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  • 1
    Digitale Medien
    Digitale Medien
    Extrusion behavior of starch graft copolymers: Starch-g-polystyrene and starch-g-poly(methyl acrylate) (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 194 (1992), S. 23-33 
    Details
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Stärke/Styrol- und Stärke/Methylacrylat-Pfropfcopolymere wurden hergestellt und ohne vorherige Abtrennung von homopolymerem Polystyrol (PS) bzw. Poly(methylacrylat) (PMA) extrudiert. Das Extrusionsverhalten ähnelte dem thermoplastischer Schmelzen darin, daß die Copolymeren die Scherung herabsetzen, eine merkliche Strangaufweitung verursachen und Eingangsdruckverluste im Kapillarfließerhalten auftreten. Diese und andere Beobachtungen deuten darauf hin, daß diese Materialien deformierbare, mit dem jeweiligen Polymeren gepfropfte Stärkepartikel in der entsprechenden Homopolymermatrix enthalten. Die Fließeigenschaften können anscheinend eher durch solche „Superpartikel“ als durch das Model1 einer kontinuierlichen, homogenen Schmelze erklärt werden.
    Notizen: Starch-g-polystyrene and starch-g-poly(methyl acrylate) copolymers were synthesized and extruded without separating homopolymer PS or PMA. The extrusion behavior resembled that of thermoplastic melts in that these products were shear thinning and exhibited significant extrudate swelling and entrance pressure losses in capillary flow. These and other observations indicate that the materials comprise deformable polymer-grafted starch particles suspended in the corresponding homopolymer melt. Flow is apparently by superparticle, rather than continuum melt mechanisms.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/apmc.1992.051940103
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  • 2
    Digitale Medien
    Digitale Medien
    Stabilization of polystyrene/poly(methyl methacrylate) blends by in situ compatibilization with graft copolymers (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 3153-3166 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Copolymers of styrene and ortho-vinylbenzaldehyde (o-VBA) are useful precursors to multicomponent polymer systems. Graft copolymers of poly(styrene-stat-o-VBA) can be produced by free-radical chain transfer to methyl methacrylate monomer to yield materials that display some potential as interfacial agents with binary blends of polystyrene and poly(methyl methacrylate). Significant improvements in ultimate tensile strengths and energy to rupture values have been witnessed for polystyrene/poly(methyl methacrylate) mixtures that contain various levels of the graft component. Scanning electron microscopy of representative fracture surfaces demonstrate a decrease in the particle size of the dispersed phase; it is suggested that this morphological factor contributes to the superior mechanical properties of these composites. In this regard, both the isolated and the crude graft copolymers are able to compatibilize, and thereby enhance, the material properties of polystyrene/poly(methyl methacrylate) blends.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1989.021901213
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  • 3
    Digitale Medien
    Digitale Medien
    Equivalent hydrodynamic sphere models for viscosity, sedimentation, and diffusion (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 2977-2988 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Available data for intrinsic viscosity, molecular weight and infinite dilution frictional properties of polymer-solvent systems are used to establish the relation between the radius, rf, of a “frictional” equivalent sphere applicable to sedimentation and diffusion phenomena, and the radius, rη, of the “viscosity” hydrodynamic sphere. It is found that the experimental data agree with a common equivalent hydrodynamic sphere model in which rη = rf.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1978.021791218
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  • 4
    Digitale Medien
    Digitale Medien
    Characterization of non-homogeneous polymers with size-exclusion chromatography by implementing an on-line viscometer (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 1953-1963 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The viscosity distribution of a polymer sample can be obtained by using an on-line viscometer as a detector in size-exclusion chromatography. This newly defined viscosity distribution is closely related to the molecular weight distribution and expresses weight fraction times intrinsic viscosity of species i as a function of the corresponding molecular weight times intrinsic viscosity (wi[ηi] vs. Mi[ηi]). The intrinsic viscosity ([η]) and number-average molecular weight (M̄n) can be obtained directly from a viscosity distribution. If the Mark-Houwink exponent a is known (or approximately known) for non-homogeneous polymer the M̄w/M̄n can be estimated from the viscosity distribution when the molecular weight distribution is approximated with a known distribution function. These estimates are independent of any other detector and are valid even for non-homogeneous polymer samples. The relation between the moments of the viscosity distribution and the M̄w/M̄n is presented for two widely used distribution functions, the Log-Normal and the Generalized Exponential Distributions. Polymer characterization based on the viscosity distribution is shown to be a robust technique. It is particularly attractive in characterizing non-homogeneous polymers since it is solely obtained from on-line viscometer.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1993.021940709
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  • 5
    Digitale Medien
    Digitale Medien
    Multi-detector size-exclusion chromatography: a novel approach to calibration eliminating lag time estimation (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 1965-1974 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: In order to obtain the correct calibration of molecular-weight sensitive detectors (such as on-line viscometers or light scattering detectors) in size-exclusion chromatography, it is necessary to account for the (molecular) non-uniformity of the calibration standards. This is true even in the case of the narrow molecular weight distribution standards typically commercially available for calibration. Methods of taking this non-uniformity into consideration are presented. For a multi-detector size-exclusion chromatography system calibrated in this way, independent calibration curves can be established for each detector. Thus, at a given hydrodynamic volume, corresponding signals from the different detectors can be obtained. This eliminates the need to estimate additional parameters such as interdetector volumes or lag times for matching signals from different detectors. The practicability of this approach in the analysis of (molecularly) non-uniform polymers is demonstrated by combining on-line viscometer and concentration signals (to obtain intrinsic viscosity versus molecular weight information) for two different polymers, viz. polystyrene and poly(methyl methacrylate). The resultant intrinsic viscosity versus molecular weight data is then compared to that predicted from the literature.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1993.021940710
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  • 6
    Digitale Medien
    Digitale Medien
    Chemical modification of polydienes, 3Part 2: cf.2.. Copolymers with polytetrahydrofuran by grafting-from butadiene polymers (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 2763-2774 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Polybutadienes of various microstructures and some butadiene copolymers were epoxidised to low levels (〈1 mol-%) with m-chloroperbenzoic acid. The epoxide groups functioned as initiation sites for a “grafting-from polymerization” of tetrahydrofuran (THF) catalysed by BF3. By conducting the reaction in dilute THF solution ([Monomeric unit] 〈 0,3 mol · 1-1) with a large excess of BF3 over epoxide groups, gel formation was avoided. The conversion of THF was less than 2% and the copolymers contained from 10 to 50% polytetrahydrofuran (PTHF) comprising graft chains of molar mass up to 43000 g · mol-1. The relative rate of grafting tended to decrease as the content of trans-1,4 units in the backbone polymer increased, and, unusually, there was a small increase in volume during the graft copolymerization. The graft copolymers had a two-phase morphology consisting of amorphous rubber and crystallites of PTHF. The latter function as physical crosslinks which break down above the melting point of PTHF, so that the materials behave as thermoplastic elastomers.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1986.021871203
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  • 7
    Digitale Medien
    Digitale Medien
    Gel permeation chromatography of polymer mixtures (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 2801-2809 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: When mixtures of polymers are analyzed in a common gel permeation chromatographic solvent the peak elution volumes of both components are shifted with respect to their values at their nominal concentrations in the same solvent and column set. In this article a theory which has been applied previously to account for concentration effects of a single polymer in a GPC solvent is modified to predict peak elution volumes in polymer mixtures. The model invokes solvent-solute interactions only and provides quantitative predictions of the behavior of mixtures of anionic polystyrene samples with other polystyrenes and with polybutadienes. There is no indication of polymer-polymer repulsive effects except for polystyrene-poly(methylmethacrylate) mixtures at relatively high concentrations.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1981.021821025
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  • 8
    Digitale Medien
    Digitale Medien
    Effect of carbon black on time dependence of the melt flow indexPaper presented at 22nd ANTEC Meeting, Society of Plastics Engineers, Montreal, Canada, March 1966. (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 1043-1053 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Time dependence in the melt indexing of polyolefins stabilized against thermally induced changes is well known, the prevalent effect being an increase in melt index toward a steady-state value. The melt index of polyethylenes compounded with carbon black has been found to decrease, in some cases radically, although oxygen uptake data show no evidence of thermal instability. The melt index-time plot can be restored to its normal shape by adding excess quantities of a standard thioether antioxidant. Data are rationalized by assuming that polyethylene adsorbs on the available pigment surface, forming a crosslink network. The thioether antioxidant, however, may adsorb preferentially, thereby restoring the normal response of the polymer to forces resulting in its capillary extrusion. The results emphasize the contribution of chain orientation effects to the time dependence of melt index.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1967.070110704
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  • 9
    Digitale Medien
    Digitale Medien
    Estimation of viscosities of mixed polymer solutions (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1281-1293 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A semiempirical model for estimation of viscosities of concentrated polymer solutions1 can be applied to mixtures of polymers in a common solvent. The data required for estimation of mixture viscosity are: solvent viscosity, polymer molecular weight, density, concentration, and intrinsic viscosity in the particular solvent. Calculated and experimental viscosities agree to within a few per cent for the relatively nonpolar systems for which comparative data are available. The model does not appear to be adequate for mixtures in which there are extensive hydrogen-bonding interactions.Results of the new model are equivalent to those of an empirical equation2 reported to be effective for fairly concentrated binary polymer mixtures.Specific interactions between polymeric solutes can be conveniently assessed by comparing measured mixture viscosity to that calculated from the model presented. It is not clear, however, that such assessments have any fundamental significance, since the interactions which are calculated depend on the assumptions inherent in the estimation of the “ideal” mixture viscosity. The same reservations apply to other models which have been proposed for this purpose.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1972.070160518
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  • 10
    Digitale Medien
    Digitale Medien
    Falling coaxial cylinder viscometer for polymer solutions (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 1467-1473 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A simple, inexpensive glass viscometer can be constructed to time the rate at which a rod falls into a liquid held in a concentric closed-end glass cylinder. This equipment can be used to measure absolute values of apparent viscosities of Newtonian and non-Newtonian fluids. Calibration is not required. The technique is an adaptation of a method used previously with polymer melts at elevated temperatures. The present article describes the modifications needed for lower-viscosity fluids, such as paints, and validates the flow analysis with results of study of a characterized Newtonian fluid.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1976.070200605
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