Influence of molecular arrangement on the γ-ray-irradiation solid-state polymerization of 1-octadecyl vinyl ether with a characteristic polymorphism
✍ Scribed by Atsuhiro Fujimori; Hideki Saitoh; Yoshio Shibasaki
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 251 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0887-624X
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✦ Synopsis
The polymorphic behavior of 1-octadecyl vinyl ether was investigated by DSC and X-ray diffraction measurements under various temperatures. In DSC measurement of 1-octadecyl vinyl ether in the temperature range of Ϫ30 to approximately 50°C, four transition peaks were observed on heating, whereas three transition peaks appeared on cooling. The phase-transition behavior was investigated by the repeating scanning DSC measurements. It was concluded that this compound exhibited four crystalline modifications: ␣, sub ␣,  0 , and  1 . It was confirmed by the temperaturecontrolled X-ray diffraction measurement that these phase transitions are attributed to the change of crystal systems from hexagonal packing (␣ form) to a distorted orthorhombic (OЌЈ) system ( 1 form) via orthorhombic (OЌ) (sub ␣ form) and intermediate  0 form, although the  0 form has not yet been clarified. In the ␥-ray-irradiation solid-state polymerization for these crystal forms of this compound, the polymerizability of the sub ␣ form is higher than that of other forms, and that of the ␣ form is lowest. The polymerizability demonstrated an unusual increase at a temperature of Ϫ83.6°C, probably because the cationic polymerization mechanism is dominant over that of the free radical.