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81.
82.
Synthesis of an asymmetric tadpole-shaped aliphatic copolyester consisting of a poly(-caprolactone) ring and two poly(l-lactide) tails was reported for the first time. First, a high molecular weight cyclic PCL macroinitiator (Mn = 31,000) was prepared by intramolecular photocross-linking of “living” chains. Polymerization of l-lactide was resumed by the tin dialkoxide containing macrocycles, thus making the targeted tadpole-shaped copolyester available. A preliminary investigation of the crystallization of these copolyesters was carried out by differential scanning calorimetry and polarized optical microscopy. 相似文献
83.
TP/LCP原位复合材料 总被引:1,自引:0,他引:1
陈延明 《现代塑料加工应用》1998,10(1):58-61
综述了以PP、PET、PC等几种常见的热塑性高聚物为基体的LCP(液晶共聚酯)原位复合材料,讨论了TP(热塑性高聚物)/LCP的结构与性能以及TP与LCP之间的相容性。 相似文献
84.
Yongjian Liu 《应用聚合物科学杂志》2001,82(14):3396-3401
A series of wholly aromatic thermotropic copolyesters based on 4‐hydroxybenzoic acid, hydroquinone, and 2,6‐naphthalene dicarboxylic acid were synthesized by direct melt polymerization with or without different added transesterification catalysts. Nine procedures for calculation of the intrinsic viscosities from a single viscosity measurement for polymer solutions, including a proposed one, were applied for the thermotropic copolyesters in 1,1,1,3,3,3‐hexafluoro‐2‐propanol at 30°C. Various forms of the Huggins and Kraemer equations, singly or combined, yielded intrinsic viscosities that were in good agreement with extrapolated values obtained in the usual manner from multipoint viscosity measurements over a wide range of concentrations. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3396–3401, 2001 相似文献
85.
The sequence distribution and the crystal structure of copolyesters synthesized from ethylene glycol, 1,3-propanediol, and dimethyl terephthalate with different molar volume ratios were investigated in this study. The triad sequence probabilities of ethylene/trimethylene terephthalate were characterized from the aromatic quaternary carbons by 13C NMR. The composition of the copolyesters was determined from the aromatic quaternary carbons by 13C NMR, and the methylene protons by 1H NMR. Results show that 1,3-propanediol reacted faster with terephthalic acid in copolyester polymerization than ethylene glycol. The difference in monomer reactivity is significant in the polymerization. Although the constitutional units revealed a random distribution in the molecular chain by 13C NMR, crystallites formed across the full range of ethylene glycol/1,3-propanediol composition by use of differential scanning calorimetry, a hot stage polarizing microscope, and a wide angle X-ray diffraction method. The WAXD deconvolution results show that the major constitutional repeating unit in the molecular chain dominates the crystal structure as a host crystal. The crystal structure was examined by a scanning electron microscope after a solvent etching. Photomicrographs show that the random distribution of the third constitutional unit in the molecular chain of copolyester significantly disturbs the host crystal formation and lamellar orientation. 相似文献
86.
《国际聚合物材料杂志》2012,61(7):366-383
Changes in opto-thermal and -mechanical properties of polyethylene terephthalate and glycol-modified polyethylene terephthalate (4 wt% of ethylene glycol) subjected to γ-irradiation at doses up to 30 Mrad and a dose rate of 138.8 rad/sec, were investigated by interferometry. Empirical formulae are suggested to correlate the opto-thermal and -mechanical properties of the γ-irradiated fibers with the applied dose. Microinterferograms and relationships between the parameters obtained are given for illustration. 相似文献
87.
Yunbo Chen Daniil Nozdriukhin Sandra Michel-Souzy Clemens Padberg Frederik R. Wurm Daniel Razansky Xosé Luís Deán-Ben Olga Koshkina 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(29):2370221
Optoacoustic (OA, photoacoustic) imaging synergistically combines rich optical contrast with the resolution of ultrasound within light-scattering biological tissues. Contrast agents have become essential to boost deep-tissue OA sensitivity and fully exploit the capabilities of state-of-the-art OA imaging systems, thus facilitating the clinical translation of this modality. Inorganic particles with sizes of several microns can also be individually localized and tracked, thus enabling new applications in drug delivery, microrobotics, or super-resolution imaging. However, significant concerns have been raised regarding the low bio-degradability and potential toxic effects of inorganic particles. Bio-based, biodegradable nano- and microcapsules consisting of an aqueous core with clinically-approved indocyanine green (ICG) and a cross-linked casein shell obtained in an inverse emulsion approach are introduced. The feasibility to provide contrast-enhanced in vivo OA imaging with nanocapsules as well as localizing and tracking individual larger microcapsules of 4–5 µm is demonstrated. All components of the developed capsules are safe for human use and the inverse emulsion approach is known to be compatible with a variety of shell materials and payloads. Hence, the enhanced OA imaging performance can be exploited in multiple biomedical studies and can open a route to clinical approval of agents detectable at a single-particle level. 相似文献
88.
热致性液晶共聚酯的流动诱导取向及织态结构 总被引:2,自引:0,他引:2
采用简易的熔融纺丝装置分别考察了拉伸,剪切流动以及加工温度对PET/PHB系液晶共聚酯取向发展的影响,对流动过程中的织态及其变化也进行了细致的研究,发现在拉伸流动中出现了宏观取向有序的织态结构,纤维达到较高的的取向度,而在剪切流动中保持局部取向有序织态,取向度较低;挤出温度对取向度和织态也有显著影响。 相似文献
89.
PBT/PET共聚酯是兼有PET和PBT优良特性的新材料。本文研究了共聚酯的合成条件。结果表明催化剂和反应温度对EG/BD与DMT的酯交换和共聚合反应有明显的影响,混合催化剂比单一催化剂效果好,Zn-Co-Ti催化体系对酯交换有较高的催化活性,缩聚催化荆以Sb-Ti体系为佳。共聚酯的色泽与反应温度、时间、催化剂种类及EG/BD的比例有关。在合适条件下,得到特性粘度为0.9以上的无着色的共聚酯。 相似文献
90.