Dynamic mechanical behaviour and its dependence on preparation method of structural epoxide resin

Mikołajczak, G.; Cavaillé, J.Y.; Johari, G. P.

doi:10.1016/0032-3861(87)90036-x

Cited by 63 publications

(34 citation statements)

References 19 publications

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“…The first section, from −100 to 0 °C, refers to the β‐transition of the system with the characteristic temperature T β . At tan(δ) maximum of about −60 °C the inner mobility of pendant groups or chain defects is released, whereas the main chain of the polymer is generally frozen, with limited local motions . This value is in good agreement with literature data for epoxy resins .…”

Section: Resultssupporting

confidence: 89%

Effect of resin modifiers on the structural properties of epoxy resins

Kregl

Wallner

Lang

et al. 2017

J of Applied Polymer Sci

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Thermomechanical, mechanical and fracture mechanical properties of modified epoxy resins with two different modifiers are investigated. Carboxyl‐terminated butadiene‐acrylonitrile (CTBN) is used as toughening agent and hexanediole diglycidyl ether (HDDGE) as reactive diluent. Both modifiers are admixed in contents from 0 up to 100 phr (parts per hundred resin) and exhibit flexibilizing and toughening qualities. The glass transition temperature is strongly depressed by the admixed reactive diluent, whereas the tensile modulus exhibits greater dependency on the toughening agent contents. The tensile strength and strain at break values are higher for the formulations with diluent compared to resins with toughening agent. Up to a content of 45 phr both modified systems exhibit comparable fracture toughness values. Only the toughened systems comprise increasing values for modifier amounts higher than 45 phr. For the formulation with both modifiers (toughening agent and diluent) a significantly higher toughness but a reduced glass transition temperature was obtained. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45348.

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Section: Resultssupporting

confidence: 89%

Effect of resin modifiers on the structural properties of epoxy resins

Kregl

Wallner

Lang

et al. 2017

J of Applied Polymer Sci

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“…In detailed studies of the curing kinetics of thermosets, [12][13][14][15][16][17][18][19] we have found that an analysis in terms of the electrical modulus formalism, originally developed by Macedo et al" and Moynihan et al, n is useful for determining the conductivity of thermosets during curing. We adopt a similar procedure for analyzing the dielectric permittivity and conductivity data taken from our previous studies [14][15][16][17] and determine the dc conductivity of a thermoset at the early stages of its curing process.…”

Section: Introductionmentioning

confidence: 99%

Relaxations in thermosets. IX. Ionic conductivity and gelation of DGEBA‐based thermosets cured with pure and mixed amines

Mangion

Johari

1991

J Polym Sci B Polym Phys

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The results obtained during the isothermal curing of diglycidyl ether of bisphenol‐A‐based thermosets cross‐linked with pure diaminodiphenyl methane and pure diaminodiphenyl sulfone and with their mixtures have been analyzed to determine how the dc conductivity changes with time during the conversion of its liquid to a gel. The complex permittivity data are first analyzed to show that ac measurements can be used to obtain the ionic conductivity over a considerable period of the curing process. The procedure allows one to obtain the dc conductivity without having data as a function of frequency. The shape of the complex plane plots of the electrical modulus are semicircles, but with small deviations that appear at long times during the curing process. The dielectric consequences of the chemical changes with time during the cross‐linking of the thermoset are analogous to the frequency dependence of the complex permittivity of a liquid. The analysis shows that the dc conductivity σo of a thermoset during its cure follows a power law, σo∝ (tg—t)x, where t is the curing time (t < tg). The results can also be described equally well by a new equation, σo ∝ exp[—B/(to—t)], where x, tg, B, and to are empirical constants all of which vary with the temperature of the cure. tg is close to the time for gelation known from independent studies and to is close to but longer than the time for vitrification. These conclusions are discussed in terms of scaling concepts for the gelation phenomenon.

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“…1,3,8,9,13 In view of the different observations, it seems appropriate to discuss the results separately in terms of (1) the temperature and molecular structure dependence of the limiting mechanical moduli, (2) the shape of the spectra and the distribution of relaxation times, (3) the relaxation time and the temperature dependence of GЈ and GЉ at a fixed frequency, (4) the timetemperature superposition of the relaxation spec- tra, and (5) the contributions from the ␤-relaxation process.…”

Section: Discussionmentioning

confidence: 99%

“…Mikolajczak et al 9 studied the effect of the processing techniques of epoxy-based thermosets on the final properties of the polymer. They found that when the reactants are dissolved in a solvent and polymerized, the mechanical properties of the polymer produced differs from that prepared by reacting without a solvent.…”

Section: Introductionmentioning

confidence: 99%

“…They found that when the reactants are dissolved in a solvent and polymerized, the mechanical properties of the polymer produced differs from that prepared by reacting without a solvent. Earlier studies 9,10 investigated the differences in the T g of such differently prepared polymers. The results showed that the polymers prepared from the solvent mixture had a lower mechanical modulus compared with the polymer prepared without it.…”

Section: Introductionmentioning

confidence: 99%

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