New materials by grafting acrylic acid onto Cassava starch

PhD ceremony: Ms. M.T.J.R.B. Witono, 12.45 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: New materials by grafting acrylic acid onto Cassava starch

Promotor(s): prof. L.P.B.M. Janssen, prof. H.J. Heeres

Faculty: Mathematics and Natural Sciences

The objective of the research is to investigate the possibilities for utilizing more cassava starch. Because of its low price it is well known as a foodstuff for poor people in tropical areas, e.g. Indonesia. The low price however does not stimulate farmers to produce more. If an industrial non-food application could be developed, the resulting increasing demand could break this deadlock.

Up to now, (other) research based on this starch especially for non-food applications is still very limited. Starch itself cannot fully replace yet the functionality of synthetic polymers in most applications. Therefore, starch has to be modified. A first choice with respect to replacing current polymers and a strong link to these is, to graft monomers onto starch. By graft copolymerization, some properties of the original starch backbone will be retained while new properties are added.

Since the application of the acrylic acid based polymers is widespread, the current investigation focused on grafting of acrylic acid onto cassava starch. The conclusions from this laboratory scale study can be used for the further development of products and of a process to make these. An adequate analytical method was further developed successfully. An Experimental Design method allowed for a screening of the important reaction variables. A kinetic model has been developed that fits well to actual experiments. Torque monitoring resulted in an unprecedented view of the viscosity during the graft copolymerization reaction.

The resulting material shows prospects for use as superabsorbent and other applications e.g. thickening agents.