NUCLEATION ACTION OF THERMOTROPIC LIQUID CRYSTAL POLYMERS IN THE BLENDS WITH PET

The present work concerns the crystallization of PET accelerated by addition of thermotropic liquid crystalline polymers (TLCP)based on two aromatic copolyesters: PHB/PET (60:40 ) and PHB/HDA/2,6-DNA /IPA ( 50:25 : 12.5 : 12.5 ). The investigation has been made by measurements of the cold-crystallization and melt-crystallization temperatures by DSC and of the changes of density and depolarizing light intensity during the isothermal process. In addition, the morphology of selectively etched surface of compressing pellets proved the presence of crystalline fibrillar structure, it can be supposed to have grown up from the micelle nucleus based on bundle of rigid TLCP chains.     

液晶聚芳醚酮/含甲基苯侧基聚芳醚酮共混体系的环带球晶

本文通过研究含氯侧基液晶聚芳醚酮/含甲基苯侧基聚芳醚酮共混体系(结晶/非晶)环带球晶的形态演变和发展过程; 利用选择性溶剂刻蚀方法确定共混体系环带球晶的相组成和相结构, 探讨了环带球晶的形成机理.     

生物可降解聚乳酸的改性及其应用研究进展

综述了近年来国内外关于生物可降解材料聚乳酸(PLA)通过共聚、共混、增塑和复合等方法得到聚乳酸改性材料的研究进展,以及对其在生物医学领域、纺织领域和包装领域中的应用作了广泛而深入的总结和评述,并预示了聚乳酸材料的研究开发前景。     

氧化石墨烯/聚合物复合质子交换膜研究进展

氧化石墨烯/聚合物复合质子交换膜(GO/Polymer blend PEM)是一种新型的质子交换膜,广泛应用于直接甲醇燃料电池(DMFC)中,已成为质子交换膜研究的热点之一。氧化石墨烯/聚合物复合质子交换膜具有较高的传导质子率、力学性能、阻醇性能和电池性能。本文综述了氧化石墨烯(GO)处理方法、氧化石墨烯/聚合物复合质子交换膜制备方法,氧化石墨烯/聚合物复合质子交换膜的质子传导、阻醇、离子交换容量和电池的性能,氧化石墨烯/聚合物复合质子交换膜质子传递机理及阻醇机理。     

Photodegradation of polycaprolactone/poly(vinyl chloride) blend

The photodegradation of a 1:1 w/w blend of polycaprolactone and poly(vinyl chloride) has been studied by following carbon dioxide emission during UV exposure. Similar measurements were performed for polycaprolactone and poly(vinyl chloride) homopolymers which were prepared and irradiated in the same way. It was found that the blend gave lower CO₂ emission than either of the two homopolymers, indicating that the interaction of the two components in the blend provided a beneficial reduction of photodegradation. It is therefore deduced that the detailed morphological characteristics of the blend have a controlling influence over the photo-oxidation.     

A study on the blending effect of polyvinyledene fluoride in the ionic transport mechanism of plasticized polyvinyl chloride + lithium perchlorate gel polymer electrolytes

The gel polymer electrolytes composed of the blend of polyvinylchloride (PVC) and polyvinylidene fluoride (PVdF) as host polymers, the mixture of ethylene carbonate (EC) and propylene carbonate (PC) as a plasticizer, and LiClO₄ as a salt was studied. An attempt was made to investigate the effect of PVdF in the plasticized PVC + LiClO₄ system in three blend ratios. The differential scanning calorimetry study confirms the formation of polymer–salt complex and miscibility of the PVC and PVdF. The X-ray diffraction results of plasticized PVC (S1, S2, S3) and PVdF-blended films (S4, S5, S6) were compared, in that an increase in PVC concentration decreases the degree of crystallinity for S1 and S3, respectively, but drastically increases for PVC (S2). The increase in PVC content has not accounted in the conductivity studies also noted. However, the blending effect of PVdF showed decreases in crystallinity homogeneously for (S6 > S5 > S4), which were reflected in ionic conductivity measurements. The surface morphology of the films were also studied by scanning electron microscope, and it corroborates the same. Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006.     

Temperature dependence of photoluminescence in MEH-PPV blend films

The temperature dependence of the optical properties in poly [2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) blending with 2-(4-biphenyl)-5-(4-tertbutylphenyl)-1,3,4-oxadiazole (PBD) has been investigated. The blending influence on the chain conformation and exciton energy migration in blend film is described. The PL emission from the pure and blend films are all blue shifted with increasing temperature. An addition of PBD in MEH-PPV films suppresses the relative intensity of 0-1 vibronic peaks at lower temperature. This phenomenon will not be promoted with increasing temperature, attributed to a temperature-dependent migration process of singlet excitons.     

Thermorheological properties of LLDPE/LDPE blends

The thermorheological behavior of a number of linear low-density polyethylene and low-density polyethylene (LLDPE/LDPE) blends was studied with emphasis on the effects of long chain branching. A Ziegler–Natta, LLDPE (LL3001.32) was blended with four LDPEs having distinctly different molecular weights. The weight fractions of the LDPEs used in the blends were 1, 5, 10, 20, 50, and 75%. Differential scanning calorimetry (DSC) analysis has shown that all blends exhibited more than one crystal type. At high LDPE weight fractions, apart from the two distinct peaks of the individual components, a third peak appears which indicates the existence of a third phase that is created from the co-crystallization of the two components. The linear viscoelastic characterization was performed, and mastercurves at 150 °C were constructed for all blends to check miscibility. In addition, Van Gurp Palmen, zero-shear viscosity vs composition, Cole–Cole, and the weighted relaxation spectra plots were constructed to check the thermorheological behavior of all blends. In general, good agreement is found among these various methods. The elongational behavior of the blends was studied using a uniaxial extensional rheometer, the SER universal testing platform from Xpansion Instruments. The blends exhibit strain-hardening behavior at high rates of deformation even at LDPE concentrations as low as 1%, which suggests the strong effect of branching added by the LDPE component.     

聚醚醚酮/聚醚醚酮酮共混体系的熔融和等温结晶行为

采用熔融共混方法制备了聚醚醚酮和聚醚醚酮酮的共混物,用DSC对共混物的熔融行为和等温结晶行为进行了研究.结果表明,共混物熔点随聚醚醚酮含量增加而降低,但与聚醚醚酮酮有相同的平衡熔点,二者共混没有改变其结晶的成核与生长机制.     

Biodegradation study of plasticised corn flour/poly(butylene succinate-co-butylene adipate) blends

Plasticised corn flour/poly(butylene succinate-co-butylene adipate) (PBSA) materials were prepared by extrusion and injection in order to study the impact of PBSA ratio on their physicochemical properties and biodegradability. Scanning electron microscopy observations showed that corn flour and PBSA are incompatible. Three types of morphology have been observed: (i) starch dispersed in a PBSA matrix, (ii) a “co-continuous-like” morphology of starch and PBSA, and (iii) PBSA dispersed in a starch matrix. As expected, the extent of plasticised corn flour starch hydrolysis by amylolytic enzymes decreased when the amount of PBSA increased. Addition of a lipase to hydrolyse PBSA ester bonds enhanced enzymatic hydrolysis of starch by amylolytic enzymes in materials where PBSA formed a continuous phase. This suggests that PBSA formed a barrier restricting the access of amylolytic enzymes to starch. This was consistent with aerobic and anaerobic biodegradation assays, which also showed lower biodegradability of materials containing a majority of PBSA.