Examination of the emulsification rate of polymerization to assume persulphuric acid potassium and Rongalite a start agent ~Influence of pH~
[the first step to a discussion] The behavior of the emulsification polymerization using the redox start agent is not known very much. Therefore emulsification of the vinyl acetate polymerized Rongalite using persulphuric acid potassium (KPS) as an oxidizer as a reducing agent and, as an example of the redox start agent, examined the rate of polymerization by the reaction calorimeter which developed in our laboratory in detail. Particularly, I checked influence of pH.
[experiment method], in a reactor, added sodium dodecyl sulfate as an emulsifier 0.24 g , vinyl acetate 68 g, water 320 g, Rongalite (a type of radical vegetables with dressing) 0.0015-0.2 g . When I adjusted it to pH = 4, with 0.350 g of acetic acid and sodium acetate 0.132 g, in the case of pH = 7, I added 0.00233 g of acetic acid and sodium acetate 0.920 g. After stirring the reactor in 400rpm, and having blown nitrogen to remove oxygen, I raised temperature to 45 degrees Celsius. After having blown nitrogen into 20 g of water solutions which included KPS 0.018 g, I raised temperature to 47 degrees Celsius, and let it start a reaction in what cast it into in a reactor. I measured a change in a reaction calorimeter at time of the fever speed after the reaction start.
[a result and consideration] With pH = 4, the fever speed shows two peaks, and it is thought that a decrease in intragranular monomer concentration, the second peak are caused by a gel effect as for the decrease after the first peak. On the other hand, with pH = 7, fever speed is remarkably lower than pH = 4 generally and is supposed when the first peak seen in the case of pH = 4 does not appear. In the case of pH = 4, particularly early radical outbreak speed compares it, and, in the case of pH = 7, it is thought that it is considerably low as this cause. When I did not perform pH adjustment, it was around pH =7 at the time of the reaction start and was pH = 3.9 in 60 minutes later when a polymerization rate became approximately one. That purpose or pH = 4 and middle result of pH = 7 are provided. In this way, fever speed (rate of polymerization) is high so that pH is low.
Similar behavior was seen in the result by the experiment that varied in quantity of training of the Rongalite. When molar numerical degree (1.2x102μmol = 0.018 g) to double of KPS increases Rongalite, Q25 becomes maximum, and Q25 decreases when increase quantity of Rongalite addition further. Formaldehyde which Rongalite dismantles it like the next expression as the cause that Q25 decreases when quantity of Rongalite increases too much, and generates it may deactivate it in response to a radical.
HOCH2SO2Na (Rongalite )→ CH2O( formaldehyde) + NaHSO2
Therefore I add formaldehyde in the middle of polymerization and will confirm whether a rate of polymerization decreases in future. In addition, because it confirms it to vinyl acetate that fever speed is influenced by a thing and pH to take the maximum value with increase in quantity of training of the Rongalite whether it is special, I polymerize it using a different monomer likewise and measure fever speed. Because a result may vary according to a kind of the buffer solution, I think about testing it using other types of buffer solutiOn equally.
[the first step to a discussion] The behavior of the emulsification polymerization using the redox start agent is not known very much. Therefore emulsification of the vinyl acetate polymerized Rongalite using persulphuric acid potassium (KPS) as an oxidizer as a reducing agent and, as an example of the redox start agent, examined the rate of polymerization by the reaction calorimeter which developed in our laboratory in detail. Particularly, I checked influence of pH.
[experiment method], in a reactor, added sodium dodecyl sulfate as an emulsifier 0.24 g , vinyl acetate 68 g, water 320 g, Rongalite (a type of radical vegetables with dressing) 0.0015-0.2 g . When I adjusted it to pH = 4, with 0.350 g of acetic acid and sodium acetate 0.132 g, in the case of pH = 7, I added 0.00233 g of acetic acid and sodium acetate 0.920 g. After stirring the reactor in 400rpm, and having blown nitrogen to remove oxygen, I raised temperature to 45 degrees Celsius. After having blown nitrogen into 20 g of water solutions which included KPS 0.018 g, I raised temperature to 47 degrees Celsius, and let it start a reaction in what cast it into in a reactor. I measured a change in a reaction calorimeter at time of the fever speed after the reaction start.
[a result and consideration] With pH = 4, the fever speed shows two peaks, and it is thought that a decrease in intragranular monomer concentration, the second peak are caused by a gel effect as for the decrease after the first peak. On the other hand, with pH = 7, fever speed is remarkably lower than pH = 4 generally and is supposed when the first peak seen in the case of pH = 4 does not appear. In the case of pH = 4, particularly early radical outbreak speed compares it, and, in the case of pH = 7, it is thought that it is considerably low as this cause. When I did not perform pH adjustment, it was around pH =7 at the time of the reaction start and was pH = 3.9 in 60 minutes later when a polymerization rate became approximately one. That purpose or pH = 4 and middle result of pH = 7 are provided. In this way, fever speed (rate of polymerization) is high so that pH is low.
Similar behavior was seen in the result by the experiment that varied in quantity of training of the Rongalite. When molar numerical degree (1.2x102μmol = 0.018 g) to double of KPS increases Rongalite, Q25 becomes maximum, and Q25 decreases when increase quantity of Rongalite addition further. Formaldehyde which Rongalite dismantles it like the next expression as the cause that Q25 decreases when quantity of Rongalite increases too much, and generates it may deactivate it in response to a radical.
HOCH2SO2Na (Rongalite )→ CH2O( formaldehyde) + NaHSO2
Therefore I add formaldehyde in the middle of polymerization and will confirm whether a rate of polymerization decreases in future. In addition, because it confirms it to vinyl acetate that fever speed is influenced by a thing and pH to take the maximum value with increase in quantity of training of the Rongalite whether it is special, I polymerize it using a different monomer likewise and measure fever speed. Because a result may vary according to a kind of the buffer solution, I think about testing it using other types of buffer solutiOn equally.