廖永霞，楊鳴波*
（四川大學高分子材料科學與工程學院；高分子材料工程國家重點實驗室，
四川 成都，610065，Email:yangmb@scu.edu.cn）
眾所周知，PE和PC為不相容的聚合物，但在DBTO(氧化二丁基錫)的存在下，PC和EVA（或EAA）在加工過程中發(fā)生酯交換反應原位生成接枝共聚物，可起到增容作用。該共聚物的生成通過選擇性抽提PC/EVA（或EAA）/DBTO重量比為50/50/0.05（0.5，1）的熔融混合體系，用紅外光譜分析可溶物和不溶物的結(jié)構(gòu)得到驗證。紅外光譜結(jié)果表明，該共聚物的譜峰對應PC和EVA（或EAA）序列的特征峰以及其他可能的接枝產(chǎn)物的特征峰。并且哈克轉(zhuǎn)矩流變儀的實驗數(shù)據(jù)表明，催化劑的加入大大縮短了反應時間，但同時也可能促進了EVA和EAA的交聯(lián)，混合體系隨混合時間的延長出現(xiàn)了轉(zhuǎn)矩抬升現(xiàn)象；且催化劑含量越大越明顯。當熔融條件能在加工過程中原位合成PC-g-EVA（或EAA）共聚物時，就會觀測到PE/PC/EVA（or EAA）/DBTO共混體系形態(tài)的重要改變。掃描電鏡分析顯示加入催化劑的體系PC分散相尺寸大大降低（F-3較F-2），而PC和PE兩相有了較好的界面粘結(jié)；尤其是先混合PC和EVA（or EAA），反應產(chǎn)物再與PE共混的體系（E-5），相界面極其模糊。同時加入EVA或EAA的體系熔體流動速率也大大降低，進一步證明了大分子產(chǎn)物的生成，酯交換反應確實發(fā)生了。同時我們還初步探討了形態(tài)改變后對性能的影響，值得關(guān)注的一點是當我們加入30份的EAA代替體系的部分PE，而PC和催化劑含量固定的前提下，體系的拉伸強度出現(xiàn)了顯著的上升現(xiàn)象，超過了30MPa；伴隨著電鏡圖也出現(xiàn)了微妙的變化，普遍呈現(xiàn)一種抱芯結(jié)構(gòu)（F-4），即分散相芯層含有第三相，這在其他的PE/PC/EVA（或EAA）體系的電鏡圖上并未發(fā)現(xiàn)。
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.
