W. Gerum et al., HYDROGENATED BUTADIENE ETHENE/1-OLEFIN TERPOLYMERS AS MODEL SUBSTANCES FOR SHORT-CHAIN BRANCHED POLYETHYLENE/, Macromolecular chemistry and physics, 197(5), 1996, pp. 1691-1712
butadiene-alt-ethene)-co-(butadiene-alt-1-olefin)] terpolymers were sy
nthesized by Ziegler-Natta polymerization using VO(O-neopentyl)(2)Cl/A
l(i-Bu)(3) catalyst system in toluene. Variation of the 1-olefin/ethen
e ratio in the monomer feed produces terpolymers with mixed units of b
utadiene-alt-ethene and butadiene-alt-1-olefin. After hydrogenation on
e obtains model substances for LLDPE with a special distribution of me
thylene sequences between branching points. Differential scanning calo
rimetry (DSC) was used to determine the degree of crystallinity and th
e melting behavior. From the melting temperature region, the thickness
distribution of the crystal lamellae, and thus the average number of
C-atoms between the alkyl branches, can be determined. From detailed X
-ray diffractometry, the mean crystallite size, the lattice distortion
s and the degree of crystallinity was determined for those products wh
ich show distinct reflections. The crystallization behavior can only b
e described by a three-phase model.