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  • 1985-1989  (12)
  • 1955-1959
  • Polymer and Materials Science  (8)
  • Engineering  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Temperature dependence of ESR spectra of methyl methacrylate radicals from 77 K to 300 K (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 127-136 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radicals formed in poly(methyl methacrylate) (PMMA) under vacuum by UV irradiation at room temperature were carefully examined from 77 K to 300 K by electron spin resonance (ESR). The conventional nine-line spectrum was observed with significant overall intensity changes in contrast to previous reports. The intensity decreases greatly as the temperature increases from 77 K to 100 K. The intensity of the ESR spectrum increases as the temperature increases gradually from 100 K to 260 K. The spectral changes were reversible at all temperatures. Three different models are considered to interpret the temperature dependence of the intensity of the ESR spectrum. The results indicate that the ESR spectrum depends on (1) the steady-state concentration of the propagating radical in the polymer, (2) the conformational distributions of the radicals, and (3) the environmental structures of the polymer matrix.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250111
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  • 2
    Electronic Resource
    Electronic Resource
    Solid state suspension polymerization of N-vinyl-t-butylcarbamate (1986)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 24 (1986), S. 627-630 
    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.1986.140241202
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  • 3
    Electronic Resource
    Electronic Resource
    Syntheses of stereoregular and optically active polyamides from active 4-chloro-1-benzotriazolyl diesters and diamines (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 75-85 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new route to prepare optically active polyamides was established, based on the polycondensation of two new active diesters: the active diesters of 4-chloro-1 hydroxybenzotriazole, such as 1,1'-(terephthaloyldioxy)bis(4-chloro-benzotriazole), and 1,1'-(isophthaloyldioxy)bis(4-chlorobenzotriazole), with optically active isomers of 2,4-diaminopentane. Dipolar aprotic solvents such as N,N-dimethylformamide and dimethyl sulfoxide were used as reaction solvents. The solution polycondensation carried out in solution at room temperature afforded optically active polyamides. The aminolysis of the two active diesters was carried out as a model reaction study.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240106
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  • 4
    Electronic Resource
    Electronic Resource
    Novel optical resolution of an unprotected adenine derivative followed by grafting the pendant onto polyethylenimine (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 167-171 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240115
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  • 5
    Electronic Resource
    Electronic Resource
    Grafting of optically active nucleic acid base derivatives onto poly(vinylamine) as polynucleotide analogsPreliminary results are reported in J. Polym. Sci. Polym. Lett. Ed., 23, 345 (1985). (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 389-403 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polynucleotide analogs consisting of poly(vinylamine) as the backbone and optically active thymine and adenine derivatives as the pendants were synthesized. The pendants were prepared by the addition reaction of the nucleic acid base to ethyl crotonate followed by hydrolysis. The pendants were resolved using brucine as the resolving agent and an acetone-water mixture as the fractional crystallization solvent. The active esters of the pendants also were prepared. Poly(vinylamine) was isolated from water employing a weak acid, N-hydroxysuccinimide (HOSu), to protect the amino group of the poly(vinylamine). Model reactions for grafting were examined. Grafting reactions were carried out by reacting the active esters with the PVAm.6HOSu complex at room temperature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250134
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of polynucleotide analogs by grafting optically active nucleic acid base derivatives onto polyethyleniminePreliminary results are reported in J. Polym. Sci. Polym. Chem. Ed., 24, 167 (1986). (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 373-388 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polynucleotide analogs with a polyethylenimine backbone and optically active thymine- and adenine-containing pendants and their model compounds were synthesized. The pendants were prepared by the addition reaction of the nucleic acid base to ethyl crotonate. The ammonium salt of 3-(adenin-9-yl)butyric acid was employed to replace its free acid for the formation of diastereomeric salt with brucine. Fractional crystallization of the diastereomeric salt generates the partially resolved enantiomers. The solubility difference between the racemic mixture and its enantiomer was utilized to obtain the pure enantiomers. The active esters of the pendants were prepared. Grafting reactions were carried out by the reaction of active esters with PEI at room temperature. Completely grafted polymers were obtained.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250133
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  • 7
    Electronic Resource
    Electronic Resource
    The boron trifluoride monoethyl amine complex cured epoxy resins (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 1105-1124 
    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 curing exotherm pattern is affected by the equivalent ratio of curing agent, boron trifluoride monoethylamine complex (BF3 · MEA), to epoxy resin. The diglycidyl ether of 9,9-bis(4-hydroxyphenyl) fluorene (DGEBF) cures more slowly than the diglycidyl ether of bisphenol A (Epon 828). The glass transition temperatures (Tg's) of BF3 · MEA cured Epon 828 are increased with inceasing concentration of curing agent (0.0450-0.1350 eq.) cured DGEBF. The activation energies for the thermal decomposition for BF3 · MEA (0.0450-0.1350 eq.) cured DGEBF. The activation energies for the thermal decomposition for BF3 · MEA (0.0450 eq./epoxy eq.) cured Epon 828 and DGEBF are almost equivalent 43 and 44 kcal/mol, respectively. DGEBF when added to DGEBA improves the Tg and char yield with the BF3 · MEA curing system. The Tg of both resin systems can be increased by longer post cure, whereas the char yield does not appear to change significantly. No ester group formation is found for the BF3 · MEA-cured DGEBF, although this has been previously reported for the DGEBA system. The BF3 · MEA cure at 120°C is better than at 140°C because of vaporization and degradation of the curing agent at the higher temperature. The rapid gelation of the epoxy resin may be another reason for the lower degree of cure at high temperature.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070370421
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  • 8
    Electronic Resource
    Electronic Resource
    Multi-level finite element solution algorithms based on multiplicative and additive correction procedures (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 27-41 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Owing to the failure of the finite element analyst to employ a properly refined computational model, the accuracy of preliminary finite element computations is often low. Thus, it is useful to introduce a computational procedure for improving the results obtained from a preliminary finite element solution. Such a procedure is presented in this paper. In this procedure the solution error components are decomposed into two parts. One of the error components is assumed to have a long period variation. The other component is assumed to have a short period variation. Multiplicative and additive correction procedures are introduced to iteratively eliminate the two error components. The multiplicative and additive correction procedures are implemented using multi-level solution techniques.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280105
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  • 9
    Electronic Resource
    Electronic Resource
    Modelling and simulation of load transfer in reinforced soils: Part 1 (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 12 (1988), S. 141-155 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Results of both triaxial and direct shear tests on reinforced soil samples performed by different investigators have shown that soil dilatancy and extensibility of the reinforcements have a significant effect on the generated tension forces in the inclusions. An appropriate soil--reinforcement load transfer model, integrating the effect of soil dilatancy and reinforcement extensibility is therefore needed to adequately predict forces in the inclusions under expected working loads. This paper present a load transfer model assuming an elastoplastic strain hardening behaviour for the soil and an elastic--perfectly plastic behaviour for the reinforcement. This model is used to analyse the response of the reinforced soil material under triaxial compression loading. A companion paper present the application of this model for numerical simulations of direct shear tests on sand samples reinforced with different types of tension resisting reinforcements. The model allows an evaluation of the effect of various parameters such as mechanical characteristics and dilatancy properties of the soil, extensibility of the reinforcements, and their inclination with respect to the failure surface, on the development of resisting tensile stresses in the reinforcements. A parametric study is conducted to evaluate the effect of these parameters on the behaviour of the reinforced soil material. An attempt is also made to verify the proposed model by comparing numerical predictions with available experimental results of both triaxial and direct shear tests on reinforced soil samples. This model can be used for analysis and design of reinforced soil walls with different types of tension resisting inclusions to predict tension forces under expected working loads.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610120203
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  • 10
    Electronic Resource
    Electronic Resource
    Numerical analysis of the response of reinforced soils to direct shearing: Part 2 (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 12 (1988), S. 157-171 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A soil-reinforcement load transfer model was developed by the authors1 to simulate the response of the reinforced soil material to triaxial compression and direct shearing. This paper presents the application of the proposed model for the numerical analysis of direct shear tests on sand samples reinforced with different types of tension resisting reinforcements. A parametric study is conducted to evaluate the effect of the mechanical characteristics and dilatancy properties of the soil, extensibility (elastic modulus) of the reinforcements, and their inclination with respect to the failure surface on the response of the reinforced soil material to direct shearing. An attempt is made to verify the proposed model by comparing numerical test simulations with experimental results reported by Jewell,2 and Gray and Ohashi.3 Comparisons of predicted and experimental results illustrate that the model can provide adequate simulations of the response of the reinforced soil material to shearing. In particular, it allows an evaluation of the effect of soil dilatancy (or contractancy), and extensibility of the reinforcement on tension forces generated in inclusions during shearing.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610120204
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