Reason for the effect of free radical polymerization chain transfer agent on molecular weight distribution

Taking the free radical aggregation as an example, the chain transfer reaction mechanism can be expressed as follows:

mx \u0026#8226; + ys ----- \u0026 gt; mxy + s \u0026#8226;

] Among them, YS is a chain rotor, MX \u0026#8226; is a chain liberal basis. In the process, the free radicals are transferred from the long chain to S, S \u0026#8226;The molecular amount is reduced. As a chain transfer agent, it is a compound with a large chain transfer constant.

Personally, I think that the chain transfer agent makes the molecular weight release, because the chain transfer reduces the average molecular quantity, that is, the number of small molecules increases, and the distribution curve becomes higher

The influencing factors are temperature. The increase in temperature enhances the chain segments and single activities, which increases the conversion rate to increase molecular weight, and sometimes branches to increase molecular weight.There are also pressure, the pressure rises to increase the system in the direction of decreased volume, the conversion rate increases the volume, and the molecular volume becomes larger.Wait, most of the above molecular quantity becomes wider release