TITLE:
Controlling and Evaluating the Structure and Morphology of Polymers on Multiple Scales
AUTHORS:
Geoffrey R. Mitchell, Ana Tojeira, Thomas Gkourmpis, James J. Holt, Peter Harris, Marilena Pezzuto
KEYWORDS:
Component, Semi-Crystalline Polymers, Morphology, Texture, Nucleation, Growth, Shear Flow
JOURNAL NAME:
Journal of Materials Science and Chemical Engineering,
Vol.3 No.12,
December
17,
2015
ABSTRACT:
Crystalline polymers spontaneously form
hierarchical structures although the precise manner in which these scales of
structure are interconnected especially terms of the formation and evolution of
the complete structure remains unclear. We have set out to control these scales
of structure by introducing additional components which self-assemble in to
nano-scale units which then direct the crystallisation of the polymer matrix.
In other words, we first assemble a low concentration top-level structure which
is designed to template or direct the sub-sequent crystallisation of the matrix
polymer. This top level structure takes on the role of controlling the
structure. We have set out to both establish the design principles of such
structures and to develop experimental procedures which allow us to follow the
formation of such complex hierarchical polymer structures. In particular we
focus of the relationships between these different levels of structure and time
sequence of events required for the structure to evolve in the targeted manner.
In this programme, we have exploited time-resolving small-angle X-ray
scattering and electron microscopy together with neutron scattering to probe
and quantify the different scales of structure and their evolution. We
highlight new neutron scattering instrumentation which we believe have great
potential in the growing field of hierarchical structures in polymers. The addition
of small quantities of nanoparticles to conventional and sustainable
thermoplastics leads to property enhancements with considerable potential in a
number of areas Most engineered nano-particles are highly stable and these exist
as nano-particles prior to compounding with the polymer resin, they remain as
nano- particles during the active use as well as in the subsequent waste and
recycling streams. In this work we also explore the potential for constructing
nano-particles within the polymer matrix during processing from organic
compounds selected to provide nanoparticles which can effectively control the
subsequent crystallization process. Typically these nano-particles are rod-like
in shape.