Structural biomaterials engineered from lignocellulosic agricultural waste

Abstract

Milled sunflower husk was added to three types of polyolefins (polypropylene, low-density and high-density polyethylene) in a wide composition range. Composite series were prepared with or without maleic anhydride-grafted polyolefin coupling agents to investigate the effect of coupling on the mechanical properties and micromechanical deformation processes. Several independent approaches were followed to estimate interfacial adhesion qualitatively and quantitatively, respectively. The results show that interfacial adhesion is significantly improved in the presence of a coupling agent. As a result, coupling changes the dominant deformation process from matrix/filler debonding to the fracture of sunflower husk particles. Milled sunflower husk can enhance significantly the modulus of polyolefins; however, elongation-at-break values are very small, especially at larger filler content, which represents the largest obstacle of practical application.

Progress and challenges in sustainability, compatibility, and production of eco‐composites: A state‐of‐art review

“…In this case, it is recommended to treat the natural filler surface to expose the hydroxyl groups, which are covered by the waxy layer on the filler cells. The most common chemical groups for this approach are maleic anhydride (MAH) and acids such as acrylic acid that react with the filler hydroxyl group during melt mixing to form “ester bonds.” 149,170–174 Another similar and novel method that is not widely used is the functionalization of the polymer surface using an isocyanate group. This group is highly reactive with the hydroxyl group and capable of forming urethane bonds between the bio‐filler and the mating polymer, as shown in Figure 26(a) 168,175 .…”

Effect of fiber surface treatment on mechanical, interfacial, and moisture absorption properties of cattail fiber‐reinforced composites

“…Natural lignocellulosic fibers, such as flax, hemp, ramie, kenaf, sisal, and jute, have been studied as sustainable substitutes for glass fibers for reinforcing polymer matrix composites. [1][2][3][4][5][6][7][8][9][10][11][12] In terms of specific mechanical properties, these plant-based fibers, extracted from bast, leaves, seeds, fruits, wood, stalks, and grasses/reeds, [13][14][15] are on par with those of glass fibers. [16][17][18] The properties of the natural fiber composites are influenced by the properties of the fiber, fiber aspect ratio, fiber orientation, fiber moisture absorption, and fiber volume fraction.…”

“…Natural fibers are preferable as reinforcement for polymer matrix composites because of their low density and renewability over synthetic fibers. Natural lignocellulosic fibers, such as flax, hemp, ramie, kenaf, sisal, and jute, have been studied as sustainable substitutes for glass fibers for reinforcing polymer matrix composites 1–12 . In terms of specific mechanical properties, these plant‐based fibers, extracted from bast, leaves, seeds, fruits, wood, stalks, and grasses/reeds, 13–15 are on par with those of glass fibers 16–18 …”

Chemical, Thermal and Mechanical Characterization of Licorice Root, Willow, Holm Oak, and Palm Leaf Waste Incorporated into Maleated Polypropylene (MAPP)

“…In addition, MAPP also offered a sufficient compatibility with different types of lignocellulosic waste. In particular, when using MAPP, composites including lignocellulosic agricultural waste, such as sunflower husk, offered a much more effective interfacial adhesion with the matrix, resulting in improved hardness and notched impact strength to the composite [ 9 ]. Significant effects were also observed on the modification of thermal degradation profile of the polymer via filling it with by-products, such as oil palm empty fruit bunch (OPEFB), in which case a polypropylene waste matrix was selected [ 10 ].…”