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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and reversible photocleavage of novel polyurethanes containing coumarin dimer components (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 613-624 
    Details
    ISSN: 0887-624X
    Keywords: anti head-to-head 7-hydroxycoumarin dimer ; anti head-to-tail 7-hydroxy-4-methylcoumarin dimer ; polyurethane ; photocleavage ; photopolymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Six polyurethanes containing coumarin dimer components in the main chain have been prepared by polyaddition of diisocyanates with anti head-to-head 7-hydroxycoumarin dimer or anti head-to-tail 7-hydroxy-4-methylcoumarin dimer. 7-Acetoxycoumarin and 7-acetoxy-4-methylcoumarin were first prepared and then photodimerized under 350 nm UV light to give anti head-to-head 7-acetoxycoumarin dimer and anti head-to-tail 7-acetoxy-4-methylcoumarin dimer, respectively. After hydrolyzing under acidic conditions to 7-hydroxycoumarin dimer and anti head-to-head 7-hydroxycoumarin dimer, they were polymerized with aliphatic and aromatic diisocyanates in N,N-dimethylacetamide to give the polyurethanes. Addition of dibutyltin dilaurate (T-12) as catalyst increases the polymer yield with the viscosity remaining almost unchanged. It was also found that lithium chloride enhances both the yield and viscosity of the polyurethanes by increasing their solubility possibly through complexation. The polyurethanes are symmetrically photocleaved at cyclobutane rings under 254 nm UV light to dicoumarins. Reversible photodimerization of the photocleaved compounds have also been investigated under 300 and 350 nm UV light. The polyurethanes from aromatic diisocyanates or with 4-methyl substituent exhibit greater reactivity in the photocleavage reaction. © 1997 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of soluble C60-chemically modified poly(p-bromostyrene) (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 3297-3302 
    Details
    ISSN: 0887-624X
    Keywords: C60 ; poly(p-bromostyrene) ; chemical modification ; fullerenes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of bulky C60 moiety, a powerful electron acceptor (EA = 2.6-2.8 eV), to the poly(p-bromostyrene)(PBS) by a novel organometallic reaction considerably changes the chemical and physical properties of this polymer. The product obtained is a “charm-bracelet” non-crosslinked brownish yellow polymer which is easily soluble in many common organic solvents, and has a single glass transition temperature [134.0°C vs. 83.2°C for poly(p-bromostyrene)], this being congruent with its chemical structure. Covalent attachment of C60 to the brominated polystyrene backbone is confirmed by a variety of techniques such as UV-VIS, FT-IR, TGA, DSC, SEM, ESR, GPC, and 13C-NMR. The results show that both the stereo-electronic effect and the steric hindrance of C60 have an important influence on the structure and physical properties of polymer. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation of styrene-divinyl benzene copolymer-supported platinum complexes and their catalytic properties in hydrosilylation (1996)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 7 (1996), S. 76-78 
    Details
    ISSN: 1042-7147
    Keywords: polymer-supported platinum catalyst ; hydrosilylation ; dichloromethylsilane ; unsaturated monomer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A new type of catalyst for the hydrosilylation of unsaturated monomers with dichloromethylsilane (DCMS) was prepared, which consisted of thiolmethylene-substituted styrene-divinyl benzene copolymer and platinum. When using DCMS as a hydrosilylation agent, these catalysts showed a high activity in the hydrosilylation of vinyl and acetylene monomers as styrene, alkyl vinyl silanes, acetylene, phenyl acetylene, butyl acrylate. The activities of catalysts were not significantly reduced even after 20 reuse cycles.
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Preparation of polyacrylate-polysiloxane core-shell latex particles (1996)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 7 (1996), S. 888-890 
    Details
    ISSN: 1042-7147
    Keywords: polyacrylates ; polysiloxane ; core-shell particles ; latex film property ; seeded emulsion polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Crosslinked polymer seed latexes of butyl acrylate, methyl methacrylate and methacrylic acid were synthesized with ethylene glycol dimethacrylate as a crosslinking agent in a first step. Three different processes of seeded emulsion polymerization were used to prepare an outlayer of polysiloxane on the above seed latex particles: (A) direct anionic polymerization of D4 (octamethyl tetracyclosiloxane) catalyzed by potassium hydroxide; (B) direct cationic polymerization of D4 onto the seed catalyzed by dodecylbenzene sulfonic acid; (C) a vinyl-containing polysiloxane prepared by copolymerization of D4 and vinyl septamethyl tetracyclosiloxane was added before the D4 cationic polymerization. Characterization by transmission electron microscopy showed that only process C provided satisfactory results. Film hardness was measured, and the latex film from process C demonstrated the lowest hardness of all the films. The mechanism of polymerization is discussed.
    Additional Material: 1 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of silicone-acrylate copolymer latexes and their film properties (1996)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 7 (1996), S. 95-97 
    Details
    ISSN: 1042-7147
    Keywords: emulsion copolymerization ; siloxanes ; silicone-acrylate copolymer ; polymerization process ; film properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Emulsion copolymerization of silicones (octomethyl tetracyclosiloxane, D4 and methacryloxypropyl trimethoxy silane, MATS) and acrylics was carried out using three different polymerization processes: semicontinuous monomer emulsion addition, batch and initiator solution addition. Results showed that only the semicontinuous process led to a stable latex with monodisperse particles. Various polymerizations were carried out through this process with varying silicone/acrylic ratios and MATS content. Films were obtained from different latexes: their properties are significantly influenced by silicone and MATS contents in copolymers.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Editorial (1996)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 7 (1996), S. 59-59 
    Details
    ISSN: 1042-7147
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 7
    Electronic Resource
    Electronic Resource
    A study on the tribological behavior of polyethylene. II. Effects of operating conditions on the friction behavior of polyethylene (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 903-910 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this article, the effects of the operating conditions, i.e., load, oscillation speed, temperature, and contact modes on the friction behavior of polyethylene were studied through the SRV vibration friction test machine, the MHK-500 friction and wear test machine, as well as an on-line temperature testing device. The experimental results showed that the friction coefficient μ of polyethylene increases with increase of the oscillation frequency and amplitude, the speed, and PV value, while load has a quite complex impact on μ; suitable choice of load could reduce μ and smoothen the friction process. Contact modes of friction pairs have considerable effects on μ, because all the real contact area of the friction assembly, the pressure, the indentation of surface asperities, as well as the temperature rise and distribution in the contact region are related to contact modes. Temperature is a key factor determining the viscoelastic properties of polyethylene, and therefore has great effect on μ. On-line temperature testing offers a way to reveal the relations between temperature and the friction behavior of polyethylene. All the results obtained provide the basic data for establishing mathematical models and computational simulation methods to describe and study the tribological behavior of some polymer materials. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580507
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  • 8
    Electronic Resource
    Electronic Resource
    Microtacticity of polypropylene fractions produced by different active sites of heterogeneous Ziegler-Natta catalyst (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 727-731 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polypropylene (PP) prepared with the MgCl2/TiCl4-AlEt3/Ph2Si(OMe)2 catalyst system was fractionated by a preparative temperature rising elution fractionation (TREF) technique in the wide temperature range of room temperature to 130°C. The results of fractionation showed that there were plural active sites in this heterogeneous catalyst. Some key fractions were selected for characterization of 1H- and 13C-NMR. 1H-NMR results suggested that the fractionation takes place according to tacticity. Based on analysis of 13C-NMR, it was concluded that the polymerization mechanism proceeding on highly stereospecific active sites was active site-controlled and nonstereospecific active sites were able to convert into syndiotactic active sites during the polymerization, which led to the formation of a syn-diotactic block. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Plasma polymerization of octafluorocyclobutane and hydrophobic microporous composite membranes for membrane distillation (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 191-199 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this paper, hydrophilic microporous cellulose nitrate membranes have been surface-modified by plasma polymerization of octafluorocyclobutane (OFCB). The microporous composite membranes with a hydrophilic layer sandwiched between two hydrophobic layers have been obtained. The obtained composite membranes have been used in a membrane distillation (MD) process and have exhibited good performance. The effects of polymerization conditions, such as glow-discharge power and deposition time, on the structures and MD performances of the obtained composite membranes have been investigated by SEM, X-ray microscopical analysis, and XPS. The polymerization conditions should be as mild as possible in order to prepare the hydrophobic composite membrane with good MD performance. The typical MD behaviors of the obtained hydrophobic composite membranes are in agreement with that of hydrophobic membranes directly prepared from hydrophobic polymeric materials, like PVDF, PTFE, or PP.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460201
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  • 10
    Electronic Resource
    Electronic Resource
    Block copolyetheresters. V. Low-temperature properties of thermotropic block copolyetheresters (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 1027-1031 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The low-temperature properties of block copolyetheresters with hard segments of poly(alkylene p,p′-bibenzoate) and soft segments of poly(tetramethylene ether) were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). In the temperature range of -100 to 60°C, two transition temperatures, a glass transition temperature (Tg) and a melting temperature (Tm), were found by DSC and are attributed to the polyether segments. The Tg monitored by DSC of the polyether segments of the block copolyetheresters is around -68°C and independent of the composition and the type of polyester segment. Thus, the amorphous parts of the polyether segments should be immiscible with the amorphous parts of the polyester segments. The polyether segments of the block copolyetheresters exhibit a lower Tm and a lower crystallinity than those of the poly(tetramethylene ether)glycol due to the presence of the polyester segments. The crystallizability of the polyether segments is dependent on the composition to some extent. The DMA data show that the dynamic modulus drops more abruptly around -10 to 15°C, indicating that the mechanical properties may change significantly due to the melting of the polyether segments. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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