摘要:

AbstractThe photocopolymerization of ethyleneglycol dimethacrylate (EGDMA) with methylmethacrylate (MMA) containing benzoin methyl ether (BME) as initiator was carried out in a glass tube to fabricate a light‐focusing plastic rod (radius Rp) with a parabolic refractive index distribution (distribution constant A) in the region near the center axis (radius Rc). The dependence of A and Rc/Rpon MMA/EGDMA feed ratio, influence of BME concentration on the refractive index distribution, and the reproducibilities of the photopolymerizations were investigated. The Rc/Rpincreased with the feed ratio used under BME = 1.0 wt.‐% at velocity of UV lamp V = 0.58 mm/min. On the other hand, Rc/Rpincreased with the feed ratio to 0.2 and then decreased remarkably with the feed ratio in the range of 0.2–0.25 with BME = 0.6 wt.‐% at V = 0.735 mm/min. Plastic rods fabricated in the investigation using photopolymerization have lens characteristics and good reproducib

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740101

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractDer Zusammenhang zwischen der Molekularstruktur eines linearen teilkristallinen Polymeren (HDPE) und seiner Dauerfestigkeit wurde untersucht. Durch die Untersuchung einer größeren Zahl von HDPE‐Proben mit unterschiedlichem Molekulargewicht konnte ein Zusammenhang zwischen der Lebensdauer und dem Viskositätsmittel des Molekulargewichts gefunden werden, der eine quantitative Voraussage der Lebensdauer ermög

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740102

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractMonofilaments possessing various degrees of birefringence were obtained by changing the drawing rate, the molten polymer temperature, and the molecular weight of polystyrene (PS) and poly(methyl methacrylate) (PMMA). The “brittle‐toductile” transition point of optically pure PS was found in the range of birefringences of −0.6 · 10−3to −2.6 · 10−3. Both the height and position of this point are influenced by M̄w, molecular weight distribution, and polymer melt temperature. The birefringence of PS is higher by two orders of magnitude than that of PMMA in which this transition point has not been observed. The mechanical and optical properties depend not only on the average amount of orientation characterized by the birefringence but on what portion of the relaxation spectrum of the polymer is preferentially oriented. During the drawing of PS and PMMA monofilaments crazes are formed in the centre of the fibers and do not r

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740103

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractDie Temperaturabhängigkeit der Ammoniak‐Diffusion in 14 transparenten filmbildenden Polymeren wurde zwischen 15 und 90°C mit Hilfe einer neuen absorptionsspektroskopischen Methode untersucht. Eine lineare Freie‐Energie‐Beziehung zwischen der Aktivierungsenergie der Diffusion (ED) und dem präexponentiellen Faktor der Arrhenius‐Gleichung (DO) entspricht dem Verhalten permanenter Gase im Glaszustand der Polymeren, die NH3‐Diffusionskoeffizienten sind jedoch im Mittel etwa eine Größenordnung kleiner. Wie ein Vergleich der Aktivierungsenergien für die Diffusion von Ammoniak und Sauerstoff in drei Polymeren zeigt, ist dafür nicht ein größerer effektiver Van‐der‐Waals‐Radius des NH3verantwortlich, sondern die verminderte Aktivierungsentropi

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740104

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe polymer composites were prepared by reticulate doping of polystyrene and poly(γ‐methyl‐L‐glutamate)(PMGA) with 1‐methyl‐3‐alkylimidazolium‐7,7,8,8‐tetracyano‐p‐quinodimethane simple salts I and complex salts II. The electric conductivity strongly depends on the chemical structure of the donor, on the stoichiometry and concentration of the radical salts, on the type of the polymer, and on the preparation conditions of the films. A high conductivity, even higher than that of pure radical salts measured in pressed pellets, was obtained in the PMGA doped films, and is most probably due to the α‐helical conformation. This high order conformation of molecules forces microcrystals of charge transfer salts to grow in long hair‐like shapes distributed regularly in the

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740105

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractEs wird gezeigt, daß hydroxyterminierte Polydiene mit guter Mikrostruktur und Funktionalität sowie enger Molekulargewichtsverteilung unter Verwendung von Azobis‐isobuttersäure‐di‐hydroxyethylamid hergestellt werden können. Die Aktivierungsenergie des Initiatorzerfalls wurde durch volumetrische Messung des bei dieser Reaktion freiwerdenden Strickstoffs

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740106

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe reaction of bisphenol A‐diglycidyl ether (BADGE) with butane‐1,4‐diol (BD) in the presence of Mg(ClO4)2leads to linear and branched oligomers. The formation ratio of these products depends on the reaction temperature. In experiments at 100°C, an epoxide consumption of up to 70% can be observed using HPLC. In this range all products show good solubility in THF, so that it is possible to follow the increasing molar mass by using SEC. A characteristic relation of the molar mass against the conversion rate is derived and SEC data of a branched product are dis

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740107

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

Abstracto,m,p‐Polyphenylenes were prepared by oxidation‐cationic polymerization of biphenyl and then pyrolyzed up to 800°C. The o,m,p‐polyphenylenes as well as their pyrolysis residues were doped with anhydrous FeCl3from their solution in acetonitrile. The real part of the alternating electrical conductivity σ′ of the undoped and doped materials was determined at room temperature.Decreasing σ′‐values of pyrolyzed residues at 600°C without doping were observed because of the large weight losses during the pyrolysis leading to chain scission reactions within the polymer. At higher pyrolysis temperatures (i.e. 700°C, 800°C) the σ′‐values are increased due to the formation of closed aromatic systems in the polymer. The doped materials have higher σ′‐values in relation to the corresponding specimens without doping, with the exception of the pyrolysis residues at 800°C. The dependence of doping effect and time was also determined. The transition of the organic polymer to the pyropolymers can be followed and characterized by the measurement of alterna

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740108

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractDie Möglichkeiten des Einsatzes von ataktischem Polypropylen als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylacetates und Vinylchlorids bzw. von Polypropylen‐Vinylacetat‐Pfropfprodukten als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylchlorids werden in Abhängigkeit von der Ausgangsgemischzusammensetzung untersucht.Nach Abmischung der Pfropfprodukte mit Polyvinylchlorid bzw. ABS/Polyvinylchlorid‐Mischungen werden ausgewählte mechanische Eigenschaften sowohl in Abhängigkeit von der Menge des enthaltenen Pfropfproduktes als auch von der Zusammensetzung der Pfropfpolymerisate da

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740109

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractFor a number of applications the use of polyethylenes with a high polydispersity is recommended. In order to prepare such grades polymerisation tests were performed in a stirred autoclave in laboratory scale. The autoclave was run continuously at 1800 bar in the range of 210 to 285°C with 60 s residence time. Difunctional peroxides with identical and with different substituents on both OO groups were tested. For comparison, monofunctional compounds from industrial processes were used. The concentration of the peroxides in the feed was varied between 3 and 60 mol ppm.By GPC, polydispersities of 5 to 9, comparable to those of commercial polyethylenes, were measured on the samples produced with the monofunctional peroxides. Distinctly higher polydispersities of up to 13 were achieved by the use of the difunctional peroxides, especially with the symmetrical compou

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740110

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY