Vanadium nuclear magnetic resonance spectroscopy

The study of ethylene and propylene copolymerisation, on vanadium and titanium catalysts of various compositions [70], led to the conclusion that studied catalytic systems contain two or three types of AC. This conclusion has been made as a result of the analysis of the MWD curves, carbon nuclear magnetic resonance spectroscopy analysis, and copolymers composition fractionation data. The analysis of a large number of copolymer fractions, produced by their dissolution in several solvents at various temperatures, has indicated the existence of several types of AC different both in stereospecificity and in reactivity. According to the authors of [70], a combination of copolymer fractionation results with gel chromatography data indicates the presence of two or three types of AC. 

Howarth OW (1990) Vanadium-51 NMR. Progress in Nuclear Magnetic Resonance Spectroscopy 22 453-485. 

The preparation of natural rubber-gra/t-methyl methacrylic acid has been reported by Lenka and coworkers. The vanadium ion was used as an initiator, which initiated the creation of free radicals on the backbone of natural rubber and this increased the interaction between the natural rubber and the methyl methacrylate surfaces. The coordination complexes derived from the acetylacetonate of Mn(III) ions could also be used as an initiator to form the natural rubber-gra/t-methyl methacrylic acid. Under different conditions, silver ions could be used as a catalyst to produce natural rubber-gra/t-methyl methacrylic acid with different concentrations of methyl methacrylic acid monomers, and potassium peroxydisulfate as an initiator. Consequently, these methods were successful in the preparation of compatible blended natural rubber and methyl methacrylic acid by graft copolymerization. This compatibility was confirmed by nuclear magnetic resonance and infrared spectroscopy techniques. The interaction between natural rubber and methyl methacrylic acid was significantly increased and was useful for further blending with other polyacrylate molecules or different polymer types. 

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