Controlling and Evaluating the Structure and Morphology of Polymers on Multiple Scales

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.

Highly insulating thermoplastic blends comprising a styrenic copolymer for direct‐current power cable insulation

The impact of the composition of blends comprising low‐density polyethylene(LDPE),isotactic polypropylene(PP)and a styrenic copolymer additive on the thermomechanical properties as well as the direct‐current(DC)electrical and thermal conductivity is investigated.The presence of 5 weight percent(wt%)of the styrenic copolymer strongly reduces the amount of PP that is needed to enhance the storage modulus above the melting temperature of LDPE from 40 to 24 wt%.At the same time,the copolymer improves the consistency of the thermomechanical properties of the resulting ternary blends.While both the DC electrical and thermal conductivity strongly decrease with PP content,the addition of the styrenic copolymer appears to have little influence on either property.Evidently,PP in combination with small amounts of a styrenic copolymer not only allows to reinforce LDPE at elevated temperatures but also functions as an electrical conductivity‐reducing additive,which makes such thermoplastic ternary formulations possible candidates for the insulation of high‐voltage power cables.