Moisture transport

The performance of a textile fabric is characterized by terms such as strength, hand, drape, flexibiUty, moisture transport, and wrinkle resistance. Although the interactions among fibers in a fabric array are complex, its properties reflect in part the inherent properties of the fiber as well as how the fibers are assembled. 

Physically or chemically modifying the surface of PET fiber is another route to diversified products. Hydrophilicity, moisture absorption, moisture transport, soil release, color depth, tactile aesthetics, and comfort all can be affected by surface modification. Examples iaclude coatiag the surface with multiple hydroxyl groups (40), creatiag surface pores and cavities by adding a gas or gas-forming additive to the polymer melt (41), roughening the surface... 

The fabric may also be given one or more of a number of other finishing treatments, either ia tandem with web formation and bonding or off-line as a separate operation, as a means of enhancing fabric performance or aesthetic properties. Performance properties iaclude functional characteristics such as moisture transport, absorbency, or repeUency flame retardancy electrical conductivity or static propensity abrasion resistance and frictional behavior. Aesthetic properties iaclude appearance, surface texture, and smell. 

Antistats such as polyoxyethylenes (151,152) and A/-alkyl polycarbonamide (153) are added to nylon to reduce static charge and improve moisture transport and soil release in fabrics. These additives also alter the luster of fiber spun from bright polymer. Static reduction in carpets is achieved primarily by the use of fibers modified with conductive carbon black (see Antistatic agents Carbon, carbon black). 

To predict the comfort of a material, a combination of hand evaluation, eg, using the Kawabata system, as well as deterrnination of the heat and moisture transport properties, is necessary. Often, these values are correlated with a sensory evaluation of the tactile qualities of the material by a human subject panel. A thorough discussion of the many physical and psychological factors affecting comfort is available (134,135). 

The hunnidity ratio oJ a rotjm at any given time is given by a Jatent heat balance equation including the water vapor flows due to infiltration to ventilation to moisture transport through envelope elements... 

Moisture-transport simulation includes transport as well as storage phenomena, quite similar to the thermal dynamic analysis, where heat transfer and heat storage in the building elements are modeled. The moisture content in the building construction can influence the thermal behavior, because material properties like conductance or specific heat depend on moisture content. In thermal building-dynamics simulation codes, however, these... 

This measurement methodology and data analysis is general and can be extended to other porous media. The results from MRI moisture profiles can also be used to measure moisture diffusivity that enable moisture transport models to be developed for a wide range of materials. 

This type of water uptake measurement is very general in application. It is applicable to most porous media, where moisture transport properties need to be measured. 

Some of the key factors that lead us to select polyurethane foam for upholstery are its durability, resilience, and controllable hardness (or softness, depending on your point of view). Vibration dampening and shock absorbance are important attributes in automobile and public transportation seating. Open cell foams are preferred for these applications because they allow for air and moisture transport, which improve the comfort of passengers who may occupy a seat continuously for several hours. This inherent breathability is also a valuable attribute in mattresses. Shock absorbance plays a key role in selecting flexible polyurethane foams for the packaging of fragile items. 

Every modification in design, as well as remedial actions, must be made after due consideration of building physics. Otherwise negative side effects can occur. Examples are locally high relative humidity in air, condensation of moisture and development of mold. With due consideration to the constraints laid by building physics, however, modifications to radon safe design can give positive tradeoffs as reduced possibility for moisture transport and development of mold. 

Alvarez, C.A., Aguerre, R., Gomez, R., Vidales, S., Alzamora, S.M., and Gerschenson, L.N. 1995. Air dehydration of strawberries Effects of blanching and osmotic pretreatments on the kinetics of moisture transport. J. Food Engineer. 25, 167-178. 

Mazza, G. 1983. Dehydration of carrots Effects of pre-drying treatments on moisture transport and product quality. J. Food Technol. 18, 113-123. 

Vaccarezza, L.M. and Chirife, J. 1975. On the mechanism of moisture transport during air drying of sugar beet root. J. Food Sci. 40, 1286-1289. 

Modified Cross Sections. Nylon filaments are spun in a variety of cross-section shapes that include the conventional round to irregular solid and hollow shapes (Fig. 13). The cross-section shape is an important variant in designing the functionality and luster of fibers. The round cross section is used for strength in industrial applications and for subdued luster in apparel and upholstery. The multilobal cross sections are used to enhance bulk and for bright luster in both BCF and spun staple yams for carpets and upholstery. The grooves in the multilobal shapes also enhance moisture transport by wicking water through capillary action. Flat-sided ribbon-like cross sections provide cover in apparel applications. 

Talma AS, Netterberg F (1983) Stable isotope abundances in calcretes. In Residual Deposits Surface Related Weathering Processes and Materials. Wilson, RCL (ed) Oxford Blackwell Scientific Publ., p 221-233 Tian L, Masson-Delmotte V, Stievenard M, Tao T, Jouzel J (2001) Tibetan Plateau summer monsoon northward extent revealed by measurements of water stable isotopes. J Geophys Res 106 28,081-28,088 Tian L, Yao T, White JWC, Yu W, Wang N (2005) Westerly moisture transport to the middle of Himalayas revealed from the high deuterium excess. Chinese Sci Bull 50 1026-130 Uba CE, Heubeck C, Hulka C (2006) Evolution of the late Cenozoic Chaco foreland basin, southern Bolivia. Basin Res 18 145-170... 

The atmospheric processes of moisture transport that are directly connected with the temporal variations of meteorological elements, play an important role in the global water cycle. Global atmospheric circulation can be described by the Monin model (Monin and Krasnitsky, 1985) ... 

Pel, L. (1995) Moisture transport in porous building materials, PhD thesis. Eindhoven University of Technology, Eindhoven... 

Similar studies of moisture transport across a barrier also have been done using in vitro methods that determine the movement of water vapor across a film coated with a measured amount of the material to be tested. These are rapid methods for rough determinations of occlusivity and work very well for screening several ingredients at a reasonable cost. Once again, petrolatum s occlusivity has been shown in tests of this nature.28,29... 

Another apparatus based on the rate of cooling or warming has the provision for measuring moisture transport through textiles. simultaneously with thermal diffusion and is considered by its developer to be superior to other instruments which neglect moisture transport (36). 

Similar studies are needed on the insulative value or thermal efficiency of blankets and representative bedding materials under end-use conditions. An instrument comparable to Rowland s apparatus (68) would be useful in measuring and comparing the thermal resistance of blankets under conditions which provide specific levels of moisture transport. However, fundamental studies on both the importance of moisture transport and relative humidity of bedding microclimate with regard to thermal resistance... 

Numerous efforts have focused upon the nature of moisture transport of epoxy systems. Previous-sorption desorption work demonstrated that equilibrium moisture levels In an epoxy system can be related to thermodynamic states (1,2,3). Transient and equilibrium dynamic mechanical experiments are performed In this work with two epoxy systems TGEBA-TETA and N-5208. These experiments provide Insight Into the nature and extent that network changes have on the dynamic mechanical properties as a result of hygrothermal cycling. 

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