Synthesis And Application Of A Novel Flame Retardant Of Tri(2,2-Dimethyl-1,3-Dioxole)Cyclotriphosphazene

Polymers are widely used in various fields of our daily life for its good general performance,but the further applications are limited for the reason of flammable.The traditional halogen flame retardant will release lots of smoke,toxic and corrosive gases when it burning,which do harmful to environment and people's health.Phosphonitrile flame retardant has been used as a substitute for halogen flame retardant,because of its excellent thermal stability,no corrosive gases,lower smoke and toxicity.For this reason,phosphonitrile flame retardants have good research and application prospects in the field of flame retardancy.A novel cyclotriphosphazene derivative,tri?2,2-dimethyl-1,3-dioxole?cyclotriphos-phazene?TDPCP?was synthesized by hexachlorocyclo-triphosphazene?HCCP?,neopentyl glycol?NPG?and sodium.The chemical structure and thermal property of TDPCP were characterized and tested by FTIR,¹HNMR,³¹PNMR,EA,TG and DTG.At the same time,the influence of solvent selection,temperature,reaction time and feed molar ratio on the yield of TDPCP were investigated.The results showed that HCCP and sodium NPG dissolved in THF at a molar ratio of 1:4.5,reacted at the temperature of 70?for24 h,which the best yield of TDPCP was 85.5%.The thermal property showed that the TDPCP decomposed at 243.47?,the amount of residual carbon was 14.6%at 800?.Then the TDPCP was used as filler to improve the flame retardancy of polypropylene?PP?by melting blending method.The influence of TDPCP content on PP composites mechanical properties,thermal stability,flame retardantcy and thermal decomposition kinetics were tested and analysised.The results showed that the thermal degradation activation energy of PP was improved,and the PP composite could reach UL 94 V-1classification and the limiting oxygen index?LOI?value was increased from 17.3%to26.5%at the addition of 20 wt%TDPCP,and the carbon residual rate was gained from 0 to9.90%in the N₂ at 800?.The tensile strength and flexural strength were decreased by14.10%and 17.18%respectively,and the notched impact strength was increased at low content and then decreased by 3.14%when the content was 20%.The TDPCP was also used as filler to improve the flame retardancy of nylon 6?PA6?by melting blending method.The influence of TDPCP content on PA6 composite's mechanical properties,thermal stability,flame retardantcy and thermal decomposition kinetics were tested and analysised.Its turned out that TDPCP greatly promoted the rate of carbon residue from 0%to 10.03%,the PA6 composite could reach UL 94 V-0classification and the limiting oxygen index?LOI?value was increased from 23.3%to29.3%when the addition of 20 wt%TDPCP.The tensile strength and flexural strength of PA6 composites were decreased by 18.29%and 15.7%respectively at 20 wt%addition,and the notched impact strength was increased at low content and then decreased by15.67%at 20%addition.