RADIATION-INDUCED POLYMERIZATION OF FORMALDEHYDE IN LIQUID STATE (in Japanese)
Monomeric formaldehyde is rapidly polymerized by ionizing radiation, especially in the liquid state, and gives the polyoxymethylene of high molecular weight. The reaction rate itself is large but considerably different in bulk and solution systems. There is no linear relation between the polymerization rate and monomer concentration. This paper confirms these facts for solution polymerization in acetone, methylene dichloride, toluene, and isopropylbenzsne. In the heterogeneous polymerization of formaldehyde the monomer is not dispersed completely enough to produce polymer particles with good reproducibility in the case of high conversions. This is due to the fact that monomerpolymer particles have a tendency to adhere to the giass surface of the reaction flask as the reaction proceeds and the reaction products can not be easily collectad. This was observed in the reactions of the monomer dispersed in nheptane and methylcyclohexane. In lower monomer concentrations the rate is relaxed in rather low conversions. Polymerization of the monomer dispersed in methylcyclohexane and n-heptane was carried out using some purified sorbitan oleates as surfactants. Polymer thus obtained was microscopically in the pearl-like form. The reaction proceeds smoothly even in high conversions and the rate is scarcely influenced by surfactant concentration in the region of 5.0--0.05%. It is concluded that the polymerization is initiated by active species directly produced in monomer particles by irradiation. Polymer particles thus obtained gradually grow up as the reaction proceeds. In the final state of conversions beyond 96%, mean polymer particle size is almost the same. In the initial state of the reaction monomer particles have dimensions reversely relative to surfactant concentration. (A.G.W.)
- Research Organization:
- Sumitomo Chemical Co., Ltd.
- NSA Number:
- NSA-17-030138
- OSTI ID:
- 4690340
- Journal Information:
- Proc. Japan Conf. Radioisotopes, Journal Name: Proc. Japan Conf. Radioisotopes Vol. Vol: 5th, No. 3
- Country of Publication:
- Country unknown/Code not available
- Language:
- Japanese
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