Synthesis Of Polyalkoxy Imidazoline Rust Inhibitor And Its Performances Study In Reinforced Concrete

At present,with the vigorous implementation and development of China’s marine development strategy,the demand of reinforced concrete for marine infrastructure construction is increasing.The harsh and complicated Marine environment leads to a series of cruel tests for reinforced concrete structures.In particular,there are a lot of chloride ions in the sea water,which is no different from the natural enemy of reinforced concrete and seriously damages the service life of reinforced concrete construction facilities.In many anticorrosive methods,adding rust inhibitor is one of the most economical and effective methods.With the exposure of the shortcomings of inorganic rust inhibitor,more and more attention has been paid to the research of new organic rust inhibitor.There are electronegative N atoms and unsaturatedπbonds in the imidazoline structure,which can interact with the empty d orbital energy of metal to form coordination bonds,forming a protective film on the surface of the steel bar and isolating the contact between the steel bar and corrosion ions.But the poor water solubility of oil soluble imidazoline restricts its application in practice.In this paper,imidazoline structure as the main body,by modifying the structure of imidazoline,improve its hydrophilic properties,and then further study the rust inhibitor performance and the impact on the performance of concrete itself,for its application in reinforced concrete to provide theoretical guidance and technical support.(1)With oleic acid and hydroxyethyl ethylenediamine as raw materials,xylene as water carrying agent,through amidation,cyclization into alkyl imidazoline intermediate,and then through polymerization and ethylene oxide to improve the hydrophilic structure of imidazoline,synthesis of polyalkoxy imidazoline rust inhibitor.The optimum reaction conditions of alkyl imidazoline intermediate are as follows:molar ratio of reaction raw material n(oleic acid):n(hydroxyethyl ethylenediamine)=1:1.3,amidation reaction temperature is 150℃,reaction temperature is 5h,cyclization reaction temperature is 220℃,reaction time is 5h.(2)The obtained alkyl imidazoline intermediate is put into an autoclave,and an alkoxylation reaction is carried out to obtain the final product,the polyalkoxy imidazoline rust inhibitor.After the optimization of the alkoxylation reaction conditions,it was determined that the optimum addition amount of potassium hydroxide for the reaction catalyst was 0.3%of the mass of the alkyl imidazoline intermediate,the temperature was 125°C,and the pressure in the kettle was 0.2MPa.And the determination of hydroxyl value also proved the integrity of the synthesized molecular structure.And the successful synthesis of the reaction product was proved by infrared spectrometer,proton nuclear magnetic resonance spectrum and carbon spectrum.(3)With distilled water as solvent,take different mass fraction of poly alkoxy imidazoline inhibitor shall be dissolved in the conical flask,different mass fraction of poly alkoxy imidazoline rust inhibitor and dispersant aqueous solution are uniform and transparent liquid,and placed a year without stratification,precipitation,and through the water number method the alkoxy change of corrosion inhibitors for imidazoline HLB value of 17.78,It has good hydrophilicity.(4)The rust resistance performance of polyalkoxy imidazoline rust inhibitor was evaluated by weight loss method,saline immersion method,saline baking experiment,electrochemical experiment and scanning electron microscopy.The results show that when the additive amount is 40g/L,the rust accumulation rate of steel bar is 0.8%,the corrosion current density is 0.55μA/cm~2,and the rust inhibition efficiency reaches 99.13%.Moreover,A dense protective film can be formed on the surface of carbon steel to prevent corrosion between corrosion ions and steel bar.The adsorption process of the rust inhibitor conforms to the Langmuir isothermal adsorption equation and is spontaneous,and the increase of the amount of rust inhibitor and temperature are conducive to the enhancement of the rust inhibitor performance.(5)The influence of the addition of rust inhibitor on the fluidity of cement slurry,the strength of concrete and the setting time of mortar was studied.The results show that the fluidity of oil-soluble imidazoline rust inhibitor is 216mm and 207mm respectively in 30s and60min,which is lower than the optimal application range of 220mm～260mm,and the fluidity of polyalkoxy imidazoline rust inhibitor in the research range has been kept above 240mm.The compressive strength and flexile strength of concrete are improved with the increase of the amount of rust inhibitor,indicating that the addition of polyalkoxy imidazoline rust inhibitor improves the structure of concrete.The setting time of mortar decreases slightly with the increase of rust inhibitor,but it is within the range of±120min in the industry standard.