Approaching a Zero-Waste Strategy in Rapeseed (Brassica napus) Exploitation: Sustainably Approaching Bio-Based Polyethylene Composites

Abstract

The current need to develop more sustainable processes and products requires the study of new materials. In the field of plastic materials, the need to develop 100% bio-based materials that meet market requirements is evident. In this sense, the present work aims to explore the potential of rapeseed waste as a reinforcement of a bio-based plastic matrix that does not generate new sub-waste. For this purpose, three types of processing of rapeseed residues have been studied: (i) milling; (ii) mechanical process; (iii) thermomechanical process. In addition, the reinforcing capacity of these materials, together with the need for an optimized coupling agent at 6 wt.%, has been verified. The micromechanics of the materials have been evaluated to determine the development of these fibers in the composite material. The results obtained show remarkable increases in mechanical properties, reaching more than 141% in tensile strength and 128% in flexural strength. There is a remarkable difference in the impact behavior between the materials with milled rapeseed and the fibers obtained by mechanical or thermomechanical processes. It was found that by sustainable design it is possible to achieve a 76.2% reduction in the amount of plastic used to manufacture material with the same mechanical properties.

Behavior of the Flexural Strength of Hemp/Polypropylene Composites: Evaluation of the Intrinsic Flexural Strength of Untreated Hemp Strands

“…It is customary to split the contributions of the reinforcement fibers and matrix to the tensile strength of the composite (σ t C ) in terms of the modified rule of mixtures [ 29 , 30 ]: σ t c = f c × σ t F × V F + (1 − V F ) × σ t m where V F is the volume fraction of fibers, σ t F is the strength of the matrix at composite failure, σ t F is their intrinsic tensile strength, and f c is known as the coupling factor. The product of the latter two parameters, f c and σ t F , is referred to as the fiber tensile strength factor (FTSF) [ 31 ].…”

Valorization of Kraft Lignin from Black Liquor in the Production of Composite Materials with Poly(caprolactone) and Natural Stone Groundwood Fibers

“…On the other hand, as seen in previous works, the increase in the volume fraction of reinforcement causes a greater generation of shear forces during the processing of the material, both in the kinetic mixer and in the injection of the piece, which causes a decrease in the length of the fiber and its diameter [ 75 ]. The fibers used initially have an arithmetic length of 259 µm, a weight-weighted length of 1659 µm, and a diameter of 34.1 µm, resulting in an aspect ratio of 7.6.…”

“…One of the main limitations when incorporating natural fibers in a polymeric matrix is the modification of density. It is known that natural fibers with a higher density than most polymers of fossil origin, between 1.35 and 1.45 g/cm 3 , cause an increase in the density of the composite material by increasing the reinforcement content [ 74 , 75 ]. However, in this study the blend used as a matrix for the composite material presents a density similar to that of the fibers and therefore the density remains practically constant.…”

Tensile Strength of Poly(lactic acid)/Bleached Short Hemp Fiber Fully Green Composites as Replacement for Polypropylene/Glass Fiber

“…According to the modified rule of mixtures [ 27 , 28 ], the tensile strength of a fiber-reinforced composite material (σ t c ) as a function of the volume fraction of fibers (V F ) is given by: σ t c = f c × σ t F × V F + (1 − V F ) × σ t m* where σ t m* is the tensile strength of the matrix at composite fracture, σ t F is the intrinsic tensile strength of fibers, and f c is a coupling factor. The product of the latter two parameters corresponds to the slope of σ t c against V F .…”