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  • Polymer and Materials Science  (44)
  • Ziegler-Natta catalysts  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Modified syndiotactic polypropene: Poly(propene-co-octene) and blends with atactic oligopropene (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 229 (1995), S. 93-112 
    Details
    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: Propen und 1-Octen wurden mit dem syndiospezifischen Metallocen-Katalysator Me2C(Cp)(Flu)ZrCl2/MAO copolymerisiert. Es wurde ein hoher, statistischer Octeneinbau beobachtet. Niedrige Octenkonzentrationen beeinflußten die Aktivität des Katalysators nur wenig; Molekulargewicht, Kristallinität, E-Modul und Glastemperatur wurden dagegen mit ansteigendem Octengehalt erniedrigt. Blends aus ataktischem Oligopropen und syndiotaktischem Polypropen bzw. Poly(propen-co-octen) wurden aus einer Toluol-Lösung hergestellt. Diese Lösungsblends wurden mit einem Reaktorblend verglichen, der mit einem Hybrid-Katalysator bestehend aus einer Mischung von syndiospezifischem Me2C(Cp)(Flu)ZrCl2/MAO und unspezifischem Cp2ZrCl2/MAO hergestellt wurde. Das ataktische Oligopropen wirkte als Weichmacher, der E-Modul und Glastemperatur der Blends erniedrigte.
    Notes: Propene and 1-octene were copolymerized with the syndiospecific homogeneous metallocene catalyst Me2C(Cp)(Flu)ZrCl2/MAO. Large amounts of octene were incorporated randomly. While catalyst activity was not affected markedly by low octene content, molecular weight, crystallinity, Young's modulus, and glass transition temperature were reduced with increasing octene content. Blends of atactic oligopropene with syndiotactic polypropene and poly(propene-co-octene) were prepared from toluene solution and compared with a reactor blend prepared with a hybrid catalyst containing a mixture of syndiospecific Me2C(Cp)(Flu)ZrCl2/MAO and non-specific Cp2ZrCl2/MAO. Atactic oligopropene acted as plasticizer reducing Young's modulus and glass transition temperature of the blends.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052290106
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  • 2
    Electronic Resource
    Electronic Resource
    Progress in synthesis and application of segmented polymersDedicated to Prof. Dr. H. Sinn on the occasion of his 65th birthday (1994)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 223 (1994), S. 47-60 
    Details
    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: Maßgeschneiderte segmentierte Polymere spielen eine Schlüsselrolle bei der Entwicklung von neuen polymeren Materialien. In Abhängigkeit von den molekularen Architekturen der segmentierten Polymeren kann die Ausbildung von Polymermorphologien und von Eigenschaftssynergien gesteuertwerden. An ausgewählten Beispielen werden grundlegende Konzepte und neuere Entwicklungen vorgestellt. Segmentierte Silikon-Flüssigkautschuke, wo unverträgliche Silikonsegmente von zwei mischbaren Oligo(caprolacton)-Segmenten flankiert werden, sind wirkungsvolle Zähmodifikatoren für Epoxidharze. In nanophasenseparierten IPNs auf Basis dieser Silikon-modifizierter Epoxidharze kann die Schlagzähigkeit ohne Verlust der Dimensionsstabilität erhöht werden. Kompatibilisierte Blends aus segmentierten phenolischen Polyurethan- und epoxidfunktionellen Nitril-Flüssigkautschuken bilden diskrete Blend-Mikrophasen, die in Epoxidprepregs dispergiert sind und strukturelles Verkleben von Aluminium in Faser-Metall Laminaten ermöglichen. Reaktive Blendtechnologien werden entwickelt, um während der Polymerverarbeitung, z.B. von Polypropylen/Polyamid 6 Blends, in-situ Phasenvermittler herzustellen. Durch Einbau von definierten Oligo(tetrafluoroethene) Segmenten in Kodensationspolymere werden neben thermischen und mechanischen Eigenschaften auch Oberflächenspannungen und Gasdurchlässigkeiten variiert.
    Notes: Tailor-made segmented polymers play a key role in the development of novel polymeric materials exhibiting unsual bulk and surface properties. As a function of molecular architectures of segmented polymers, it is possible to control polymer morphologies and to achieve property synergisms. Selected examples are presented to illustrate basic concepts and recent developments. Segmented reactive liquid rubbers, containing an immiscible silicone segment flanked by two miscible oligo(caprolactone) segments, are efficient epoxy toughening agents. In such nano-phase-separated silicone-modified IPNs impact strength is improved without sacrificing dimensional stability. Compatibilized blends of segmented phenolic polyurethane and nitrile liquid rubbers produce rubber blend microphases dispersed in epoxy prepregs which are used to bond aluminum sheets in structural laminates. Reactive blending technologies are developed to produce segmented polymers as blend compatibilizers during melt processing, e.g., of polypropylene/polyamide 6 blends. Incorporation of oligo(tetrafluoroethene) segments into various condensation polymers modifies thermal and mechanical properties as well as surface tension and gas permeabilities.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1994.052230104
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  • 3
    Electronic Resource
    Electronic Resource
    Surface modification and bonding of poly(p-phenylene sulfide) (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 97-107 
    Details
    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: Es wird gezeigt, daß es sowohl durch Oxidation, z.B. mittels Essigsäure/Wasserstoffperoxid oder Chromschwefelsäure, als auch durch Plasmabehandlung möglich ist, auf Poly(p-phenylensulfid) (PPS)-Oberflächen polare Gruppen einzuführen. Die änderungen and den PPS-Oberflächen wurden mit FTIR-Spektroskopie, Röntgen-Photoelektronenspektroskopie und Kontaktwinkelmessungen verifiziert. Die verbesserte Adhäsion der behandelten Oberflächen wurde mit Hilfe von Zug-Scher-Messungen nach dem Verkleben mit Acrylatklebstoffen quantitativ erfaßt. Die Untersuchung der Oberflächen mittels AFM (Atomic Force Microscopy) zeigt, daß die verbesserte Adhäsion auch durch eine größere Oberflächenrauhigkeit als Folge der Oberflächenbehandlung erreicht wird. Dieser Effekt ist besonders deutlich bei Proben, die mit Chromschwefelsäure behandelt wurden.
    Notes: It is demonstrated that both chemical oxidation, e.g. by using acetic acid/hydrogen peroxide or chromosulfuric acid, and plasma treatment of poly(p-phenylene sulfide) (PPS) surfaces introduce polar groups. The changes of the surface chemistry are detected by FTIR spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The increased polarity is partially responsible for better adhesion as verified by lap shear measurements using acrylic adhesive. Another important contribution to the improved adhesion originates from increased surface roughness after surface modification as measured by atomic force microscopy. This effect is very pronounced for PPS surfaces treated with chromosulfuric acid.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052460108
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanism of the NCA polymerization 7.Part 6, cf. H. R. Kricheldorf, J. Polym. Sci. Polym. Chem. Ed. 17, 97 (1979) The primary and secondary amine-initiated polymerization of β-amino acid NCAsN-Carboxyanhydrides (perhydro-1,3-oxazine-2,6-diones). (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 1419-1433 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction of β-alanine N-carboxyanhydride (β-Ala NCA) (1) with various primary and secondary amines was investigated at room temperature. Three reaction products were found: poly(β-alanine), β-alaninamides, and N′-substituted β-ureidopropionic acids. The mole ratio of these reaction products depends on the reaction conditions, above all on the NCA/amine ratio, and on the nucleophilicity/basicity ratio of the amines. All amines with pKa-values 〉 8,0, including the amino end-groups of the growing chains, cause the formation of β-isocyanatocarboxylate ions by deprotonation of the β-NCAs, and thus, the formation of β-ureidocarboxylic acids. If the chain ends are involved, this reaction sequence is a termination step, and it is this termination step which is responsible, for that high polymerization degrees (〉 60) are not accessible by a primary or secondary amine-initiated polymerization of β-NCAs. The β-ureidocarboxylic acid end-groups are detectable in the 13C NMR spectra of the poly(β-amide)s.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800603
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  • 5
    Electronic Resource
    Electronic Resource
    Copolymerization of ethene with styrene using different methylalumoxane activated half-sandwich complexes (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1571-1578 
    Details
    ISSN: 0887-624X
    Keywords: half-sandwich metallocenes ; mono-Cp-amido complexes ; homogeneous catalysis ; ethene-styrene copolymers ; polymerization kinetics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethene was copolymerized with styrene using five different methylalumoxane (MAO) activated half-sandwich complexes of the general formula Me2Si(Cp)(N—R)MCl2, varying the substituents on the cyclopentadienyl ring and the substituent on the amide (Cp = tetramethylcyclopentadiene CBT, 1-indenyl IBT, 3-trimethylsilyl-1-indenyl SIBT, or fluorenyl FBZ, R = tert-butyl (complexes CBT, IBT, SIBT, FBZ) or benzyl CAT), as well as the metal center (M = Ti, except FBZ: M = Zr). Polymerization behavior was analyzed with respect to catalyst activity and polymerization kinetics, styrene incorporation, copolymer microstructure, and molecular weight. All complexes produced random poly(ethene-co-styrene) without any regioregular or stereoregular microstructure. Complex CBT showed the highest catalytic activity, the fluorenyl-substituted complex FBZ produced the highest molecular weight polymer, and complexes SIBT and CAT promoted high styrene incorporation. Cp-substitution pattern influenced deactivation of the catalytic system with bulky substituents of the Cp-ring slowing down deactivation at the expense of styrene incorporation. Moreover, deactivation was accelerated with increasing styrene concentration. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1571-1578, 1997
    Additional Material: 6 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Photoinitiated cationic polymerization of 2-phenylsubstituted 4-methylene-1,3-dioxolanes (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 587-592 
    Details
    ISSN: 0887-624X
    Keywords: 2-phenyl-4-methylene-1,d-dioxolane ; methylene-1,3-dioxolanes ; cationic photopolymerization ; poly(keto-ether)s ; poly(alkylene-ether-ketone)s ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330326
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  • 7
    Electronic Resource
    Electronic Resource
    Metallocene-catalyzed ethene/styrene co- and terpolymerization with olefinic termonomers (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 2549-2560 
    Details
    ISSN: 0887-624X
    Keywords: halfsandwich metallocene ; homogeneous catalysis ; terpolymerization ; ethene ; styrene ; 1-octene ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethene was co- and terpolymerized with 1-octene and styrene using the methylalumoxane (MAO) activated halfsandwich metallocene Me2Si(Me4Cp)(N-t.-butyl)TiCl2(Cp = cyclopentadienyl, Me = methyl) as catalyst. At temperatures of 40 and 60°C styrene concentration was varied in order to investigate the influence of the comonomers. Despite decreasing the overall activity with respect to ethene/1-octene copolymerization, polymerization activity was found to exibit a relative maximum with increasing styrene concentration. An explanation is given taking two different comonomer effects into account. Low styrene concentration promoted higher 1-octene incorporation compared to ethene/1-octene copolymerization but significantly lowered the molecular weight of the terpolymers. With constant ethene and 1-octene concentration it was possible to produce ethene/1-octene/styrene terpolymers with styrene content varying from 0 to 25 mol % and 1-octene content varying from 8 to 21 mol %. All terpolymers were amorphous. With constant ethene content it was found possible to vary their glass transition temperature with 1-octene/styrene molar ratio incorporated in the terpolymer. 13C-NMR spectroscopic microstructure analysis showed that no styrene/1-octene sequences were found in the terpolymer backbone. Furthermore terpolymerizations were conducted successfully incorporating norbornene, 1,5-hexadiene and propene as monomers in terpolymertization with ethene and styrene. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2549-2560, 1997
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Propene polymerization using homogeneous MAO-activated metallocene catalysts: Me2Si(Benz[e]Indenyl)2ZrCl2/MAO vs. Me2Si(2-Me-Benz[e]Indenyl)2ZrCl2/MAO (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1305-1317 
    Details
    ISSN: 0887-624X
    Keywords: propene ; polymerization ; zirconocene ; methylalumoxane ; chain transfer ; end groups ; hydrogen ; 2,1-insertion ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propene was polymerized at 40°C and 2-bar propene in toluene using methylalumoxane (MAO) activated rac-Me2Si(Benz[e]Indenyl)2ZrCl2 (BI) and rac-Me2Si(2-Me-Benz[e]Indenyl)2ZrCl2 (MBI). Catalyst BI/MAO polymerizes propene with high activity to afford low molecular weight polypropylene, whereas MBI/MAO is less active and produces high molecular weight polypropylene. Variation of reaction conditions such as propene concentration, temperature, concentration of catalyst components, and addition of hydrogen reveals that the lower molecular weight polypropylene produced with BI/MAO results from chain transfer to propene monomer following a 2,1-insertion. A large fraction of both metallocene catalyst systems is deactivated upon 2,1-insertion. Such dormant sites can be reactivated by H2-addition, which affords active metallocene hydrides. This effect of H2-addition is reflected by a decreasing content of head-to-head enchainment and the formation of polypropylene with n-butyl end groups. Both catalysts show a strong dependence of activity on propene concentration that indicates a formal reaction order of 1.7 with respect to propene. MBI/MAO shows a much higher dependence of the activity on temperature than BI/MAO. At elevated temperatures, MBI/MAO polymerizes propene faster than BI/MAO. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330813
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of oxazoline-functional polymer particles by free radical nonaqueous dispersion polymerization (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 2539-2548 
    Details
    ISSN: 0887-624X
    Keywords: nonaqueous ; dispersion polymerization ; functional submicron particles ; poly(methyl methacrylate) ; SEP stabilizer ; oxazoline ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel oxazoline-functional methacrylate was prepared and employed as comonomer to produce nonaqueous dispersions of oxazoline-functional polymer particles. In nonaqueous free radical dispersion copolymerization of methylmethacrylate in the presence of oxazoline-functional methacrylate, ethyleneglycoldimethacrylate crosslinking agent, AIBN initiator, and polystyrene-block-poly(ethene-alt-propene) dispersing agent, the average polymer particle size, varying between 100 and 500 nm, was controlled by the dispersing agent contents. According to titration with HClO4 all oxazoline groups regardless of their location at particle surface or bulk, were accessible. Glass transition temperature decreased from 120 to 0°C when oxazoline functional methacrylate was increased from 0 to 95 mol %. As imaged by atomic force microscopy incorporation of the new oxazoline-functional methacrylate improved film formation. Oxazoline-functional polymer particles were easy to redisperse in a variety of other diluents. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2539-2548, 1997
    Additional Material: 6 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Morphology and grafting of oxazoline-functional polymer particles with various carboxylic acids (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1821-1827 
    Details
    ISSN: 0887-624X
    Keywords: morphology ; grafting ; oxazoline-functionalized polymer particles ; carbolic acids ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxazoline-functionalized, crosslinked PMMA-particles, prepared by free radical nonaqueous dispersion polymerization, were grafted with n-decanoic acid and carboxylic acid-terminated polystyrene. Oxazoline groups, separated by an alkylspacer from the PMMA backbone, showed enhanced mobility with respect to the backbone, as evaluated by solid-state NMR spectroscopy using a dipolar filter. As a function of molecular mass of the carboxylic acid, the oxazoline conversion varied from 70 mol % for n-decanoic acid to 1% for monocarboxylate-terminated polystyrene CT-PS with Mn: 15,900 g/mol. Morphological studies, performed by TEM, showed that reaction with acid terminated polystyrene results exclusively in interfacial grafting at the particle surface. At low grafting levels a raspberry-like morphology was obtained, whereas grafting levels exceeding 14 wt % CT-PS resulted in core-shell morphology. Core-shell morphology was also verified by static light scattering using toluene solvent, which is isorefractive to the PMMA core. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1821-1827, 1998
    Additional Material: 6 Ill.
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