Effect of Polymerization Temperature on Polymerization Degree and Structure of Calcium Polyphosphate

The properties of calcium polyphosphate (CPP) were greatly affected by its polymerization degree. A series of CPP with different polymerization degree were prepared by polymerization of calcium phosphate monobasic monohydrate (MCP) at different temperatures. Polymerization degree was analyzed by liquid state P-31 nuclear magnetic resonance (P-31-NMR). The effect of different temperature on polymerization degree and structure of CPP was discussed. MCP was analyzed by differential scanning calorimetry-thermmogravimetry (DSC-TGA) and possible mechanism of the polymerization reaction was proposed. The results show that polymerization of MCP mainly produces CPP. When the elevation temperature is below 1000 degrees C, polymerization degree increases; however the opposite is true when the polymerization temperature exceeds 1000 degrees C. Additionally, the formation of a ring-structure phosphate, namely calcium metaphosphate (CMP), is also promoted with increasing polymerization temperature. The CMP content increases with increasing polymerization temperature and significantly increases when the polymerization temperature is above 1000 degrees C.