chapter9detergencyofsurfactants(專業(yè)版)
【正文】 , ?? 0, ?BOCos? 0, R = 0, anew force balance (c) Three kinds of rollup ? Complete removal ? Spontaneously rollup (自動(dòng)卷離 ) ? = 180176。 ? No surfactants by self can clean a surface。 3. Detergents 1. Composition of detergents (1) Surfactants – enhancing the cleaning power (2) builders – increasing the efficiency and effectiveness of surfactants as detergents and supplement their beneficial effects on soil removal (協(xié)助去污 ) (3) Other auxiliary agent 2. The relation of the chemical structure of the surfactant to its detergency (1) Effect of soil and substrate – hydrophilic head oriented toward the bath or substrates (a) Oily soil ? hydrophobic substrates (. polyester, nylon) – POE ? hydrophilic substrates (. cotton, wool) – negative charge at neutral or alkaline pH – anionics nonionics (partly hydrogen bond) cationics (b) Particulate soil – anionics nonionics cationics (2) Effect of the hydrophobic group of the surfactants – extent and orientation of adsorption (efficiency of adsorption) 。 polar or polar amp。 porous substrates, particle diameter r of the particles ?, then force?, r 100nm, then difficult to wash off (2) Electrostatic force – surface potentail ?wool/water= 48mV ?cotton/water= 38mV ?silk/water= 1mV cation bridge (陽離子橋 ) polyvalency ions Electrostatic force Mechanical force Soil ++++ (3) Chemical force – polar soils proteins , fats
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