Solution polymerization of chlorophosphazene with sulfur modifier
AssigneeThe Firestone Tire & Rubber Company
InventorsAdel F. Halasa, James E. Hall
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Abstract
Solution polymerization of cyclic dichlorophosphazenes represented by the general formula (NPCl.sub.2).sub.n in which "n" is less than 15 to essentially linear polydichlorophosphazenes in which the degree of polymerization is within the range of 20 to 50,000 is improved by the use of selected solvents and by the presence of elemental sulfur or sulfur donating compounds in the polymerization mixture.
Claims13
In a process for producing substantially linear polydichlorophosphazenes in which the degree of polymerization is between about 20 and 50,000, from cyclic oligomers represented by the general formula (NPCl.sub.2).sub.n in which n is an integer from 3 to about 15, the improvement which comprises conducting the polymerization of said cyclic oligomers in solution in a solvent for said oligomers, for up to about 300 hours and at a temperature between 140.degree. and 225.degree. C., in the presence of an amount of sulfur or sulfur-containing compound, effective to prevent the formation of appreciable amount of gel, said solvent being a liquid having a dielectric constant of at least two, and being a solvent for said sulfur or sulfur-containing compound, and being a solvent for said dichlorophosphazenes, and recovering the resulting polydichlorophosphazene produced by said process.
Dependencies are inferred from the claim text.