Porter S C, Ridgway K
J Pharm Pharmacol. 1983 Jun;35(6):341-4. doi: 10.1111/j.2042-7158.1983.tb02953.x.
When submitted to X-ray crystallography, two enteric coating polymers, cellulose acetate phthalate and polyvinyl acetate phthalate, were found to be essentially amorphous in structure. Values for the glass transition temperature, Tg, of each polymer have been obtained using both a surface microindentation technique and differential scanning calorimetry. The effect on this parameter of an increasing concentration of a plasticizer, diethyl phthalate, has also been determined. Measured values for Tg have been compared with predicted values obtained using a suitable mixture-rule model: the surface microindentation technique values were closer to the predicted.
当对两种肠溶包衣聚合物——邻苯二甲酸醋酸纤维素和邻苯二甲酸聚醋酸乙烯酯进行X射线晶体学分析时，发现它们在结构上基本为非晶态。已使用表面微压痕技术和差示扫描量热法获得了每种聚合物的玻璃化转变温度（Tg）值。还确定了增塑剂邻苯二甲酸二乙酯浓度增加对该参数的影响。已将测量得到的Tg值与使用合适的混合规则模型获得的预测值进行了比较：表面微压痕技术得到的值更接近预测值。
