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Two grades of LLDPE were analysed by a number of methods for fractionation and molecular structure determination (molecular weight, branching density). Methods used were: preparative fractionation according to comonomer content (TREF) and molecular weight (solvent -non solvent), CRYSTAF, SEC, SEC-FTIR and NMR. We explore different ways of combining and processing data to obtain two and three dimensional results. Methods to correct for chain end effects in and construct bivariate distributions from preparative TREF + SEC + NMR data is presented. The methods studied have different drawbacks and advantages. Preparative TREF + SEC + NMR and SEC-FTIR provide most information relative to the labour requirement. In general, the most complete information is obtained from combined interpretation of results from different methods.

The 13C DD-MAS spectra of six ethene/1-hexene (E/H) copolymers were fitted simultaneously to a sum of four pseudo Voigt functions in which two were assigned to the all-trans crystalline region. These two peaks possessed the same chemical shift but differed in both line width and line shape. Regarding the amorphous region, it was found to be represented by a sum of a Lorenzian function and a Gaussian function possessing different chemical shifts. The latter simply reflects the asymmetry of the spatial distribution of trans−gauche conformations. The crystallinity of the samples, as determined by DSC, was found to be in excellent agreement with the crystallinity determined from 13C DD-MAS spectra. Moreover, the crystalline part of the 1H-FID (acquired at 0.5 and 4.7 T) was fitted by using a Pake function and Abragamian function, respectively. The latter was found to give a crystallinity in quantitative agreement with the 13C DD-MAS and DSC. In contrast, the replacement of the Abragamian function with a Pake function (to represent the crystalline part of the FID) resulted often in unstable and poor model fits with rather unreliable estimate of the crystallinity. The inherent problem related to the necessary blanking of the receiver during the initial part of the FID (dead-time) is discussed.

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