Synthesis Of Dipropyl Phosphinic Acid Aluminum Salt And Its Applicationin Glass Fiber Reinforced PBT Flame Retardant Composites

As one new type of green and halogen-free flame retardants,the dialkyl phosphinic acid salts possess advantage such as excellent flame retardant efficiency,high temperature oxidation resistance and hydrolysis resistance.Negative effects are not discovered from the angle of toxicology and environmental protection.The polymer materials with dialkylphosphinic acid salts as flame retardants show good mechanical performances,high gloss and low smoke density.So,it has been widely used in motor vehicles,household appliances,electronic and electric industry.But the only commercial products about the dialkylphosphinic acid salts are diethylphosphinic acid saltsin the present global market.Therefore,the development and industrialization of high quality flame retardants of dialkylphosphinic acid salts has significant effects to the national economy.Based on the dipropyl phosphinic acid aluminium salt(Aluminium Dipropylphosphinate,ADPP)has many disadvantages such as tedioussynthetic process,high manufacturing cost,lowpurity,poor heat stability.In this dissertation,author investigated systematically that the effects of types and concentrations of phosphinic acid,solvents,initiators,reaction temperatures and pressure on the alkylation reaction extent of dipropyl phosphinic acid sodium salt.The synthetic conditions and purifyprocess of dipropyl phosphinic acid sodium salt were optimized.By adding ADPP to prepared glass fiber reinforced PBT(GFPBT)flame retardant composite were investigated.All the results of this study were listed as below:(1)Dipropyl phosphinic acid sodium salt with high purity were firstly synthesized using free radical synthesis method,then ADPP with high purity was prepared.The optimal synthetic conditions of the dipropyl phosphinic acid sodium salt were: 33wt% hydration phosphinic acid sodium salt acetic acid solution as the resource ofphosphinic acid,1,1-bis(tert-buty peroxy)-3,3,5-trimethyl-cyclohhexane(CH335)as the initiator,the initiator feeding speed 0.2mol%/h,the reaction temperature 120 oC,the reaction pressure 1.5MPa and the reaction time 7hrs.At the optimal conditions,the dipropyl phosphinic acid sodium salt was obtained with the highest alkylation reaction extent,and the highest absorption of propylene was above the 98%.The ADPP synthesized in 50 L reaction system had same effects on the properties of GFPBT flame retardant composites in comparison with the ADPP synthesized in 2L reaction system.(2)The structure of ADPP were confirmed by FTIR,31P-NMR and 1H-NMR.SEM showed that ADPP particles(D50=13?m)were aggregation particles which consists of many primary particles with 0.5~1?m.ADPP possessed excellent heat stability,and its thermolysis temperature range covered that of GFPBT.Therefore,ADPP was suitable for GFPBT as flame retardant.(3)The ADPP,ADPP/MPP and ADPP/MCA were used to prepared flame retardant GFPBT composites,respectively.The flame retardant GFPBT composites with the excellent flame retardant properties were obtained by adding ADPP or ADPP/MPP.Flame retardant synergism was found between ADPP and MPP.When the mass ratio of ADPP to MPP was 2/1,the prepared GFPBT composites showed better flame retardancy.The flame retardant GFPBT composites with 13.0wt% of ADPP or ADPP/MPP(ratio was 2/1)reached above 33 of limiting oxygen index(LOI)and reached UL 94 V-0 at 3.0mm sample band.When the flame retardant GFPBT composites with 16.7wt% of ADPP or ADPP/MPP(ratio was 2/1),it reached above 34.9 of LOI and reached UL 94 V-0 at 1.5mm sample band.The flame retardant GFPBT composites have longer ignition time,lower heat release rate,lower mass loss rate and lower smoke produce rate.It is indicated that ADPP and ADPP/MPP were valid for slowingin flame propagation and reducing the fire hazard.(4)In the flame retardant GFPBT composite,ADPP and ADPP/MPP were dispersed well and were enclosed by PBT resin.The flame retardants particles of ADPP and MPP were not observed on impact fracture surface zooming to 2000 times.With increasing the amount of ADPP or ADPP/MPP,the mechanical performances of the flame retardant GFPBT composites were decrease.At the same additive amount in GFPBT composites,the mechanical performances of the flame retardant GFPBT composites prepared by ADPP/MPP were better than that by ADPP.