Determination of Short-Chain Branches in Poly(vinyl chloride) and Ethylene-Vinyl Chloride Copolymers by Pyrolysis-Hydrogenation-Gas Chromatography

Abstract

ABSTRACT:Short-chain branches (SCB) of poly(vinyl chloride) (PVC) and ethylene-vinyl chloride copolymer (EVC) samples were determined by reduction of the samples with tri-n-butyltin hydride(Bu3 SnH) followed by high-resolution pyrolysis-hydrogenation-gas chromatographic measurement in the presence of nickel (Ni) as a hydrogenation catalyst. The branch contents were estimated from the relative peak intensities of characteristic key isoalkanes on the C 10 and C 11 fragment region in the observed pyrograms by comparing the data of reference model ethylene-IX-olefin copolymers with known contents of methyl (C 1 ), ethyl(C 2 ), and butyl (C4 ) branches, respectively. The results obtained by this method were in reasonably good agreement with those found by 13 C NMR. The correlations between polymerization conditions and the SCB contents in the PVC and EVC samples were also discussed. Significant features of the proposed method such as extremely high sensitivity using less than I mg of the sample and rapidness to finish one run in about I h would meet the potential needs for the SCB characterization in various polymers containing chlorine, which were used in practical fields.

Divergent silylium catalysis enables facile poly(vinyl chloride) upcycling to poly(ethylene-co-styrene) derivatives

“…We note the 13 C NMR signal broadening may have been amplied by branching and structural defects in the starting PVC. [54][55][56][57] For comparison, branched ES copolymers prepared by cooligomerization followed by copolymerization, and hydrogenated styrene/butadiene copolymers have yielded similarly ill-dened 13 C NMR signals. 58,59 The ATR-IR spectrum of the ES copolymer is displayed in Fig.…”