Synthesis And Flame Retardant Mechanism Of Alkyl Phosphinate Flame Retardant

Alkyl hypophosphonate flame retardants are widely acknowledged for their exceptional overall performance,low toxicity,and eco-friendliness.However,the production of these flame retardants using gaseous olefins(ethylene,propylene)involves harsh and monopolistic production conditions,resulting in high prices.To address this issue,this study aims to synthesize three novel alkyl hypophosphonate flame retardants,namely aluminum bis(hydroxyphenylmethyl)hypophosphonate(AlBPi),aluminum dicyclohexyl hypophosphonate(ADCP),and aluminum diisobutyl hypophosphonate(ABPA),using non-gaseous and cost-effective reactants under mild conditions.The study investigates the effect of experimental conditions on the yield and flame retardancy of the synthesized products.Additionally,suitable co-effectors are selected for each flame retardant to be used in combination,and their synergistic flame retardant effect and mechanism are examined.Finally,using intelligent computing technology,a nonlinear prediction model of the flame retardant performance of alkyl hypophosphonates is constructed and validated using experimental data.The research results of this paper are as follows:AlBPi was synthesized using benzaldehyde and hypophosphoric acid as raw materials under atmospheric pressure.The best reaction conditions obtained by the orthogonal test study were a reaction temperature of 88.7℃,a reaction time of 12.5hours,and a salt formation reaction temperature of 85.9℃,resulting in a yield of62.94%.Thermogravimetric analysis showed that the temperature of 5%weight loss was 224.5°C,which could meet the demand of PLA processing.The flame retardant test found that the UL-94 was only V-2 level at 15%addition of AlBPi,and the LOI was only improved by 1.5%.The co-effector Ammonium polyphosphate(APP)was selected and combined with AlBPi,the LOI of the PLA/10%AlBPi/5%APP composite reached 28.1%,and the UL-94 improved to V-1.The cone calorimetric test showed that the PHRR,THR,PSPR,and TSP of PLA/AlBPi/APP composites were significantly reduced co MPared to the pure sample and PLA/AlBPi material.The SEM analysis showed a continuous and dense carbon layer on the residue surface of the synergistic flame retardant samples,demonstrating their excellent synergistic flame retardant effect.ADCP was prepared via the free radical addition method under atmospheric pressure,using cyclohexene and sodium hypophosphite as raw materials.Thermogravimetric analysis revealed that the temperature of 5%weight loss was 305℃,indicating good thermal stability.The optimal reaction conditions were determined via an orthogonal test,yielding a reaction temperature of 87.0℃,a reaction time of 11.3hours,and an initiator dosage of 6.3%,which resulted in the highest yield of 82.48%.The flame retardant test demonstrated that ADCP exhibited excellent flame retardancy,achieving a V-0 grade according to UL-94 at a 15%addition and a LOI of 30.8%.The co-effector Melamine polyphosphate(MPP)was selected and combined with ADCP,resulting in an LOI of 34.6%and a UL-94 grade of V-0 for the PA66/10%ADCP/5%MPP composite.Moreover,the Peak Heat Release Rate(PHRR)and Total Heat Release(THR)of the PA66/ADCP/MPP and PA66/ADCP composites were significantly lower than those of the pure sample.The co-flame retardant material exhibited a superior smoke suppression effect co MPared to ADCP alone.The synergistic flame retardant effect was observed by SEM,revealing a continuous and dense carbon layer on the residue surface.ABPA was synthesized via the free radical addition method under atmospheric pressure,using tert-butanol and sodium hypophosphite as raw materials.Thermogravimetric analysis revealed that the temperature of 5%weight loss was 313℃,indicating good thermal stability.The flame retardant test demonstrated that ABPA exhibited good flame retardancy,achieving a V-0 grade according to UL-94 and a LOI of 31.1%at a 15%addition.The co-effector MPP was chosen and combined with ABPA,resulting in a LOI of 34.7%and a UL-94 grade of V-0 for the PA66/10%ABPA/5%MPP composite.Moreover,the PHRR and THR of the PA66/ABPA/MPP and PA66/ABPA composites were significantly lower than those of the pure sample.The co-flame retardant material exhibited a superior smoke suppression effect co MPared to ABPA alone.The synergistic flame retardant effect was observed by SEM,revealing a continuous and dense carbon layer on the residue surface.Prediction models(ANN,ANFIS-GP,and ANFIS-SC)were established to predict the LOI values of alkyl hypophosphite flame retardants using the neural network fitting module and ANFIS program,respectively.The prediction models were validated,and evaluation criteria,such as Root Mean Square Error(RMSE),R-squared(R~2),and Mean Absolute Percentage Error(MAPE),were calculated to determine model reliability.The results showed that the prediction model established by ANFIS-SC exhibited relatively higher reliability and accuracy,providing more satisfactory prediction results.