廖永霞，杨鸣波*
（四川大学高分子材料科学与工程学院；高分子材料工程国家重点实验室，
四川 成都，610065，Email:yangmb@scu.edu.cn）
众所周知，PE和PC为不相容的聚合物，但在DBTO(氧化二丁基锡)的存在下，PC和EVA（或EAA）在加工过程中发生酯交换反应原位生成接枝共聚物，可起到增容作用。该共聚物的生成通过选择性抽提PC/EVA（或EAA）/DBTO重量比为50/50/0.05（0.5，1）的熔融混合体系，用红外光谱分析可溶物和不溶物的结构得到验证。红外光谱结果表明，该共聚物的谱峰对应PC和EVA（或EAA）序列的特征峰以及其他可能的接枝产物的特征峰。并且哈克转矩流变仪的实验数据表明，催化剂的加入大大缩短了反应时间，但同时也可能促进了EVA和EAA的交联，混合体系随混合时间的延长出现了转矩抬升现象；且催化剂含量越大越明显。当熔融条件能在加工过程中原位合成PC-g-EVA（或EAA）共聚物时，就会观测到PE/PC/EVA（or EAA）/DBTO共混体系形态的重要改变。扫描电镜分析显示加入催化剂的体系PC分散相尺寸大大降低（F-3较F-2），而PC和PE两相有了较好的界面粘结；尤其是先混合PC和EVA（or EAA），反应产物再与PE共混的体系（E-5），相界面极其模糊。同时加入EVA或EAA的体系熔体流动速率也大大降低，进一步证明了大分子产物的生成，酯交换反应确实发生了。同时我们还初步探讨了形态改变后对性能的影响，值得关注的一点是当我们加入30份的EAA代替体系的部分PE，而PC和催化剂含量固定的前提下，体系的拉伸强度出现了显著的上升现象，超过了30MPa；伴随着电镜图也出现了微妙的变化，普遍呈现一种抱芯结构（F-4），即分散相芯层含有第三相，这在其他的PE/PC/EVA（或EAA）体系的电镜图上并未发现。
Compatibilizing Polycarbonate-Polyethylene Blends by Transesterification during Processing Operations in the Presence of Dibutyltin Oxide
Yongxia Liao，Mingbo Yang*
(College of Polymer Science and Engineering, Key Laboratory of Polymer Materials Engineering,
Sichuan University, Chengdu, Sichuan, 610065, China, Email: yangmb@scu.edu.cn )Abstract: PE and PC are known to be incompatible polymers. A grafted copolymer PC-EVA or PC-EAA has been generated as a compatibilizer in situ during the processing operation by redistributive transesterification between PC and EVA(or EAA) in the presence of dibutyltin oxide（DBTO）.This copolymer has been evidenced by a FTIR study of the soluble and the insoluble fractions after selective extractions from PC/EVA（or EAA）/DBTO（50/50/0.05 or 0.5、1% in weight）blend which is processed in the melt. This copolymer presents all the resonances of PC and EVA（or EAA）sequences and some others that have been assigned specifically to grafting. And it can be concluded by means of Haake Torque Rheometer that reaction time is reduced dramatically in the presence of DBTO，whereas it may accelerate the crosslink of EVA or EAA，especially when the content of catalyst is greater. On the other hand，when the melt condition enable synthesis of the grafted copolymer PC-EVA（or EAA）in situ during processing operations，important changes in the morphology of PE/PC/EVA（or EAA）/DBTO blends are
observed. SEM analysis shows a decrease of PC particle size and a good adhesion between the PC and PE phase. If PC and EVA（or EAA）are mixed first before added to PE，it becomes more difficult to distinguish the two phases，compared to that all are blended simultaneously. Further more，the drop in MFR of PE/PC/EVA（or EAA）/DBTO proved the macromolecular copolymer generated authentically during processing operations. It suggests that the reaction really takes place at the interface. What’s more，pilot studies are in progress to evaluate the influence of this copolymer，located at the interface，on the mechanical and rheological properties for PE/PC blends. We are amazed at remarkable increase in tensile strength，even beyond 30 MPa，when 30% EAA is added to the blend to substitute for PE，while other components keep invariable. Along with it there are delicate changes in the morphology. The structure of “core in core” presents at large in the high-tensile-strength group of blends, viz. there is a third phase in the core of dispersed phase, which is not observed in the others.
