Effect of Morphology on the dielectric properties of a segmented copolyester
TL;DR: In this article, the dielectric relaxation has been investigated for a segmented copolyester film containing 76% hard segments (PBT) and 24% soft tetramethylene oxide segments grown under different conditions.
About: This article is published in European Polymer Journal.The article was published on 1991-01-01. It has received 11 citations till now. The article focuses on the topics: Copolyester & Dielectric.
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TL;DR: In this article, the electrical properties of polyester elastomer filled with various metallic and ferrite fillers have been investigated as a function of temperature, frequency and filler concentration.
Abstract: The electrical properties, namely d.c. and a.c. conductivity, of polyester elastomer filled with various metallic and ferrite fillers have been investigated as a function of temperature, frequency and filler concentration. The temperature dependence of resistivity exhibited two regions of low and high activation energy (ΔE). The value of ΔE the lower temperature region (I) decreased while in the higher temperature region (II) it increased with the increase of work function of the metal used. Only in the case of ferrite-filled composites could a positive temperature coefficient of resistance be observed. The frequency dependence of conductivity revealed that there is a very large intergranular capacitance which was even more in the case of ferrite-filled samples than in metal-filled ones. The various results have been explained on the basis of Schottky barrier formation and the depletion regions formed near the polymer-metal interface.
37 citations
TL;DR: In this paper, thermoplastic polyester elastomer (TPEE) blends with poly(butylene terephthalate) (PBT) were prepared by melt compounding for the phase morphology and mechanical property studies.
24 citations
TL;DR: In this paper, the crystallization behavior of thermoplastic polyester elastomer (TPEE) with nanosilica as the nucleating agent was studied and the results reveal that all types of nanosilicas have evident nucleating effects, leading to a remarkable increase of the crystallisation temperature of TPEE even by about 30 °C.
Abstract: Crystallization control of the hard polyester segments is an important way to design the final properties of a thermoplastic polyester elastomer (TPEE). In this work, the crystallization behavior of TPEE with nanosilica as the nucleating agent was studied. Three kinds of nanosilica with various sizes and surface treatments were chosen for nucleation design. The results reveal that all types of nanosilicas have evident nucleating effects, leading to a remarkable increase of the crystallization temperature of TPEE even by about 30 °C. However, the overall crystallization process is highly dependent on the particle size and surface treatment of silica because it is closely related to the nucleation ability of the particles and alteration of the system viscosities. The crystallization temperature of TPEE is more sensitive to the surface treatment of silica, while its crystallization rate shows a higher dependence on the particle size of silica. This work provides a facile way to well tailor crystallization of...
20 citations
TL;DR: In this paper, nano-alumina was used as a reinforcing agent in polyvinyl chloride (PVC)/thermoplastic polyester elastomer (Hytrel) blend system.
Abstract: Poly(vinyl chloride) (PVC)/thermoplastic polyester elastomer (Hytrel) blend system prepared in 50/50 composition was found to have the highest possible percentage elongation-at-break. This is due to better molecular compatibility between the two; however, they had lower strength and modulus values. In order to improve the strength and modulus property, alumina nano-particles were added as a reinforcing agent in concentrations as 1, 3, 5, and 7 phr in the blend system. The prepared nanocomposites were characterized for mechanical, thermal, rheological, morphological, and electrical properties. The 5-phr nano-alumina loaded PVC/Hytrel blend had optimal improvement in its strength values, but above that concentration nano-alumina started forming aggregates as was apparent from scanning electron microscopy (SEM) analysis. SEM images showed uniform distribution of nano-alumina in both PVC and Hytrel phases of the blend. Tensile strength and modulus were found to have increased by about 20 and 97 %, respectively, whereas elongation at maximum load decreased by 50 %, indicating the effect of nano-alumina as a reinforcing agent in the PVC/Hytrel system. The glass transition temperature, onset degradation temperature, viscosity, surface resistivity and volume resistivity increased, whereas degradation weight loss (%) decreased with increase in nano-alumina concentration in PVC/Hytrel blend system. No chemical interaction happened between PVC, Hytrel or alumina nano-particles, as proved by FTIR analysis.
13 citations
Cites methods from "Effect of Morphology on the dielect..."
...Mechanical blending of Hytrel with PVC provides improved characteristics of physical/processing properties and optimum cost performance [6, 7]....
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TL;DR: In this paper, the authors used thermally stimulated currents and a.c. dielectric spectroscopy to study poly(butylene terephthalate) (PBT) and blends of PBT with segmented copoly(ester-ether) elastomers.
12 citations
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127 citations
TL;DR: The use of polymeric compatibilization additives to polymer blends has shown promise as a method to improve mechanical compatibility in phase-separated blends, and will be expected to be the subject of future research programs as discussed by the authors.
Abstract: In the past decade, polymer blend technology has achieved an important position in the field of polymer science. With increased academic and industrial research interest, the application of polymer blend technology to commercial utility has grown significantly. This review on the applications of polymer blends will cover the major commercial blends in the categories of styrene-based polymer blends, poly(vinyl chloride) blends, polyacrylate blends, polyester and polycarbonate blends, polyolefin blends, elastomer blends, polyelectrolyte complexes, and interpenetrating polymer networks. New developments in polymer blend applications will be discussed in more detail. These systems include linear low-density polyethylene blends with either low- or high-density polyethylene, styrenemaleic anhydride terpolymer/ABS (acrylonitrile-butadiene-styrene) blends, polycarbonate/poly(butylene tetephthalate) blends, new PPO/polystyrene blends, and tetramethyl bisphenol A polycarbonate/impact polystyrene blends. Areas for future research to enhance the potential for polymer blend applications will be presented. The need for improved methods for predicting miscibility in polymer blends is discussed. Weldline strength is a major property deficiency of two-phase systems (even those with mechanical compatibility), and future research effort appears warranted to resolve this deficiency. The use of polymeric compatibilization additives to polymer blends has shown promise as a method to improve mechanical compatibility in phase-separated blends, and will be expected to be the subject of future research programs. Finally, the reuse of polymer scrap is discussed as a future application area for polymer blends. Unique applications recently proposed for polymer blends include immobilization of enzymes, permselective membranes, reverse osmosis membranes, selective ion-exchange systems, and medical applications using polyelectrolyte complexes.
125 citations
TL;DR: The molecular and crystal structure of polytetrahydrofuran has been determined by X-ray diffraction analysis as discussed by the authors, and the infrared dichroism and pleochroism were measured, and the tentative assignments for the infrared absorption bands were given and discussed.
Abstract: The molecular and crystal structure of polytetrahydrofuran has been determined by X-ray diffraction analysis. The unit cell dimensions are a = 5.48, b = 8.73, c (fiber axis) = 12.07 A., and β = 134.2°. The space group is C2/c—C. Two molecular chains pass through the unit cell. The skeleton of the molecular chain has a planar zig-zag conformation and the zig-zag plane is parallel to the (100)-plane.
The infrared dichroism and pleochroism were measured, and the tentative assignments for the infrared absorption bands were given and discussed.
Molekulare Struktur und Kristallstruktur von Polytetrahydrofuran wurden durch eine Rontgenbeugungsanalyse bestimmt. Die Elementarzelle besitzt die Abmessungen a = 5,48, b = 8,73, c (Faserachse) = 12,07 A und β = 134,2°. Die Raumgruppe ist C2/c—C62h. Zwei Molekulketten durchlaufen die Elementarzelle. Die Ketten liegen in einer ebenen Zick-zack-Konformation vor; die dadurch definierte Ebene fallt mit der kristallographischen (100)-Ebene zusammen.
Der Infrarot-Dichroismus und -Pleochroismus wurden gemessen und eine versuchsweise Zuordnung der Absorptionsbanden angegeben und diskutiert.
79 citations