Mechanical Properties of Hemp Fibers and Hemp/PP Composites: Effects of Chemical Surface Treatment (original) (raw)
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Effects of Fibre Surface Treatments on Mechanical Properties of Hemp Fibre Composites
Effects of heat treatment, acetylation and plasma treatment of hemp fibres on tensile, impact and fatigue properties of composites made from them have been studied. Laminates were made with unsaturated polyester resin using hand lay-up and compression moulding techniques. Overall no appreciable improvements were observed for composites made following these three fibre treatments. 100 and 150°C heat-treated hemp fibre composites showed some improvement in tensile properties but no appreciable improvement was observed for 200°C heat-treated hemp fibre composites. No improvement in impact damage tolerance was observed for all three heat-treated fibre composites. 100°C heat-treated fibre composites also showed no appreciable improvement in fatigue properties. Acetylation of hemp fibres did not show measurable improvement in tensile properties or impact damage tolerance of composites made from these fibres. Plasma treatment of hemp fibres improved tensile properties of composites made from these fibres.
A Study in Physical and Mechanical Properties of Hemp Fibres
This paper presents the results of the experiments undertaken to evaluate various physical and mechanical properties of hemp fibres. The study of these properties is vital for comparison with similar properties of synthetic fibres and for assessing hemp fibres' suitability for use as reinforcement in composite materials. The properties of hemp fibres were found to be good enough to be used as reinforcement in composite materials. However, the issues of relatively high moisture content of fibres, variability in fibre properties, and relatively poor fibre/matrix interfacial strength were identified as factors that can reduce the efficiency with which these fibres can be utilised.
Hemp fiber and its composites – a review
Journal of Composite Materials, 2012
The use of hemp fibers as reinforcement in composite materials has increased in recent years as a response to the increasing demand for developing biodegradable, sustainable, and recyclable materials. Hemp fibers are found in the stem of the plant which makes them strong and stiff, a primary requirement for the reinforcement of composite materials. The mechanical properties of hemp fibers are comparable to those of glass fibers. However their biggest disadvantage is the variability in their properties. Composites made of hemp fibers with thermoplastic, thermoset, and biodegradable matrices have exhibited good mechanical properties. A number of hemp fiber surface treatments, used to improve the fiber/matrix interfacial bonding, have resulted in considerable improvements in the composites' mechanical properties.
Mechanical Characterization of Hemp Fiber Reinforced Polyester Composites: A Review
2016
The natural fibers are bio-form of plant and animal skin. The natural fibers are abundant in quantity. They possess lightweight and high strength capabilities. The use of those fibers leads no harms in environment, are biodegradable and renewable source of energy. The paper reviews different types of natural fiber, among them hemp fiber, and recognize their mechanical and chemical characteristics. The paper investigates the composite form, which is formed using the natural fiber hemp and polyester resin, varying their proportion and obtaining its mechanical and other properties. The composites made are proposed to be used in other applications. Keywords: Natural fibers, hemp and its properties, composite form Cite this Article Biren J. Saradava, Abhishek J. Kathwadia, Ajit D. Gorviyala, Vatsal K. Joshi . Mechanical Characterization of Hemp Fiber Reinforced Polyester Composites: A Review. Journal of Polymer & Composites. 2016; 4(1): 1–3p.
Review on Mechanical, Thermal and Morphological Characterization of Hemp Fiber Composite
IOP Conf. Series: Materials Science and Engineering, 2020
Hemp, (Cannabis sativa), also known as industrial hemp, a family plant of Cannabaceae cultivated for its fiber or edible seeds. Hemp is sometimes confused with cannabis plants that serve as sources of prescription weeds and preparation of hashish products. Although all three products-hemp, marijuana, and hashish-contain tetrahydrocannabinol (THC), a compound that induces psychoactive effects in humans, the cannabis variety grown for hemp has only small amounts of THC compared to that grown for marijuana or hashish growth. Bast fiber plants are distinguished by long slender primary fibers on the outer portion of the stem. Hemp grows in countries
Polymer Composites, 2019
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 proper...
Effect of processing route on the composition and properties of hemp fibre
Fibers and Polymers, 2008
There is great interest in the plant Cannabis sativa (hemp) as a source of technical fibres for the reinforcement of polymers in composite materials due to its high mechanical properties. In this work, the effect of enzymatic, hydrothermal and alkaline treatments on the composition and mechanical properties of hemp fibre are compared. The influence of enzyme concentration and treatment time was examined (2.5-80 % Pectinex® Ultra SP-L, 6-48 hrs). Additionally, hydrothermal (170 o C, 10 bars) and alkaline treatments (18 wt. % NaOH, 40 o C) were used as pre-treatments to observe their effect on subsequent enzymatic treatment. The composition of hemp fibre was analysed by wet chemistry and Fourier transform infrared spectroscopy, while microstructure and mechanical properties were examined by scanning electron microscopy and tensile testing, respectively. Enzymatic treatment resulted in extensive fibrillation and removal of non-cellulosic components, especially when combined with hydrothermal treatment. However, a lengthy enzymatic treatment or combinative enzymatic-alkaline treatment led to extensive fibre breakdown that was accompanied by a pronounced reduction in the mechanical properties. Enzymatic treatment decreased Young's modulus and tensile strength by 77 and 73 % respectively, and alkaline treatment by 83 and 36 %. The hydrothermal treatment resulted in only minor changes in these properties.
Development of HEMP Fiber Reinforced Polypropylene Composites
Journal of Thermoplastic Composite Materials, 2008
Nonwoven mats from hemp and polypropylene fibres in various proportions were produced and hot pressed to make composite material. The effect of fibre content and the anisotropy in nonwoven mat resulting from the carding technology were examined on the three-point bending, tensile and impact properties of resultant composite material. Because of the hydrophilic nature and poor dimensional stability of cellulosic fibres due to swelling, the effect of water sorption on mechanical performances was also investigated. Optimal mechanical properties were achieved in composites made from 40-50 % of hemp fibre by weight. As it was expected, better mechanical properties were found in the specimens cut from the composite sheets parallel to the direction of carding. A strong decrease in three point bending properties was noticed after immersing the composite samples in the distilled water for 19 days, while the impact strength increased. Double carding of raw materials resulted into decreased anisotropy in composite material.
Surface characteristics of untreated and modified hemp fibers
Polymer Engineering & Science, 2006
Natural cellulosic fibers, including hemp, are increasingly being used for composite reinforcement. However, their poor adhesion with synthetic resins limits their use as reinforcing agent. It is generally accepted that interfacial adhesion can be best described in terms of dispersion forces and acid-base interactions. Therefore, there is a need for quantitative determination of acidbase character of natural cellulosic fibers. In this study, acid-base characteristics and dispersion component of surface energy of hemp fibers have been determined using inverse gas chromatography. Effect of alkalization and acetylation on acid-base characteristics has also been examined. The results indicate that alkalization and acetylation make the hemp fiber amphoteric, thereby improving their potential to interact with both acidic and basic resins. Finally, a parallel is drawn between the changes in fiber-matrix acid-base interactions and the actual improvement in the mechanical properties of the composites manufactured using resin transfer molding process. POLYM. ENG. SCI., 46:269 -273, 2006.
Comparisons between some composite materials reinforced with hemp fibers
Materials Today: Proceedings, 2019
For this research we have built original composite materials that have a dammar-based bio-resin as matrix and are reinforced with hemp fibers. These composite materials have been subjected to tensile tests to find their mechanical characteristics and elastic constants: ultimate tensile strength, Young's modulus, Poisson's ratio and elongation at break. In the second part of the paper we have studied other composite samples with dammar-based resin/hemp fibers and classical composite samples epoxy/hemp fibers. By recording their free vibrations, we have determined the damping factor with respect to their mass, length, loss factor, dynamic flexural stiffness and dynamic Young's modulus respectively. In the end, we have compared the studied samples with other composite materials reinforced with hemp fibers that have been studied in the scientific literature.