Dielectric behaviour of epoxy and polyester laminates in moisture and electronic packaging exhalates

Singh, Dharmendra; Kumar, Amit; Tayal, V. P.; Sanyal, Biplab

doi:10.1007/bf01174680

Cited by 15 publications

(11 citation statements)

References 1 publication

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“…The dipoles in the viscoelastic polymers could get more time to align according to the direction of the applied electric field at a low frequency; therefore, dipole orientation polarization was a major contributing factor for E r . [19][20][21][22] However, the noise was too high to get reliable results at very low frequencies.…”

Section: Degradation Analysismentioning

confidence: 97%

“…The color change was correlated with surface oxidation. 17 There was sufficient evidence that the exposure time caused resin decomposition, 1,6,7,17,22 which was visualized with the photographs. However, the magnitude of damage was immeasurable by visual inspection.…”

Section: Degradation Analysismentioning

confidence: 98%

“…With increasing temperature, the chain-segment mobility increases. When the temperature approaches T g , E r increases dramatically 22 as the dipoles attached rigidly to the polymer backbone gain sufficient mobility and become free to orient in an electric field. [19][20][21][22][23][24][25][26] The BMI, EP, and VE resins were heated far above their T g 's (348, 101, and 127 C for BMI, VE, and EP, respectively).…”

Section: Degradation Analysismentioning

confidence: 98%

“…As a result, E r decreases with increasing frequency. 11,[19][20][21][22] Besides, the polymer system contains discrete networks, and these are interpenetrated with one another in the cured resin structure. Such a polymer structure effectively restricts the orientation and relaxation of dipoles in some polar groups of BMI, EP, and VE resins and reduces E r and the dissipation factor.…”

Section: Degradation Analysismentioning

confidence: 99%

“…22 Thermooxidation implies the transport of oxygen from the surface toward the bulk or the transport of mobile groups from the bulk toward the surface, where they react with oxygen. 11,[19][20][21][22] As a result, below 250 C, the effects of thermooxidation are generally observed to be limited to a few tens of micrometers below the surface. 24 In the case of thermolysis, bond scission and chemical transformation occur because of the effect of elevated temperatures.…”

Section: Degradation Analysismentioning

confidence: 99%

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Thermal degradation analysis of thermoset resins

Chatterjee

2009

J of Applied Polymer Sci

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Dynamic mechanical analysis, thermogravimetric analysis, and dielectric analysis (DEA) were conducted for three thermoset resin systems: bismaleimide, epoxy, and vinyl ester. The resin samples were subjected to various degrees of thermal exposure (400, 270, and 330 C for 5-150 min). Dielectric constants were measured along with the thermomechanical properties. The glasstransition temperature, modulus, and weight loss were important parameters for correlating the material property changes with the heat exposure. A linear relation was determined between the thermomechanical properties and the dielectric properties of the resins under the selected exposure conditions. Therefore, DEA can be introduced as a significant technique for evaluating thermally exposed polymer materials. Interestingly, it is a nondestructive evaluation process. In the future, it could be used for onsite health monitoring of thermally exposed polymer matrix composite structures.

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Section: Degradation Analysismentioning

confidence: 97%

Section: Degradation Analysismentioning

confidence: 98%

Section: Degradation Analysismentioning

confidence: 98%

Section: Degradation Analysismentioning

confidence: 99%

Section: Degradation Analysismentioning

confidence: 99%

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Thermal degradation analysis of thermoset resins

Chatterjee

2009

J of Applied Polymer Sci

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The effect of absorbed moisture on dielectric behavior of silica (micro)‐unsaturated polyester composites

Sharma¹,

D’Melo²,

Chaudhari³

et al. 2012

J of Applied Polymer Sci

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It is well known that most of the dielectric failures occur in high voltage equipment due to absorption of moisture by the insulating material from the environment. Hence, the effect of absorbed moisture on electrical and mechanical properties of silica-unsaturated polyester resin (UPR) composites has been evaluated. The absorption of moisture in silica-UPR composites does not show any significant change in electrical and mechanical properties. The effect of acetone and water absorption on silica-UPR composites was determined and it was that found silica-UPR composite shows higher acetone absorption when compared with water. The differential scanning calorimetry and thermal gravimetric analysis studies of silica-UPR composites show no significant change in glass transition temperature using prehumidified (0-95% RH) silica filler. As there is no significant change in thermal and mechanical properties after exposure to humid conditions, it can be concluded that water does not penetrate inside the polymer matrix. Hence, the silica particles are the best choice to use as filler in UPR matrix for UPR composite used in electrical equipment. The developed silica-UPR composite was successfully used in the preparation of medium voltage inductive transformers.

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