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.
Highlights
The properties of polymer products depend as much on the skill and expertise of the polymer processor as they do on the ingenuity of the polymer maker
We will focus our attention on semi-crystalline polymers as these make up the vast majority of thermoplastic used in traditional manufacturing and in emerging technologies such as 3D printing and other Direct Digital Manufacturing techniques
It is well established that under sufficiently vigorous flow conditions, that long chain molecules of crystallisable polymers become extended in the flow field, for extensional flow, weakly in the case of shear flow and these extended chains may act as row nuclei for subsequent chain folded lamellar crystal growth which grow out from this central core with a high degree of common lamellar orientation
Summary
The properties of polymer products depend as much on the skill and expertise of the polymer processor as they do on the ingenuity of the polymer maker. We will focus our attention on semi-crystalline polymers as these make up the vast majority of thermoplastic used in traditional manufacturing and in emerging technologies such as 3D printing and other Direct Digital Manufacturing techniques
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