Characterization On Polymerization Degree Of Long Chain Ammonium Polyphosphate

The dissolve process and solution properties of type II ammonium polyphosphate(APP) were studied and a method to improve the solubility of APP was put forward byadding suitable amount of NaCl. Systematic studies on characterization of thepolymerization degree of APP were carried out with31P nuclear magnetic resonance (NMR)with low concentration NaCl solution as solvent, and this kind of solvent was also used inthe viscosity measurements of APP as well as converting APP into sodium polyphosphate(NaPP) through ion-exchange. New experimental formulas were founded to measure thepolymerization degree of APP by specific viscosity which cover a range of20-2000andable to come into practical application in the industrial analysis of APP. The phenomenonof high viscosity while low polymerization degree results from31P-NMR was explainedand way to improve the accuracy of31P-NMR characterization was also proposed.The amount of the testing sample affects the solubility result mostly becauselong-chain APP can’t be dissolved in water while orthophosphate and short-line APP can bedissolved under normal temperature. It was put forward in the paper that the ratio ofdissoluble part in APP samples could be used to analysis the polymerization degree of APP.The determination of n of APP by31P-NMR was studied in detail with lowconcentration NaCl solution as solvent. The disturbing factors and the range of n in31P-NMR analysis for APP were investigated.31P-NMR is suitable for samples with narrowmolecular weight distribution and less short-line APP. Ammonium triphosphate andtetraphosphate affect the results most as they cannot be distinguished in the spectra. Theresults of31P-NMR are probably are more connected to short chains in APP. It was alsofound for the first time that the31P NMR relaxation time would affect the results of NMRand an experimental relaxation time of APP was obtained as10s.Stable solutions of APP were studied by converting APP into sodium polyphosphate(NaPP) through ion-exchange and dissolving APP into low concentration NaCl solution.The chains of APP maintain different forms in two kinds of solutions and thus affect theviscosity results. The polymerization degree measurement by viscosity based on theexperimental formulas for APP was studied with two new experimental formulas werefounded.