19 июня, 2015 
Malyar Once the monomer radical has been formed, propagation proceeds rapidly as the number of monomer units increases successively to produce a growing polymer chain. After each successive addition, the free radical is retained on the vinyl carbon atom of the end chain unit.
RO—CH2— CHX + CH2 = CHX————- ► RO—CH2— CHX — CH2— CHX
• nCH2=CHX Г 1
RO—CH2—CHX — CH2— CHX ———— — ——— ► RO—CH2— CHX — j — CH2 — CHX-I- CH2— CHX
-*n
Figure 1-1
A reaction can only be considered as a chain propagating reaction if the overall molecular weight of the resulting radical is increased, and if the radical remains available for further propagating reactions.
The ease with which a monomer forms a free radical and the reactivity of the radical, once formed, determines the rate at which propagation proceeds. Each propagation step proceeds at a speed determined by the propagation rate kp which is constant for a given monomer at a given temperature. The propagation rate is independent of the degree of polymerisation of the growing chain.
For homopolymerisation, the reaction rate (Rp) is given by the equation
Rp = kp [M] [M-]
kp is the rate constant for propagation of monomer M
[M] is the molar concentration of monomer M
[M1] is the molar concentration of monomer radicals M’
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