Study On Polysiloxane Modified By Alkynol And Control Performance Of Its Foam

Polysiloxane modified by alkynol as a kind of non-toxic,non-polluting new silicone surfactant has been widely used in many field.However,the application in defoamer is seldom reported.This thesis is divided into four parts:The first part aims to investigate the method and process conditions of the synthesis of low hydrogen-containing polysiloxane(LPMHS).Under nitrogen atmosphere,the mixture contained of octamethylcyclotetrasiloxane(D4),methylhydrogenpolysiloxane(PMHS),hexamethyldisiloxane(MM)and the catalyst was heated and stirred to reflux in a three-necked flask.The reaction was incubated at 100 ?.After 4 h,the low boilers were filtered and centrifuged after distilled off under reduced pressure.Then,low hydrogen polysiloxane was obtained from the dried upper oil content in the oven.In the second part,the method and process condition of synthesis of polysiloxane modified by alkynol were investigated.Under the protection of nitrogen,homemade low hydrogen polysiloxane and 3-butyne-1 alcohol were added into the three-necked flask.Stirred to 70?,chloroplatinic acid catalyst was added at a certain speed,then kept at 100?.The reaction was finished in 3 hours,and the low boilers were distilled off under reduced pressure.After centrifugal separation,the polysiloxane modified by alkynol was obtained from the dried upper oil content.The third part studies the synthesis conditions of silicone paste.The polydimethylsiloxane and hydrophobic solid particles were added into the three-necked flask with the polysiloxane modified by alkynol added slowly.When the temperature was at 100?,add MQ resin and keep stirring for 30 mins.Then alkaline catalyst was added.After 30 mins' stirring,the silicone paste was gained in the room temperature which was naturally cooled to get.The fourth part mainly focus on the defoamer emulsification technology condition and the defoaming performance test.To get silicon paste emulsified,the influence factors of emulsifying agent were adjusted and water-soluble defoaming was obtained.The performance of defoamer was tested in different pH,temperature and compared with defoamer at home and abroad.It is concluded that the self-made water soluble defoamer has advantages of anti-corrosive alkali,high temperature resistance and good depressor performance.