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  • Polymer and Materials Science  (20)
  • core-shell  (2)
  • 21.10.−Jx  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Polystyrene(1)/poly(butyl acrylate-methacrylic acid)(2) core-shell emulsion polymers. Part II: Thermomechanical properties of latex films (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 1208-1221 
    Details
    ISSN: 1435-1536
    Keywords: Polystyrene(1)/poly(butyl acrylate-methacrylic acid)(2) ; core-shell ; morphology ; latex films ; phase arrangement ; mechanical properties ; differential thermal analysis ; scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polystyrene(1)/poly(n-butyl acrylate-methacrylic acid)(2) structured latex particles were prepared through a two-stage emulsion polymerization procedure, using a polystyrene (PS) latex seed (118 nm), and differentn-butyl acrylate (BA)/methacrylic acid (MAA) ratios. Polymerization kinetics, particle morphology, and MAA location have already been discussed in the first part of this series. In this second part the thermomechanical behavior of films cast from these latexes was studied. Differential Thermal Analysis and Dynamic Mechanical Analysis (DMA) were employed as characterization techniques for the films. Two polymer phases corresponding to polystyrene and a poly(BA-MAA) copolymer were distinguished. Comparison was made to analogous unfunctionalized PS/PBA systems, as a result of which an effect of MAA upon the phase arrangement in the film was found. Scanning Electron Microscopy of film samples and DMA showed that the evolution of the phase arrangement as a result of annealing was strongly dependent on the type of mechanical and heat treatments being applied to functionalized systems. Finally, the thermomechanical behavior of films was related to the structural features of the corresponding latexes, and computer simulation techniques wer eemployed to establish a mechanistic support for these relationships.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01095062
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  • 2
    Electronic Resource
    Electronic Resource
    Valence and inner proton hole states in119in via the (d,3He) reaction (1989)
    Springer
    The European physical journal 334 (1989), S. 133-141 
    Details
    ISSN: 1434-601X
    Keywords: 21.10.−Jx ; 21.10.Pc ; 25.45.−6h
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Proton holes states have been studied up toE x=17 MeV andE x=3.5 MeV in the119In nucleus via the120Sn(d,3He)119In reaction respectively atE d=108.4 MeV andE d=51 MeV. DWBA analysis of angular distributions has allowedl attributions for a large number of new levels and the determination of valence and inner hole strength distributions. The first 1g 9/2, 2p 1/2 and 2p 3/2 levels only exhaust 40%, 60% and 32% of their respective sum rule limits. The missing strengths are shared among several low lying levels and significant higher lying contributions. The 1f strength, not identified in the previous experiments is spread fromE x=1 MeV to about 17 MeV. The low lying levels aroundE x=2.4 MeV could exhaust some 40% of the 1f 5/2 sum rule. The higher lying strength with a flat maximum aroundE x=7.5 MeV could account for the 1f 7/2inner hole strength and the missing 1f 5/2 valence strength. The experimental strength functions compare rather well with the predictions of the quasiparticle-phonon model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294214
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  • 3
    Electronic Resource
    Electronic Resource
    Some thermodynamic aspects in emulsion copolymerization (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 10 (1985), S. 235-264 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Emulsion polymerization proceeds in a heterogeneous medium; in copolymerization, due to discrepancy in water solubility and interactions with the resulting copolymers, monomers are partitioned in a complex way between droplet, water and particle phases. As monomer swollen polymer particles are the main loci of polymerization, it is of great interest to know the monomer feed within the particle phase to understand the behaviour of this copolymerization whatever may be the process and the experimental conditions. Two approaches are examined in this lecture to investigate emulsion copolymer and colloid properties of the latexes. A first, simple one is based on experimental partition coefficients and a second one is based on more theoretical thermodynamic considerations (volume fractions, interaction χ parameters …). The latter gives a more general insight of emulsion processes and allows to investigate influence of many parameters like monomer-monomer, monomer-polymer, monomer-emulsifier interactions, interfacial tension, particle size, surface charge density… Computer programs are derived which give predictions in rather good agreement with experiments. The thermodynamic approach allows to study crosslinking effect as well as competition between polymerization rate and monomer diffusion rate if some control by diffusion does occur. Owing to these computer programs it becomes possible to correlate many experimental parameters. Most of experimental date are relative to styrene-acrylonitrile copolymerization.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.020101985118
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  • 4
    Electronic Resource
    Electronic Resource
    Preface (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 10 (1985), S. XVII 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.020101985102
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  • 5
    Electronic Resource
    Electronic Resource
    Copolymerisation azeotropique en emulsion (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 10 (1985), S. 165-184 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: While in solution or bulk radical polymerization, only one azeotropic copolymerization can be observed at the best- if reactivity ratios are both 〉 or 〈 1, on the contrary in emulsion batch copolymerization, many more such azeotropic copolymers can be synthesized. Monomer partitioning between droplet, water and particle phases is at the origin of this behaviour of a particular interest, hence water solubility of the monomers plays a determining role. Experimental works confirm the theoretical predictions derived from an approach, based on partition coefficient and thermodynamics, which allows to compute the optimum monomer/water ratio to be used, in order to get, in a batch process, a copolymer of constant composition up to high conversion. The optimum depends upon reactivity ratios, monomer water solubility, monomer feed composition. Examples are given for acrylonitrile/methyl acrylate copolymerizations. It appears that it is not any more Lecessary that they are both greater or lower than unity; for instance, batch emulsion copolymerizations of acrylonitrile/butyl acrylate (rAN = 0.89; rBuA = 1.2) result in homogeneous copolymers at the optimum monomer/water ratio, in the whole range of monomer feed. The approach can also be applied to semi-continuous process to select the best experimental conditions to “tailor” the copolymer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.020101985114
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  • 6
    Electronic Resource
    Electronic Resource
    Preface (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 10 (1985), S. XIII 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.020101985101
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  • 7
    Electronic Resource
    Electronic Resource
    Batch emulsion copolymerization of n-butyl acrylate and methyl methacrylate in the presence of a nonionic surfactant (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 10 (1985), S. 43-57 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Batch emulsion copolymerization studies of n-butyl acrylate and methyl methacrylate have been investigated using potassium persulfate as initiator and a nonionic surfactant (REWOPAL HV 25) as emulsifier. Higher polymerization rates, shorter nucleation stage and complete conversion are obtained by comparison to the SDS-emulsified copolymerization. The kinetic and particle number data support a micellar-type mechanism for the formation of copolymer particles. Strong affinity between the two monomers and the nonionic surfactant results in significantly high solubilization of the surfactant in the initial monomer phase and its subsequent burial inside the final latex particles.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.020101985106
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  • 8
    Electronic Resource
    Electronic Resource
    Study of the thermal decomposition of potassium persulfate by potentiometry and capillary electrophoresis (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1271-1281 
    Details
    ISSN: 0887-624X
    Keywords: potassium persulfate ; decomposition ; soap-emulsified systems ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two methods of analysis, potentiometry and capillary electrophoresis, were used to study the decomposition of potassium persulfate (KPS) in aqueous solutions. The experiments were carried out in a glass reactor equipped with continuous control of temperature and pH during the reaction. The effect of the pH on the decomposition of KPS was investigated. The rate of KPS decomposition in the presence of a variety of additives (surfactants, inhibitor, monomer-like molecules, and monomers), which are used in emulsion polymerization recipes, was also studied over the temperature range of interest. The rate of disappearance of the persulfate ion was greatly increased in the presence of hydroquinone, but changed very little in the presence of surfactants. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Consistent values of rate parameters in free radical polymerization systems (1988)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 26 (1988), S. 293-297 
    Details
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1988.140260704
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  • 10
    Electronic Resource
    Electronic Resource
    Emulsifier-free emulsion copolymerization of styrene and butyl acrylate. II. Kinetic studies in the presence of ionogenic comonomers (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 1937-1959 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Batch emulsifier-free copolymerizations of styrene (S) and butyl acrylate (BuA) have been performed for a S/BuA weight ratio = 50/50 in the presence of two types of functional comonomers [methacrylic acid (MAA) at different pHs] or potassium sulfopropylmethacrylate (SPM) and two initiators [potassium persulfate or 4-4′azobiscyanopentanoic acid (AZO)]. The use of AZO/MAA system results in the formation of polymer particles with only surface carboxylic end groups. The particle size of the final latexes can be adjusted with the MAA concentration, provided the polymerization is carried out at pH 〉 6.5. However, the higher the MAA concentration, the sooner the polymerization levels off in conversion. With the K2S2O8/SPM system, particles bearing only sulfate and sulfonate groups are produced and the polymerization is complete. In that case, the particle size of the final latexes is smaller than with the previous system and 30% of the SPM is fixed on the particle surface, instead of 10% with MAA. Using SPM, a too high functional monomer concentration results in the latex destabilization caused by the formation of a large amount of polyelectrolytes. Kinetic studies indicate that most of the functional monomer is incorporated onto the particle surface during the last 30% conversion of the polymerization. A tentative explanation of such a behavior is discussed, based on the existence of two polymerization loci in the latex system.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260719
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