Analyse de la cinetique d'absorption d'eau prevue par la loi de diffusion de fick d'un composite renforce par tissus de verre-resine epoxyde

Abstract EN

The present article constats in following ihe resumption of weight according to the duration of hygrothermal conditioning of a lamina teconstituted of 12 loyers ofglass fiber fabric / epoxy resin.

The experimental analysis of the kinetics of moisture absorption of the specimens conditioned in wet medium at différent relative humidifies, 0, 60 and 96% RH at 60 °C was carried out by a measurement of resumption of weight (gravimétrie method) according to the duration of conditioning with an aim of determining the two parameters characteristic of the law of diffusion ofFick (the diffusion coefficient D and the maximum quantity of water of saturation Mm which admits the reversibility of the phenomenon.

The comparison carried out between the values obtained of the characteristic parameters of the kinetics of water absorption by the hygrothermal test of conditioning carried to the laboratory and those given by Loos and Springer (1981) confirms the following principal remarks clearly : * the coefficient of diffusion D and the maximum quantity of water retained with saturation Mm depend not only on the nature of material, of the temperature but also of the relative humidity rate, * the maximal concentration of water at the saturation of the composite Mm becomes more significant beyond 60% of relative humidity.

The approximate estimated calculation of the maximal concentration of water (matrix + interface) which admits a homogeneous diffusion phenomenon inside the material (Df = 0) permitted to clearly show that the presence of fibres in a polymeric matrix decreases about 4 times the quantity of water absorbed by this matrix.

Kev-words : Hygrothermal conditioning, moisture absorption, woven fabric reinforced composite and organic matrix.

The present article consists in following the resumption of weight according to the duration of hygrothermal conditioning of a laminate constituted of 12 layers of glass fiber fabric / epoxy resin.

The experimental analysis of the kinetics of moisture absorption of the specimens conditioned in wet medium at different relative humidities, 0, 60 and 96% RH at 60 °C was carried out by a measurement of resumption of weight (gravimetric method) according to the duration of conditioning with an aim of determining the two parameters characteristic of the law of diffusion ofFick (the diffusion coefficient D and the maximum quantity of water of saturation Mm which admits the reversibility of the phenomenon.

The comparison carried out between the values obtained of the characteristic parameters of the kinetics of water absorption by the hygrothermal test of conditioning carried to the laboratory and those given by Loos and Springer (1981) confirms the following principal remarks clearly: * the coefficient of diffusion D and the maximum quantity of water retained with saturation Mm depend not only on the nature of material, of the temperature but also of the relative humidity rate, * the maximal concentration of water at the saturation of the composite Mm becomes more significant beyond 60% of relative humidity.

The approximate estimated calculation of the maximal concentration of water (matrix + interface) which admits a homogeneous diffusion phenomenon inside the material (Df = 0) permitted to clearly show that the presence of fibres in a polymeric matrix decreases about 4 times the quantity of water absorbed by this matrix.