Could someone explain in detail the differences between various additives in PVC polymerization formulations and their functions?
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In VCM suspension polymerization, additives such as initiators, dispersants, stabilizers, and chain transfer agents are required. Could someone tell me what the roles of CNP and EHP, which are among the initiators, are in the reaction system? Also, what effects does heating have when polyvinyl alcohol is dissolved as a dispersant?
The role of CNP and EHP is to generate free radicals, thereby initiating the polymerization of monomers. The temperature is increased when dissolving polyvinyl alcohol in the dispersant in order to speed up its dissolution, as its dissolution rate is very slow at low temperatures ； However, it cannot be dissolved directly with hot water (above 65°C), as this will make the surface of the polyvinyl alcohol particles sticky and poreless, preventing water molecules from diffusing inward.
Thank you. I mainly want to know what the half-lives of EHP and CNP are, as well as what the approximate ratio between the two is during use
The half-life depends on the polymerization temperature: it is 3.9 hours at 50 degrees for EHP, and 1.1 hours at 60 degrees. CNP has higher activity; I don’t have specific figures for that.
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