Blends with low-density polyethylene (LDPE) and plastomers

[摘要] ENGLISH ABSTRACT:This study describes the design, building and optimization of a fully functionalpreparative TREF (Prep-TREF) apparatus. This apparatus allows for the fractionation of semicrystallinepolyolefins according to the crystallizability of the molecules. Various factors, such asthe sample cooling rate and the effect of on-support and off-support crystallization, areinvestigated.The preparative TREF is used to fractionate a commercial low-density polyethylene(LOPE), two commercially available plastomers (polyethylene-l-octene copolymers), as well asblends of the LOPE and the respective plastomers. It is shown that in each case the samplesfractionated by crystallizability. The fractions recovered from the Prep-TREF were characterizedby CRYSTAF, OSC and NMR analysis. It is shown how the results of this preparativefractionation allow for a better understanding of the molecular heterogeneity in the LOPE andplastomers.New ways of presenting the data from the preparative fractionation, in terms of 3-dimensional plots, are also investigated. These plots offer a novel way of presenting themolecular heterogeneity in the samples in terms of the molecular crystallizability. These plotshighlight features that are difficult to detect in the conventional two-dimensional plots.In conclusion, the influences of various blending ratios of LOPE and plastomer on themorphological and physical properties of the blends, such as haze, clarity, and tear-and impactstrength are determined.

[发布机构] Stellenbosch University