Study On The Synthesis And Flame Retardant Properties Of Melamine Polyphosphate With High Thermal Stability

In this paper,high thermal stability of melamine polyphosphate(MPP)was synthesized by the reaction of melamine and phosphoric acid in two steps.Compared to the traditional synthesis process,the following conditions were optimized:the mole ratio of melamine and phosphoric acid reaction was 1:1,heteropoly acid was added as the catalyst by the 1.5 wt%in the first step of the synthesis of melamine phosphate.Thermal condensation process was used the temperature programmed route in the second step.It reduced the occurrence of side reactions and obtained high thermal stability of MPP.Its molecular structure was determined by FT-IR,³¹P-NMR,elemental,XRD.The thermal properties were characterized by thermogravimetric analysis(TGA).The results showed that the MPP synthesized by the optimized synthesis process had good whiteness and excellent thermal performance.The temperature was 372.1?at 1%weight loss in TGA.The temperature was 382.7?at 5%weight loss in TGA.And the mass residue at 650?was 38.5%.Glass Fiber reinforced polyamide 6(GFPA6)was flame retardanted by synthesis of MPP and MPP with ethyl phosphonate(ADP)composite system(MPP/ADP).Flammability properties and mechanical properties of FR-GFPA6 were characterized by limit oxygen index,vertical burning,tensile test and impact test.The results showed that the flame retardant properties of the FR-GFPA6 was gradually increased with the increase of the flame retardant.When the added amount of MPP reached 20.0 wt%,the flame retardant level of the FR-GFPA6 reached UL 94 V-2level(3.2 mm).When the added amount of the flame retardant reached 25.0 wt%,the flame retardant level of the FR-GFPA6 did not increase further,and it was still UL 94 V-2 grade(3.2mm).However,when the MPP and ADP were combined to flame retarded GFPA6,the total amount of the compound flame retardant reached 20 wt%,the flame retardant grade of the FR-GFPA6 reached the UL 94 V-0 level.And the addition of oxygen index of flame retardants had been improved to a certain extent,the oxygen index of the modified GFPA6 had reached a nonflammable level.When the addition of 5.0 wt%MPP and 15.0 wt%ADP,the oxygen index of flame retardant materials reached the maximum of 32.0%.In terms of mechanical properties,the tensile strength and impact strength of FR-GFPA6 were still higher after MPP addition.But the effect of the addition of flame retardant on the elongation at break of the material was relatively large.When the 15.0 wt%was added,the elongation at break of the FR-GFPA6 was decreased by almost 40.0%.The mechanical properties of the materials had small effect of with the addition of compound flame retardant,and the tensile strength,impact strength and elongation at break of the FR-GFPA6 can be retained by 80.0%.MPP respectively with melamine coated APP(M-APP)and dipentaerythritol(Di PER),piperazine modified APP(Pi-APP)flame retardant were flame retarded respectively on the copolymerization PP(CO-PP)and homopolymer PP(HO-PP).And its flame retardant properties,water resistance and mechanical properties were evaluated.In the study of flame retardant modification by CO-PP found that the flame retardant property of CO-PP was improved by the addition of compound flame retardant.When MPP respectively with Pi-APP and Di PER were the best flame retardant effect.When the added amount of the compound flame retardant reached 25.0wt%,the vertical combustion level respectively reached UL 94 V-0(3.2mm)and UL 94 V-1(3.2mm)and the oxygen index respectively reached 32.5%and 24.7%.But the mechanical properties of CO-PP have a greater impact with the addition of MPP compound flame retardants.The mechanical properties of the CO-PP partly decreased with the addition of flame retardant.Especially the elongation and impact strength respectively decreased the maximum amplitude reached 81.9%and 64.4%.In the study of flame retardant modification by HO-PP found that the MPP compound system had certain effects on the flame retardant property of HO-PP.Adding the formula of flame retardant oxygen index of HO-PP had improved to some extent,reached more than 23.0%,the addition of 25.0 wt%MPP and Pi-APP,the oxygen index reached 36.4%.The vertical burning test reached UL 94 V-0 when respectively used for MPP,Di PER and MPP,Pi-APP flame retardant.But after the water resistance of 168 h,MPP with Di PER flame retardant modified HO-PP has no flame retardant level,and MPP with piperazine modified APP flame retardant level was still UL 94 V-0.In the mechanical properties,Tensile strength and impact strength had small influence when added to composite flame retardant.When the flame retardant added to 25.0 wt%,Tensile strength and impact strength of pure can be maintained in 82.0%and more than 86.8%compared with HO-PP.But the effect elongation break of HO-PP was relatively large with addition of flame retardant,generally decline reached more than 70.5%,the biggest decline reached 89.0%.