Viscoelastic response of model epoxy networks in the glass transition region

Gérard, Jean‐François; Galy, Jean; Pascault, Jean‐Pierre; Cukierman, Serge; Halary, Jean Louis

doi:10.1002/pen.760310813

Cited by 82 publications

(49 citation statements)

References 15 publications

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“…The relaxation temperature, α-relaxation, which is considered as the glass transition temperature, T g , was determined as the temperature corresponding to the maximum in the loss modulus E (according to ASTM D 4065). The frequency was 1 Hz [25]. When considering the T g as the temperature at which the loss factor, tan δ, presents a maximum, similar results were obtained.…”

Section: Resultssupporting

confidence: 67%

See 1 more Smart Citation

The Effect of Surface Modification of Silica Microfillers in an Epoxy Matrix on the Thermo-mechanical Properties

Olmos

Baselga

Mondragón

et al. 2008

Journal of Adhesion Science and Technology

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Section: Resultssupporting

confidence: 67%

“…As it is common in highly crosslinked systems [25], the dynamic mechanical spectra of the samples can be compared in the glass transition region, and the timetemperature principle can be applied. The time-temperature superposition relationship is usually expected to hold only for thermo-rheologically simple materials.…”

Section: Resultsmentioning

confidence: 99%

The Effect of Surface Modification of Silica Microfillers in an Epoxy Matrix on the Thermo-mechanical Properties

Olmos

Baselga

Mondragón

et al. 2008

Journal of Adhesion Science and Technology

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“…The influence of network architecture on the properties of the matrices has been clarified by using series of model systems, designed to present a systematic variation of the network rigidity while keeping the crosslink density constant, and vice versa. 4 -7 Thus, unambiguous results were obtained dealing with the glass transition temperature T g , 5,[7][8][9] , the free volume, 10 the secondary relaxation ␤, 5,11,12 and the antiplasticization phenomenon. 13,14 In the case of composites, additional pending questions refer to the interaction between matrix and fiber.…”

Section: Introductionmentioning

confidence: 80%

“…The temperature increment between two consecutive measurements was 2°C, and the overall temperature range under study extended from Ϫ90°C to T g ϩ 30°C. According to the observations made in previous articles, 8,21,22 the glass transition temperature T g was supposed here to be identical to the temperature at which the EЉ goes through a maximum when the frequency is 1 Hz.…”

Section: Viscoelastic Measurementsmentioning

confidence: 98%

Relationships between thermally induced residual stresses and architecture of epoxy-amine model networks

Bauchiere

Halary

Monnerie

et al. 2000

J. Appl. Polym. Sci.

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ABSTRACT:The capability of epoxy-amine resins to develop residual stresses was studied as a function of temperature and network architecture. These residual stresses were induced while cooling epoxy-glass bilayers from temperatures higher than the network glass transition temperature, T g . This behavior was the result of the marked differences (␣ r Ϫ ␣ g ), in linear thermal expansion coefficient of the two components, as evidenced by the measurement of ␣ r for the epoxy networks under study. Various network architectures were selected, resulting from variation of (1) the chemical nature of both epoxide and curing agent, (2) the nature and relative amount of the chain-extensor agent, and (3) the stoichiometric ratio. Three ranges of cooling temperature were observed systematically: first, the range of temperatures above T g , where no stress has been detected, then an intermediate temperature range (from T g to T*), where stresses develop quite slowly, and finally, the low temperature range (T Ͻ T*), where a linear increase in stress accompanies the decrease of temperature. The two latter regimes were quantitatively characterized by the extent, T g Ϫ T*, of the first one and by the slope, SDR, of the second one. T g Ϫ T* values were shown to be governed by the T g of the network: the higher the T g , the larger the gap between T g and T*. This result was interpreted by accounting for the variation of relaxation rate at T g from one network to the other. It was also shown that a semiempirical relationship holds between SDR and T g : SDR decreases monotonically as T g increases. By inspecting the effects of network architecture in more details, it turned out that SDR is governed by the Young's moduli, E r (T Ϫ T g ), of the epoxy resins in the glassy state: the lower E r (T Ϫ T g ), the lower SDR in a series of homologous networks. As E r (T Ϫ T g ) values are known to be related to the characteristics of the secondary relaxation ␤, which depends, in turn, on crosslink density, SDR values were finally connected to the amplitude of the ␤ relaxation processes. This finding was corroborated by the measurements on an antiplasticized dense network. Finally, data relative to thermoplastic-filled networks showed that the addition of thermoplastic reduces the development of residual stresses, whatever the system, is homogeneous or biphasic.

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“…Therefore, the large half-width observed in ECC/ PAMS suggests the presence of additional relaxation mechanisms associated to the presence of the polysiloxane. The analysis of the shape of the a relaxation can provide useful information about the structure of the crosslinked network [39]. The height of the transition is related to the extent of cure and decreases as the distance between crosslinks shortens.…”

Section: Curing Processmentioning

confidence: 99%

Preparation of cycloaliphatic epoxy hybrids with non-conventional amine-curing agents

González

Cabanelas

Pozuelo

et al. 2010

J Therm Anal Calorim

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Cycloaliphatic epoxy resin has been successfully thermally cured using a polyamino siloxane oligomer as hardener. The curing reaction was followed by infrared spectroscopy in the near range, and thermal transitions were measured by dynamic mechanical thermal analysis. The use of accelerants and a plasticizer (dodecylphenol), and different curing schedules were explored. Cured materials showed high Tg values (around 125 164°C), and the analysis of laser scanning confocal microscopy images showed that they are homogeneous in the microscale.

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Viscoelastic response of model epoxy networks in the glass transition region

Cited by 82 publications

References 15 publications

The Effect of Surface Modification of Silica Microfillers in an Epoxy Matrix on the Thermo-mechanical Properties

The Effect of Surface Modification of Silica Microfillers in an Epoxy Matrix on the Thermo-mechanical Properties

Relationships between thermally induced residual stresses and architecture of epoxy-amine model networks

Preparation of cycloaliphatic epoxy hybrids with non-conventional amine-curing agents

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