Development of Hemp Fibre – PP Nonwoven Composites

Abstract

Summary: Nonwoven mats from hemp and polypropylene fibres in various proportions were produced and hot pressed to make composite material. The effect of hemp fibre content and anisotropy in nonwoven mats resulting from the carding technology were examined on the basis of the three‐point bending, tensile and impact properties of the resultant composite materials. 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 distilled water for 19 days, while the impact strength increased. Double carding of raw materials resulted in a decreased anisotropy in composite material.

Conversion of Natural Fibres into Structural Composites

“…Preferential fibre orientation impacts significantly on the anisotropy of the mechanical properties of resulting composites. Elastic modulus and failure stress along the carding direction have been found to be 20 -40% higher than that perpendicular to the carding direction [43,44]. On the other hand, little difference in moisture take-up along these two directions was found [44].…”

A review of aspects affecting performance and modeling of short‐natural‐fiber‐reinforced polymers under monotonic and cyclic loading conditions

“…Therefore, the fatigue models are usually built on empirical forms conducted from experimental data. There are two main methodologies used to analyze and predict the fatigue behavior (they are used for metals and composites as well) : The first methodology, fracture mechanics, predicts fatigue damage using empirical equations of crack growth, which is generally assumed to be under linear elastic mechanics; The second methodology is based on the use of stress‐life (S‐N) curves and fatigue damage accumulation (such as residual strength and stiffness degradation); sometime this methodology is referred to as the safe life technique. …”

“…Applications of these composites include a variety of interior parts for automobiles, packaging, and components used in the aerospace and construction industries . Compared to synthetic fibers (e.g., glass fibers, one of the most important synthetic fibers), natural fibers provide many features: They feature a low density and acceptable mechanical properties (see Table ); hence, there will be lower fuel consumption if the natural fiber composite is used for parts in the aerospace and automobile industries. They are an economical and sustainable source of fibers, rendering the composite product toward being an ecological and, most likely, a biodegradable material . They are easier to manufacture with lower production energy use; for example, the energy needed to produce 1 kg of flax‐fiber mats is about 9.55 MJ kg −1 , which is 83% less than the energy needed to produce 1 kg of glass‐fiber mats . They offer less abrasive wear to the processing machine parts . They avoid many of the health and ecological problems caused by synthetic fibers, such as the hazard of small particles emitted during manufacturing, skin irritation, renewability, and recyclability . …”

Thermal, Mechanical and Morphological Properties of Composites Developed from Glycerol and Dicarboxylic Acids Reinforced with Piassava Fiber

“…Vegetable fibers are more affordable than synthetic ones and can replace them in many applications where cost is a more important factor than strength and stiffness. Vegetable fibers such as bananas,4, 5 jute,6 sisal,7, 8 coconut,9, 10 piassava,11–13 curauá,14, 15 cane sugar,16 pineapple,17 cumbaru,18 hemp19–21 and wood22 have been used as reinforcement in polymer matrices 23. Among those fibers, the use of waste piassava fiber, called sludge, is particularly interesting because it has good chemical and mechanical properties and can be used as reinforcement in polymer matrices, adding value 24…”