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  • 1
    Electronic Resource
    Electronic Resource
    Initiation mechanisms in radical polymerization: reaction of cyanoisopropyl radicals with styrene (1997)
    Springer
    Polymer bulletin 38 (1997), S. 149-155 
    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: Abstract. The reaction of styrene with AIBN in the presence of the aminoxyl scavenger 1,1,3,3-tetramethyl-1,3-dihydro-1H-isoindol-2-yloxyl is reported. By keeping the concentration of the aminoxyl radicals very low, the addition of cyanoisopropyl radicals to styrene becomes competitive with radical trapping. Traces of adventitious oxygen give rise to some unusual reactions and products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002890050031
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  • 2
    Electronic Resource
    Electronic Resource
    Investigations into the AIBN initiation steps in the free radical polymerisation of acrylonitrile by the aminoxyl trapping technique (1996)
    Springer
    Polymer bulletin 36 (1996), S. 435-441 
    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 A modification of the radical trapping technique employing the stable nitroxide 1,1,3,3-tetramethyl-2,3-dihydro-1 H-isoindol-2-yloxyl, has been used to study the reaction of cyanoisopropyl radicals with acrylonitrile. By keeping the concentration of the aminoxyl radical very low (strategically added via a syringe pump), the addition of acrylonitrile to cyanoisopropyl radicals becomes competitive with radical trapping. Thus, sufficient quantities of alkoxyamines produced by the trapping of ‘second generation’ carboncentred radicals (cyanoisopropyl plus one monomer unit), and even ‘third generation’ carbon-centred radicals were obtained for identification by HPLC/MS techniques. Trapping by traces of adventitious oxygen was also competitive and the various peroxy radicals thus formed, underwent addition to acrylonitrile followed by further reaction or trapping by the aminoxyl. *** DIRECT SUPPORT *** AEB03077 00003
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315060
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  • 3
    Electronic Resource
    Electronic Resource
    Post-gamma-irradiation grafting of polypropylene. Part II. Butadiene: E.S.R. experiments (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 3089-3099 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ESR spectra of gamma irradiated annealed and quenched forms of polypropylene film have been studied at the temperatures used for post-irradiation grafting experiments with butadiene, described in Part I. On warming from low temperature there is radical loss by termination and some radical transformation to radicals with optimum stability in annealed polypropylene at approximately 45°C. These radicals, which may be allyl type, are sited at the crystal faces, and decay more rapidly at higher temperatures in annealed polypropylene; in quenced polypropylene their concentration never exceeds one third the optimum observed in annealed polypropylene. Correlation with the grafting experiments suggests that allyl radicals are important for long-term grafting. Effects on the ESR spectrum of adding butadiene to the system show that in the long-term butadiene adds exclusively to the allyl radicals and that alkyl radicals still present at that stage are precursors to the allyl radicals. They do not react directly with butadiene presumably because they are sited in the inaccessible crystal core. Experiments at lower temperature show that butadiene does react with alkyl radicals in accessible regions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080241133
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  • 4
    Electronic Resource
    Electronic Resource
    Initiation mechanisms in copolymerization: Reaction of t-butoxyl radicals with co-monomers ethyl vinyl ether and methyl methacrylate (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 263-270 
    Details
    ISSN: 0887-624X
    Keywords: free radicals ; initiation ; vinyl ethers ; methyl methacrylate ; nitroxide trapping ; copolymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical trapping technique employing 1,1,3,3-tetramethyl-1,3-dihydro-1H-isoindol-2-yloxyl as a scavenger has been used to investigate the reaction of t-butoxyl radicals with mixtures of ethyl vinyl ether and methyl methacrylate. The range of identified products includes those from both addition and hydrogen abstraction with both monomers, head addition with ethyl vinyl ether, and some second monomer addition products. Relative rate constants have been obtained for various pairs of constituent reactions. t-Butoxyl radicals add to ethyl vinyl ether one to two times faster than to methyl methacrylate, depending on which monomer is in excess. The ratio is less than 1 in nonolefinic solvents and as high as 6 in t-butanol. This solvent effect is thought to be due to the radicals complexing to either methyl methacrylate or t-butanol (H-bonding), thereby increasing its electrophilic character. © 1997 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Initiation mechanisms in free radical polymerization: Competitive reaction of cyanoisopropyl radicals with styrene and acrylonitrile (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2169-2176 
    Details
    ISSN: 0887-624X
    Keywords: free radical ; initiation ; styrene ; acrylonitrile ; copolymerization ; nitroxide trapping ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The competitive reactions of cyanoisopropyl radicals with the mixed monomers styrene and acrylonitrile have been investigated using the nitroxide radical trapping technique. When the trap concentration is kept low, second, third, and even fourth generation (in terms of successive monomer addition) carbon radicals have been observed as trapped products. The ratio of rate constants for the addition of styrene and acrylonitrile to cyanoisopropyl radicals is 2.7 at 75°C and 5.3 at 105°C. These values are compared with the ratios for reactions of these two monomers with a number of other radicals and discussed in terms of the polarities of the radicals and monomers. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2169-2176, 1998
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Identifying crosslinks in polyethylene following gamma-irradiation in acetylene: A model compound study (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1549-1562 
    Details
    ISSN: 0887-624X
    Keywords: polyethylene ; γ-irradiation ; crosslinking ; NMR ; alkanes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Long-chain linear alkanes have been used as model compounds for polyethylene in an attempt to identify the chemical nature of crosslinks formed in polyethylene when it undergoes γ-irradiation in the presence of acetylene. IR and UV spectral analysis of alkanes and polyethylene following acetylene-sensitized irradiation shows the formation of vinyl, trans-vinylene, and diene groups. A correlation of the conditions of formation suggests that in polyethylene the vinyl groups are restricted to amorphous regions, diene groups are restricted to the crystalline regions, and trans-vinylene groups are formed in both regions. There is no information on the nature of crosslinks. 13C-NMR analysis of alkanes following irradiation of molten alkanes in the presence of 13C-enriched acetylene has shown that a range of saturated alphatic structures are formed by inclusion of acetylene molecules in the alkane structure. They include ethyl branches, γ-branches,—CH(CH3)—, and —CH2—CH2— branches as the major species; the latter two are potential crosslink sites in the irradiation of polyethylene. In addition, the NMR analysis confirmed that the C atoms of the vinyl groups come from acetylene molecules and those of the trans-vinylene groups come from alkane molecules. Data on irradiation of the alkanes in the crystalline state showed that acetylene inclusion in the alkane structure is minimal under these conditions. The principal finding of this work is that acetylene can be incorporated as saturated aliphatic crosslinks in the amorphous regions of polyethylene during high-energy irradiation. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1549-1561, 1997
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Extensive stereoregularity changes induced in molten isotactic polypropylene by high energy radiation and other morphology effects (1988)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 26 (1988), S. 225-228 
    Details
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1988.140260502
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  • 8
    Electronic Resource
    Electronic Resource
    Acetylene-sensitized irradiation crosslinking of polyethylene: A model compound study by 13C-NMR (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 3197-3200 
    Details
    ISSN: 0887-624X
    Keywords: polyethylene ; γ-irradiation ; crosslinking ; NMR alkanes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321622
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  • 9
    Electronic Resource
    Electronic Resource
    Block copolymers of fluoral oligomer with urethanes: Preparation and thermal propertiesThe experimental work described in this paper was carried out at the University of Dundee and the University of Stirling, Scotland. (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 1775-1786 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two series of block copolymers have been synthesized comprising of soft polytrifluoroacetaldehyde (polyacetal) segments and of hard 4,4′-methylenedi(phenyl isocyanate)/cis-cyclohexane-1,4-diol polyurethane segments. The series-A copolymers in which the soft segments were directly bound to the hard segments had significantly lower thermal stability than the series-B copolymers in which the soft segments were linked to the hard segments by sebacic ester units. In both series the thermal stability decreased with increasing soft segment content. The series-A copolymers exhibited two thermal transitions both characteristic of Tg's and separated by about 60 K. In contrast the series-B copolymers exhibited two characteristic Tg's separated by 200-250 K, depending on composition, together with an additional endothermic transition at about ambient temperature. All transitions for both series decreased with increasing soft segment content. The observations have been compared with those of other polyether and polyester based polyurethanes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800715
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  • 10
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    Unknown
    Hydrogenation of palm stearine: Changes in chemical composition and thermal properties (1990)
    Wiley
    Details
    Publication Date: 1990-03-01
    Print ISSN: 0003-021X
    Electronic ISSN: 1558-9331
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Published by Wiley
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