| The waste residue produced in the productive process of melamine contains a high proportion of melamine,cyanuric acid and other recyclable chemical products.If it is not properly used,it will not only waste resources,but also pollute the environment.So far,there have been a lot of studies on the treatment of solid waste,but there are relatively few studies on the treatment and resource utilization of melamine waste residue.Therefore,the recycling of melamine waste residue and the pretreatment of melamine cyanurate(MCA)as raw material can not only reduce environmental pollution but also turn waste into treasure to meet the market demand of green flame retardant MCA.Based on this,this paper takes the pre-treated melamine waste residue as raw material,The flame retardant MCA was synthesized by cyanuric acid method,The synthesis conditions of MCA were optimized by single factor experiment and response surface methodology;The prepared MCA was applied to polyamide 6(PA6)material,and the effect of different MCA content on the flame retardant properties of PA6/MCA composites was investigated.The flame retardant PA6 composites with MCA composite system were prepared,and the effect of the ratio of MCA,MMT and AHP on the flame retardant properties of the composites was investigated.The impurities in melamine waste residue were removed by sedimentation and dissolution and precipitation.After pretreatment,the waste residue sample with melamine content of 94.88%was obtained.MCA was prepared by cyanuric acid method with pretreated sample as raw material and alkali metal salt as catalyst.Using the single factor method to synthesis process conditions were studied,compared to the mass ratio of raw materials,the liquid-solid,reaction temperature,stirring speed and reaction time influencing on the yield of MCA quality,get the suitable technological conditions as follows:raw materials quality ratio of 0.88,compared to liquid-solid 6,reaction temperature 100?,200 r·min-1 stirring speed,reaction time is6 h.Under these conditions,the mass yield of MCA can reach 90.54%.On the basis of single factor experiments,RSM was used to further optimize the synthesis conditions of MCA.The effects of raw material mass ratio,liquid solid ratio,reaction temperature,stirring rate and other factors on the mass yield of MCA were investigated.The optimized process conditions were as follows:mass ratio of raw material 0.90,liquid-solid ratio 6,reaction temperature 95?and stirring rate 198r·min-1.The average mass yield of MCA was 90.75%,and the relative error was0.14%compared with the predicted value of 90.88%,which indicated that the established model was reliable.The synthetic products were characterized and analyzed by infrared spectroscopy and purity analysis.The composite flame retardant MCA was used to separate and compound the flame retardant of PA6.PA6 composite was prepared by melt blending method.The effects of MCA and the compound system on the properties of the composite were studied by vertical combustion experiments and limiting oxygen index.The results show that when the MCA content is 25%,the vertical combustion grade of MCA flame retardant PA6 composite is UL-94V-2,and the limiting oxygen index is26.8%.MCA flame retardant PA6 was compounded and modified to study the influence of MCA,AHP and MMT ternary compound system on the material properties of PA6,and the optimal ternary compound ratio was obtained as follows:0.5%AHP,2.5%MMT and 17.5%MCA,the vertical combustion grade of the composite reaches UL-94V-0,and the limiting oxygen index reaches 27.8%.The results can not only realize the recycling of melamine waste residue,but also provide a basis for the application of MCA in the flame retardant of PA6. |
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