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  • 1
    Electronic Resource
    Electronic Resource
    On the intermolecular and intramolecular branching distribution. in ethylene/α-olefin copolymers (1990)
    Springer
    Polymer bulletin 23 (1990), S. 127-131 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary For the complex phenomena of comonomer distribution in ethylene/α-olefin copolymers prepared on heterogeneous Ziegler-Natta catalysts, a branch distribution function P(b) was proposed to quantify the intermolecular branch distribution (InterBD). P(b) values calculated from solvents extraction fractions were found to correspond to the alleged sequence length distribution represented by r1·r2 as determined from13C NMR data. The InterBD is attributed to thermodynamically-controlled polymerization processes due to the presence of multiple active centers. Literature data also showed a decrease in reactivity parameter r1·r2 with increasing comonomer ratio. A diffusion-controlled model is suggested for the intramolecular branch distribution (IntraBD).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00983974
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  • 2
    Electronic Resource
    Electronic Resource
    Phase diagrams of polyethylene blends by Raman spectroscopy (1990)
    Springer
    Polymer bulletin 24 (1990), S. 241-246 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The Raman internal mode region analysis of polyethylene (PE) is extended to studies of blends of different PEs so as to obtain a phase diagram showing the magnitude of crystalline (Pc), amorphous (Pa) and interfacial (Pb) phases at different compositions. The non-cocrystallizable HDPE/LDPE blends shows additivity in phase structure with blend composition. Enlarged share of Pb is seen for compatible blends of HDPE/LLDPE and especially for HDPE with VLDPE of low crystallinity. This method offers an easy access to direct observing compatibility of different PEs on a molecular level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297324
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  • 3
    Electronic Resource
    Electronic Resource
    Study on the surface properties and morphology of blends of HDPE/PE-g-PDMS (1988)
    Springer
    Polymer bulletin 20 (1988), S. 531-535 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Film surface properties and morphology of blends of HDPE with PE-g-PDMS were studied by contact angle, ESCA and SEM measurements. All the results showed clearly the surface enrichment of PDMS segments on the film surface although the difference in the surface tension of the two components is smaller than that between PDMS and hydrophilic polymers. According to the SEM results, the PDMS segments were enriched on the surface in separate domains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263668
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  • 4
    Electronic Resource
    Electronic Resource
    Miscibility of linear low density polyethylene (LLDPE)-graft-poly(methyl methacrylate) with poly(vinylidene fluoride) (PVF2) and its application as compatibilizer LLDPE/PVF2 blends (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 241 (1996), S. 77-93 
    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: Die Verträglichkeit von Blends eines mit Polymethylmethacrylat gepfropften linearen Polyethylens niedriger Dichte (LLDPE-g-PMMA, G-3) mit Polyvinylidenfluorid (PVF2) wurde mittels Differentialkalorimetrie, Fourier-Transform-Infrarot-spektroskopie, Rasterelektronenmikroskopie und Röntgen-Photoelektronenspektroskopie untersucht und mit der von LLDPE/PVF2-Blends verglichen. Die spezifischen Wechselwirkungen zwischen den PMMA-Seitenketten und PVF2 sind in den binären G-3/PVF2-Blends schwächer als zwischen den Homopolymeren PMMA und PVF2. PVF2, liegt in der Schmelze des G-3/PVF2 (60/40 w/w)-Blends sowohl in reiner Phase als auch in Wechselwirkung mit den PMMA-Seitenketten vor. Die Mischbarkeit zwischen den PMMA-Seitenketten und PVF, beeinflußt die Kristallisation von PVF2. LLDPE-g-PMMA wirkt als guter Phasenvermittler in LLDPE/PVF2-Blends, wobei es die Grenzfláchenadhäsion und die Dispersion in letzterem verbessert. Die Diffusion der PMMA-Seitenketten in PVF2 an der Grenzfläche verringert die Kristallisationsgeschwindigkeit und führt zu einer Erniedrigung des Schmelzpunktes und der Kristallisationstemperatur des PVF2 in den Blends.
    Notes: Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to study the miscibility of blends of a graft copolymer of poly(methyl methacrylate) on linear low density polyethylene (LLDPE-g-PMMA, G-3) with poly(vinylidene fluoride)Systematic name: poly(1,1-difluoroethylene).(PVF2) and the compatibilization of blends of LLDPE/PVF2. The specific interaction between PMMA side chains and PVF2 in G-3/PVF2 binary blends is weaker than that between the homopolymers PMMA and PVF2. There are two states of PVF2 in the melt of a G-3/PVF2 (60/40, w/w) blend, one as pure PVF2 and the other interacting with PMMA side chains. The miscibility between PMMA side chains and PVF2 affects the crystallization of PVF2. LLDPE-g-PMMA was demonstrated to be a good compatibilizer in LLDPE/PVF2 blends, improving the interfacial adhesion and dispersion in the latter. Diffusion of PMMA side chains into PVF2 in the interfacial region reduces the crystallization rate and lowers the melting point (Tm) and the crystallization temperature (Tc) of PVF2 in the blends.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052410107
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  • 5
    Electronic Resource
    Electronic Resource
    WAXS studies on block copolymers of ethylene and propylene (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 1829-1837 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Wide-angle X-ray scattering from presumed block copolymers of polypropylene (PP) and ethylene-propylene copolymer (EPR), i.e., PP-EPR and PP-EPR-PP, synthesized by sequential polymerization with δ-TiCl3—Et2AlCl, was examined and compared with WAXS of mechanical blends and chain-transfer mixtures of PP and EPR with comparable compositions. The peak at 2θ = 20° for both the copolymers and the mixtures was attributed to the γ modification of PP in EPR. A strong variation in the ratio of diffraction intensities I040/I110 of PP in block copolymers and mixtures was explained in terms of crystallite growth in different directions. Analysis of the patterns and calculation of crystallinity, crystallite size, and lattice parameters led to the conclusion that block structure existed in the prepared copolymers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1987.090250904
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  • 6
    Electronic Resource
    Electronic Resource
    Structure and properties of propylene-ethylene block copolymers and the corresponding blends (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 937-949 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Structure and properties of presumed polypropylene(PP)-b-polyethylene(PE) block copolymers (PPPE) and the corresponding blends (PP/PE) have been investigated by wide-angle x-ray scattering (WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), torsional pendulum apparatus, and other techniques measuring mechanical properties. Crystallinity, morphological structure, and mechanical properties of the block copolymers and blends vary with the PP and PE compositions. Compared with PP homopolymers and PP/PE blends, PP and PE segments in PP-PE block copolymers have a reduced crystallinity, especially PE segments. An additional peak at about -40°C is observed in dynamic relaxation spectra; substantially different morphology is revealed; and mechanical properties are greatly improved for the sequentially copolymerized PP-PE block copolymers, indicating the existence of PP-PE block structure.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090280610
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  • 7
    Electronic Resource
    Electronic Resource
    DSC and 13C NMR studies of ethylene-propene copolymers prepared by a highly active and stereospecific catalyst (1994)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 1063-1073 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ethylene-propene copolymers (EPR) were synthesized at different feed compositions using a highly active and isospecific MgCl2-supported Ti-based catalyst. The thermal behavior of EPR was studied by differential scanning calorimetry, the heterogeneity by fractionation, and the chain structure by 13C NMR using the method of substituent chemical shift. The results show that EPR of very low crystallinity (1,0 wt.-%) can be obtained at high propene content in the feed with a heptane-insoluble fraction of only 0,9 wt.-%. Thus, a high isotacticity in propylene sequences and a high randomness in EPR can be achieved at the same time, and producing high-impact poly(propylene) in a reactor is possible with this catalyst. Sequence distribution and length distribution of ethylene sequences indicate that EPR is produced at multiple active sites, and each site is dominated not only by a first-order Markovian model but also by unsteady diffusion factors.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1994.021950321
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  • 8
    Electronic Resource
    Electronic Resource
    Compatibilizing effect of polystyrene-block-poly(4-vinylpyridine) for poly(2,6-dimethyl-1,4-phenylene oxide)/chlorinated polyethylene blends (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 2625-2630 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The compatibilizing effect and mechanism of compatibilization of the diblock copolymer polystyrene-block-poly(4-vinylpyridine) P(S-b-4VPy) on immiscible blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)/chlorinated polyethylene (CPE) were studied by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), mechanical properties and FTIR measurements. The block copolymer was synthesized by sequential anionic polymerization and melt-blended with PPO and CPE. The results show that the P(S-b-4VPy) added acts as an effective compatibilizer, located at the interface between the PPO and the CPE phase, reducing the interfacial tension, and improving the interfacial adhesion. The tensile strength and modulus of all blends increase with P(S-b-4VPy) content, whereas the elongation at break increases for PPO-rich blends, but decreases for CPE-rich blends. The polystyrene block of the diblock copolymer is compatible with PPO, and the poly(4-vinylpyridine) block and CPE are partially miscible.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of a polydimethylsiloxane macromonomer and its copolymerization with ethylene (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 2373-2380 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An allyl-terminated polydimethylsiloxane (PDMS) macromonomer was synthesized by anionic polymerization of hexamethylcyclotrisiloxane (D3) initiated by allyllithium. The molecular weight (MW) of the macromonomer was consistent with that calculated from the ratio of the monomer consumed to the amount of the initiator used, and the molecular weight distribution (MWD) of the macromonomer was narrow. Graft copolymers with polyethylene backbone and uniform PDMS grafts, PE-g-PDMS, were prepared by copolymerization of the macromonomer with ethylene using VOCl3/Et2AlCl as the catalyst. Under the copolymerization conditions, the scission of Si—O—Si bonds by the catalyst is negligible, so that MW and MWD of the PDMS grafts could be considered to be the same as those of the original PDMS macromonomer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1989.021901003
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  • 10
    Electronic Resource
    Electronic Resource
    Studies of the characteristics in the synthesis of polystyrene-block-poly(ethylene-co-propylene) through a transformation of an anionic to a Ziegler-Natta mechanism (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 1765-1774 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Restriction of β-elimination in polystyrene-lithium (PSLi) in the block copolymerization of polystyrene with poly(ethylene-co-propene) catalyzed with PSLi/TiCl4 (resulting in sample A-2) by adding a spacer of a few monomeric units of isoprene (I) (PS-InLi/TiCl4 (n ≤ 3)); resulting in sample A-3), was evidenced by a M̄w/M̄n-value of 2,67 lower than that of sample A-2, and a crystallinity (χ) of 7,4% in the poly(ethylene-co-propene) (EPR) block in sample A-3. These, together with shorter ethylene (E)-sequences EEEn≥1, 27,6%) and a higher content of inverted propylene units (P) make the EPR-block in A-3 look like a polymer obtained with a soluble vanadium catalyst. This is due to the solubilization of the active centers by the PS chains. Higher M̄w/M̄n-values (4,23) and crystallinity of the EPR block (18,3%) and longer EEEn≥1 sequences (55,4%) in the case of sample A-2 make it to look like a typical polymer as obtained with a heterogeneous Ti-catalyst. Comparison of sample A-3 with that obtained by E-P copolymerization with BuLi/TiCl4 (sample A-1) corroborates the solubilization effect of PS in A-3 and the effects of the typical heterogeneous catalyst used for the preparation of A-1, showing up in EEEn≥1 (A-1: 63,4% A-3: 27,6%), M̄w/M̄n (A-1: 35,7; A-3: 2,67) and P̄ (A-1: nil; A-3: 4%).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910803
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