ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Effect of crosslinking on the properties of poly(2-hydroxyethyl methacrylate) hydrogels (1991)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 189 (1991), S. 195-205 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2-Hydroxyethyl-methacrylat wurde durch Initiierung mit γ-Strahlung in Masse mit zwei verschiedenen tetrafunktionellen Monomeren (Ethylenglycol-dimethacrylat und 1,2-Bis(acryloxymethyl)-tetramethyldisiloxan) und einem hexafunktionellen Monomeren (1,1,1-Trimethylolpropan-trimethacrylat) als Vernetzungsmittel copolymerisiert. Die erhaltenen Xerogele wurden anschließend mit Wasser bis zum Erreichen der Gleichgewichtsquellung behandelt. Um die drei Vernetzungsmittel vergleichen zu können, wurde unter Berücksichtigung von Molmasse und Funktionalität der Xerogele die theoretische Konzentration an Vernetzungsstellen zwischen 0,032 und 0,644 mol/l variiert. Die relative Hydrophobie der drei Vernetzungsmittel hat einen ausschlaggebenden Einfluß sowohl auf die Gleichgewichtsquellung als auch auf den Elastizitätsmodul der gequollenen Gele. Der Gehalt an nicht-einfrierbarem Wasser in mit 1,1,1-Trimethylol-propan-trimethacrylat vernetzten Gelen wurde anhand von DSC-Untersuchungen analysiert. Das Verhältnis von nicht-einfrierbarem zum Gesamtgehalt an Wasser in den Gelen nimmt mit steigender Vernetzungsdichte zu.
    Notes: By means of γ-irradiation 2-hydroxyethyl methacrylate has been copolymerized in bulk with two different tetrafunctional monomers, ethylene glycol dimethacrylate and 1,3-bis(acryloxymethyl) tetramethyl disiloxane and with a hexafunctional monomer, 1,1,1-trimethylolpropane trimethacrylate. The resultant xerogels were subsequently swollen to equilibrium in water. In order to allow a comparison among the three crosslinkers, their molar masses and funtionalities were taken into account, the theoretical crosslink concentrations being varied from 0.032 to 0.644 mol dm-3. The relative hydrophobicity of the three crosslinkers was found to have a significant effect on both the equilibrium swelling and elastic modulus of the swollen gels. Non-freezing water in several gels crosslinked with 1,1,1-trimethylolpropane trimethacrylate was analysed by differential scanning calorimetry (DSC). The proportion of non-freezing water in the gel relative to the overall water content was found to increase with increasing crosslink density.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1991.051890118
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Contamination of surfaces: Origin, detection and effect on adhesion (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 368-372 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Surface contamination is one of the most insidious factors affecting adhesive bond performance and, hence, reliability of bonded structures. Sources of contamination are widespread and include primary materials, secondary materials, equipment, human operators, adjacent processes and the atmosphere. A successful approach to solving contamination problems involves the identification of the contamination and its source, establishment of the level of contamination that degrades the given bond, development of a plan to correct the problem and prevent contamination from occurring again, and subsequent verification of adequate substrate cleanlines prior to bonding. This generic approach is discussed and examples are cited to illustrate its use.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740200507
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A molecular orbital study of the interactions of acrylic polymers with aluminum: Implications for adhesion (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 3185-3219 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present results of molecular orbital thory calculations of the interactions of acrylic polymers with aluminum, with a view toward understanding the nature of chemical bonding at the corresponding polymer-metal interfaces. The reported results are for the interactions of polymer model compounds with metal atoms (as opposed to our ongoing studies with metal surfaces). As such, the results relate to experimental studies where small dosages of metal atoms are evaporated onto polymer surfaces in pristine high vacuum environments. Our studies have been conducted within the theoretical framework of Hartree-Fock molecular orbital theory. We find that aluminum atoms interact primarily with the carbonyl group of acrylic polymers. The reaction proceeds by the metal atoms interacting with both the carbon and the oxygen atoms of the carbonyl functionality. This weakens the C=O bond. Finally, the carbonyl bond loses double bond character, and strong AL - O bonds are formed. Our results are compared to experimental data, and the implications of the detailed nature of bonding for adhesion applications are discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281201
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Determining the chromophore in the amylopectin-iodine complex by theoretical and experimental studies (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2257-2265 
    Details
    ISSN: 0887-624X
    Keywords: helix in amylopectin-iodine complex ; I4 unit in amylopectin-iodine complex ; spectra of amylopectin-iodine complex ; amylopectin-iodine chromophore composition ; amylopectin fine structures and complex formation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A partial hydrolysis of amylose followed by the addition of iodine provides a spectrum almost identical to that of the amylopectin-iodine (API) complex suggesting the involvement of smaller “amylose-like” units in the API complex. Our theoretical studies on different polyiodine and polyiodide species suggest that a nearly linear I4 unit stabilized within the cavity of a small “amylose-like” helix is responsible for the characteristic API spectrum. Since there are 2.75 anhydroglucose residues (AGU) for every iodine atom in the amylose-iodine (AI) complex and a structural similarity exists between the API and the AI (amylose-iodine) complexes, we identify (C6H10O5)11I4 to be the chromophore in the API complex. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321207
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Liquid crystal elastomers: Synthesis and characterization (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 1455-1472 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis is described of some acrylate based polymers containing both a mesogenic group (4-cyanophenyl benzoate) connected to the polymer backbone by a flexible spacer, and varying degrees of crosslinking, introduced by copolymerization. Optical and calorimetric techniques are used to determine the phase behavior, which is found to depend strongly on the crosslink density (and the flexible spacer length); though (nominally) a relatively high degree of crosslinking is possible without completely destroying the liquid crystal phase. Mechanical measurements in conjunction with supplementary analytical data, where available, are used to determine the efficiency of copolymerization at introducing intermolecular crosslinking. Some possible explanations for the unexpectedly low efficiency of this process are discussed. The properties of materials prepared in this fashion are compared briefly with some examples where crosslinking is introduced after polymerization; this latter process is seen to be rather more efficient.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280613
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Characterization of a thermally imidized soluble polyimide film (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 3107-3122 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A soluble aromatic poly (amic acid) film was converted to a soluble polyimide by staging at 25°C intervals to 325°C and characterized at each interval by several analytical methods. The behavior observed was consistent with an interpretation that a reduction occurred in molecular weight of the poly (amic acid) during the initial stages of cure before the ultimate molecular weight was achieved as a polyimide. This interpretation was supported by the results of solution viscosity, gel permeation chromatography, low angle laser light scattering photometry, and infrared spectroscopy analyses. The results of this study serve to increase our fundamental understanding of how polyimides are thermally formed from poly (amic acid)s.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281117
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Preparation and properties of poly(alkyl vinyl ether-2-ethyl-2-oxazoline) diblock copolymers (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 1709-1717 
    Details
    ISSN: 0887-624X
    Keywords: poly(methyl vinyl ether); poly(butyl vinyl ether) ; poly(2-ethyl-2-oxazoline) ; block copolymers ; living cationic polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for the synthesis of well-defined poly(alkyl vinyl ether-2-ethyl-2-oxazoline) diblock copolymers with hydrolytically stable block linkages has been developed. Monofunctional poly(alkyl vinyl ether) oligomers with nearly Poisson molecular weight distributions were prepared via a living cationic polymerization method using chloroethyl vinyl ether together with HI/ZnI2 as the initiating system and lithium borohydride as the termination reagent. Using the resultant chloroethyl ether functional oligomers in combination with sodium iodide as macroinitiators, 2-ethyl-2-oxazoline was polymerized in chlorobenzene/NMP to afford diblock copolymers. A series of poly(methyl vinyl ether-2-ethyl-2-oxazoline) diblock materials were found to have polydispersities of ≈ 1.3-1.4 and are microphase separated as indicated by two Tg's in their DSC thermograms. These copolymers are presently being used as model materials to study fundamental parameters important for steric stabilization of dispersions in polar media. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310709
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Iodine binding by amylopectin and stability of the amylopectin-iodine complex (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2267-2274 
    Details
    ISSN: 0887-624X
    Keywords: amylopectin, iodine binding capacity ; amylopectin, iodine binding energy of ; iodine binding and amylopectin fine structures ; Amylose-iodine and amylopectin-iodine complexes of fixed composition ; peak shift in amylose-iodine spectrum and different iodine species ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The iodine binding capacity (IBC) of amylopectin (AP, from potatoes) is determined to be around 0.38% (w/w) of the total AP in the solution. The mass of iodine bound comprises about 13.6% of the mass of AP involved with the complex, suggesting that with every four iodine atoms bound there are 23 anhydroglucose residues (AGU). Since our previous study indicates that four iodine atoms within the helix of 11 AGUs form a chromophore unit in the API complex, only 48% of the AGUs (11 out of 23) in the AP molecule are directly involved with the iodine. The heat of reaction for the API complex formation is determined to be around -47 kJ/mol of I-I units bound and is significantly lower in magnitude than that of the amylose-iodine (AI) complex [Biopolymers, 31, 57 (1991)]. A possible mechanism has been proposed for the formation of AI and API complexes with fixed compositions. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Copolymerization kinetics of 4-methoxystyrene with methyl methacrylate and 4-methoxystyrene with styrene: A test of the penultimate model (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2097-2106 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The propagation kinetics for the copolymerization of 4-methoxystyrene with methyl methacrylate and 4-methoxystyrene with styrene have been investigated using a pulsed laser technique. The dependence of the copolymerization propagation rate constant on the monomer feed ratio shows a diviation from classic Mayo-Lewis model kinetics for 4-methoxystyrene with methyl methacrylate but not for 4-methoxystyrene with styrene. These results have been interpreted to indicate that a penultimate effect is apparent in the first monomer pair but not in the second. With r1r2 = 0.092 for the copolymerization of 4-methoxystyrene with methyl methacrylate and r1r2 = 0.95 for 4-methoxystyrene with styrene, it is suggested that a deviation of the product of the coplymerization reactivity ratios from unity may be an indication of the presence of a penultimate effect.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280807
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Studies of alkylthio-substituted aromatic diamines as curatives for polyurethane cast elastomers (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 3701-3724 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of alkylthio-substituted aromatic diamines was synthesized using a convenient high yield procedure. The method consisted of heating a mixture of dialkyl disulfide and aromatic diamine in the presence of cuprous iodide or other Lewis acid catalyst. Dialkyl disulfide was continually replenished as consumed, throughout the reaction, to maintain the desired reaction temperature. Compounds so prepared were isolated by first precipitating the catalyst with solid caustic and then vacuum flashing the crude products. When desired, the final product purity could be increased by washing with acid to remove starting material or reaction intermediates. The final products were often liquids or low melting solids and showed utility as curatives for polyurethane cast elastomers. Alkylthio substitution of the aromatic diamines lowered reactivity toward isocyanates and generally provided for facile processing during molding. The series of derivatives allowed for great flexibility in controlling both diamine reactivity and the physical properties of the final elastomers. These benefits arose from the diverse electronic, steric and isomeric properties of the derivatives. Polymers were prepared from the alkylthio-substituted compounds and commercially available TDI-based prepolymers using conventional cast elastomer techniques. The physical properties of the polymers were determined and their relation to alkylthiodiamine structure examined.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281315
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...