Supercritical fluids and their application to the recycling of high-performance carbon fibre reinforced composite materials

Dandy, Luke (2015). Supercritical fluids and their application to the recycling of high-performance carbon fibre reinforced composite materials. University of Birmingham. Ph.D.

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Abstract

The decomposition of high-performance thermoplastic and thermoset polymers is carried out by using supercritical fluids, in conjunction with a caesium carbonate catalyst (Cs\(_2\)C0\(_3\)). Polyetheretherketone (PEEK) and its carbon fibre filled composite are used as the high-performance thermoplastic, owing to its strong chemical resistance and excellent thermal and chemical stability. 2,2-Bis[4-(glycidyloxy)phenyl]propane (BADGE) is cross-linked with 4,4' –diaminodiphenyl sulfone (DDS) to produce a high-performance thermoset resin used to investigate the decomposition of the polymer matrices used in the manufacture of carbon fibre reinforced polymers (CFRP’s). It is determined that the complete decomposition of the BADGE based thermoset resin is possible at 573 K when using a catalyst concentration ([Cs\(_2\)C0\(_3\)]) of 10 ml\(^-\)\(^1\) in 100% ethanol or propanol and a reaction time of 30 minutes, with a percentage degradation of 90 % being achieved after 45 minutes. The decomposition of PEEK at 623 K, 7 K above its melt temperature, is possible within 30 minutes when using a supercritical fluid mixture of ethanol and water ([EtOH] = 20 %v) and a Cs\(_2\)C0\(_3\) concentration of 10 mg ml\(^-\)\(^1\) decomposition of PEEK in 100 % ethanol was not observed, indicating that the decomposition reaction is hydrolysis. Conversely, the decomposition of the BADGE based thermoset resin was essentially impeded by the presence of water and is therefore one of solvolysis. Both decomposition reactions were found to be 1st order with respect to [Cs\(_2\)C0\(_3\)].

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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