Rain water resistivity

Water resistance test methods include AATCC 127 (hydrostatic pressure test), AATCC 42 (impact penetration test), and AATCC 35 (rain test). In the hydrostatic pressure test, a sample is subjected to a column of increasing water pressure until leakage occurs. The impact penetration test requires water to be sprayed on the taut surface of a fabric sample from a height of two feet. The fabric is backed by a blotter of predeterrnined weight, which is reweighed after water penetration. The rain test is similar in principle to the impact penetration test. 

Designing effective water-repellent, water-resistant, or waterproof fabrics to provide protection in inclement weather or during certain outdoor activities requires an understanding of the chemical and physical properties of water. Whether you are sailing in wind-driven rain, hiking in a downpour, or sitting on a wet surface, chemistry can keep you dry ... 

One could compare this to an umbrella made out of paper that is not resistant to rain. If, a second umbrella, made out of strong and water-resistant material, is deployed over it, thus providing protection, the first and lower umbrella is shielded. Thus, the more fragile paper umbrella appears to provide some degree of protection only because of the action of the upper second umbrella. The paper umbrella by itself would be quickly destroyed in the rain. What is then the role and use of the paper umbrella ... 

AATCC Test Method 35-2000, Water resistance rain test . Technical Manual of the American Association of Textile Chemists and Colorists, Research Triangle Park, American Association of Textile Chemists and Colorists, 2003, 85-86. 

The appearance of the surface of 16th century bricks in Venice, Italy, exposed to rain water run-off is shown in Figure 1. Surface erosion, as can be seen, is fairly appreciable, and especially noticeable is the uneveness in the erosion due to difference in vitrification. These bricks, and even older ones (12th century) have been studied because they have resisted rain water run-off for seven centuries and high air pollution for the past half century, the latter due to the proximity of Venice to the refinery at Porto Marghera. 

Figure 1. Surface of a 16th century Venetian brick eroded by rain water run-off. A highly-vitrified nodule resists deterioration better than the less vitrified matrix.

The biggest fault with this plastic formulation is that it is not at all water resistant. Exposure to rain will just wash away the binder in the mixture. A humid day is likely to cause it to absorb water from the air and become runny. One is therefore advised to keep the plastic inside the zip-lock baggie until it is time to use it. 

PROBABLE FATE photolysis-, probably occurs slowly, in an isooctane solvent, it hardly adsorbs any radiation above 300 nm, direct photolysis in the environment should not be significant oxidation resistant to autooxidation by peroxy radical in water oxidation by hydroxyl radicals occurs in atmosphere photooxidation half-life in air 6.4 days-63.7 days hydrolysis not important, first-order hydrolysis half-life >879 years volatilization generally rapid volatilization occurs, half-life <9 hr, volatilization from soil surfaces may be an important transport mechanism sorption significant amount of adsorption by organic materials expected in environment biological processes bioaccumulated more than chlorobenzene, volatilization is more important than biodegradation will wash out in rain water... 

PROBABLE FATE photolysis, probably occurs slowly will react with photochemically produced hydroxyl radicals with a half-life of 31 days oxidation resistant to autooxidation by peroxy radical in water, oxidized by hydroxy radicals in atmosphere hydrolysis unimportant process first-order hydroxyl half-life >879 yrs volatilization volatilizes at a relatively rapid rate volatilization half-life <24 hr sorption probably absorbed by organic materials adsorption to sediment is a major environmental fate process biological processes bioaccumulates more than ehlorobenzene, too resistant to biodegradation to compete with volatilization will wash out in rain water... 

SFl 1.2. Withstanding exposure to ambient humidity, to rain, to aging Water resistance Aging resistance Water resistance Aging resistance... 

PEEK is not chemically attacked by water. It has excellent long-term resistance to water at both ambient and elevated temperatures. It also has excellent rain erosion resistance. Because PEEK is not hydrolyzed by water at elevated temperatures in a continuous cycle environment, the material may be steam sterilized using conventional sterilization equipment. 

Uses Water resist, aid for architectural coatings, textured finishes Features Improves early resist, to rain Properties 50% act. 

AATCC Test Method 35 provides a method of testing the penetration of water by impact. This method can be used to predict the rain penetration resistance of fabrics. A test specimen of 20 x 20cm backed by 15.2 x 15.2 cm blotter paper is mounted in a vertical rigid support frame, as shown in Hg. 2.11. The specimen is exposed to horizontal... 

AATCC test method 35-1980. Water resistance rain test. AATCC technical manual. vol. 82. 2007. 

In rain water of high electrical resistance, the cathodic protection of steel by zinc extends only 0.25-0.4 mm (Schafer, 1962). As the electrical conductivity increases, however, so does the distance over which cathodic protection is elective at scratches and edges. 

Cured polyester resins are resistant to the normal chemicals found in motor vehicles, i.e. hydraulic fluids, coolants, battery electrolyte, oils, petroleum, salt water, rain water, and detergents. 

After the film is applied, the water, solvent, and amine evaporate, and the film cross-links by autoxidation. Since there are a fairly large number of residual carboxylic acid groups left in the cross-linked binder, the water resistance and particularly the alkali resistance of the films are reduced, but are still satisfactory for some applications (35). Early water resistance can be a problem if, for example, a freshly painted surface is rained on before all the amine has evaporated from the film. Commonly, ammonia is used as the neutralizing amine because it is... 

Rain-resistant fabrics protect against water penetration during a rain of moderate intensity and pass AATCC Test Methods 22 and 35 (Rain Test). 

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