Unravelling the kinetics of the homogeneously catalysed oxidation of amylopectin
toon extra info.
|[S.l.] : [s.n.]|
|Bsc Thesis||BSc Thesis Biotechnology - Biotechnology - unknown - Wageningen University|
|Trefwoorden (cab)||biobased economy / polymeren / biomassa / bioplastics / materialen uit biologische grondstoffen / zetmeel / oxidatie / pectinen|
|Chemie (algemeen) / Industriële sector|
|Toelichting (Engels)||The production of anionic polymers is an expansive industry with widespread applications. The production process of anionic polymers is ever changing. Both the method of catalysis and the raw materials have changed or are prone to change in the near future. A greater understanding of the reaction kinetics of macromolecules would help with the improvement of production processes. Gaining this knowledge is the aim of this research; more specifically the effect both the degree of polymerisation (DP) and the degree of substitution (DS) have on the oxidation rate (r ox) of amylopectin. To achieve this, four starches with different sizes were used, each starch originates from the strain of potato called Eliane. These starches will be oxidised with hypochlorite and TEMPO ((2,2,6,6 - Tetramethylpiperidin - 1 - yl)oxyl) , to a DS of 20%. The oxidation was done in a stepwise manner and in one go. The r ox was measured and modelled yielding the corresponding reaction constants. It is unexpected to see the DP affect the r ox , because there should not be a difference in availability of the C6 in anhydroglucose for a range of DP’s, because all starches have the same properties and even with branching the hypochlorite is still able reach the all the C6 atoms of the starch. A decrease in r ox for an increase in DS is expected, because there are less available C6 atoms at higher DS’s. The results found from both the oxidation methods show that r ox decreases for both DP and DS. A plausible explanation for these results is a combination of the change of the micropolarity around the starches in solution as the DS changes and the starch becomes more negatively charged. The inability to homogeneously dissolve starch in water at room temperature strengthens this theory, because it would further develop pockets of polarised starch. The found results give new insights into the reaction kinetics of the oxidation of amylopectin, these results however can be applied to other macromolecules as well.|