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Intrinsic self-healing thermosetting nanocomposites based on physical and thermally-reversible linkages

Santosa, D.S. (2016) Intrinsic self-healing thermosetting nanocomposites based on physical and thermally-reversible linkages. Master's Thesis / Essay, Chemical Engineering.

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Abstract

In this thesis, we investigated the intrinsic self-healing property and electrical response of a thermoset nanocomposite containing both covalent, although thermally-reversible, and physical linkages. Previous research into this topic has shown that a similar system based on a polyketone containing both thermally-reversible crosslinks and physical linkages are able to undergo self-healing that is triggered by heat and electricity (via resistive heating). However, this published work did not study further the effect of composition (i.e. the ratio between these two kinds of modified polyketones) on the electrical response and self-healing efficiency. Thus, the main goal of this thesis was to investigate the influence of different crosslinking density on the self-healing property and electrical response. The influence of different crosslink density was investigated by two means: by changing the degree of functionalization of the polymer backbone and by changing the ratio between polymers containing thermally reversible crosslinks and polymers containing physical links. First, polyketone functionalized with furan (the precursor of thermally reversible linkages via the Diels Alder mechanism) at several predetermined conversion degree was prepared using Paal-Knorr reaction. The materials were then characterized to confirm that the functionalization has reached the desired level. The functionalization was followed by the nanocomposite preparation, where both types of polyketones were mixed at different ratio and had multi-walled carbon nanotubes (MWCNT) added as reinforcement and electrical conductor. The resulting materials were then tested for its self-healing capability and electrical response at different degree of conversion. The results from the research confirm what the previous findings: a mixture between polyketone functionalized with furan (precursors for the thermally reversible covalent bonds) and polyketone functionalized with aminopropanol (able to interact via hydrogen bonding, i.e. physical linkages) are able to exhibit self-healing behaviour when exposed to sufficiently high temperature. The presence of MWCNT also allowed the heat to come from electrical source via Joule / resistive heating. Additionally, it was discovered that increasing the amount of polyketones functionalized with furan in a given system results in a composite that has lower electrical resistance, most likely due to the crosslinks that can form between polyketones and MWCNT, allowing better dispersion and reducing the chance for MWCNT to form aggregates.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Chemical Engineering
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 08:30
Last Modified: 15 Feb 2018 08:30
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/15530

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