact strengthincreased31.04%(reached5.8KJ/m2). In addition, Novolac/MRP/MHSH system showed abetter thermal stability performance and vertical burning property with the stablecarbonaceous layer generated at a high temperature.Thirdly, the Novolac/MRP flame retardant ABS was toughened with nitrile butadiene rubber (NBR). The effect of toughener on flame retardant performance, mechanical properties,thermal stability and carbonaceous layer structure of flame retardant ABS were investigated.With10.0wt%of NBR, the impact strength of ABS/9.0wt%Novolac/6.0wt%MRP systemcan reach9.40KJ/m2(increased276.0%), have no effect on pyrolysis products, and thermalstability of flame retardant ABS was improved at the same time. When Novolac and MRPsynergetic with the mass ratio of2:3(total content was15.0wt%), the stable C-O-P structureof organic-inorganic hybrid flame retardant carpet generated at a high temperature can resistescape of combustible volatiles and other low molecules products produced by NBRefficiently, and have a perfect protection with the internal matrix. However, when cooperatedwith3:2, the flame retardant carpet was not stable enough to limit the process of gas escaping,and lead to declining of final flame retardant performance.