Hygrothermal

R. Byron Pipes, Jack R. Vinson, and Tsu-Wel Chou, On the Hygrothermal Response of Laminated Composite Systems, Journal of Composite Materials, April 1976, pp. 129-148. 

Apicella,A., Nicolais, L. and de Cataldis, C. Characterization of the Morphological Fine Structure of Commercial Thermosetting Resins Through Hygrothermal Experiments. Vol. 66, pp. 189-208. 

Characterization of the Morphological Fine Structure of Commercial Thermosetting Resins Through Hygrothermal Experiments... 

In order to evaluate the effect of hygrothermal fatigue on the physical and mechanical properties of composites in actual service, it is crucial to resolve the basic phenomena driving the complex water sorption behaviour and degradation mechanisms in various combinations of moist environment and temperature. 

Fig. 11. Water vapour sorption kinetics in the same external conditions for as cast and hygrothermally damaged DGEBA-TETA neat resin...

This study reveals the need for separate investigative tools for quantitatively characterizing the influence of manufacturing defects and chemical characteristics on the hygrothermal fatigue response and morphology of epoxy thermosets. 

Differences have been noted between species in the way in which they respond to heat treatment, but most notably between hardwoods and softwoods. Thermal, hydrothermal or hygrothermal treatment of various woods results in weight losses that are generally found to be higher for hardwood compared to softwood species (MacLean, 1951 Zaman etal., 2000 Militz, 2002). 

The presence of water, or water vapour, affects the chemistry of thermal modification and heat transfer within the wood (Burmester, 1981). Under dry treatment conditions, the wood is dried prior to thermal modification, or water is removed by the use of an open system, or a recirculating system equipped with a condenser. In closed systems, water evaporated from the wood remains as high-pressure steam during the process. Steam can also be injected into the reactor to act as a heat-transfer medium, and can additionally act as an inert blanket to limit oxidative processes. Such steam treatment processes are referred to as hygrothermal treatments. Where the wood is heated in water, this is known as a hydrothermal process. Hydrothermal treatments have been extensively studied as a... 

ThermoWood is produced by a heat-treatment process in the presence of steam, and is thus a hygrothermal treatment. The steam acts as a blanket to limit the oxidative degradation of wood, and there are also additional reactions occurring as a result of the presence... 

Schrader (1974) reported that the interface shear strength in a hygrothermal environment is at its maximum when the multi-layer silanes on the glass fibers remain after being washed in boiling water. On the other hand, the pull-out strength... 

Anstice P. D. and Beaumont P.W.R. (1981). Hygrothermal aging effects on the micromechanisms of crack extension in glass fiber and carbon fiber composites. In Proc. ICF 5 (Francois D. et al.. eds.). Pergamon Press, Oxford, Vol. I, pp. 473-483. 

Figure 1. Environmental chamber. A, air entrance B, air exit C, hygrotherm D, temperature and humidity probe E, Pyrex tray F, crystallizing dish G, air dispersion tube H, 12 rubber stoppers (covered with aluminum foil) I, pesticide vapor traps J, flow meter. Reproduced with permission from Ref. 18. Copyright 1983, Pergamon Press.

Apicella, A., Nicolais, L., Cataldis, C. de Characterization of the morphological fine structure of commercial thermosetting resins through hygrothermal experiments , Advance in Polymer Science vol. 66, Kausch Ed., Springer-Verlag 1984... 

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