Characterization of α-tocopherol as interacting agent in polyvinyl alcohol–starch blends

In this study, the interactions of α-tocopherol (α-TOH) in PVOH–starch blends were investigated. α-TOH is an interacting agent possesses a unique molecule of polar chroman “head” and non-polar phytyl “tail” which can improve surface interaction of PVOH and starch. It showed favorable results when blending PVOH–starch with α-TOH, where the highest tensile strengths were achieved at 60 wt.% PVOH–starch blend for 1 phr α-TOH and 50 wt.% for 3 phr α-TOH, respectively. This due to the formation of miscible PVOH–starch as resulted by the compatibilizing effect of α-TOH. Moreover, the enthalpy of melting (ΔHm) of 60 wt.% PVOH–starch and 50 wt.% PVOH–starch added with 1 and 3 phr α-TOH respectively were higher than ΔHm of the neat PVOH–starch blends. The thermogravimetry analysis also showed that α-TOH can be used as thermal stabilizer to reduce weight losses at elevated temperature. The surface morphologies of the compatible blends formed large portion of continuous phase where the starch granules interacted well with α-TOH by acting as compatilizer to reduce surface energy of starch for embedment into PVOH matrix.