Studies On The Transition Metal Compounds Modified Combustion Performances Of Poly(Vinyl Chloride)

This article main concerns focused on the great smoke release amount and poor flame retardancy of semi-rigid PVC,smoke suppressant and flame retardant simple compounding effect of low efficiency,through preparing additives of both smoke suppression and flame retardant.Under the conditions of a small amount of additives added,which can remarkable enhance the smoke suppression properties,flame retardancy and thermal stability of semi-rigid PVC.This paper main includes three aspects as follows:Ammonium phosphomolybdate?APM?was synthesized via chemical precipitation method,with ammonia,MoO₃,nitric acid and phosphoric acid as raw material;preparation of phosphomolybdic acid with MoO₃,phosphoric acid and hydrogen peroxide as raw materials,then on this basis,through its reaction with ferric hydroxide,zinc carbonate and copper carbonate,respectively,iron phosphomolybdate?Fe-PM?,zinc phosphomolybdate?Zn-PM?,copper phosphomolybdate?Cu-PM?were prepared.And preparation of phosphomolybdate were characterized by the test means such as IR,XRD and EDS.The results showed that,the samples of phosphomolybdate contain the [PMo12O40]3-group of Keggin structure,thereinto the ammonium phosphomolybdate was successful synthesized and it is the major product,the samples of transition metal phosphomolybdate contain iron element,zinc element,and copper element,respectively.The smoke suppression,flame retardancy,thermal stability and mechanical property of semi-rigid PVC treated with APM,traditional smoke suppressants?molybdenum trioxide?MoO₃?,ammonium octamolybdate?AOM??were comparative studied by means of smoke density instrument,cone calorimeter,thermogravimetic analysis?TGA?,stretch test machine and charpy impact tester,respectively.The test results indicate that the smoke suppression,flame retardancy,thermal stability properties and mechanical property of the PVC/APM composites are higher than that of the pure PVC,PVC/MoO₃ and PVC/AOM composites.The most great smoky density?MSD?and smoke density rating?SDR?are decreased to 78.47 and 61.82,respectively.Total heat release?THR?is decreased by 21.98%.By adding 5 phr APMs,the charring residue at 700 oC for semi-rigid PVC is increased by 21.61%.PVC/phosphomolybdate composites were prepared via molten blending method,and smoke suppression and thermal stability of PVC/phosphomolybdate composites were studied by means of smoke density instrument and thermogravimetic analysis.The test results indicate that iron phosphomolybdate,zinc phosphomolybdate,copper phosphomolybdate can remarkable enhance the smoke suppression properties and thermal stability of semi-rigid PVC.Among the synthesized three different kinds of phosphomolybdates,Cu-PM shows the best effect,by adding 5 phr Cu-PMs,the MSD and SDR are decreased to 78.47 and 61.82,respectively,the charring residue at 700 oC for semi-rigid PVC is increased by 26.52%.