Monomer mixture inside, composition

Explanation may be related to the heterogeneity of the reaction medium polymerization location is mostly limited to within the polymer particles, so the copolymer composition is dependent on the composition of the monomer mixture inside the particles, which may be different from that of the whole reactor, monitored by the apparatus. So, compositions of various phases, monomer droplets, polymer particles, aqueous phase, were measured using gas chromatographic (GC) analysis, after they were separated by ultracentrifugation (33,000 rpm). 

The PVA/PAAc IPNs were prepared by sequential method. PAAc as an initial network was synthesized inside a PVA solution using UV irradiation. PVA as a secondary network was then formed by repetitive freezing-thawing process. The whole reaction scheme of PVA/PAAc IPNs is described in Fig. 6.2. PVA was dissolved in deionized water and heated at 80 °C for 2 h to make 10 wt% aqueous solution. AAc monomers were mixed with 0.2 wt % DM PAP as a photoinitiator and 0.5mol% MBAAm as a cross-linking agent. The mixture was combined with PVA solution to yield PVA-PAAc. The feed composition and designation of each sample are listed in Table 6.1. 

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