Synthesis Of Phosphorus-Containing Flame Retardant/Monomer And Study On Thermal Stability And Combustion Properties Of Polyamide

Polyamides with the excellent performance is widely used in machinery,electrical and electronic,communication,home appliance,automobile,railway,aerospace and other major areas.Since some decades,it has become the largest production of engineering plastics.For polyamides,especially the alphatic polyamides,the combustion with flame drops will expand the fire area rapidly.At present,the halogenated flame retardants are mainly used in polyamides.Research show these flame retardants have come under environmental criticism.So the development of some new flame retardants has become a very important research field.In the halogen-free flame retardants,the phosphorus-based flame retardants has attracted wide attention because of the higher flame-retardant efficiency and variable chemical structure.However,the flame retardant polyamides also face some challenges:the main common phosphorus-based flame retardants need higher additive amount in polyamides to achieve effective flame retardant effect;phosphorus-based flame retardants currently used in polyamides are mainly inorganic compounds and are poor in interface compatibility with polymer;only a few kinds phosphorus-based flame retardants can adapt the processing temperature of polyamides.In this dissertation,based on the review of the flame retardant polyamides,several kinds of phosphorus-based flame retardants were synthesized to prepare the flame retardant polyamides.Then,the thermal stability and flame retardancy of the flame retardant polyamides were investigated,and the flame retardant mechanism of the phosphorus-based flame retardants was illustrated.The main research contents are as follows:1.MCAHP was prepared by MCA and MMA-GMA as the capsule material and the relationship between structure and properties of MCAHP was studied by FTIR,XPS,TGA and SEM.The results showed that the capsule material can delay the decomposition of AHP and postpone the release of PH3,even to improve the safety of AHP.The flame retardancy of PA6 composites were studied by LOI,UL-94,Cone and so on.The results showed that MCAHP with MCA as the capsule material show a better flame retardancy due to the synergistic effect of MCA and AHP between gas phase and cohesive phase.According to MCAHP with MMA-GMA as the capsule material,MMA-GMA can form a carbon layer on the surface of flame retardant during the combustion,which inhibits the decomposition products of AHP react with PA6 matrix to reduce flame retardance.2.Two novel halogen-free flame retardants,CEPPA-A1 and CEPPE-Al,were prepared with CEPPA as materials by a simple process in aqueous solution.The chemical structure,thermal stability and morphology were characterized by FT-IR,NMR,SEM and TGA.The results showed that CEPPE-Al has a higher thermal stability than CEPPA-Al.The two flame retardants were used to flame retardant polyamide 6 by melt-mixing.The thermal stability and flame retardancy of the flame retardant polyamide 6 has been investigated by TGA,LOI,UL-94 and Cone.The results showed CEPPE-Al has better flame retardance owing to the phosphorous-nitrogen synergetic system.By analyzing the product of the flame retardant polyamide 6,CEPPE-Al act in the condensed phase to promote more char during combustion.3.The organic monophosphonic acid and organic bisphosphonic acid were synthesized by phosphorous acid react with PD and PIP by mannich reaction.Then two new ZrP were synthesized by the HF method.The structure,thermal stability and morphology of PD-ZrP and PIP-ZrP were characterized by FTIR,NMR,XRD,SEM and TGA.The results show that PD-ZrP and PIP-ZrP have typical nano-layered structure,and the thermal stability can adapt the processing temperature of PA6.The PA6 nanocomposites were prepared by melt blending method.The thermal properties and flame retardancy of the PA6 nanocomposites were characterized by TGA,LOI,UL-94 and Cone.The results showed that the nanocomposites performed higher thermal stability and flame retardancy than PA6.By comparison,PD-ZrP can advance higher graphitized char residual compared to PIP-ZrP,which due to the structural defferences.4.Four novel DOPO based phosphonamidates were synthesized in this work.Two bis DOPO-phosphonamidates were synthesized by Atherton-Todd reaction between DOPO and EDA or PIP;two polyphosphamides were synthesized by solution polycondensation between diamine and BPOD or MPCP.The structure and thermal stability of these phosphonamidates were characterized by FTIR,NMR and TGA.The results show that four phosphonamidates can adapt the processing temperature of PA6.Although incorporating these phosphonamides into PA6,the flame retardant PA6 show the lower thermal stability.These phosphonamides have superior fire performance properties in PA6 matrix and work primarily in gas phase by recombining radicals.5.DDP was acyl-chlorinated as the monomer to synthesise the inherent flame-retardant copolyamides containing DOPO side-group by interfacial polymerisation,and PIP and PPD as the monomer were synthesized into the main-chain of copolyamides.Then,the chemical structures,thermal properties,thermal stabilities,crystalline structures and flame retardancy of the resultant copolyamides were characterized by FTIR,NMR,DSC,TGA and MCC.These results show that the inherent flame-retard ant copolyamides have better thermal stability and flame retardancy compared to polyamide.So,the introduction of even a few content of the phosphorus-containing unit into copolyamides can remarkable improve the flame retardancy,especially synergistic effect with PIP or PPD.