Sun Jiyu

Preparation and flexural properties of biomimetic laminated boards made from starch and maize straw fibers

In this study, maize stalk tegument separated from the maize pith was crushed to obtain the fiber. The cross-linking maize starch adhesives considering four main factors (water content, gelatinization temperature, NaOH as gelatinization agent and Na2B4O7·10H2O as cross-linking agent) with three levels were prepared based on an orthogonal test scheme L9(3 ) in order to increase the water-resisting property and the bonding strength of the common maize starch adhesives. The bonding properties of maize starch adhesives were characterized using shearing strength under compression loading. Physical models of fiber reinforced composites were established according to the microstructure analysis of the four species of insects’elytra including Protaetia orentalis, Copris ochus Motschulsky, Anoplophora chinensis and Cytister bengalensis Aube, which will provide the biomimetic models for the biomimetic laminated boards. The maize stalk fiber biomimetic laminated boards were prepared based on the structural models of the elytra material. The flexural strength and flexural elastic modulus of the biomimetic boards were examined. The results showed that the flexural strengths of the single layer jute fiber, -reinforced maize stalk fiber boards and the dual layer jute fiber reinforced maize stalk fiber boards are higher than those of the common maize stalk fiber boards and the other three groups of jute fiber hybrid reinforced stalk fiber boards because of the biomimetic laminated design.

Application of Nanoindenter in Investigating Properties of the Cuticle of Dung Beetle

The cuticle of insects is multilayered structure at micro- or nano-scale in vertical direction. This work investigated the mechanical properties of the cuticle of dung beetle Copris ochus Motschulsky using nanoindenter. It was shown that the nanomechanical properties of the cuticle were different for each layer of the cuticle and its normal nanoindentation was resulted from the composite effect of the all layers