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Title: Characterisation of interfaces in micro- and nano-composites
Author: Young, Timothy James
ISNI:       0000 0004 2716 2034
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2012
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There is a current industrial requirement for the development of suitable testmethodology that is capable of in-situ mechanical and physical characterisation of the interface and interfacial region in composite materials. The most promising tool for micro- and nano-scale measurements is the atomic force microscope (AFM) although, for suitable test-methodology to be realised, further development is required. The work contained within this thesis documents the development of AFM procedures for the measurement of elastic moduli variation across the interface and considers the physical size of the interfacial region. The first AFM procedure is for the analysis of multiple (AFM) indentations and the quantification of each indentation (in terms of reduced elastic moduli). Results of interfacial testing using this procedure highlighted short transition regions of apparently increased elastic moduli between the glass reinforcement and the polymeric matrix. It was not possible to identify whether the increase in elastic moduli was representative of an interphase due to the possibility that the indentations in this region were restricted by the presence of the glass fibrereinforcement. A second, novel procedure was then developed to independently verify whether or not any indentations were restricted, and identify whether a measured transition is representative of an interphase. This procedure was based on the principle that the any indentation performed in close proximity to the glass fibre-reinforcement would have an uneven distribution of loading between the surface and the indenter tip. The uneven distribution of loading resulted in torsion of the indenter tip, which was measured during multiple indentations across the interface of a glass fibre-reinforced phenolic composite. It was found that the apparent increase in elastic moduli measured across the interface was directly related to restriction due to, and contact with, the proximity of the glass fibrereinforcement. Finally, the latest AFM technique with the potential for quantitative measurement, is reviewed. The work has shown that AFM nanomechanical mapping has the potential to be a useful supplement to liT for measuring the small-scale elastic modulus of a polymer surface. It was found that the technique can provide repeatable measurements of polymer moduli for a number of different probes provided that careful calibration procedures are used.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available