Chain separation, activation energy

Consider the activation energy for various radical chain polymerizations. For a polymerization initiated by the thermal decomposition of an initiator, the polymerization rate depends on the ratio of three rate constants kp (kj/k,) 2 in accordance with Eq. 3-32. The temperature dependence of this ratio, obtained by combining three separate Arrhenius-type equations, is given by... 

The conductivities of this type of compound increase dramatically with increasing pressure. Studies of the [M(en)2][M(en)2X2]C104 complexes showed that the conductivity increased by a factor of 103 under 7 kbar pressure but that the activation energy was less affected-136 Pressures of 140 kbar on the neutral chain M(NH3)2X3 complexes produced an increase in conductivity of about six orders of magnitude and a reduction in the Mh—MIV separation of over 0.2 A at 60 kbar.140... 

At first, the bulkiness of the CMI group creates sites with a lower local density, in which ester group 7r-flips with a smaller activation energy occur. This effect gradually disappears for MMA units located farther away from the CMI group along the chain, in such a way that the pure PMMA behaviour is recovered for MMA units separated from CMI cycle by five or more C - C bonds. 

The activation energy for a symmetrical separation of polymer chain centers by a distance of z over a length x is given by (12),... 

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