| Abstract
| - Network polyesters were prepared from1,1,1-trimethylolethane (Ye), 1,1,1-trimethylolpropane (Yp), 1,2,3,4-butanetetrol (Xe), and d-glucitol (Zs) with aliphatic dicarboxylic acids containing differentnumbers of methylene groups (HOOC(CH2)n-2COOH, n =4, 6−14, 16, and 20). Prepolymers preparedby melt polycondensation were cast from dimethylformamide solution and postpolymerized at 230 °C for4 h to form a network. The resultant films were transparent, flexible, and insoluble in organic solvents.The network polyesters obtained were characterized by infrared absorption spectra, wide-angle X-raydiffraction analysis, density measurement, thermomechanical analysis, differential scanning calorimetry,and tensile test. The enzymatic degradation was estimated by the weight loss of the network polyesterfilms in a buffer solution with lipase enzymes at 37 °C. The enzymatic degradation for Yen films wascompared with that for the network polyester films of glycerol (Yg) or pentaerithritol (Xp) with variousaliphatic dicarboxylic acids reported earlier., After the incubation in Rhizopus delemar lipase solutionfor 2 days, the weight loss was hardly observed for Ye4−7, while it increased drastically for Ye8−13(13−15 g/m2) and then decreased gradually for Ye14−20. Other lipases of porcine pancreas andPsedomonas cepacia hardly degraded Yen films. The degradation rate for 10 series films was decreasedas follows:Yg10 >Ye10 > Yp10 = Xe10 > Xp10 > Zs10, corresponding to the increase in the number ofhydroxyl groups in the polyhydric alcohols.
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