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  • 1
    Electronic Resource
    Electronic Resource
    Hydrogels by atom transfer radical polymerization. I. Poly(N-vinylpyrrolidinone-g-styrene) via the macromonomer method (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 823-830 
    Details
    ISSN: 0887-624X
    Keywords: atom transfer radical polymerization ; poly(N-vinylpyrrolidinone-g-styrene) ; macromonomer method ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Atom transfer radical polymerization has been used to prepare well-defined vinyl macromonomers of polystyrene using vinyl chloroacetate as an initiator. Because styrene and vinyl chloroacetate do not copolymerize, no branching or incorporation of the initiator into the backbone was observed. Macromonomers of several molecular weights were prepared and copolymerized free radically with N-vinylpyrrolidinone in varying feed ratios in order to produce poly(NVP-g-Sty) graft copolymers. The macromonomers used were of sufficiently high molecular weight to form physical crosslinks in solvents which favor the hydrophilic NVP, such as water, which prevent the copolymer from dissolving and cause it to swell. These materials, therefore, formed hydrogels of swellabilities in water exceeding 95%, depending on the amount of styrene that was incorporated into the copolymer. Limitations of and alternatives to this method are also discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 823-830, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: Tellurium dithiocarbamates as antioxidants for polypropylene (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 4857-4864 
    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 tetrakis (dialkyldithiocarbamato)tellurium(IV) complexes are highly effective thermal antioxidants and melt stabilizers for polypropylene and the evidence suggests that they are converted to the bis(dialkyldithiocarbamato)tellurium(II) complexes and the corresponding dithiocarbamoyl disulfides during processing. The Te(IV) complexes are also effective photoantioxidants and their activity increases with increasing processing time. The bischelates are in general less effective when used alone.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320508
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: The role of nitroxyl radicals in the stabilization of PVC (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 6063-6071 
    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: Hindered amines and their derived oxidation products, the hindered nitroxyls and hydroxylamines are processing stabilizers and photoantioxidants for poly(vinyl chloride). The evidence suggests that oxidation of the amines occurs very rapidly and completely during mechanooxidation and that the resulting redox couple operates by a catalytic mechanism as described previously for hydrocarbon polymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320733
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: Photoantioxidant activity of polymer-bound hindered amines. II. Bis acrylates (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 1287-1296 
    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: 1-Acryloyl-4-acryloyloxy-2,2,6,6-tetramethylpiperidine (AATP) has been covalently attached to polypropylene under conditions of reactive processing to give substantial concentrations of essentially 100% grafted antioxidant (AATP-B). Solution of the concentrates showed that at high concentration of grafted antioxidant some homopolymerized AATP was present and the polymer undergoes transient cross-linking during processing. Concentrates of bound AATP (AATB-B) when used as conventional additives for polypropylene are very effective photoantioxidants due to conversion to the related polymer-bound nitroxyl radicals by photosensitized oxidation. A typical commercial hindered phenol, Irganox 1076, when used at low concentration in combination with -B also acts as a photosensitizer for nitroxyl formation. Unlike low molar mass-hindered piperidinoxyl, polymer-bound nitroxyls are effective thermal antioxidants that synergize very effectively with low concentrations of Irganox 1076.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440719
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: The effect of spin traps during the processing and photooxidation of PVC (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 2673-2679 
    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: It is demonstrated by the use of spin traps that during the early stages of thermal processing of PVC considerable concentrations (〉 3 × 10-6 mol g-1) of free radicals are produced which are primarily responsible for the initial products (hydroperoxides, unsaturation, and hydrogen chloride) previously shown to be formed in the polymer. From a semiquantitative analysis of these products, it is estimated that more than 50% of the radicals are formed from hydroperoxides and the rest by mechanoscission of the polymer chain. The spin traps are effective processing stabilizers in combination with a tin maleate HC1 scavenger. One of them (2-methyl-2-nitroso propane, MNP) has also been shown to be a photoantioxidant.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070340804
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: Mechanochemical transformation products of 2,2,6,6-tetramethyl-4-hydroxypiperidinoxyl in polypropylene (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 703-713 
    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 effect of the processing operation on the nature and quantity of transformation products of 2,2,6,6-tetramethyl-4-hydroxypiperidinoxyl (〉NO.) and its corresponding hydroxylamine (〉NOH) was investigated in polypropylene. It was found that both 〉NO. and 〉NOH are actively involved in a regenerative cycle and that this redox couple is responsible for the stability of the polymer whether the initial additive is 〉NO. or 〉NOH. The alkyl hydroxylamine (〉NOR), on the other hand, does not appear to play a significant role in the melt stabilization of the polymer. Quantitative measurements of 〉NOH and 〉NO. concentrations show that, under conditions of both restricted oxygen (CM) and oxygen excess (OM), the concentrations of both species change reciprocally throughout the processing operation. In a closed mixer (CM), the total overall concentration of 〉NO. and 〉NOH remains at a high constant level, whereas in an open mixer (OM), their total concentration decreases continuously to a low level, indicating the irreversible destruction of the redox couple (〉NO. and 〉NOH). The photo-oxidative stability of the polymer was found to depend on the total concentration of the redox couple left in the system after processing in either CM or OM.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330302
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  • 7
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: Nature of transformation products of dithiophosphates. II. Antioxidant action of thiophosphoryl disulphides (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 1297-1305 
    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 nature of transformation products of high-temperature reactions of thiophosphoryl disulphides with hydroperoxides in the absence and presence of oxidisable substrates and the role of the disulphide in the overall antioxidant mechanism was investigated using a range of techniques such as oxygen absorption, 31P nuclear magnetic resonance (NMR), gas-liquid chromatography (GLC), and peroxide determination. The major transformation products of the above oxidation reactions were found to be the thio and thiono-phosphoric acids, in addition to mono and polysulphides. At high molar ratios of peroxide to disulphide (〉10), these oxidation products are the main catalysts for peroxide decomposition, while at lower ratios the disulphide itself was found to play a major role in the antioxidant mechanism.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440720
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  • 8
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: Nature of transformation products of dithiophosphates. Part III. The antioxidant action of dithio and thio/thionophosphoric acids (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 1823-1831 
    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 nature of transformation products of dithio- and thionophosphoric acids in the presence and absence of hydroperoxides and their role as transformation products formed during oxidation of thiophosphoryl disulfide at high temperatures is investigated. The major transformation product of dithiophosphoric acid was found to be the corresponding disulfide while thiophosphoric acid was the major oxidation product of the reaction of thionophosphoric acid with hydroperoxide. In the case of thiophosphoryl disulfide, it is shown that thionophosphoric acid was found to be one of the major transformation products in the presence of hydroperoxides, whereas no acids were formed in the absence of added hydroperoxides. © 1993 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070501019
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  • 9
    Electronic Resource
    Electronic Resource
    Bis(diisopropyl) thiophosphoryl disulfide in cis-1,4-polyisoprene vulcanization reactions. I. As a sulfur donor (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 865-877 
    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: Bis(diisopropyl)thiophosphoryl disulfide (DIPDIS) is used as a sulfur donor vulcanizing system for cis-1,4-polyisoprene. It is shown that the network structure consists of poly- and disulfidic crosslinks at early stages of cure, simplifying at optimum cure to monosulfidic crosslinks. It is thought that pendent accelerator groups are bound to the rubber molecule at early stages of cure, but are subsequently replaced by cyclic sulfidic groups. The good thermal and thermal oxidative aging behaviour of the vulcanizate is due to the formation of zinc diisopropyldithiophosphate (ZDP) in situ.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1975.070190322
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  • 10
    Electronic Resource
    Electronic Resource
    Stabilization of ABS with bound synergistic stabilizers added as masterbatches (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 2581-2592 
    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: ABS masterbatch concentrates in antioxidants and UV stabilizers were added as conventional additives for normal ABS. The thermal and photo-oxidative performance of these polymers were compared with that of the commercial ABS and additives by measurement of carbonyl index and embrittlement times. From the result obtained, it is concluded that the addition of these additives in the form of masterbatches appears to be a better practical way of incorporating antioxidants and UV stabilizers into ABS simply by dilution of ABS, as these give thermal and light-stabilizing effects that cannot be achieved by stabilizers added in a conventional way. The bound stabilizers are resistant to leaching and chemical extraction.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260808
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