Modified hemp fibers intended for fiber‐reinforced polymer composites used in structural applications—A review. I. Methods of modification

Abstract

Natural fiber composites have experienced a renaissance in the last two decades as a response to societal demands for developing eco‐friendly, biodegradable and recyclable materials. They are now being extensively used in everyday products as well as in automotive, packaging, sports and construction industries. Hemp fiber is being used in most of these products because of its superior mechanical properties. Like other natural fibers, hemp fibers require modifications in order to improve their properties and interfacial bonding with polymer matrices, and to reduce their hydrophilic character. These modification methods can be grouped into three major categories: chemical, physical and biological. Chemical methods use chemical reagents to reduce fibers' hydrophilic tendency and thus improve compatibility with the matrix. They also expose more reactive groups on the fiber surface to facilitate efficient coupling with the matrix. Physical methods change structural and surface properties of the fiber and thereby influence the interfacial bonding with matrices, without extensively changing the chemical composition of the fibers. They are cleaner and simpler than the chemical methods. Biological methods use biological agents like fungi, enzymes and bacteria to modify the fiber surface properties. These methods are not toxic like chemical methods and are not energy‐intensive like physical methods. This paper presents an overview of recent developments in these methods. It is concluded that these methods almost invariably result in improvement in fiber/matrix interfacial bonding, resulting in increase in mechanical properties of the composites.

Manufacturing and characterization of hemp‐reinforced epoxy composites

“…Several natural reinforcements can be found in literature, including flax, hemp, jute, sisal, cotton, silk, and others . Among these classes of materials, hemp‐reinforced polymeric composites are especially suitable to be applied in industrial design because of their unique mechanical and physical properties …”

Elaboration by Wrapping Process and Multiscale Characterisation of Thermoplastic Bio-Composite Based on Hemp/PA11 Constituents

“…After wrapping, the yarn structure becomes more compact and uniform, and its section is more circular. In addition, the wrapping process preserves the structure of the core roving and its properties by creating a mechanical bond between the two materials, unlike conventional methods used to improve the interfacial bond with polymer matrices, which use chemical, physical or biological treatments instead [39]. This hybrid yarn has, in weight, 50% of hemp fibre and 50% of PA11.…”

Influence of Epoxy Resin Treatment on the Mechanical and Tribological Properties of Hemp-Fiber-Reinforced Plant-Derived Polyamide 1010 Biomass Composites

“…In particular, to further enhance the eco-friendliness of these biomass polymer composites, fully bio-based polymers such as polylactic acid (PLA) [ 17 , 18 , 19 , 20 , 21 , 22 ] and plant-derived polyamide (PA1010, PA11) [ 12 , 23 , 24 , 25 ] should ideally be used as the matrix polymer. However, these biomass composites have such drawbacks as poor interfacial adhesion between natural fiber and matrix biopolymer [ 3 , 12 , 14 , 26 ] and may, therefore, show poor mechanical and tribological properties. Consequently, there is a need to control the interfacial adhesion between natural fiber and matrix polymer in order to further enhance the mechanical and tribological properties of these biomass composites.…”