Use of water as a catalyst for the polymerization of chlorocyclophosphazenes
AssigneeThe Firestone Tire & Rubber Company
InventorsHarry Rex Allcock, James Earl Gardner, deceased, Karen M. Smeltz
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AssigneeThe Firestone Tire & Rubber Company
InventorsHarry Rex Allcock, James Earl Gardner, deceased, Karen M. Smeltz
Estimating the term…
The polymerization of hexachlorocyclotriphosphazene to poly(dichlorophosphazene) at elevated temperatures is a highly unpredictable process. The rate of polymerization varies over a wide range and is dependent on the history of the trimer and on the method of handling prior to polymerization. It appears that small amounts of water may possibly function as catalytic species for the polymerization. The addition of controlled amounts of water to the system results in a marked increase in reaction rate, and the rigorous exclusion of water from the system inhibits the reaction. The results favor the view that complete exclusion of water from the system may result in a system that cannot be polymerized. Thus, water appears to be a key component for polymerization.
In the polymerization of chlorocyclophosphazenes to produce a substantially linear (NPCl.sub.2).sub.n polymer product in which n is from about 16 to about 20,000, wherein hexachlorocyclotriphosphazene, octachlorocyclotetraphosphazene or mixtures of said hexa- and octachlorocyclophosphazenes are polymerized at temperatures between 200.degree. and 300.degree.C, the improvement which comprises conducting the polymerization in the presence of between 0.005 and 1.0 mol % of H.sub.2 O.
Dependencies are inferred from the claim text.