Surface characterization of cellulose acetate propionate by inverse gas chromatography |
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Authors: | B Praveen Kumar S Ramanaiah T Madhusudana Reddy K S Reddy |
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Affiliation: | 1. Department of Chemistry, Sri Venkateswara University, Tirupati, 517 502, India
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Abstract: | The purpose of this paper is to study the surface energetics of the polymer excipient cellulose acetate propionate (CAP) in the solid form. The net retention volumes, V N, for n-alkanes and polar solutes have been measured in the temperature range 353.15–403.15 K by inverse gas chromatography. The dispersive surface free energy, $ \gamma_{\text{S}}^{\text{d}} $ , and Lewis acid–base parameters $ K_{\text{a}} $ and $ K_{\text{b}} $ , have been determined using V N values. The $ \gamma_{\text{S}}^{\text{d}} $ values are decreased linearly with increase of temperature. The $ \gamma_{\text{S}}^{\text{d}} $ value at 353.15 K is 24.50 ± 1.54 mJ/m2, and the temperature gradient was found to be ?0.287 mJ/m2/K1. The $ K_{\text{a}} $ and $ K_{\text{b}} $ values are 0.410 ± 0.021 and 1.708 ± 0.388, respectively, which suggest that the CAP solid surface contain relatively more basic sites. The K a and K b values of CAP are compared with the similar values obtained on the cellulose acetate butyrate solid surface. |
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