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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of polymer research 3 (1996), S. 165-171 
    ISSN: 1572-8935
    Keywords: IPN ; Damping peak ; Viscosity increase ; Network interlock ; Impact resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Polyurethane (PU) was made by reacting stoichiometric equivalent of trimethylol propane (TMP) and desmodur L. Fully interpenetrating polymer networks (fully IPN's) of various compositions based on PU and poly(ethylene glycol) diacrylate (PEGDA) were prepared by blending various ratios of PU/PEGDA, and cured by benzoyl peroxide (BPO). Semi-interpenetrating polymer networks based on PU and poly(ethylene glycol) monomethyl ether of acrylate (PEGMEA) were prepared in a similar way. Shift of exothermic peaks during IPN formation were examined with dynamic DSC. Viscosity increases were investigated with a Brookfield RVT type viscometer. Dynamic mechanical properties were probed via a rheometric dynamic spectroscopy (RDS). Expermintal results revealed a good compatibility of both IPN systems, as evidenced from the single damping peak of the RDS curves for each composition. Shifts of exothermic peaks to higher temperatures during the formation of fully IPN were observed, especially for the composition of PU/PEGDA = 50/50, which showed an exothermic peak at the highest temperature. Experimental results also revealed delayed viscosity increases and decreased gel fractions for all fully IPN's. On the contrary, the semi-IPN did not exhibibt similar phenomena. All these findings supported an effect of network interlock during fully IPN formation. The existence of a network not only provided a sterically hindered environment, but also restrained the chain mobility of the growing network, and vice versa, thus retarding the curing rates of both networks. Network interlock also broadened the width of the half damping peak, ΔT1/2, and subsequently led to improved mechanical properties such as the impact resistance and Young's modulus of fully IPN material.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of polymer research 3 (1996), S. 173-176 
    ISSN: 1572-8935
    Keywords: SIN formation ; Kinetics ; Network interlock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Poly(ethylene glycol) diacrylate (PEGDA) was synthesized by reacting poly(ethylene glycol) and acrylol chloride. PEGDA network formation was induced by using benzoyl peroxide (BPO) as a curing agent. Polyurethane (PU) network was prepared by reacting equimolar amounts of trimethylol propane (TMP) and desmodur L. Simultaneous interpenetrating polymer network (SIN) was prepared by using the same curing method. Changes of functional groups were monitored by FTIR. Kinetic study of the SIN formation was done at 70, 75, 80, and 85 °C. The kinetic parameters were compared with those of the respective PEGDA and PU network formation. Experimental results revealed that SIN indicated a lower rate constant and a higher activation energy than the respective pure PEGDA and PU components. A network interlock effect was proposed to explain the observed phnomenon.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 815-827 
    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: Study of the simultaneous interpenetrating polymer network (IPN) between diglycidyl ether of bisphenol-A (DGEBA) and unsaturated polyester (UP) was carried out at ambient temperature. Fourier transform infrared (FTIR) spectroscopy was employed to investigate the intermolecular H-bonding and functional group changes. Viscosity changes due to H-bonding and crosslinking were examined with a Brookfield viscometer. Gelation time was measured by a Techne gelation timer. Complexation between Co(II) (the promoter for UP cure) and diamine (the curing agent for DGEBA) was detected with UV-visible spectrometer. Experimental evidence revealed that intermolecular interactions were observed in systems such as DGEBA/UP, DGEBA/diamine, Co(II)/diamine, DGEBA/uncured UP, and UP/uncured DGEBA. All such interactions had measurable effects on the curing behaviors for both networks, as were indicated by the viscosity changes and gelation time. The IPNs thus obtained were further characterized with rheometric dynamic spectroscopy (RDS) and differential scanning calorimetry (DSC). Partial compatibility between UP and DGEBA networks was evidenced from a main damping peak with a shoulder near glass transition temperature (Tg) for lower UP content; while at higher UP content, only a main damping peak near Tg was observed. DSC revealed a broad glass transition for all IPNs. The resultant IPN materials were all transparent. © 1992 John Wiley & Sons, Inc.
    Additional Material: 18 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2303-2312 
    ISSN: 0887-624X
    Keywords: crosslinkable ; allylation ; epoxidation ; 1H-NMR integration ; degree of substitution (DS) ; anhydroglucose (AHG) unit ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Allyl cellulose was synthesized by reacting cellulose with allyl bromide in homogeneous LiCl/DMAc solution containing NaOH powder. The degree of substitution (DS) per anhydroglucose (AHG) unit was determined by titrating the allyl cellulose with bromine in chloroform solution, and an allyl DS of 2.80 was found. Glycidyl cellulose was then prepared by reacting this allyl cellulose with peracetic acid in methylene chloride at ambient temperature for 6 days. The measured reaction rate constant was 1.33 × 10-3 min-1. The glycidyl cellulose thus obtained with a glycidyl DS of 2.58 was determined by titrating the product with perchloric acid in conjunction with tetrabutylammonium iodide. The 2.58 of glycidyl DS was also confirmed by 1H-NMR integration. Both allyl cellulose and glycidyl cellulose were analyzed and characterized with FTIR, 1H-NMR, 13C-NMR, TGA, and GPC. During epoxidation of allyl cellulose, possible side reaction leading to ester formation was evidenced from the continuous increase of vC—O at 1735 cm-1 in FTIR analyses. In addition, a bimodal distribution and a decreased molecular weight for glycidyl cellulose were found from GPC data, which might suggest a possible chain scission at the cellulosic ether linkage. © 1992 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1941-1951 
    ISSN: 0887-624X
    Keywords: IPN formation ; H-bonding ; network interlock ; viscosity increase compatibility ; cure rate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(ethylene glycol) diacrylate was synthesized from poly(ethylene glycol) of molecular weight 600 with acryloyl chloride in a molar ratio of 1:2. Poly(ethylene glycol) diacrylate (PEGDA) was then blended with diglycidyl ether of bisphenol A (DGEBA) in various ratios, followed by curing with 2,2′-azobisisobutyronitrile (AIBN) and isophronediamine (IPDA) simultaneously. Viscosity changes before and during IPN formation were examined with a Brookfield viscometer. Formation of H-bonding and functional group changes were investigated with FTIR. Exothermic curing thermograms were recorded with dynamic DSC. Optically clear IPNs thus obtained were characterized with rheometric dynamic spectroscopy (RDS) and scanning electron microscopy (SEM) to check possible compatibility of the two networks. Experimental results revealed that during IPN formation hydrogen bonds between PEGDA and DGEBA and interlock of networks had profound effect on viscosity change and pot-life. Complete compatibility of the IPNs was found as DGEBA content was higher than 50% by weight. The compatibility between PEGDA and DGEBA networks was evidenced from inner shift of a single damping peak in RDS. In the meantime, SEM micrographs confirmed the coincidence with the result of RDS © 1992 John Wiley &Sons, Inc.
    Additional Material: 14 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 2093-2102 
    ISSN: 0887-624X
    Keywords: network interlock ; compatible ; viscosity increase ; SIN's ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diallyl phthalate (DAP) was blended with diglycidyl ether of bisphenol A (DGEBA) in various weight ratios: 100/0, 75/25, 50/50, 25/75, and 0/100. These blends were then cured simultaneously with dicumyl peroxide (DCP) and hexahydrophthalic anhydride (HHPA) in conjunction with 2-cyanoethyl-4-methyl immidazole (EMI-CN, 0.5% as catalyst) to obtain simultaneous interpenetrating polymer networks (SIN's). H-bonding between DAP and DGEBA was detected with FTIR. The SIN's thus obtained were characterized with rheometric dynamic spectroscopy (RDS) and differential scanning calorimeter (DSC) to check the compatibility of components. Gel fractions were measured with a Soxhlet extractor. Viscosity increases of all SIN's were measured with a Brookfield viscometer at curing temperatures. Conversions of C = C and epoxide versus cure time were monitored with FTIR and kinetic parameters were calculated and discussed. Experimental results revealed that H-bonding in the DAP/DGEBA blends was evidenced from the shift of the IR band (vc=o) to a lower wave number, as well as the shift of epoxide band (vδ) to a higher wave number. Complete compatibility between DAP and DGEBA was supported from the single damping peak in DRS and single glass transition in DSC for each of SIN's. Cure dynamic DSC showed shifts of exothermic peaks to higher temperatures for all SIN's. During SIN formation, the slower viscosity increases of SIN's were found, compared with pure DAP and pure DGEBA, indicating retarded cure rates for all SIN's. In addition, lower gel fractions of SIN's were observed, indicating incomplete cure of SIN's. The retarded cure rate was further confirmed by kinetic study. Lower rate constants with higher activation energies for all SIN's were found. An effect of network interlock was proposed to account for these findings. © 1993 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 3317-3325 
    ISSN: 0887-624X
    Keywords: simultaneous interpenetrating polymer network (SIN) ; kinetic parameter ; network interlock ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simultaneous interpenetrating polymer networks (SINs) based on diglycidyl ether of bis-phenol A (DGEBA) and poly(ethylene glycol) diacrylate (PEGDA) in weight ratios of 100/0, 50/50, and 0/100 were blended and cured simultaneously by using benzoyl peroxide (BPO) and m-xylenediamine (MXDA) as curing agents. A kinetic study during SIN formation was carried out at 45, 55, 63, and 70°C. Concentration changes for both the epoxide and C=C bond were monitored with FTIR. A rate expression for DGEBA cure kinetics was established with a model reaction of phenyl glycidyl ether (PGE) and benzylamine. Experimental results revealed that lower rate constants and higher activation energy for the SIN were found, compared with those for the constituent DGEBA and PEGDA network formation. A model of network interlock was proposed to account for this phenomenon. During simultaneous cure of DGEBA and PEGDA, the interlock (mutual entanglement) between DGEBA and PEGDA networks provided a sterically hindered environment, which subsequently increased the activation energy and reduced cure rates for both DGEBA and PEGDA. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 1607-1617 
    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: Simultaneous interpenetrating polymer networks (SIN) based on diglycidyl ether of bisphenol-A (DGEBA) and unsaturated polyester (UP) in weight ratios of 100/0, 50/50, and 0/100 were blended and cured simultaneously by using cumene hydroperoxide (CHP) and m-xylenediamine (MXDA) as curing agents. A kinetic study during SIN formation was carried out at 43, 53, 58, and 64°C. Concentration changes for both epoxide and C=C bond were monitored with Fourier transform infrared (FTIR). Rate expressions for epoxide polymerization were established with model reactions for phenyl glycidyl ether (PGE) and benzylamine in dichloroethane containing benzyl alcohol. Experimental results revealed that a lower cure rate constant for the C=C bond during SIN formation was found, compared with pure UP network formation. A model of network interlock is proposed to account for this phenomenon. During simultaneous cure of DGEBA and UP, the network interlock should provide a sterically hindered environment, which subsequently retards cure rate for UP. On the other hand, epoxide cure during SIN formation indicates higher rate constants for both uncatalyzed and catalyzed reactions, compared with those of pure DGEBA cure. Presumably the catalytic effect of hydroxyl end groups in UP overcomes the effect of network interlock. Kinetic parameters were calculated and are discussed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 9
    Publication Date: 1998-05-18
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 10
    Publication Date: 2004-08-01
    Print ISSN: 0379-6779
    Electronic ISSN: 1879-3290
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Elsevier
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