| Alkylphosphinates are a new kind of green flame retardant.Commercializedalkylphosphinate is mainly aluminium diethylphosphinate, but its production is very difficultfor main material-ethylene with very low boiling point of-103.7℃, so that its liquefaction,storage, transportion are inconvenient. However, propylene with a higher boiling point of-47.4℃is convenient to liquefaction, storage, transportion， so that aluminiumdipropylphosphinate (ADPP) is relatively easy for synthesis and industrial production.However, the research on ADPP is very seldom. Therefore, the study on it is verymeaningful for the development of alkyl phosphinate flame retardants.The flame retardancy of ADPP and its combinations in polyamide6(PA6) was studiedin this work.The results showed that ADPP had good flame retardancy in PA6.When theloading of ADPP was15wt%based on the total weight of the composite, the LOI of theflame retarded(FR-) PA6was30.7%,and the vertical burning meet V-0according to the UL94standard, and the peak heat release rate(PHRR),average heat release rate（MHRR）,average mass loss rate（MMLR） was significantly decreased，but total heatrelease and average effective heat of combustion（MEHC）increased slightly；There wasobvious synergistic flame retardancy between ADPP and ME. As the weight ratios of ADPPto Me was75:25and the loading of the combination was10wt%, the LOI was30.9%, andthe V-0could be achieved. Compared with FR-PA6only with ADPP, complete combustiontime was increased significantly which suggested slower combustion, PHRR was decreasedsignificantly；As the weight ratios of ADPP to MCA was85:15and the loading of thecombination was15wt%, the LOI could be up to31.3%and V-0could be achieved.Compared with the FR-PA6with only ADPP, the HRR，THR， MLR，PHRR，MHRR，PEHC and MEHC of them had no significant difference，but combustion slower，whichconfirmed that there was not obvious synergistic flame retardancy between ADPP and MCAin PA6.There was no synergistic flame retardancy between ADPP and MPP in PA6. Thematerials containing additive ADPP/MPP of15wt%(the weight ratios of ADPP to MCA is65:35) received a V-2classification and has an LOI of25.0%. The PHRR, MHRR for theFR-PA6with ADPP/MPP were increased compared to the FR-PA6with ADPP. There was some synergistic flame retardancy between ADPP or ADPP/MCA and nanometer Mg(OH)2in PA6. The LOI and the vertical burning rat didn′t be changed,but THR和PHRR werereduced markedly by combining small amount of the Mg(OH)2.The thermal stability of the FR-PA6with ADPP, ADPP/ME, ADPP/MCA, ADPP/MPPdecreased compared to PA6,and more obviously with the combinations，especially withADPP/ME. The thermal stability of the FR-PA6with ADPP could be improved bycombining small amount of the Mg(OH)2.The analysis of residues obtained in cone calorimeter test revealed that ADPP playedthe role of flame retardance by gaseous and condensed phase mechanisms, where on the onehand, it was decomposed into non-volatile aluminum phosphate and promoted thecarbonization of PA6, and the formed intumescent layer resulted in flame retardancy by thebarrier effect on heat, air and decomposition products, on the other hand, it was decomposedinto volatile phosphorus compounds which brought about flame retardancy by flameinhibition.Using a combination of ADPP and ME or MCA improved charring of PA6andraised the residual rate of P and Al, thus improving the barrier efect in the condensedphase.The resulting loose non-intumescent layer by combining MPP weaken the fire retandancy ofADPP. |
