Number: 2005-023-2-400
Title: Micro-structural, melt processing
and mechani-cal properties of compatibilised PA 6/ABS -blends
Task Group
Chairman: Helmut
Steininger
Members: Volker
Altstädt, Rob
Bailey, Dick Dijkstra,
Andrzej Galeski,
Ulrich Handge, Sung
Chul Kim, Martin Laun,
and Goerg H. Michler
Objective:
Investigation of the influence of compatibilisation of PA6/ABS blends
on melt processing, micro-structure and mechanical properties and
their mutual interactions.
Description:
Blending of polymers is a technologically important procedure in
polymer processing and a powerful tool in order to improve the end
use properties of polymeric materials. The understanding of relevant
micro-structural mechanisms during melt processing and of deformation
on morphology in the solid state is essential in order to optimise
the blending of polymers with respect to processability and performance.
For example, it is often necessary to prepare a two phase polymer
blend with a co-continuous morphology during extrusion. Therefore
it is crucial to understand quantitatively the deformation of the
phases and the processes leading to the break-up or the coalescence
of micro-structures during mixing. Compatibilisation of the constituents
generally improves the mechanical properties of the blend. In this
context, the degree of compatibilisation, the mobility of the compatibiliser
at the interface and in the bulk and its influence on interfacial
tension and coalescence of droplets are important properties, which
determine the final blend morphology and the mechanical performance.
In the past, the relevant physical phenomena in complex multiphase
blends (e.g., the industrially important PA 6/ABS blends) have only
been partially explored. Especially, melt elongational properties,
their influence on morphology and melt stability during processing
were not the focus of previous studies.
This project aims to clear up those physical mechanisms in compatibilised
PA 6/ABS blends, which are relevant to melt processing and to mechanical
performance. The degree and the effect of compatibilisation as well
as the formation of the morphology as a function of the overall
composition of the blend will be investigated and their influences
on the flow and the mechanical properties will be elucidated. Particularly,
the deformation of the morphology during elongation in the solid
and in the molten state will be investigated. The materials will
be supplied by BASF AG (Ludwigshafen, Germany). The preparation
of blends of selected composition ratios, including reactive compatibilisation,
will be done by melt mixing in a twin-screw extruder. The melt processing
properties will be investigated by performing elongational and shear
rheometry. The mechanical properties of compatibilised PA 6/ABS
blends will be evaluated by determining fracture mechanical quantities
like the critical value of the stress field and the critical value
of the energy release rate (fracture toughness). In addition, dynamic-mechanical
analysis, fatigue crack growth tests, impact tests and micromechanical
tests will be performed. The morphology of the blends will be investigated
by microscopic (e.g. AFM and TEM) and scattering methods (SAXS /
WAXS).