Journal of Polymer Science Polymer Physics Edition · 1973 · 143 citations · 7 references
EngineeringC ResonancesC NmrResponsive PolymersOrganic ChemistryCarbon‐13 NmrChemistryMolecular PolymerPolymersPolymer MaterialMacromolecular EngineeringPolymer ProcessingPolymer ChemistryBiophysicsLow‐density PolyethylenePolyethylene MaterialsPolymer AnalysisBranch ResonancesShort‐chain Branch DistributionPolymer SciencePolymer CharacterizationPolymer PropertyPolymer Synthesis
Abstract As model polymers for isolated short‐chain branches in low‐density polyethylene, a series of ethylene–1‐olefin copolymers was examined by use of 13 C NMR at 25.2 MHz. An array of 13 C resonances was observed that could be associated independently with methyl through amyl branches. The 13 C chemical shifts became insensitive to branch length with hexyl and longer branches. Assignments of the various carbon resonances associated with branching were accomplished by using off‐resonance decoupling techniques and the behavior of alkane chemical shifts previously observed by other investigators. The ratio of certain backbone and branch resonances could be used to establish the short‐chain branch distribution in a low‐density polyethylene.
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