Effect of filler and sonication time on the performance of brown alga (Sargassum plagiophyllum) filled cassava starch biocomposites

Abstract

A biocomposite was prepared from a mixture of pre-gelatinized cassava starch and a brown alga (Sargassum plagiophyllum) as a potential alternative material to synthetic plastic. The brown alga was ground using a planetary ball mill and its morphology was characterized and particle size determined. Mixtures of starch and milled brown algae were sonicated to improve dispersion of the algae in the starch matrix. Biocomposites of starch and milled brown algae were prepared using compression molding. The effects of milled brown algae content and sonication time on the properties of the obtained starch-based biocomposites were investigated. The biocomposite with the highest tensile strength (2.22 MPa) and the lowest weight loss after accelerated weathering for 24 h (20.65%) was from a mixture of starch and 10 wt% milled brown algae sonicated for 120 s. These results were consistent with the good dispersion and adhesion of the milled brown algae in the starch matrix as revealed by scanning electron microscopy (SEM) images. Stress transfer in this biocomposite was more effective and photo-degradation and hydrolytic degradation were inhibited. Thermogravimetric analysis (TGA) results showed that the addition of 10 wt% of milled brown algae and sonication for 120 s also improved the thermal stability of the obtained biocomposite.