Properties Of Intumescent Flame Retardant Polypropylene And Its Master Batch

Polypropylene was flame-retraded with IFR composed of melamin polyphosphate(MPP)and pentaerythritol(PT),and environmentally friendly intumescent flame retardant master batch(IFRS)was prepared in this paper.The main work is as follow:Limiting oxygen index(LOI)and UL94 vertical burning test were used to investigate the effect of blowing agent/char former ratio of IFR on the flame retardancy of IFR/PP blend.The results showed that,at MPP/PT=2/1 with 30wt.%IFR loading in IFR/PP blend,the flame retardancy is optimum,i.e.LOI value is 31.5 and UL94 reached V-0 grade at 3.0mm thickness.The mechanism of IFR/PP system was studied by SEM,thermogravimetric analysis(TG)and FTIR,MPP and PT esterify first,followed by a series of complex chemical reaction,finally an intumescent char that can insulate heat and oxygen forms on the surface of PP matrix,thus makes the material extinguish,meanwhile the importance of suitable blowing agent/char former ratio of IFR to the excellent flame retardacy of IFR/PP blend was proved.On the other hand,mechanical properties and water resistance of IFR/PP blend were tested,results showed that mechanical properties substantially losed because of the poor compatibility of IFR with PP matrix,and the flame retardancy disappeard after treatment of hot water.The grafting PP with maleic anhydride(PP-G-MAH)was prepared by reactive extraction and used as compatibilizer for IFR/PP system.SEM analysis showed that the compatibility of IFR/PP blend added with PP-G-MAH was efficiently improved. PP-G-MAH can greatly increase mechanical properties of the composite and good comprehensive property was obtained when the addition of PP-G-MAH is 5 wt.%,i.e.the tensile strength was raised to 29MPa from 24MPa that of the composite with no PP-G-MAH,and UL94 still reached V-0(3.0mm)grade.The synergistic properties of four kinds of agents:zinc oxide,boric acid,nylon-6/nano-clay compound(PA6-nano)and micro capsulated red phosphorus(MRP)to IFR/PP composite were researched.Results showed that,the sequence of synergistic flame-retarded effect(SE)is as follow:MRP＞PA6-nano＞ZnO＞BA.Because of good thermostability,low cost and moderate SE,zinc oxide as syngernist for IFR is expected to be chosen firstly,but the concentration of ZnO is less than 2 wt.%.The intumescent flame retardant master batch(IFRS)composed of MPP,PT,catalyst zinc oxide,a small amount carrier and other additives were prepared.The test results of LOI and UL94 showed that,in order to obtain the similiary flame retardant effect,the concentration of IFRS is almost same as that of directive addition way.However,mechanical properties of the composites have been improved considerable by the way of adding IFRS,the decreasing degree of tensile strength of IFRS/PP(30/70)composite is not more than 15%,comparing with that of pure PP,but to the directive addition way,the decreasing degree is above 30%.Moreover,properties of IFRS based threee carrier:PP,PP/PP-G-MAH(1/1)and PP/POE-G-MAH(1/1)were studied,the test results showed that they all have excellent water resistance,i.e.UL94 rating of the three IFRS/PP composites still reached V-0(3.0mm)grade after treatment of hot water for 168 hours,especially to the IFRS based PP/PP-G-MAH(1/1)as carrier,the composite with it has outstanding comprehensive properties.