Structural analysis and adhesive capacity of cassava starch modified with NaOH:urea mixtures

In this research the interactions and structural changes induced by NaOH:urea mixtures on cassava starch suspensions as well as their adhesive capacity were studied. Cold gelatinization of 10–20% w/w cassava suspensions was induced by adding different NaOH:urea mixtures (0.5–2:1). Chemical modification of cassava starch was analyzed through optical microscopy as well as SEC-HPLC and size particle determinations, ATR-FTIR spectral and chemometric analysis were also carried out. Cassava starch treatment with NaOH:urea mixtures generated structural disorganization, induced cold gelatinization and promoted the hydrolysis of the polymeric chains. SEC-HPLC and ATR-FTIR results showed that the modifications induced in the adhesive formulations depend both on the starch content and the NaOH:urea ratio. All tested formulations exhibited adhesive capacity, being effective for Kraft paper substrate bonding. Thus, this simple and low-cost procedure was effective to chemically modify cassava starch allowing to obtain derivatives with tailor-made adhesive properties.