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Stalk lodging contributes to significant crop yield losses. Therefore, understanding the biomechanical strength and structural rigidity of grain stalks can contribute to improving stalk lodging resistance in crops. From the structural constituents of the stalk, the rind provides the principal structure, supporting cells against tension and bending loads. In this work, the biomechanical and viscoelastic behavior of the rind from the internodes of two sweet sorghum varieties (Della and REDforGREEN (RG)), grown in two different growing seasons, were evaluated by three-point micro-bending tests using a dynamic mechanical analyzer (DMA). In addition, the chemical composition of rinds and the microfibril angle (MFA) of the cell wall were determined using XRD. The results revealed that the biomechanical behavior of Della varieties was stiffer and more resistant to loads than that of RG varieties. Two features of the rind biomechanical properties, flexural modulus (FM) and flexural strength (FS), showed a significant reduction for RG. Particularly, a reduction in FS of 16–37% and in FM of 22–41% were detected for RG1. Changes in the stalks’ rind biomechanical properties were attributed to cell wall components. Total lignin and glucan/cellulose contents were positively correlated with the FM and FS of the rind. Subsequently, an increase in the two cell wall components drove an increase in stiffness. Furthermore, the MFA of the rind was also found to influence the rind strength. 

This study evaluated the mechanical, thermal, water soak, and rheological properties of mixed plastic waste (MPW) in combination with fibers derived from residual hops bines and coupling agents or dicumyl peroxide (DCP) to form composite materials. Hop bines were pulped to afford individual hop fibers (HF) in 45% yield with 78% carbohydrate content. The MPW comprised mainly of PET, paper, PE and PEVA. Tensile moduli and strength of the formulations ranged between 1.1 and 2.0 GPa and 11 and 14 MPa, respectively. The addition of hops fiber (HF) improved the tensile modulus of the formulations by 40%. Tensile strength was improved by the addition of coupling agents by 11% and this was supported by determining the adhesion factor by dynamic mechanical analysis. However, the addition of DCP resulted in a reduction of tensile properties. The melt properties of the formulations showed shear thinning behavior and followed the power-law model. The water absorption tests for most of the MPW formulations gave an 11% weight gain over 83 d except for the DCP treated composites (14–16%). The fabricated composites can be used in non-structural applications such as (garden trim, siding, pavers, etc.).