Optical characterisation of polymeric nanocomposites using tomographic, spectroscopic and Fraunhofer wavefront assessment

摘要

Polymers are often embedded with specific nanofillers such that the functional characteristics and properties of theresulting polymeric nanocomposite (PNC) are enhanced. The degree to which these enhancements can be achieveddepends not only on the level of particle loading of nanofillers, but most importantly on the resulting dispersion profileachieved within the matrix. Agglomeration (often referred to as clustering) is a result of the mixing process and verymuch depends on the chemistry between the polymer and nanofiller. Depending on the PNC type, different mixingprocesses can be applied but the general consensus is that such processes are not repeatable themselves. Not only it isquite difficult to achieve the desired level of dispersion, but in addition there is a limited number of characterization toolsthat can be employed to routinely check the homogeneity achieved within a produced sample. Transmission electronmicroscopy (TEM) and X-ray diffraction (XRD) techniques are usually employed, but they are very time consuming,expensive, require special sample preparation and treatment, often produce results that are difficult to interpret and canonly analyse very small areas of sample. This work reports on the adaptation and development and three opticaltechniques that are non-destructive, can accurately characterize the dispersion achieved as a result of the mixing processand can analyse larger material areas. The techniques reported are based on static and dynamic visible and infra-red lightscattering.