Quantitative branch determination in polyolefins by melt-state NMR has been investigated paying particular attention to sensitivity per unit time. Comparison of spectra obtained using spectrometers operating at 700, 500 and 300 MHz 1H Larmor frequency, with 4 and 7 mm MAS probeheads, showed that the best sensitivity was achieved at 500 MHz using a 7 mm 13C-1H optimised high-temperature probehead. For materials available in large quantities static melt-state NMR, using large-diameter detection coils at 300 MHz, was shown to produce comparable results to melt-state MAS measurements in less time. Artificial line broadening, introduced by FID truncation, was reduced by the use of π pulse-train heteronuclear dipolar-decoupling. This decoupling method, when combined with a higher duty-cycle, allowed for the whole FID to be acquired. Optimised methods have been applied to the characterisation of short-chain branching (SCB) in polyethylene- and poly(propylene)-co-α-olefins with varying comonomer incorporation. Long-chain branch (LCB) concentrations of 8 branches per 100 000 CH2 were quantified for an industrial ‘linear’ polyethylene in 13 h, with a signal-to-noise ratio of 10 for the α branch site used. The use of J-coupling mediated polarisation transfer techniques were also shown to be viable for branch quantification in the melt-state.
