Cure of Thermosetting Resins

Vergnaud, J.M.; Bouzon, J.

doi:10.1007/978-1-4471-1915-9

Cited by 50 publications

(26 citation statements)

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“…These data are typical, in the sense that the order of the overall reaction is far from being equal to 1, as often found in the literature 4,9,10 with natural rubbers vulcanised with sulphur. In fact, it would not have been necessary to use experimental values, as the purpose of the present study is to test a method of evaluation of these parameters, provided that they were taken in a reasonable range.…”

Section: Parameters Of Cure Introduced For Calculating Curvesmentioning

confidence: 71%

“…3 per 10 K was also found for the sulphur vulcanisation of ethylenepropylene diene monomer (EPDM) blends around the reference temperature of 150uC. 8 Numerical models taking into account all the known facts, especially heat conduction through the sample and the kinetics of the heat generated by the cure reaction have been built and tested, either for the cure of NR with sulphur 4,9,10 or EPDM with peroxide. 11 These models are able to evaluate not only the profiles of temperature developed through the sample but also the profiles of state of cure, provided that the kinetics of the cure reaction are known.…”

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confidence: 99%

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Rheometers in scanning mode for cure of rubbers with low enthalpy: effect of heating rate and rubber–die contact

Rosca¹,

Granger²,

Vergnaud³

2004

Plastics, Rubber and Composites

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Rheometers are usually run under isothermal conditions for the cure of rubbers, in spite of the following drawbacks: three experiments at least are necessary at different temperatures selected within a narrow temperature window, and it takes some time for thermal equilibrium to establish between the rubber sample initially at room temperature and the dies. In scanning mode, the dies of the rheometer and the sample should be heated from room temperature up to the selected final temperature at a constant rate. The effect of the value given to the heating rate, which is the main factor in this new method, is especially studied, as well as the quality of the contact between the dies and the sample. The rubber used in the present study is a natural rubber vulcanised with 2% sulphur with a low enthalpy. The kinetic parameters of this cure reaction have been previously determined by isothermal rheometry, and the enthalpy measured by calorimetry. The state of cure-temperature curves in scanning mode have been calculated using a numerical model taking into account the conduction heat transfer through the rubber, the coefficient of heat transfer at the die-rubber interface, and the kinetics of the heat evolved from the cure reaction with the enthalpy. The kinetic parameters are determined from the state of cure-temperature curves, which are similar to the torque-temperature curves, using a least squares method. The values of the kinetic parameters obtained by this last calculation, based on the mathematical treatment of these curves, are the same as those introduced for obtaining these curves using the numerical model. Thus, whatever the heating rate, ranging from 2 to 10 K min -1 , and the value of the coefficient of heat transfer at the die-rubber interface expressing the quality of the contact, in scanning mode the moving die rheometer (MDR) can be used to determine the kinetics of the cure of rubbers.Nomenclature b heating rate, K min 21 C heat capacity of rubber in equation (8) Dt increment of time for calculation Dx increments of space for calculation E activation energy of cure reaction n order of overall cure reaction l thermal conductivity of rubber k 0 pre-exponential factor for rate of cure reaction in equation (5) M dimensionless number expressed by equation (9) Q heat generated by cure reaction in equation (8) r density of rubber S function defined by equation (12) used for calculating state of cure of rubber T temperature (K) TN n new temperature after elapse of time Dt at position n x longitudinal abscissa through thickness of rubber Z value of torque as a fraction of its maximum value in equation (3)

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Section: Parameters Of Cure Introduced For Calculating Curvesmentioning

confidence: 71%

mentioning

confidence: 99%

Rheometers in scanning mode for cure of rubbers with low enthalpy: effect of heating rate and rubber–die contact

Rosca¹,

Granger²,

Vergnaud³

2004

Plastics, Rubber and Composites

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“…The curing process of epoxy composites is currently based almost exclusively on thermal curing cycles, for which an oven or an autoclave is used [ 15 ]. This kind of curing, besides being an energy- and time-consuming process, requires wasteful costs for infrastructure [ 16 ], most of all when carbon nanotubes (CNTs) are incorporated in the matrix. Moreover, the low thermal conductivity of unfilled polymeric resins strongly limits the dimensions and geometries that can be employed during the manufacturing processes [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Design of Multifunctional Composites: New Strategy to Save Energy and Improve Mechanical Performance

et al. 2020

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In this paper, an alternative curing strategy, based on the application of an electric field, is proposed to harden nano-filled multifunctional resins. The resin is obtained through the dispersion of carbon nanotubes, which act as nanometric heater elements in the epoxy matrix. The electro-curing is activated by applying an external electric voltage, which allows tunable cross-linking within the epoxy matrix entrapped between the nanotubes. The electro-curing method allows reaching higher curing degrees with respect to the conventional ones and, consequently, higher glass transition temperatures. This is a direct consequence of the fact that the curing reactions start directly in the regions at the interphase between carbon nanotubes, acting as heater nano-filaments, and the polymeric matrix. The proposed method is able to give composites better properties, making the curing process fast and energy-saving.

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“…Many rubber compounds are routinely prepared and analysed 1,2 , in order to be used in various applications, so any studies of their cure processes are of great importance 3,4 . In the same way as for thermosetting resins, when curing rubbers the samples should be heated up to a temperature at which the irreversible reaction starts, whereupon the fresh plastic uncured material is changed into an elastic three-dimensional molecular network.…”

Section: Introductionmentioning

confidence: 99%

“…The curing of rubbers is complex, since the heating process consists of two stages, one involving heat transfer by conduction through the sample thickness, the other resulting from the slightly exothermic cure reaction. Moreover, the cure reaction itself is highly complex, kinetically speaking 3 , even if it is often expressed in terms of temperature and of the activating agent concentration by an Arrhenius' equation 3,4 over a 30 K range. From the point of view of economics, the curing rubbers is of great importance if we are to optimise the cure time and minimise the production of defective products.…”

Section: Introductionmentioning

confidence: 99%

Linear Temperature Programming Rheometers for the Cure of Rubbers. Effect of the Various Parameters

Rosca

Granger²,

Vergnaud³

2004

Polymers and Polymer Composites

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In spite of their drawbacks, rheometers are usually run under isothermal conditions for the cure of rubbers: At least three experiments are needed at different temperatures selected within a narrow temperature window to determine the kinetic parameters of the cure of rubbers, and it takes some time for thermal equilibrium between the sample, initially at room temperature, and the dies to be established. With the rheometer in scanning mode, the dies and the sample are heated from room temperature up to the selected final temperature at a constant rate. The heating rate is crucial in this new method. The rubber used in this study is an ethylene propylene diene monomer vulcanised with 20% sulphur and with a rather high cure enthalpy. The state-of-cure versus temperature curves obtained in scanning mode have been calculated using a numerical model that takes into account the heat transfer by conduction through the rubber, the coefficient of heat transfer at the die-rubber interface, and the kinetics of the heat generated by the cure reaction. The kinetic parameters were determined mathematically from these state-of-cure versus temperature curves, which are similar to torque-temperature curves, by obtaining straight lines from them or using a least squares method. The kinetic parameters calculated in these ways were similar to those introduced by obtaining the state-of-cure versus temperature curves using the numerical model. Whatever the heating rate, ranging from 2 to 10 K/min, and whatever the coefficient of heat transfer at the die-rubber interface which expresses the quality of the contact, the moving die rheometer can be used in scanning mode to determine the kinetics of the cure of rubbers, even when the enthalpy of cure is high.

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Cure of Thermosetting Resins

Cited by 50 publications

References 0 publications

Rheometers in scanning mode for cure of rubbers with low enthalpy: effect of heating rate and rubber–die contact

Rheometers in scanning mode for cure of rubbers with low enthalpy: effect of heating rate and rubber–die contact

Design of Multifunctional Composites: New Strategy to Save Energy and Improve Mechanical Performance

Linear Temperature Programming Rheometers for the Cure of Rubbers. Effect of the Various Parameters

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