Research On Preparation Of Halogen-free Flame Retardant ABS Composites In A Novel Non-twin Screw Extruder

Acrylonitrile–Butadiene–Styrene Copolymer(ABS)is one of the most widely used engineering plastics due to its excellent advantages,such as chemical resistance,mechanical properties and easy processing,and so on.Compared with other plastics,ABS enjoys higher favor among the electronic and electricity industries.Its extreme flammability,however,limits the broader application of ABS.In this paper,we have demonstrated the flame-retardant mechanism of “additive flame retardants” and “reactive flame retardants” based on the polymer combustion mechanism.And a novel modified intumescent flame-retardant ABS/IFR composte was prepared and investigated as follows:1.A comparative study on the mixedness of a halogen-free intumescent flame retardant ABS composite under the same condition using both novel and traditional extrusion processes has undertaken to investigate the priority of NTSE in polymer processing.By comparison with qualitative and quantitative analysis,it has been found that the mechanical and flame retardant properties of ABS/IFR composite prepared in NTSE was more excellent than TSE,and the gross uniformity was improved obviously in the variance experiment,too.It can be concluded that the NTSE offer important advantages over TSE due to the chaotic mechanism,enabling them to carry out the mixing steps more efficiency and uniformly and showing a huge superiority in functional polymeric material processing.2.A modified IFRC powder was prepared by compounding ammonium polyphosphate,pentaerythritol,and zinc stearate with silane coupling agent KH-570.This modified IFRC powder was further wrapped by EVA latex.The degree of coating was also characterized by adopting the surface contact angle measurement.The Limiting Oxygen Index values of the ABS/EVA/IFRC composites increased when compared with that of ABS/EVA/IFR composites at the same loading,and so did the mechanical properties.It was found that ABS/EVA/IFR composites did not reach V-0 rating while ABS/EVA/IFRC composites could reach V-0 rating when the addition level up to 30%.Moreover,ABS/EVA/IFRC composites produced higher residual char than ABS/EVA/IFR composites as indicated in TGA.All the results illustrated that the IFRC system was better than IFR system,and this point was also confirmed by the SEM morphologies.3.Organic illite(OILT)prepared from illite(ILT),with high aspect ratio and orderly arranged platelets intercalated by octadecyl trimethyl ammonium bromide(OTAB),was used as a synergistic agent on the flame retardancy of ABS/IFR system.The mechanic,flammability and thermal stability of ABS/IFR/OILT composites were investigated by limiting oxygen index(LOI),UL-94 testing and thermogravometric analysis.The results of LOI and UL-94 testing showed that low loading of OILT improved the flame retardancy and retarded dripping for ABS/IFR composites.OILT,with 1% loading,increased the char residue of ABS/IFR composites and could act as an effective additive for improvement in mechanic performance and flame retardancy.The composite morphological structures observed by scanning electron microscopy(SEM)showed that OILT with 1% loading can promote the compatibility between the polymer and additives.Thus,OILT with 1% loading showed a synergistic effect with IFR in the combustion of the ABS/IFR composites.4.The influence of dicumyl peroxide(DCP)as cross-linking agent on the flow property,mechanical properties,flame retardancy and thermal stability of ABS/EVA halogen-free flame retardant composites was studied.The results showed that,with the increase of DCP,the cross-linking density of ABS/EVA flame retardant composites increased at first and then decreased,and the melt flow rate of the composites decreased at first and then increased.A moderate amount of DCP led to improve the mechanical and flame retardant performance of ABS/EVA composites.When the amount of DCP was 0.3%,the tensile strength of the composite was 16.12 MPa.When the amount of DCP was 0.6%,the limited oxygen index of the composite reached 31.4%,and it arrived at V-0 rating in the UL-94 test.Through the analysis of thermal stability of the composites,it was shown that the proper amount of DCP could promote the char forming process.