C-13 And H-1-Nmr Studies Of Solid Polyolefines

The basis of 1 H and 13 C high-resolution n.m.r. investigations of solid polymers is outlined. The 13 C n.m.r. spectra of solid syndiotactic and isotactic polypropene (polypropylene) are discussed and their interpretation in terms of conformation and chain-packing effects are reviewed. The effects of decreasing temperature on the 13 C high-resolution spectrum of an annealed sample of isotactic polypropene is described and interpreted in terms of the crystal structure. The question of the proportion of the sample giving rise to 13 C signals is addressed and some results reported. The main cause for observing only part of the total sample is shown to be the 1 H rotating frame spin-lattice relaxation behaviour. The 1 H spin-lattice relaxation and spectral characteristics of a number of polyolefine samples are summarized and the role of spin-diffusion discussed. The heterogeneity revealed by the multicomponent T 1ϱ θ behaviour has been modelled numerically using a computer and the conclusions are outlined. The recovery behaviour of polybut-l-ene, following conversion to a meta -stable form by heating, is observed using both cross-polarization and single-pulse excitation techniques. In addition, an example of the investigation of a propene/ethylene copolymer by both 13 C and 1 H methods is described to illustrate the interdependence of the techniques.