Soil retardation

The unharvested parts of rice plants are generally mixed with the soil because this has been thought to be beneficial. It has been observed however, that productivity of the second crop of rice in a paddy is less than that of the first crop. Chou and Lin (45) found that aqueous extracts of decomposing rice residues in soil retarded radicle growth of rice seedlings and growth of rice plants. Maximum toxicity occurred in the first month of decomposition and declined thereafter. Some toxicity persisted for four months in the paddies. Five inhibitory phenolic acids were identified from decaying rice residues and several unidentified allelochemicals were isolated. 

Primapel . [Rdim Haas] Acrylic cartoxylic ct lymer, carpet soil retardant... 

Polymerization Studies. Anionic Polymerization of Caprolactam (the use of (CFs C0)20 (ca. 2 mole %) enabled a lower reaction temperature to be employed and higher yiel and polyamide molecular weights to be obtained]. Soil-retardant Finishing of Cotton Ooth by Vapour-phase Graft Polymerization of Fluoroalkyl Acrylates. Radical Polymerization of a-Fluoroacrylic Acid and -Vinylpyrrolidone in an Aqueous Solution. Perfluoropolyether Esters of Quinones [the preparation of the title compounds by reaction of 1.5-dihydroxyanthraquinone with per-fluoropolyetheracyl fluorides, e.g. CFj-CFi-CF -O-CF(Ci )-CaPj-O-CF(CF,)-C50F, is... 

Uses Acrylic for clear and pigmented coatings antisoil additive for carpet shampoos soil retardant for new carpet Features Improves hardness, mar resist. exc. color retention exc. compat. with water-borne urethanes films dry clear and resist yellowing from UV exposure... 

Acid rain does more than just kill aquatic organisms it harms Uchens, ferns, the leaves of deciduous trees, and the needles of coniferous trees. Forests as a whole are weakened, making plants more susceptible to infestations of disease and insects. Acid rain leaches nutrients from soil, retarding tree growth and maturation. Croplands suffer similar ill effects, resulting in a reduction of food production. 

Copper exhibits rhizotoxicity in wheat seedlings [17]. Copper and chromium retard shoot and root growth of barley [18]. The yield of wheat is decreased when soil is contaminated with cadmium oxide or zinc oxide [19]. Copper and nickel smelter-polluted soil retards biomass growth of pine trees and reduces the essential calcium, potassium, and magnesium contents of sapUngs [20]. Cadmium in the soil reduces ryegrass growth with crop yields inversely proportional to cadmium content [21]. 

Hydrocarbon repellents and their mixtures with fluorinated repellents, silicone and fluorosilicone repellents, and fluorinated repellents are described in Chapter 12. Fluorinated soil retardants are discussed in Chapter 13 and soil- and stain-resistant carpets in Chapter 14. 

Soil retardants are used to reduce soiling of textiles that cannot be laundered, such as upholstery fabrics and carpets. The soils encountered are usually composite soils, containing particulate matter and various amounts of liquid components, such as water or oil. The soils can therefore be fluids or particulate solids. 

Soil retardants designed for upholstery of furniture or automobiles are water and oil repellents that retard sorption or waterborne or oily stains by the fabric. A liquid soil on a repellent fabric can be wiped off immediately after the spills. When the soil is rubbed into the fabric with sufficient force to overcome repel-lency, a fluorocarbon finish facilitates spot cleaning [24]. 

Soil retardants for carpets reduce accumulation of soil, mainly particulate soil, transferred onto the carpet from shoe soles. Because the carpet is subjected to mechanical forces, such as pressure, rubbing, and impingement, the retardant has to be resistant to abrasion. 

Because soiling with particulate soil is caused mainly by adhesion, resistance to soiling is anti adhesion. The latest generation of soil retardants for carpets are repellent compounds that can lower the adhesion of soil particles to fibers. The attraction between nonpolar soil and the fiber surface is probably caused by London dispersion forces arising from fluctuations of electron clouds. Hence, energy of the interaction between the soil and the fiber surface should depend on electron polarizability, which, in turn, is related to the refractive index by the Lorentz-Lorenz equation ... 

The molecular refraction is an additive function of atomic refractions. Fluorine has the lowest atomic refraction (Table 13.1) of the atoms used to build compounds or polymers for coating fiber surfaces. Consequently, the refractive index and polarizability of fluorocarbons are lower than those of the corresponding hydrocarbons and chlorocarbons. Because dispersion forces constitute the major part of their cohesive forces, their surface energy is low. However, a low-surface energy is not the sole criterion for an effective soil retardant. The dispersion forces are effective only over short distances. A finish deformable by soil particles provides a larger area in close contact with soil than a finish that does not flow on impact. Hence, hardness of finish is also important. Soiling can also be affected by a liquid film on fibers, such as oil or fat, which can fill the voids between the surfaces of soil and fiber and act as an adhesive. 

The fluoropolymer finishes, A, B, C, and D, differed in their hardness and resistance to abrasion. Fluoropolymer D, inefficient as a soil retardant, was more deformable than the others. The most efficient soil retardant, fluoropolymer A,... 

A hard but brittle finish may break and flake off when the fibers are flexed. The resistance to plastic deformation has to be balanced with sufficient pliability. The temperature dependence of the physical properties and the transition temperatures are important for soil-retardant finishes cured at elevated temperatures. A soil retardant that melts below the cure temperature can spread on the fibers during cure. 

Most fluorinated soil retardants are vinyl polymers, urethanes, or oligomers derived from pyromellitates. Numerous fluorinated soil retardants have been disclosed in the patent literature, but only some examples can be given here (Table 13.2). Usually a vinyl polymer consists of (1) a fluoroalkyl group containing monomer [e.g., 2-(perfluorononyl)ethyl acrylate, the methacrylate CH=C(CH3) COOCH2CH2C F2 +i, or CH=C(CH3) C00CH2CH2(CH3) S02(CF2)8F], (2) a nonfluorinated alkyl acrylate or methacrylate (e.g., butyl or stearyl acrylate or methacrylate), and (3) a cross-linkable monomer for durability (e.g. A methylo-... 

Table 13.2 Examples of Fluorinated Soil Retardants for Carpets... 

Wehowsky et al. [44] reacted epichlorohydrin with C6 i2Fi3 250H. The product obtained was reacted with toluene diisocyanate and oligoepichlorohy-drine to yield an urethane useful as a soil retardant. 

Soil retardants can be applied to fibers, yams, fabrics, or carpets by spraying, padding, kiss-roll, or foam application techniques. Some soil retardants are applicable also by exhaust methods. Spraying is the most popular method for applying soil retardants to carpets. The required amount of a soil-retardant product is typically 0.5-1.6% of the weight of dry face fiber or about 200 ppm as fluorine. Usually, the soil retardant as applied as the last step before the carpet is dried. The presence of a fluorinated finish on the carpet can be confirmed by an oil-repel-lency test, based on the AATCC 118-1997 test (see Chapter 12), or a water-repel-lency test. Fuorier transform infrared and x-ray photoelectron spectroscopy (ESCA) (Chapter 9) provide semiquantitative information on the fluorinated soil-retardant concentration on the fibers. 

Although soil retardants reduce soiling, the deposition of soil onto a textile cannot be entirely prevented. If the textile can be washed, soil-release finishes can facilitate the removal of soil considerably. The term soil release suggests a separation of soil from a fabric immersed in water, but such a spontaneous separation is possible only with liquid oily soils. Solid soils cannot separate spontaneously and require mechanical action for their removal. 

Carpets on the floor are subjected to soiling under severe noiechanical conditions. Particulate soil is transferred from shoe soles onto the carpet while the carpet pile is being compressed, rubbed, and twisted by the mechanical action of the foot traffic. The soil particles left on fibers are ground into the fiber surface by the continuous traffic. The mechanisms of soiling with particulate soil and the deterrence of soiling by fluorinated soil retardants have been described in Chapter 13. 

Telomer B alcohol [4]. Scotchgard FC-1395, a fluorinated polymer, was made by 3M [5]. The fluorinated soil retardant is undoubtedly the most important component of the soil and stain-resist finish on the carpet because soiling by foot traffic is a daily occurrence, whereas staining with liquids is an accidental event. 

Type of fibers and heat-setting history Stain-resist agent and its chemical and physical properties Application process for the stain-resist agent Fluorinated soil retarder... 

The first defense line against staining is the fluoiinated soil retardant (see Chapter 13) which reduces soiling with particulate soil and hinders wetting of fibers. When a liquid is spilled on the carpet, the fluorinated repellent provides time for the removal of the liquid by blotting before the liquid wicks into the carpet. However, if the liquid is allowed to wick into the carpet, a stain-resist agent in the fiber surface or inside the fibers must prevent staining. 

The limitations of the model for dye-site blocking has made it necessary to invoke a barrier model as well. A fluorinated soil retarder functions as a repellent nonionic barrier on the fiber surface. The fluorinated polymer does not form a continuous film around the fibers and cannot completely prevent the stain from diffusing into fibers. An additional barrier is needed in the subsurface of fibers as well to hinder the diffusion of the stain. 

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