Synthesis And Application Of Phosphoric Flame Retardants In Polymers

The preparation and application of flame retardant have been attracted more and more attentions as the strict demand of global flame retardant rules.Flame resistant polymeric materials are used widely in many fields,such as automobile,electronics, and transportation.Therefore it's very important to develop novel flame-retardants and apply them in polymeric materials.In this paper,three kinds of phosphorus series flame retardant,i.e.N, N'-piperazinebis(neopentylglycol)phosphoramidete(PBNGP),N,N'-piperazinetetra (phenol)phosphoramidate(PTPP),and phosphonic acid,methyl-,bis[(5-ethyl-2 -methyl-1,3,2-dioxaphosphorinan-5-yl)methyl]ester,P,P'-dioxide(TPMP),were synthesized firstly.The reaction processes and synthesis conditions,such as solvent, reactant proportion,reaction temperature,reaction time and catalyzer etc.,were studied detailedly in order to gain the optimal synthesis conditions.The results indicated that the obtained compounds were just as which were expected.The therrno decomposition temperature of the flame retardants was more than 300℃,which could satisfy the requirement of preparing flame resistant polymers through melt blending.Flame resistant polyamide 6(PA6)resin were prepared by adding PBNGP/ melamine(MA)complex system.The dispersing state of flame retardant,flame resistant property,char formation and flame retardant mechanism of flame-resistant PA6 resin were investigated through SEM,DSC,TGA,FTIR and UL-94 test respectively.The results showed that the flame retardant could be dispersed equably in PA6 matrix.The LOI(limited oxygen index)value of flame resistant PA6 was 23 with adding 10%PBNGP,and the LOI value was 24 with 15%PBNGP addition.By addition of 13%PBNGP and 10%MA the LOI value increased to 28.While the LOI value of PA6 is 21.The UL-94 tests of the flame resistant systems were V-2 level. Flame retardant mechanism analysis indicated that the flame retardant could work in both condensation phase and gas phase. Flame resistant PA6 fiber was spun through melt spinning process by adding PTPP/melamine cyanurate(MC)complex.The rheological test showed that PA6/PTPP system belonged to the shear thinning liquid and was more sensitive to shearing viscosity and temperature.This indicated the melt spinning process had to be controlled strictly.Flame resistant PA6 with PTPP content from 5%to 15%showed good spinnability.When PTPP content was 5%,the mechanical property,orientation, Young modulus,and crystal structure of PA6 fiber didn't change evidently.Even as the PTPP content rised to 15%,the flame retardant fiber still possessed excellent practicality.When PTPP/MC complex system was added the flame retardant property of PA6 could be improved further.By adding 11%PTPP and 8%MC the LOI value of flame resistant PA6 increased to 29 and the UL94 test was V-0 level.In addition,the flame retardant mechanism was studied by dynamic FTIR and SEM observation.The results showed that the blending system could form surface gel and internal spumescent char layer to achieve flame retardant properties.The flame retardant properties of flame resistant PA6 contenting TPMP/MA complex system were studied by LOI,UL-94 and cone calorimeter tests.The results showed that the LOI value of PA6/17%MA system was 27.2,and the LOI value of PA6/4%TPMP/13%MA system was 28.6.The UL-94 test was V-0 level.The flame retardant mechanism analysis indicated that the TPMP/MA complex system could form thick intumescent char layer to execute the flame retardant functions both in the condensation phase and the gas phase.The flame retardant PA6 fiber was prepared through melt spinning process.The spinnability and properties of flame retardant PA6 fiber was affected less with addition of 1%to 2%TPMP/MA.Flame resistant PTT resin was prepared by adding TPMP/MA and TPMP/MA/Br series flame retardant.PTT/TPMP/MA system showed good flame retardant properties and obvious P-N-synergistic flame-retardant effects.The LOI value of PTT/2%TPMP/15%MA system reached 28.For the PTT/2%TPMP/15%Br series flame retardant system the LOI value was 26,which also showed good flame retardant properties besides the weaker P-Br-synergistic effects compared to P-N system.The SEM and DSC tests showed that the flame retardant mechanism of PTT/TPMP system was solid phase flame-retardant mechanism.Flame resistant PTT fiber was spun through melt spinning process by adding TPMP/MA complex system. The flame-retardant PTT/TPMP/MA fiber with TPMP content from 1%to 3%showed good spinnability and mechanical properties for practical applications.