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  • 1
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Novel poly(etheraroyl-co-terephthal)hydrazides with liquid crystalline (LC) behaviour, synthesized by solution polycondensation followed by non-solvent coagulation in water, have been characterized by means of Fourier Transform infrared (FT-i.r.), differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS) techniques. DSC thermograms and WAXS intensity profiles of “as polymerized” and coagulated homo- and copolymers are strongly dependent upon the molecular structure and constitution of the polymers: the poly(etheraroyl-hydrazide) homopolymer shows an LC behaviour and such a characteristic is maintained in copolymers with low content of terephthaloyldichloride comonomer, while a further increase in comonomer content attenuates this LC attitude. Annealing treatments on “as polymerized” and coagulated copolymers are able to transform the LC phase “metastable at room temperature” into crystalline and/or amorphous phases.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 34 (1988), S. 441-450 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Der Einfluß einer elastomeren Zweitphase auf die Kinetik der Aushärtung und der Gelierungszeit eines als Standard dienenden ungesättigten Polyesterharzes wurden mittels isothermer und dynamischer DSC untersucht. Insbesondere wurden zwei unterschiedliche Gummis (hydroxylendständiges und isocyanatendständiges Polybutadien) untersucht, die die Kinetik der Aushärtung des Polyasterharzes in unterschiedlicher Weise beeinflussen: hydroxylendständiges Polybutadien verringert, isocyanatendständiges dagegen erhöht die Reaktionsgeschwindigkeit.
    Abstract: Резюме Используя изотермич ескую и динамическую ДСК, а также термопару, изу чено влияние эластомерно й вторичной фазы на ки нетику реакции отверждения и время гелеобразова ния обычной ненасыщенно й полиэфирной смолы. Д обавка полибутадиенового каучука с различными концевыми группами (гидроксильной и изоц ианатной) оказывает различное влияние на полную реакцию отвер ждения полиэфирной смолы: ка учук с концевой гидроксильной групп ой понижает скорость реакции, а каучук с изотиоциана тной группой — увелич ивает.
    Notes: Abstract The influence of an elastomeric second-phase on the kinetics of the curing reaction and the gel-time of a standard unsaturated polyester resin, by using the isothermal and dynamic techniques of differential scanning calorimetry (DSC) and a thermocouple was investigated. In particular we examined two different rubbers (polybutadiene hydroxyl-terminated and polybutadiene isocyanate-terminated), that, in the presence of polyester resins, affect the overall curing reaction kinetics in two ways: the former reduces the rate of reaction whilst the latter increases it.
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  • 3
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract New formulations of rubber toughening agents for difunctional and tetrafunctional commercial epoxies are attempted, on the basis of their increased thermal stability compared with classical unsaturated elastomers. Quite satisfactory results are obtained where a block copolymer of polydimethylsiloxane and polyoxyethylene elastomer or a functionalized poly (1 -butene) in difunctional epoxy are used. On the other hand, poor results are obtained when the same elastomers are employed in tetrafunctional epoxies. A tentative explanation is given on the basis of the different networks obtained in the two matrix systems.
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  • 4
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract New formulations of rubber toughening agents for difunctional and tetrafunctional commercial epoxies are attempted, on the basis of their increased thermal stability compared with classical unsaturated elastomers. Quite satisfactory results are obtained where a block copolymer of polydimethylsiloxane and polyoxyethylene elastomer or a functionalized poly (1 -butene) in difunctional epoxy are used. On the other hand, poor results are obtained when the same elastomers are employed in tetrafunctional epoxies. A tentative explanation is given on the basis of the different networks obtained in the two matrix systems.
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  • 5
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recycling of polyethyleneterephthalate (PET) bottles for soft drinks is accomplished by depolymerization through glycolysis. Obtained intermediates are reacted with mixtures of saturated and unsaturated acids to obtain unsaturated polyesters (UP) suitable for use as a matrix for fibre-reinforced thermosetting composites. The influence of chemical structure of glycols on the chemo-rheological behaviour of resins, has been verified. By using di-ethylene glycol, the behaviour of the resulting UP closely resembles that of UP obtained from virgin monomers. Moreover, composite sheets containing UP developed in the present research, show enhanced toughness if compared with the analogous composite made of virgin UP resin.
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  • 6
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Blends of poly-ε-caproIactone (PCL) and poly-β-hydroxybutyrate (PHB) were prepared by mixing the two polymers in the presence of dicumylperoxide (DCPO) in solution of chlorobenzene. Similarly blends were obtained by mixing the two polymers with no peroxide added. The blends were prepared in a break of composition, from 85% wt PHB/15% wt PCL to 15% wt PHB/85% wt PCL, respectively. Also pure polymers were reacted with DCPO in the same way of the blends. Thermal (DSC), spectroscopic, mechanical (tensile tests) and morphological SEM)analyses were performed on the blends and on the pure polymers. Significant differences were found in the chemical-physical characteristics of the blends with and without peroxide.
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  • 7
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Modifizierung von Polybutylenterephthalat mit Gummi wurde durch Zugabe geeignet funktionalisierter Copolymerer aus Ethylen und Propylen (EPR) und gleichzeitiger Hochtemperaturpolykondensation von 1,4-Butandiol mit Dimethylterephthalat erreicht. Die Schlagzähigkeit der Blends, die reines oder mit Ester- oder Hydroxylgruppen modifiziertes EPR enthielten, wurde mit Hilfe von Schlagbiegeversuchen nach Charpy bei verschiedenen Temperaturen bestimmt. Die morphologischen Merkmale der Bruchflächen wurden auch untersucht. Es wurde ein Versuch unternommen, die Morphologie dieser Flächen mit den Bruchanalysenergebnissen zu korrelieren.
    Notes: Rubber modification of polybutyleneterephthalate was accomplished by the addition of suitable functionalized ethylene-propylene copolymers (EPR) concurrently with the high temperature polycondensation of 1,4-butanediol and dimethylterephthalate.The impact properties of blends obtained with plain EPR, with ester or hydroxyl groups modified EPR were analyzed by Charpy tests performed at different temperatures with a Ceast fracture pendulum. The morphological features of fracture surfaces have also been investigated. An attempt has been made to correlate the morphology of the surfaces with the fracture analysis results.
    Additional Material: 2 Ill.
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  • 8
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Blends aus Poly-ε-caprolacton (PCL) und Polymethylmethacrylat (PMMA) wurden durch Polymerisation von Methylmethacrylat in Gegenwart von PCL hergestellt. Die thermeischen, morphologischen, dynamisch-mechanischen und mechanischen Eigenschaften der Blends wurden ermittelt. Zum Vergleich wurden Blends durch mechanisches Mischen von PCL-und PMMA-Homopolymerschmelzen hergestellt und charakterisiert. Die nach beidenMethoden hergestellten Blends unterscheiden sich wesentlich in der phasenstrukturund den mechanischen eigenschafte, was wahrscheinlich auf die bildung von gepfropften Anteilen bei der erstgenannten Methode zuräuckgefäuhrt werden kann.
    Notes: Blends of poly-ε-caprolactone (PCL) and poly(methylmethacrylate) (PMMA) were prepared by a reactive method and characterized by thermal, morphological, dynamic mechanical and mechanical analyses. For comparison, “mechanical” blends, obtained by melt-mixing of preformed polymers, have been prepared and characterized. The two series of blends are different in phase structure and in mechanical tensile properties, probably due to the formation of grafted species during reactive blending.
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 214 (1994), S. 101-113 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyhydrazid/Polyamid-Blends (PEHZ12/PA6) wurden durch Niedrigtemperatur-Polykondensation von 4,4′-Dichlorformyl-α,ω-diphenoxydodecan und Terephthaloyldihydrazid (TDH) zu Poly(etheraroylhydrazid) in Gegenwart von Polyamid 6 synthetisiert. Die DSC-Analysen lassen vermuten, daß die zwei Polymerkomponenten nicht wechselwirken. Bei der Extraktion des PA6-Anteils der Blends mit Ameisensäure zeigt die Charakterisierung des PEHZ12-Extraktionsrückstands aber, daß zumindest bei bestimmten Zusammensetzungen Wechselwirkungen zwischen den Komponenten auftreten. Modellreaktionen erlauben die Annahme, daß die PEHZ12-Polymerisation zwischen den Amino-Endgruppen des PA6 und den wachsenden PEHZ12-Polymerketten abläuft.
    Notes: Poly(etheraroylhydrazide) is synthesized in the presence of PA6 by means of low-temperature condensation polymerization of 4,4′-dichloroformyl-α,ω-diphenoxydodecane with terephthaloyl dihydrazide (TDH) in order to prepare polyhydrazide/poly-amide 6 (PEHZ12/PA6) blends. The thermal analysis of the blends by DSC seems to indicate that the two polymers are not interacting. Nevertheless, when the blends are subjected to an extraction process with formic acid in order to remove the PA6, the characterization of the residual PEHZ12 reveales that some interactions do occur between the constituent polymers, at least for selected compositions. Model experiments permit to hypothesize that the polymerization of PEHZ12 proceeds with a chemical interaction between amino end groups of PA6 and growing PEHZ12 chains.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 1643-1651 
    ISSN: 0887-6266
    Keywords: polyoxadiazoles ; structural analysis ; cristallinity behavior ; cyclodehydration reaction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new series of poly(ether-alkyl)oxadiazoles of general formula: with m = 3, 4, and 5 has been obtained from the corresponding polyhydrazides through thermal cyclization reaction. The polymers were characterized by infrared spectroscopy, differential scanning calorimetry, wide-angle x-ray analysis, and optical microscopy. The polymers were crystalline, with a crystalline texture and structural parameters strongly dependent on the value of m. The Tm's and Tg's value decreased with increasing number of CH2. © 1994 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
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