How to judge the conversion rate of PVC polymerization?

Judgment of aggregation conversion rate: 1.Total conversion rate: It can count the number of production kettles within a period of time, the amount of monomer added to each kettle, the output of finished products, and the output of waste materials, and indirectly calculate the total conversion rate of each kettle. The larger the statistic, the more accurate it is. 2. On the basis of the total conversion rate, the heat exchange rate can be used to estimate the conversion rate after a certain reaction time when a certain initiator is added. The results obtained using the above method are basically consistent with the results calculated by the initiator kinetic model, which is very helpful to guide balanced production.

In the reacting polymerization kettle, the conversion rate of VCM within a certain period of time is estimated by the heat exchange rate, (that is, the flow rate of the cooling water, the temperature of the cooling water return water) and the pressure drop in the kettle. It is obtained by comprehensive conversion of the three factors. In fact, the real judgment of whether the polymerization reaction has reached the end time is mainly based on the pressure drop in the kettle, because after the VCM conversion rate reaches 70% (continuing polymerization), the pressure in the kettle will slowly decrease.

Thank you for your replies on the 1st and 2nd floors. I think I still didn’t explain it clearly. what i want to know is: The conversion rate of the same kettle at different times is the relationship between conversion rate and time. There are some introductions in some materials, and there are also graphs of conversion rate and time. However, the measurement method of conversion rate is more complicated and can be divided into two categories: offline and online. The offline category is divided into expansion method and weighing method, and the online category is divided into timely tracer chromatography and online timely calorimetry. (It all sounds complicated) My idea (I don’t know if it is feasible) is to calculate the conversion rate through the ratio of the heat exchange value to the heat of polymerization. The inlet and outlet temperatures of the jacket can be measured online, the circulating water flow rate can be measured online, the monomer feeding amount can be measured online, and the heat of polymerization can be calculated.

The poster's idea is good, but it is too theoretical. Calculating the heat exchange amount and polymerization heat is relatively complicated, but it is still feasible to judge the conversion rate through practice. This is just my personal idea.

You can also look up the diagram, which is introduced in "Polyvinyl Chloride Technology" (Bing Juanlin, Huang Zhiming), and shows the relationship between time and conversion rate. Under a single initiating system, it is an irregular curve, but under a compound initiating system, the curve is close to a linear relationship.

For a rough calculation, the total amount of heat released by the reaction and the latent heat of reaction of PVC can be used to calculate it.

This is a question of reaction kinetics, which is introduced in PVC Technology. You can also refer to Shi Youzhang’s Theory and Practice of PVC. I think the reaction heat measurement conversion rate envisioned by the original poster is feasible.