Branch structures in poly(vinyl chloride) and the mechanism of chain transfer to monomer during vinyl chloride polymerization

Auxiliary Mechanism for Transfer to Monomer during Vinyl Chloride Polymerization

“…Rate constants k7 and fc8 can be defined in a similar way, and the firstorder constant, k6\ can be expressed as a sum of specific rate constants for intramolecular hydrogen abstraction via cyclic transition states having rings of various sizes (eq 6). *β· = κ: + *«/ +... + kj (6) Because CMmx is equal to the IA content per monomer unit, it is given by eq 7:…”

“…Furthermore, we have found very recendy that 1,3-diethyl-and/or 2-ethyl-n-hexyl branch struc tures are present in small amounts when the polymer is synthesized under low monomer pressures (26). Both of those arrangements should possess two tertiary chlorines (6), and both of them should be formed by mechanisms that require two intramolecular hydrogen abstractions by propagating macroradicals (6).…”

Effect of Ligand X in Cp*TiX3/MAO Catalysts on the Polymerization of Vinyl Chloride

“…A typical 13 C NMR spectrum of the methine region of the polymers is shown in Figure 2. The pentad tacticity of PVC was determined by means of 13 C NMR spectroscopy according to the literature, [12] and the results are summarized in Table 2. The pentad tacticities of PVC derived from the three Cp*Ti(OR) 3 /MAO catalysts were almost same, but different from those of the PVC prepared with Cp*TiCl 3 /MAO or AIBN as a radical initiator.…”

Microkinetic Modeling of Structural Properties of Poly(vinyl chloride)

“…Two types of ethyl branches are thought to occur in poly(vinyl chloride): the 2-chloroethyl and the 1,2-dichloroethyl branch. 23 The 2-chloroethyl branch is thought to be formed via a 1,3 H-shift of radical type R (1) and the subsequent addition of the formed radical to monomer. This mechanism implies that 2-chloroethyl branches contain tertiary chlorine.…”