No abstract

No abstract

Two polypropylenes with different molecular structure were investigated in shear and elongational flow. One resin is an ethylene–propylene copolymer with linear molecules and the other is a long-chain branched propylene homopolymer. The elongational flow behavior was investigated in stressing and creep experiments. For the linear material no strain hardening can be observed whereas the strain-hardening behavior of the long-chain branched material is more pronounced than it was found for any other polyolefin up to now. The branched resin also exhibits high recoverable strains. The strain-hardening behavior is analyzed with respect to its strain and strain rate dependence. The results are discussed with regard to the molecular structure. The coexistence of a long-chain branched structure and a high molecular weight component is assumed to be the reason for the outstanding elongational flow behavior of the branched polypropylene.

No abstract

Different organophilic layered silicates and a modified hydrotalcite were used as functional nanofillers for thermoplastic and thermosetting polymers. Polyamide 6 (PA6) and poly(butylene terephthalate) silicate nanocomposites were prepared by melt compounding using a twin‐screw extruder. The morphology of the materials was investigated by transmission electron microscopy and small‐angle X‐ray scattering, and was found to be characterized by homogeneous dispersion of high aspect ratio silicate layers in the polymer matrix. The PA6 nanocomposite displayed excellent thermo‐mechanical properties at low filler loadings and improved barrier properties. Epoxy nanocomposites have also been prepared and characterized with regard to their morphology and their water vapor permeability.