Effect Of Surfactant And Emulsion Method On Emulsifying Of Castor Oil

Surgical instruments need to be lubricated after cleaning processing forimproving the cleaning quality，extending the life of the equipment，and reducingthe risk of surgery potentially．Modern lubricants are mainly consisted of mineraloil and a variety of additives．As the biodegradable ability of mineral oil-basedlubricant is poor and the mineral oil is non-renewable，new generation lubricantwith environmental friendly，renewable，less toxic and biodegradable propertieshave attracted extensive interest．In this research the environmental friendlywater-based lubricant used for medical device was prepared with castor oil inorder to protect the environment．A blended emulsifier consisting of nonionic surfactant sorbitan mono-fattyacid ester (Span) and polyoxyethylene sorbitan mono-fatty acid ester (Tween) asthe basis surfactant was applied to emulsify the castor oil．The emulsificationprocess was explored by single factor experiments under the high shear emulsifi-cation．As the indexes，the emulsion stability and rotary viscosity，the effect ofthe species and mass ratio of Span and Tween，the dosage of surfactants，thefeeding order，the emulsification temperature，the emulsification time and therotation speed on the performance of emulsion were investigated in details．Atthe same time，the effects of different surfactants，such as ionic surfactants，nonionic surfactants，zwitterionic surfactants，and the co-surfactants，such asfatty alcohol，polyethylene glycol（PEG），cellulose and polyvinylpyrrolidone（PVP）on the properties of castor oil emulsion were also investigated in detail．When the castor oil emulsion was prepared by high shear emulsificationmethod，the best emulsification conditions were as follows：Span80and Tween60was the basis surfactant and the mass ratio was3:7，the dosage of emulsifier was12.5%，adding the castor oil and Tween60to the Span80aqueous solution，theemulsification temperature was48℃，the rotation speed was2000r/min，and theemulsification time was15min．The influence of different surfactants and co-surfactants on the castor oil emulsion were as follows：when the non-ionicsurfactants polyoxyethylenated castor oil（EL-10）and zwitterionic surfactantsfatty alcohol polyoxyethylene ether disodium sulfosuccinate （MES） wasincoporated into the emulsion，the stability of the emulsion increased by0.7%and3.8%，respectively；the anionic surfactant made the stability decreased；thestabilizing effect of cationic surfactants and fatty alcohols on the castor oilemulsion increased with alkyl chain length increasing；the stability of emulsionincreased by24%when the dosage of cetostearyl alcohol was4%；hydroxyethylcellulose made the stability of emulsion significantly improved；the stabilizingeffect of PEG on the emulsion increased with the increasing of molecularweight；the adding of PVP （K90）made the stability of emulsion increased by7.3%．In order to find a more suitable emulsion methods，effects of differentemulsion methods such as constant speed mixing，high shearing and ultrasonicon stability of the caster oil emulsion were investigated．The structures of castoroil emulsion were characterized by dynamic light scattering (DLS)．The influences of different emulsion methods on properities of the caster oilemulsion were as followes：the stability of castor oil emulsion prepared byultrasounic method was better than those of prepared by high shearing andconstant speed mixing；the castor oil emulsion prepared via ultrasounic methodhad the minimum particle size and rotation viscosity，the value is239.6nm and11.7mPa·s；the castor oil emulsion prepared via ultrasounic method shows goodstability．With the rotary viscosity，particle size and the distribution of particle size asindexes，the effects of different ultrasonic sound conditions such as ultrasonicintervial time，ultrasonic power and ultrasonic action time on the properties ofthe caster oil emulsion were studied．The structures of the castor oil emulsionwere characterized by dynamic light scattering (DLS) and transmission electronmicroscopy (TEM)． And the dilution stability， centrifugal stability andfreeze-thaw stability of castor oil emulsion were tested．The influences of different ultrasonic sound conditions on properities of thecaster oil emulsion were as followes：the average particle size of emulsionsdecreased with the increasing of ultrasonic power and time，as well as the shortening of ultrasonic interval time；the castor oil emulsion prepared viaultrasonic method，both the original emulsion and diluted emulsion showed goodstability；the particle size and the rotation viscosity of the emulsion was less than300nm and4mPa s，respectively；the TEM showed that the latex particles hadthe spherical structure.