| Part I. Flammability of polymers is characteristic of a number of factors, such as polymer composition and polymer structure, bond strength, char yield, nature of pyrolysis products, exposure environment, etc. In order to assess the flammability of polymers, 44 polymers based on phenolphthalein and related compounds are prepared and evaluated. The reasons for selecting such polymers are based on the particular nature of their aromatic rings which appears to result in high char formation.; The accumulated data indicate much improved fire resistance for all phenolphthalein related polycarbonates and polyesters, compared with commercial bisphenol-A polymers and emphasizes the importance of polymer composition and polymer structure in affecting the flammability of a polymer. Polycarbonates and polyamides usually show higher oxygen indices than the corresponding polyesters of the related structures. This indicates that the nature of the pyrolysis products has a measurable effect on the flammability of a specific polymer. Among many factors, polycarbonates should release more CO(,2) from the break-down of the carbonate group, and polyamides should produce relatively nonflammable nitrogen-containing products, thus accounting in part, for these results.; Analysis of the phenolphthalein and bisphenol-A copolycarbonates reveals a linear correlation between oxygen index (OI) and char yield (Y): OI = 0.34Y + 19.6 which can be compared with the empirical equation: OI = 0.4Y + 17.5 proposed by D. W. Van Krevelen for other polymers. Analysis also suggests that no chemical interaction occurs between the two comonomers during pyrolysis leading to neither enhanced char yield nor enhanced oxygen index. Study of 4,5,6,7-tetrabromophenolphthalein and phenolphthalein copolycarbonates shows that some enhancement of char yield does occur and that the lower the char yield, the higher is the oxygen index indicating the predominence of a vapor phase bromine effect over that related to char. Study of 4,5,6,7-tetrabromophenolphthalein and bisphenol-A copolycarbonates is interpreted on the basis of two factors--that is, the char effect which predominates over the vapor phase radical scavenging effect at lower bromine content, while at higher bromine content the reverse order is observed.; Part II. Phenolphthalein polycarbonate undergoes random scission and crosslinking during thermal degradation. Kinetic parameters are determined from the dynamic TGA thermograms. During the early stages of degradation, the measured reaction order is nearly 1, suggesting a random chain scission mechanism. The measured activation energy is 42.6 kcal/mole, compared with 41.2 kcal/mole obtained from isothermal aging. The Arrhenius pre-exponential constant is found to be 3.09 x 10('11) min('-1). Below 80% weight residue, the plot of % W against 1/T reveals that complicated reactions with different activation energies occur simultaneously, resulting in a final overlap of curves for different heating rates indicative of crosslinking and a lower pre-exponential constant. The reaction order changes and keeps increasing at the latter stages of degradation.; Pyrolysis of this polymer is performed at 350(DEGREES)C under vacuum, followed by GC-MASS spectroscopic identification of products. The pyrolysis products detected are CO(,2), CO, O(,2), H(,2)O, phenol, fluorenone, diphenyl carbonate, xanthone, anthraquinone, 2-hydroxyanthraquinone, 2-benzoxyanthraquinone, phenolphthalein, diphenyl peroxide and phenyl hydroperoxide. Functional group changes are examined with FT-IR in a continuously evacuated system. Lactone, carbonate and aromatic absorptions decrease during degradation. Increasing absorptions at 1739, 1728, 1280-1200 and 1138-1075 cm('-1) are believed to be a result of two different aromatic ester crosslinkages between chains. Based on the experimental evidence, mechanisms of random scission and crosslinking are proposed. |
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