| Polycarboxylate type concrete admixture is an important research topic in the study of high-performance concrete water-reducer in nowadays,and also is the most promising concrete admixture in the future.At present,the main materials of water-reducer on the market are unsaturated polyether,which are mainly isopentenol polyoxyethylene ether(TPEG)series and methyl allyl alcohol polyoxyethylene ether(HPEG)series,and these two kinds of polyether macromer accounted for more than 90%of the water-reducer materials.Though both polyether monomer on the market has been large-scale production,but the research on the quality control of the intermediate is still less,especially for a large reactor,due to the growth ratio limit,a synthetic intermediate quantity can not be timely all the synthesis of polyether macromer,resulting in the remaining part of the intermediate needs for a period of time in the the tank,in place,due to the influence of various conditions,the adverse effects of the intermediate quality,and ultimately affect the quality of the finished macromonomer.This study is according to the actual production situation of Levima Corporation.The experiment took isopentenol as starting agent,getting intermediates of small molecule by the anionic ring opening polymerization of ethylene oxide first,investigating the content changes of by-product under different storage conditions,e.g.,different amount of catalyst,different heat preservation time,and different protection environment such as nitrogen protection and degassing vacuum protection and the moisture in the system.Then TPEG2400 monomer finished products were synthesized,taking intermediates under different storage conditions as starting materials.And the hydroxyl value and iodine value of the finished products were determined according to the nonionic surface active agent national standard method for the determination of hydroxyl value and iodine value,and double bond retention was calculated.Besides,the influence factors which were easily ignored in the testing process for hydroxyl value and iodine value were investigated based on the national standards,and the molecular weight of PEG in TPEG2400 was tested,and the PEG content was tested with the appropriate PEG standard,ensuring that the analysis data of the products can be supplied accurately when the plant is producing.Finally,the application performance of cement paste was evaluated by the corresponding synthetic water-reducers.Polycarboxylate Superplasticizer has a high performance with the lower PEG macromonomer by-product content,and high double bond retention rate in macromer.Synthetic intermediate conditions more moderate and lower water system,TPEG2400 will have lower by-product content and high double bond retention rate.At the same time,the optimization test of hydroxyl value iodine value method,will make the test results more accurate and reliable.The results of the research are helpful to control the quality of the intermediate products,to solve the quality problems macromonomer of the industry,provide the guidance and reference data related to optimize process of product quality control of polycarboxylate superplasticizer polyether macromonomer and downstream products,to enhance the performance of water reducing agent,so as to make contribution to enhance the quality of construction industry of China. |
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