Characterization of Natural Fibre Blends
Research is now ongoing into the fabrication of biodegradable composites from natural low-cost raw materials.51 As a result, renewable characters with thermoplastic nature materials are achieved through the plasticization of starch materials (TPS),52 starch materials widely found in food grains (TPS).52 The different processes associated with the process of the conversion of starch into TPS have been significantly improved due to research progress in the area of TPS.53 The reinforcing of thermoplastic starch with natural lignocellulosic fibre in composite materials improves their mechanical enactment and eco-friendliness.54
The effect of fibre content on diffractogram patterns is shown in Figure 2.2. After accumulation of up to 20% of reinforcing fibres, no significant differences can be
FIGURE 2.2 Diffractogram of corn starch TPS with sisal and hemp fibre.33
detected in the signals allotted to TPS. The depletion observed in Vh crystallinity peaks will be correlated with the decrease in the TPS content of the design. Additionally, fresh signals stare at 20 = 16.6° and 22.5°, resulting in the crystalline share of cellulose in the fibres. Thermoplastic corn starch as matrix and fibre parts are indicated as X/Y percentage in the X-ray diffractogram.33
Changes take place in the share of crystallinity Vh of TPS after the merging of two reinforcing fibres. Autonomously, the type of fibre used and a gradual reduction in the crystallinity Vh of TPS is observed with the increase of fibre content. This reduction could be related to a decrease in the movement of starch molecules triggered by the presence of the firm reinforcing fibres, hampering the retrogradation of amylose chains. This hypothesis is strengthened by the outcomes of DMTA analysis, as shown in Figure 2.З.33
The results confirm that both tensile and flexural strength improves with the increased percentage of reinforcement fibres. Hemp strand composites provide better mechanical properties than those obtained with sisal. This is due to better fibrillation obtained when the TPS is mixed the hemp strands and indicates that mechanical anchoring is the main cause of the enhanced mechanical resistance.33
Characterization of Natural Fibre with Synthetic Fibre Blends
The use of natural fibres with synthetic fibre reinforced polymer composites have been used to enhance the performance of the composite material by reducing moisture absorption, thereby reducing negative environmental impacts and lowering the
FIGURE 2.3 DMTA analysis of TPS of corn with hemp fibre. (A) E’ vs. temp; (B) tan 6 curves.53
consumption of energy level carbon footprints. Additionally, the cost of the composite material is comparable to that of glass fibre composite material, offering an alternative to chemical treatment by merging natural fibres with synthetic hydrophobic fibres.55
Akil et al. included glass fibres in a hybrid structure of polyester composites reinforced with jute fibres, resulting in the improvement of tensile and flexural properties. The addition of glass fibres into the jute polyester composite reduces its water absorption capacity.56 In Figure 2.4, alkali-treated fibre hybrid composites show higher flexural and tensile modulus because of the improvement in interfacial compatibility.57
Researchers found that in hybridized woven flax-carbon and jute-carbon laminated composites, the escalation of carbon content led to an increase in the tensile properties. Higher percentages of jute fibres with carbon fibres make the composite material significantly stronger.58-59 Based upon the reinforcement content, thermomechanical properties such as loss modulus (E") storage modulus (E'j, and tan 6 damping factors of composite material vary.60-61
Conclusion
The need for natural fibre composites in engineering applications has progressively increased. Appreciable efforts have been made in terms of research to find the most appropriate and cost-effective coupling agents, surface modifiers, or dispersion aids for both the fibre and matrix to improve its interfacial bonds, depending on the end- use application. Nano-scale level interfacial characterization of the composite material helps to characterize the stress transfer, interaction, adhesion, and interfacial penetration of components present in composite materials. Furthermore, the use of nanotechnology in natural-fibre composites will necessarily play a significant role in the near future. The study of interfacial mechanisms and bonding in bio-based nanocomposites would greatly contribute to its development and will reduce the gap between scientific challenges and industrial production.
FIGURE 2.4 Interfacial compatibility of alkali-treated and untreated natural fibre.57
