Nanostructure of Crystalline Polymer Blends and Polymer-Surfactant Complexs

• Main Authors: Ming-Siao Hsiao, 蕭明校
• Other Authors: Hsin-Lung Chen
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/28344497847536654529

碩士 === 國立清華大學 === 化學工程學系 === 87 === This thesis contains four parts. The first part investigated the morphological structure of Poly(ethylene terephthalate)/Poly(ether imide) Blends Induced by combined Crystallization and Liquid-Liquid Demixing, The size probed was between 5 and 50 nm. The second part studies the microstructure of self-assembled mesomorphic complexes of branched Poly(ethylenimine) and dodecylbenzenesulfonic acid. and the probed dimension is between 1 and 5 nm. The third part studies the nanoscopic morphological structure of the blends of polymers and polymer-surfactant complexes,The system is PEI(DBSA)0.5/PEI.The forth part evaluated the influence of polymer crystallization on the formation of ordered structure in polymer-surfactant complex.The binary blends of poly(ethylene terephthalate)(PET) and poly(ether imide)(PEI) were miscible in the melt but showed simultaneous crystallization and liquid-liquid demixing below the melting point. In our study the morphological structure induced by the crystallization and liquid-liquid demixing was probed by small angle x-ray scattering (SAXS).For the semicrystalline blends, the SAXS intensity profile was attributed to the sum of the contributed from crystalline and liquid-liquid demixing. The low-angular scattering was attributed to the electron density contrast between the "stack domains"LS domain) and the PEI-rich domains located outside the LS domains .The scattering profiles were deconvoluted by applying the Debye-Bueche model to calculate the scattering intensity associated with effect of liquid-liquid demixing. The morphological parameters, such as crystalline layer thickness, amorphous layer thickness, and long period, were subsequently determined from the intensity profile obtained by subtracting the Debye-Bueche contribution from the overall scattering pattern. We found that the crystalline layer was unperturbed upon blending with PEI. A larger amorphous layer thickness was indentified in the blends, when WPEI<0.2, some PEI was incorporated inside the interlamellar regions after crystallization. When 0.2<WPEI<0.8, the amorphous layer thickness was relatively independent of the overall blend composition. This means that PEI was pull out of the interlamellar region induced by the driving force of liquid-liquid demixing. From the data and discussion, we found the morphological structure of PET/PEI blends is controlled by the simultaneous occurrence of liquid-liquid demixing and crystallization.The second part investigated the supramolecular structure and thermal properties of the complexes of a highly branched poly-(ethyleneimine)(PEI) with dodecylbenzene sulfonic acid (DBSA) .POM and SAXS revealed the presences of mesomorphic phases and microphase-separated lamellar morphology in the complexes. The glass transition temperature of polymer layers was raised by the complexation because of the stiffening of polymer chains. Complexation with DBSA enhanced the thermal stability of PEI, where the thermal decomposition temperature can be raised by as many as 50℃.The third part studied the microstructure of the PEI(DBSA)0.5/PEI blend system. The blends were miscible. and possessed order nanoscale lamellar structure at low PEI composition(≦30wt%) . Upon blends with PEI, The size of the lamellar long period was increased and the order of the lamellar structure was disturbed. It was suggested that PEI molecules were "#34 in the polymer layer of PEI(DBSA)0.5 complexes and affected the microstructure and thermal behavior of the original complex.The forth part study focused on the effect of polymer crystallization behavior on the structure of polymer-surfactant complex. The system is linear poly(ethylenimine)(DBSA) complex. LPEI(DBSA)x complex displayed no crystallinity and still possessed highly ordered lamellar structure. The destruction of hydrogen bonding between LPEI molecules and or between LPEI and water in the complexation of LPEI-DBSA may be the cause for the disappearance of LPEI crystallization. From the detection of WAXS study, the polar-nonpolar repulsion is the main reason of affecting polymer conformation. By comparing the glass transition temperature of branched PEI(DBSA)x with that of LPEI(DBSA)x, we found that the degree of branching of polymer is also a factor that influences the Tg.