For different initiators having different half life at different temperature, which half life is more practical for polymerization temperature control ? such as ten minutes, or 30 minutes half life, which is better guide for choosing?
Dear Jackie Sun, it depends on the reactivity of the monomer(s) in question. The half-life time is an indication of the reactivity of the initiator as it expresses its decomposition rate with respect to temperature. Higher decomposition rate resulted in the problem of self-termination (cage effect), and in the same way high reactivity monomer if polymerized at at high temperature, the gel effect occurs leading to an uncontrolled reaction path. So usually a compromise between the reactivity of reactants is chosen. My Regards
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The term half-life relates to the time for one half of the starting material to decompose at a given temperature. The half-life of an organic peroxide reveals ...
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Abdelkader BOUAZIZ Dear Abde, thanks so much for your great explain from view of cage and gel effect. And these are very important for molecular weight control and runaway prevention. For BPO like initiator, sometimes are processed at around 110 degree C, sometimes are processed at 130 degree C during polymerization. So what are differences and which reason for different polymerization temperature?
Suresh Ahuja Dear Suresh, thanks so much for your sharing! Handling safety is very important for peroxides.
No thanks. Choosing the right temperature is a matter of some goals or requirements. For example the higher the temperature the lower reaction time is. This is done usually when the conversion is stopped at low level, say 60%. If you don't mind, please send the links of the works that used high temperatures, usually for polymerization with BPO, 80-90°C are enough, Vulcanization needs higher temperatures than 100°C. Best of luck in your work.
Abdelkader BOUAZIZ Dear Abde, thanks so much! yes, I think it may needs for vulcanization at high temperature for BPO.
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