Which friend’s company produces SG7 and SG8 types of PVC resin? I have a question~~
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Which friend’s company produces SG7 and SG8 types of PVC resin? I’m asking for the specific formulation details~~ Is there any version that doesn’t use mercaptoethanol? This post was last edited by xdg1201 on 2009-3-1 at 20:23.]
In the formula using thioglycolic acid, a larger amount of dispersant needs to be used; otherwise, coarse products are likely to form. The polymerization temperature should be determined based on the conditions of one’s own reactor. There are articles that describe the relationship between temperature and the amount of thioglycolic acid used, and the actual values are not very different from those calculated. Thioglycolic acid can be added all at once when it is introduced into the system, or it can be added in two stages; the method of addition affects the amount used slightly. Some manufacturers opt for high-temperature reactions
For 30-cubic-foot reactors, thioglycolic ethanol must be added; for 70-cubic-foot reactors, raising the temperature is sufficient
Basically, no chain transfer agent is used in large reactors; type 7 and 8 resins can be produced by controlling the temperature alone. The main reason is that the design pressure of large reactors is all above 1.6 MPa. The reactor with a volume of 30 cubic meters has a low design pressure, so a chain transfer agent needs to be added to reduce the polymerization pressure.
As explained in polymer chemistry, increasing the temperature raises the polymerization rate, and as a result, the proportion of various side reactions increases. It can be inferred that resins with low degree of polymerization produced at high temperatures have more branches, and more defects in their molecular chains compared to those produced using chain transfer agents; consequently, their thermal stability decreases to some extent
When a chain transfer agent is used, although the reaction temperature is lower, the transferred molecular chains may not behave in an ideal manner. As a reference, one can study this by looking at what industry colleagues have written about the use of chain transfer agents in products with low polymerization degrees*. The thermal stability of a product is not determined solely by its stability once it comes out of the reactor.
But it is certain that the thermal stability of what comes out of the kettle is the highest. Unless you can repair the defects in its molecular chain after it comes out of the kettle