Bisphenol Fluorenone Carbonate-Simethyl Siloxane Block Polymers: Transparent, Tough, Heat- and Flame-Resistant Thermoplastics.
Final rept. 14 Jan 74-13 Jun 75,
GENERAL ELECTRIC CORPORATE RESEARCH AND DEVELOPMENT SCHENECTADY N Y
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Synthesis on the 100g scale of BPF carbonate-dimethyl siloxane block polymers containing minor amounts of silicone has been improved to the point that resins of the desired silicone content and molecular weight can be closely reproduced. A number of simplifying changes have been made in the synthesis procedure during subsequent scale-up. Extrusion and injection molding of these resins into articles of good clarity and mechanical integrity have been mastered. Color varies from light straw to brownish-yellow currently. The two mechanisms of toughening are observed-stress whitening and shear flow the former is favored by lower silicone contents and complex stress configurations. Flame resistance is paramount among transparent thermoplastics containing no halogen. Limiting oxygen index is 48-51. Char formation is rapid and extensive. No dripping and little smoke are observed. A synergism between the organic and silicone blocks is suggested to be the cause of the superb flame resistance, which is better than in either corresponding homopolymer.
- Industrial Chemistry and Chemical Processing
- Polymer Chemistry
- Atomic and Molecular Physics and Spectroscopy