Baba, NM; (2014) Hydrophobic Polymers and Nanocomposites from Cassava. Doctoral thesis , UCL (University College London).

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Abstract

This project aims to benefit the sub-Saharan African economies by exploiting cassava for chemical feedstock for materials production. It anticipates the industrial changes that will follow from increased petroleum price and regulatory control of embedded fossil carbon. It offers a way to integrate industrial and agricultural sectors. Initially, glucose and fructose were dehydrated by reactive distillation over a sulfated zirconia catalyst and 1-butyl-3-methylimidazolium chloride (BMIM Cl) ionic liquid as solvent under a nitrogen atmosphere at 180 oC to produce 5-(hydroxymethyl) furan (5-HMF) as a precursor for polymeric materials. Solvent, catalyst and reaction conditions were varied to improve the yield of 5-HMF. Yields of 82% and 65% were obtained using fructose and glucose substrates with this catalyst. Secondly, 2,5-furandicarboxylic acid (FDCA) and 2,5-bis-(hydroxymethyl)furan (BHMF) were synthesised as monomers from 5-HMF. The aldehyde group of 5-HMF was oxidized using potassium permanganate to FDCA with 80% yield achieved. BHMF was synthesised from 5-HMF using sodium borohydride with 88% yield achieved. The third part focuses on the polymerization of FDCA with the following diols: 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol and BHMF via esterification reactions at 160-200 oC using titanium (IV) n-butoxide catalyst. All diols produced polymers under the same conditions. The difference within this family of polymers was the number of carbon atoms in the linking diols and that BHMF had a different diol structure with a furan ring attached. Furthermore, a study of the interaction of all the monomers and the 5-HMF with Na-montmorillonite clay was made. It was observed that all were intercalated into the clay paving the way for the manufacture of nanocomposites. Finally, all the polymers were shown to be hydrophobic with PBH-2,5-F more hydrophobic with a contact angle of 91o compared to others. Water absorption, dielectric constant and mechanical properties of the polymers were recorded.

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