Water absorptiveness tests

Mass, density, and dimensions have been grouped together largely for convenience, but there is an obvious connection between them in that density can be derived from a knowledge of dimensions and mass. They are also measurements used as essential parts of other physical tests. For example, density is used to calculate volume loss in an abrasion test, mass is an intrinsic factor in water absorption tests, and there are very few tests that do not in some way involve the measurement of dimensions. 

There arc several water absorption tests specified for plastics with various geometries and conditions. Generally they use times that would not result in equilibrium, and care needs to be taken in comparing results, particularly if surface area to volume ratios are different. Coated fabrics and textiles are normally relatively thin and hence there is less problem with very long times being needed to reach equilibrium. 

The absorption characteristics indirectly represent the porosity through an understanding of the permeable pore volume and its connectivity. In order to investigate the effect of nano-Si02 particles on cement mortar permeability, a water absorption test was carried out on various mixtures A-1 (plain cement mortar), A-5 (cement mortar with 7% nano-SiO ), A-7 (cement mortar with 20% RHA replacement) A9 (cement mortar with 20% RHA replacement and 3% nano-SiO ). The final absorption of these mixtures are shown in Table 5.4. It can be seen that mixture A-5 (cement mortar with 7% nano-SiO ) showed the lowest absorption of all the mixtures which shows that nano-SiO is more effective in reducing the permeability than RHA. Integrating nano-SiO into RHA mortar reduced the water absorption from 5.42% to 4.45%. Results showed that the presence of nano-SiO particles in cement mortar could decrease the water absorption and the likely permeability of cement mortar. This impermeability increase can be attributed to two concomitant phenomena ... 

In another study, Martinola et al. (2002) evaluated the water permeability of cracked and uncracked HPFRCC by water absorption test. In their study, the amount of water taken up by capillary suction was determined on cubes cut out from the middle section of the beams, which were subjected to a four-point bending test. Maximum crack width in the cracked HPFRCC specimens was found to be about 0.10 mm. Both cracked and uncracked HPFRCC exhibited very low water absorption coefficient in their study. 

Water absorption test on thermally modified wood showed that the differences between sapwood and heartwood of Scots pine were significantly larger than Spruce [11]. Heat treatment actually increased the water absorption of pine sapwood and decreased the water absorption of pine heartwood. 

Particle density and water absorption tests - general... 

A detailed description of specimen production and Marshall testing is provided in Annex 6.B, and a detailed description of the soaking test-capillary water absorption test is provided in Annex 6.C both annexes are found at the end of this chapter. 

ANNEX 6.C SOAKING TEST - CAPILLARY WATER ABSORPTION TEST... 

Cutinase Fusarium solani Fabric UV and fluorescence spectroscopy, dye assay, water absorption tests Hydrolysis, increased hydrophilicity, improved dye uptake [3, 6, 38, 82, 84, 85, 98]... 

Pseudomonas mendocina Fabric, fibers Contact angle, water absorption tests, HPLC, UV spectroscopy, dye assays, gravimetric analysis, SEM Increased hydrophilicity, weight loss, improved dye uptake, changes in surface morphology [10, 25, 44, 45, 49, 107]... 

BEB, DET contact angle measurement, water absorption tests hydrophilicity, changes in surface morphology [50] [51, 60]... 

Thermomyces lanuginosus Fabric, fibers, film (PET PTT) HPLC, fluorescence spectroscopy, water absorption tests, dye assay, XPS Hydrolysis, increased hydrophilicity [4, 11, 26, 27]... 

Fig. 17 Packing behavior of alumina (S) and mica (J) powder. O is the water absorption test curve is the paste-derived data.

Water absorption tests on our samples were performed by keeping the samples immersed at room temperature for one month and the increase of weight due to the water absorbed was periodically measured. The results of the tests are reported in Fig. 56. The findings show that the two homopolymers (iPP and iPPMA) absorb about the same amount of water. In contrast a lower quantity of water can penetrate into the iPPMA50/50 eomposite with respeet to the iPP-based composite (iPP50/50), owing to a better adhesion of the fibers to the matrix. Tensile tests, after this treatment, were also performed. The results are shown in Table 11 and the following ean be pointed out ... 

FIG. 56 Water absorption test increase of weight of the samples vs time ( ) neat iPP, (A) neat iPPMA, (O) iPP50/50, ( ) iPPMA50/50. 

TABLE 11 Tensile properties of iPPMA and iPP-based composites (ASTM D638) after water absorption test... 

Water absorption tests on our samples were performed according to the methods described in the experimental section. 

Broom libers obtained by steam explosion seem to produce better fiber/matrix interfacial adhesion with respect to those extracted by alkaline treatment, as clearly shown by SEM analysis and water absorption tests. 

FIG. 61 Water absorption tests weight increase of the samples as a function of time. (O iPP neat A iPP/Broom iPPMA/ Broom x iPPMA/iPP/Broom iPPMA neat iPP/Broom SEP iPPMA/Broom SEP + iPPMA/iPP/Broom SEP). 

Chemical properties of type II aramid elastomers have been reported in [43]. Water absorption tests were conducted at RT and at 100% relative humidity. The water absorption of a PTMO-containing aramid elastomer was only 1.0 wt%, while that of a poly(ethyleneoxide) (PEO)-containing elastomer was 80.5 wt% [43]. 

The cured matrix of GMAEVC and epoxy resin contains hydrophilic functionality and easily absorbs water molecules. The absorbed water leads to dimensional variations in composites and also affects the mechanical properties of the composites. Water absorption tests were performed on the matrices prepared at different curing conditions and the thermomechanical performance of matrices was compared to the dry, original samples. 

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