Surfactants used in agrochemical formulations

Three main classes may be distinguished, namely anionic, cationic and amphoteric [3, 4]. A useful technical reference is McCutcheon [5], which is produced annually to update the list of available surfactants. A recent text by van Os et al. [6] listing the physicochemical properties of selected rmionic, cationic and nonionic surfactants has been published by Elsevier. Another useful text is the Handbook of Surfactants by Porter [7]. It should be mentioned also that a fourth class of surfactants, usually referred to as polymeric surfactants, has been used for many years for preparation of EW s (emulsion concentrates) and SC s (suspension concentrates) and their stabilization. 

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Surfactants are often used in agrochemical formulations as adjuvants, e.g. as wetting agents to improve the physico-chemical characteristics of the solution and to increase the uptake of active ingredients (e.g. pesticides) [6-8]. The surfactants can be included in pesticide products and/or added to the tank mix prior to use however, they rarely exceed 1% of the total applied spray. Examples of typical surfactants used in agrochemical formulations are shown in Table 2.8.3 [9]. 

The use of organosilicone surfactants in agrochemical formulations has become increasingly widespread [13]. These products are known to enhance spray coverage and in many cases increase the foliar uptake of... 

Uses Surfactant used in formulation of textile auxs., emulsifiers, as domestic and industrial cleaner, for agrochem. prods., cosmetics, resin emulsion, etc. grease remover in tannery compounding aid for polymer and plastics industry anticoagulant for latex paints Properties Turbid Iiq. polyol char, odor sol. in water sp.gr. 0.95 vise. 25-45 cps vapor pressure < 0.01 mm Hg (20 C) m.p. = 10 C m.p. 5-6 C b.p. > 100 C HLB 8.3 hyd. no. 169-184 flash pt. (COC) > 250 C pH 6.5-7.5 (1% aq.) nonionic 0.2% moisture Toxicology Repeated contact with skin can cause dermatitis eye irritant ing. of Ig. amts, will result in diarrhea and weakness Environmental Biodeg. 

Steric repulsion results from the presence of adsorbed layers of surfactants and/or polymers. The use of natural and synthetic polymers (referred to as polymeric surfactants) for stabilization of suspension concentrates and emulsions (EW s) plays an important role in agrochemical formulations. Polymers are particularly important for preparation of concentrated dispersions, i.e. at high volume fraction ( j of the disperse phase,... 

The use of surfactants (ionic, nonionic and zwitterionic) and polymers to control the stability behavior of suspensions is of considerable technological importance. Surfactants and polymers are used in die formulation of dyestuffs, paints, paper coatings, agrochemicals, pharmaceuticals, ceramics, printing inks, etc. They are particularly robust form of stabilization which is useful at high disperse volume fractions and high electrolyte concentrations, as well as under extreme conditions of high temperature, pressure, and flow. In particular, surfactants and polymers are essential for the stabilization of suspensions in nonaqueous media, where electrostatic stabilization is less successful. 

Uses Surfactant used in formulation of textile auxs., emulsifiers, as domestic and industrial cleaner, for agrochem. prods., cosmetics, resin emulsion, etc. grease remover in tannery compounding aid for polymer and plastics industry Properties Wh. solid disp. in water m.w. 350 m.p. 42-46 C HLB 4.9 hyd. no. 

Chapters 12 to 15 deal with some specific applications of surfactants in the following industries personal care and cosmetics, pharmaceuticals, agrochemicals and the food industry. These chapters have been written to illustrate the applications of surfactants, but in some cases the basic phenomena involved are briefly described with reference to the more fundamental chapters. This applied part of the book demonstrates that an understanding of the basic principles should enable the formulation scientist to arrive at the optimum composition using a rational approach. It should also accelerate the development of the formulation and in some cases enable a prediction of the long-term physical stability. 

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