Moisture Absorption and Desorption of Composite Materials

Abstract

Expressions are presented for the moisture distribution and the moisture content as a function of time of one dimensional homogeneous and composite materials exposed either on one side or on both sides to humid air or to water. The results apply during both moisture absorption and desorption when the moisture content and the temperature of the environment are constant. Test procedures are described for determining experimentally the values of the moisture content and the diffusivity of composite materials. A series of tests using unidirectional and π/4 Graphite T-300 Fiberite 1034 composites were performed in the temperature range 300—425 K with the material submerged both in moist air (humidity 0 to 100%) and in water. The test data support the analytical results and provide the moisture absorption and desorption characteristics of such composites. Extension of the results to materials exposed to time varying environmental conditions is indicated.

Moisture Effects on the Mechanical Behavior of Fir Wood Flour/Glass Reinforced Epoxy Composite

“…The curve of the absorbed moisture m versus the square root of time t is expected to obey Fick's law in case of the composite material involved in this study after immersion in distilled water; such a relationship has been reported in studies dealing with moisture absorption in fiber-reinforced plastics (Shen and Springer 1976;Springer 1988;Dhakal et al 2007;Boukhoulda et al 2006;Naceri 2009). Therefore, by using Fick's law the diffusion coefficient denoted with D is defined as the slope of the normalized mass uptake against t and has the relationship (Eq.…”

“…where h is the thickness of the composite specimen immersed; Mm is the equilibrium absorbed distilled water inside the composite material at saturation, expressed in percentages;  tg represents the initial slope of the curve of the absorbed moisture   t m versus the square root of time t (Shen et al 1976;Boukhoulda et al 2006;Naceri 2009). The initial slope of the linear portion may be computed by using the following relationship (Eq.…”

Durability-Based Design Criteria for a Quasi-Isotropic Carbon-Fiber Automotive Composite

“…The higher the humidity, the larger the moisture effect. 16 Because strains due to changes in moisture content are so significant relative to measured time-dependent creep strains, it was decided to use full-bridge strain gage compensation in all of * It should be emphasized that the specimen in Fig. 10.5 was under stress, which accelerates moisture migration.…”

Investigations on the Effect of Moisture on Stress Distribution in FRP Using Finite Element Methods

“…Extensive research has been done in order to understand moisture absorption characteristics under various environmental conditions and its effect on the properties of composites. Moisture absorption characteristics of composites have been the subject of considerable investigation [1,2,4,8]where transient moisture diffusion under normal environmental conditions is approximated as a Fickian process and analytical models have been developed based on a homogenized model.Dewimille and Bunsell [3] presented effects of increase in temperature and moisture content on the tensile strength of different composites. joliff [5,6] studied water diffusion in unidirectional (UD) composite, associating experimental measurements, analytical and numerical modelling.…”