不同形态聚对苯二甲酸乙二醇酯对醇解效率的影响

以二甘醇(DEG)为醇解剂、无水氯化亚锡(SnCl2)为催化剂,采用一步进料和分步进料醇解法,研究了聚对苯二甲酸乙二醇酯(PET)瓶片、PET粒料和PET纤维的醇解反应。通过扫描电镜、差示扫描量热分析、热重分析、红外光谱、核磁共振等方法表征了不同形态PET材料及其醇解产物的结构与热性能。结果表明,PET材料化学结构不会因为它的形态发生变化,但熔点和结晶度有明显的不同,其中PET纤维的熔点(253℃)和结晶度(43.44%)均高于PET瓶片和PET粒料。当醇解温度为220℃、反应为180 min时,一步进料醇解法的PET材料的醇解率依次为瓶片粒料纤维(依次为98.8%,98.8%,80.8%);当醇解温度为220℃、反应时间为90 min时,分步进料醇解法的PET瓶片和粒料的醇解率均达到100%、纤维的醇解率达到92.5%;一步进料醇解法的醇解率依次为瓶片42.1%、粒料38.5%、纤维28.0%,分别提高了57.9%,61.5%和64.5%。文中研发的分步进料醇解法技术可以使PET材料醇解反应时间缩短1/2,且PET纤维的醇解率有明显提升。

Optimization of genistein solubilization byκ-carrageenan hydrogel using response surface methodology

κ-Carrageenan was explored to improve genistein solubility by matrix retention.The corresponding maximum value in the efficiency of retention(Re)(50.48 mg/100 mg)was achieved when variables were set as:pH 4.76,temperature 52.12◦C and genistein concentration 0.27 mg/mL.The coefficient of determination(R2)of the response surface regression model presented in this study was 0.9848.The evidences from XRD,DSC and FT-IR attested the amorphous form of genistein in hydrogel matrix.Importantly,the solubility of genistein in hydrogel amorphous form(16.84–34.42g/mL)was much higher than that of its free crystalline form(1.89–6.09g/mL)over 30–90◦C.©2013 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.