Effects on the interfacial and mechanical properties of reed leaf fibers reinforced agar composites induced by hot water, Na2CO3 solution and ultrasound treatment

To investigate the feasibility of preparing biodegradable composites as food packing materials from reed leaf fibers to substitute disposable plastic, the fibers were treated by hot water (HWT), Na2CO3 solution (NCT) and ultrasound (UST), respectively and then combined with agar to prepare biodegradable composites through compression molding technique. The effects on the morphology, thermal properties of reed leaf fibers and the tensile cross-section morphology, the mechanical properties, the thermal conductivity and the moisture absorption profiles of the composites were studied. The amorphous components such as lignin and hemicellulose in reed leaf fibers were removed after HWT, NCT and UST. The fibers had a rough surface after hot water treatment which can lead to a better combination with agar induce an obvious improvement on the mechanical properties of the composites. The tensile strength, flexural strength and the impact strength of the HWT composite were 3.37 MPa, 19.7 MPa and 14.01 MPa, higher than that of the untreated (UT) composite and 22.99%, 16.36% and 69%, respectively. The HWT composite had a better hydrophobicity which equilibrium moisture absorption rate was 32.12%. The thermal conductivity of all the composites were less than 0.23 W center dot m(-1)center dot k(-1), which were thermal insulating.