A Review of Significant Advances in Areca Fiber Composites

Abstract

This chapter provides a comprehensive review of the recent developments in the design of areca fiber composites. The physical, mechanical, and thermal properties of areca fiber and its composites are explained here. The species of Areca fiber represents the Arecaceae/Palmae family (like the coconut/palm trees), with regard to its physical and mechanical properties. Researchers identified that areca fiber holds prospective applications as an alternative to reinforced polymer composites in the automotive, aerospace, and construction industries. Surveys on bio-softening, adhesion, the effects of fiber length, chemical treatments of long areca fibers, the influence of mercerization on the tensile strength of long and short areca fibers, and areca husk have been done. Several researchers have utilized various natural fibers in developing bio-composites. Furthermore, the reinforced composite of natural fiber is a prospective research area, considering its mechanical properties, tensile strength, lightweight, nominal pricing, biodegradable/eco-friendly nature, and ease of procuring raw materials compared to synthetic fiber-reinforced composites. However, little research has been done on areca leaf fibers as a feasible fiber. This chapter provides information on the development and investigation of the mechanical behaviour of a natural fiber-reinforced epoxy composite of areca fiber with various configurations of areca fiber orientation.

1. Introduction

Synthetic fibers have been found to show excellent properties that describe their wide areas of application in different industries. But such fibers can pose environmental issues, with regard to landfills, owing to their non-biodegradability [1]. Natural fibers have been intended to be used in composites owing to environmental considerations in the form of individual or hybrid reinforcement fibers. Prior to being utilized in composites, natural fibers have been obtained from nature in the form of animals, plants, and minerals, using different techniques, like chemical and thermal modifications.

Areca fiber is chiefly obtained from the fruit areca, frond, and stalk leaf. The world today is facing the problem of growing new and propelled innovations and methods to eliminate or utilize solid wastes, particularly with polymers that are non-reversible in nature. The methods adopted in splitting up the wastes do not seem economical and tend to generate chemicals that prove harmful. Taking into account these factors, reinforcing polymers using natural fibers seems the only option that could result in solving the issue. Regular strands are easily available and reusable, have less thickness, and are ecofriendly. They possess high tensile properties and can be used to substitute the customary strands. The strong demerit of using characteristic strands for strengthening plastics is the contrariness, causing weak bondage between normal filaments and lattice gums and thus leading to low pliable characteristics. A number of theories and surface modification methods have been evolved to improve fiber-network interfacial holding and enhance malleable characteristics of the composites. Further, it is proved that the strength and stiffness of the natural fiber polymer composites are mainly influenced by the loading of fiber. Up to a particular extent, there is a rise in mechanical properties with increasing fiber weight ratio. In order to evaluate the tensile properties of natural fiber reinforced composites, mathematical models/finite element models are being adopted as a necessity.

Natural fiber comprises cellulose, lignin, pectin, and so on. Owing to the presence of such constituents, natural fiber possesses unique features and special properties and gives high moisture percentage, which would in turn influence the fiber–matrix bonding. In order to find a solution for this problem, certain techniques of chemical treatment have been evolved and investigated so as to satisfy the properties of other man-made fibers [2, 3, 4, 5, 6]. When considering end uses like electrical insulation, the areca/betel nut fiber reinforced composites exhibit higher merits with regard to the latest development of composite materials [7].

The requirements of high strength to weight ratio in components prompted the development of composites, which necessitated high performance and efficiency, and in turn led to advances in different polymer matrix composites having different fiber reinforcements like carbon fiber, glass fibers, aramid, natural fibers, hybrid, and so on. Natural fiber composites assume a crucial role taking into account the factor of environment-friendly materials and the necessity to manufacture different sustainable engineering and industry-oriented components.

Owing to their good mechanical properties and biodegradability, natural fibers have a crucial function as a reinforcement agent and are readily available in many parts of the world. A number of natural fibers such as jute, kenaf, sisal, hemp, bamboo, areca, pineapple, banana, and coir are being considered important for several research studies due to their availability and cost effectiveness for the design of a cost-effective reinforcing material [8, 9, 10, 11]. A number of properties arise from the use of various natural fibers as a reinforcement agent in composite materials and can effectively be utilized for different end uses.

2. Evaluation of the physical, thermal, and mechanical properties

The different parts of plants like bast, leaf, seed, stalk, fruit, grass, and wood yield cellulosic or lignocellulosic fibers. Fruits of plants yield fibers that are normally short, light, and hairy; bast (found in the stem or trunk) yields long fibers that offer strength to the plant or tree. Sturdy and rough fibers are obtained from leaves and are normally utilized in the transportation and automotive sectors. Fiber length is considered important for use of the fiber, particularly in the traditional fiber industries [12]. High-quality fabrics can be designed from yarns spun by long fibers (clothing, laces, domestic textiles, tents, sailcloth), whereas fibers like cotton, flax, hemp, ramie, and sisal can be used for production of coarser fabrics such as bagging, floor coverings, and carpets. Fibers such as jute, sisal, cotton, and hemp can be considered for cordage fiber, tying twine, rope, and binder twine [13, 14]. Also, sisal and coir fibers can be utilized in brushes and for weaving to produce hats, mats, baskets, and rugs [15]. Such fibers have also been utilized as fillers in upholstery, for seams in vessels, barrels, and piping and as reinforcement for plastic and wallboard.

Moreover, natural fibers can be used with wood pulp in manufacturing paper [16]. Investigations on natural fibers, particularly kenaf, jute, and bamboo, have increased over the past few years [17, 18, 19, 20, 21, 22, 23]. For instance, an investigation relating to the ballistic impact resistance of kenaf reinforced polyvinyl butyral composites; a study of flexural strength and ductility of kenaf reinforced concrete composites; work relating to the influence of kenaf hybridization with oil palm fiber reinforced an epoxy matrix on the tensile, flexural, and impact properties of the obtained composites; and research with regard to processing and manufacturing of kenaf reinforced that epoxy composites are worthy of consideration [24, 25, 26].

Studies have been carried out on fiber hybridization relating to kenaf and fiberglass to find out its influence on the tensile and impact properties of the materials so produced [27]. Besides, a number of workers also reported on the use of natural fibers in the design of industrial safety helmets [28].

Previous investigations on natural fibers have shown scanty research carried out on areca and other species from the Palmae family having identical properties. Despite the abundance of areca palm in South East Asia and the Pacific region, its fiber has not still attracted much attention and is presently being less used than other palm tree fibers [19].

It has been found that less substantial research has been conducted with regard to the optimization of surface treatment, production technique, and application of areca fiber as a reinforcing material in composites. At present, very little literature is available on areca fiber used as reinforcement in composites, which implies that in spite of its innumerable merits, the fiber is at present used less. The fiber enjoys merits like recyclability; renewability; sustainability; economy; wide availability; high-potential perennial crop; inherited qualities; superior properties; mechanical properties that compare well with those of other fibers like kenaf, jute, and coir; and also complete biodegradability [29]. Statistics shows that the annual world production of areca nuts is 1,073,000, and approximately 2.5 g of areca husk could be extracted from every areca betel nut [9]. The annual statistics on world natural fiber production shows the least production of areca husk fibers in comparison with other natural fibers, like jute, coir, and kenaf, which could be ascribed to the consumption of betel nuts in the tropical Pacific and Eastern Africa and Asia.

Areca catechu is known by various names like areca palm, areca nut palm, and betel palm. It is also called Pinang in Malaysia. A. catechu is found largely in the tropical Pacific, Eastern Africa, and Asia, particularly in Malaysia, Philippines, India, and Sri Lanka. As per the statistical data provided by the Food and Agriculture Organization of the United Nations, India, Myanmar, Bangladesh, China, and Indonesia are considered the major producers of betel nut [30]. Sri Lanka and India are the two countries where A. catechu trees are well grown, and the people of these countries use betel nut as a complement to betel leaves smeared with limestone paste [31]. But betel nut fibers are used as housing insulation material in a traditional way in certain countries [32]. Areca fruit finds a number of medical applications that include dental implants, drugs for wounds, healing of sores, diphtheria, heavy menstrual blood flow, diarrhea, and ulcers [33]. On the other hand, biodegradable disposable plates are made from areca leaf sheaths, which fall naturally from the trees, or green waste. As the use of plastic is banned in India, areca plates are widely used. Besides India, other countries including China, Vietnam, Ukraine, Sri Lanka, Malaysia, and the United Arab Emirates manufacture these plates.

The areca tree can reach a height of 10 to 20 m, with an erect stem that is single and thin, having a diameter ranging between 10 to 15 cm with impressions of annulated scars of fallen leaf sheaths or fronds.

The leaves span a length between 150 and 200 cm; having many pinnate-shaped leaves, the upper part normally shows 8 to 12 fronds. Fully grown areca trees measure up to 15 m. But the conditions of soil mainly influence the growth of such trees [34, 35]. A. catechu is a monocotyledonous plant that belongs to the species of the Areca and plant family of Arecaceae or Palmae [36]. It relates to the species of oil palm, date palm, coconut palm, and others. On the whole, the plants from the Palmae family can be considered tropical trees, shrubs, and vines, normally with a tall columnar trunk, bearing a crown of huge leaves. Many investigations have been carried out on the use of plant fibers extracted from the plant family. They point to the prospect of A. catechu fibers to be used as an option as reinforcement in natural fiber-based composites [37, 38, 39, 40].

2.1 Thermal properties of areca fibers

In the design of natural fiber composites, thermal stability is considered crucial. It can decide the selection of compatible processing techniques for fibers and composites. Hence, thermal properties act as a guideline during the entire design process and prevent the temperature from rising above the degradation temperature of the fiber, since it could decrease the performance of the fibers and the composites.

The fiber is found to be thermally stable up to 230°C, as evinced by lack of weight loss after the minor loss caused by moisture evaporation. Beyond this point, there is occurrence of polymerization and degradation processes of hemicelluloses and cellulose up to 330°C. Analysis of the DTG curve shows small peaks at 273.4 and 325.8°C and reveals the pyrolysis, decomposition, and degradation of hemicelluloses and cellulose. It is found that the kinetic activation energy for areca fibers falls in the range set for natural materials.

The value is indicative of areca fibers possessing excellent thermal stability, which permits it to undergo the polymerization process in the production of composites. At a temperature of about 325°C, the burning of fiber has been evinced, which is a reasonably high temperature for polymer processing to manufacture composites.

2.2 Mechanical properties of areca fiber

Single fiber tensile testing has been used to evaluate the mechanical properties and provide some basic information necessary for the design of the potential use of plant fibers. Areca fibers have been compared with coir and palm leaf fibers with regard to the mechanical properties, particularly tensile strength. This could be attributed to its high crystallinity index and spiral angle. Considering application in reinforcement, the greater strain and low modulus of areca husk fiber offer superior toughness. The results indicate that areca fiber can substitute reinforced polymer composites, similar to other representatives from the family of Palmae/Arecaceae.

On the other hand, chemical modification also determines the mechanical properties of the fiber. The untreated and alkali-treated fibers in selected concentration and weight have been characterized, and the changes undergone by the removal or minimization of non-cellulose components, like hemicellulose, lignin, and wax pectin, and other impurities from the fiber surface have been described [41, 42, 43]. The modification results in surface roughness and fibrillation due to the exclusion of cementing materials that lead to improved mechanical properties of the fiber reinforced composite [42]. 5% alkali-treated fiber has been found to exhibit the greatest tensile strength and modulus based on tensile characterization of untreated and treated areca leaf stalk fibers. This could be attributed to the disruption of hydrogen bonds in the fiber network. But a reduction in tensile strength has been observed with a rise in alkali concentration above the optimum. The tensile strength of individual fibers has been enabled by the increase in the pores and pits on the surface of fibers. Also, benzoylation treatment is found to yield better tensile properties in comparison with the alkali-treated and untreated short areca sheath fibers. The FTIR studies reveal that the absorption of alkali and benzyolation treatments have decreased the (−OH) groups compared to in the case of the untreated fiber, due to the removal of hemicelluloses. Further, the presence of phenyl nucleus has been noticed, while the C − H deformation from lignin confirmed its removal, and the aromatic ring associated with the C − O bond demonstrated the removal of hemicellulose and pectin.

3. Fabrication of natural fiber reinforced composites

3.1 Composites reinforcement of the fibers in the polymeric matrix to improve strength, stiffness, and fatigue resistance

A number of conventional methods have been adopted for the production of natural fiber reinforced composites. Among these, the pultrusion technique is apt for pulling continuous fiber rovings through a resin bath by using a puller. But filament winding is suitable for the product in the circular form of continuous fiber roving drawn through a resin bath by a puller. In the case of hand lay-up or wet lay-up, each layer of fiber is wetted by the resin with a roller to consolidate. It is an open molding process. A closed vessel or pressure gradient is used in an RTM, for streaming and then soaking with reaction resin the long or woven fibers. In the case of natural fibers, compression molding can be used, with fibers that are continuous or discontinuous, accompanied by temperature, pressure, and high volume. For preparation of thermos-setting resin, sheet molding compound (SMC) and bulk molding compound (BMC) have been commonly adopted, whereas glass mat thermoplastic (GMT) has been adopted in the case of thermoplastic polymer. Injection molding can be adopted in the preparation of polymer composites using short natural fibers in particle or powder form. The molten composites are injected into the mold, which is ejected after cooling. The fabrication selection of natural fiber reinforced polymeric composites is chosen on the basis of a few factors considered.

Very little research has been reported on the areca fiber reinforced polymer composites. Such composites are made by areca fiber reinforced polyester through utilization of hand lay-up, cured for 1 day at room temperature [37]. Compression at a temperature of 115°C for 30 min is used for the production of areca fiber mats with PLA laminate composites [44]. But hand lay-up has been used for 300–325 μm fabricated areca fiber reinforced vinyl ester resin and oven-cured at 80°C for 2 h [45]. The areca fiber reinforced polypropylene composites have been prepared by extrusion and hot molding press [46].

3.2 Mechanical properties of areca reinforced polymeric composites

The mechanical properties of areca reinforced polymer composites with different fiber loading and matrixes have been determined. The influence of adding untreated and treated betel husk fibers, in various percentages, to polypropylene composites has been studied [46]. The findings reveal that tensile, bending, and impact properties have been excellent with 30 wt% fiber loading. Hence, the formulation has been selected for further study, comprising washing with detergent and alkali for surface treatment. In comparison with untreated and detergent-washed fibers, alkali-treated fiber showed excellent properties. However, a 40 wt% areca husk fiber reinforced unsaturated polyester composite has been observed to give enhanced mechanical properties. On the other hand, a rise in the fiber loading resulted in fiber pull-out and debonding and decreased the load-bearing capacity of the composite. It has been found that chemically treated areca reinforced composites showed better mechanical properties, like tensile, flexural, and impact strength [47]. It can be described on the basis that the chemical treatment removes impurities, like pectin, fat, and lignin, from the natural fiber and subsequently improves the fiber-matrix bonding and enhancement in the mechanical properties of the composite. Also, regression studies carried out to assess the mechanical properties of untreated and treated short areca sheath reinforced polyvinyl alcohol (PVA) thermoplastic matrix have shown that 27 wt% fiber loading reveals optimum mechanical properties. It is found that benzyl chloride treatment is the perfect alternative to the various prospects of surface treatment in the case of areca sheath fiber [48]. Also, the influences of various chemical modifications in removing impurities (pectin, fat, lignin) from areca husk fiber at different compositions have been further used in polypropylene for enhancement of its mechanical properties. The results strengthen the fact that caustic, potassium permanganate, benzoyl chloride, and acrylic acid treatments improve the mechanical properties of the fibers. Depending on the studies of flexural, tensile, and impact strength properties, it has been observed that the 60 wt% fiber formulation gave the greatest values in flexural and tensile testing, whereas the 50 wt% fiber formulation showed the best effects for impact strength. The treatment with acrylic acid has been observed to be the most suitable chemical modification and has been the most effective in improvement of the tensile, flexural, and impact properties of the areca husk fiber reinforced polypropylene composites. Also, the physical, mechanical, and thermal properties of betel nut husk fibers extracted from raw fruit and used to reinforce an epoxy matrix have been studied.

Fiber percentages of different concentrations have been incorporated into the composites, and it has been found that 5% fiber loading yielded the highest tensile strength and hardness. It has been found that there is a degradation of thermal and mechanical properties at excessive fiber loading of 8% fiber content. It is caused by a lack of interface bonding between fiber and matrix that created a disruption in load transfer. It is observed that the incorporation of 10 wt % betel nut husk fiber in a vinyl ester matrix considerably decreased the flexural strength and also added to a high increment in the tensile and impact properties, mainly for the fiber extracted from raw and ripe areca fruit. In the case of matured fruit, the tensile and impact properties of the extracted fiber have been found to be lower in comparison with the matrix, due to the presence of high lignin content, which influenced brittle fracture.

However, composites have been designed on untreated short areca sheath fibers with varying proportions of fiber weights of fiber reinforced polypropylene composites, using hot and cold compression molding, and it has been observed that the 10 wt% fiber formulation gave excellent tensile strength and the best weathering resistance for the formulations investigated. Likewise, random fiber orientation with the hand lay-up method has been used to prepare the 30 vol% untreated areca sheath fiber reinforced epoxy resin composites, so as to assess the flexural strength by 3- and 4-point bending tests. The findings have been validated by the numerical simulation method.

The formulation is useful for end uses that need less load bearing structural and non-structural capacity [49]. The compatibility of areca fiber and the matrix has been studied, and it has been reported that the interfacial bonding and adhesion bonding between the fiber and the matrix can result in better mechanical properties and good stress transfer.

Just as other natural fibers, areca fiber also exhibits certain demerits, particularly with reference to compounding difficulties owing to the inherently polar and hydrophilic nature of the fiber that results in non-uniform distribution, thus weakening the properties of the composite. During the production of composites, the fiber degradation that occurs at the processing temperature of the matrix imposes another practical constraint. Fiber wettability is another aspect to be considered, which affects its compatibility with the matrix. The surface tension and matrix viscosity are determined by wettability.

Hence, it is imperative that the surface tension of the reinforcing fiber exceeds that of the matrix so as to maintain the interfacial strength. The other aspects to be taken into account are low microbial resistance and susceptibility to rotting so as to attain the successful preparation of a long-lasting composite. The bonding of the fiber matrix and surface wetting gets affected due to the natural waxy substance on the surface of the fiber [50].

3.3 Areca-based hybrid composites

The hybridization of different fibers, of natural or artificial origin, that are reinforced in a same polymer matrix results in a hybrid composite. In the case of reinforced polymer composites, the hybridization of areca fibers with other fibers has been considered in this case. Compression molding has been used for the production of hybridization of areca husk-coir fiber reinforced unsaturated polyester and areca husk-sisal fiber reinforced epoxy composites [51, 52]. On the other hand, the hot press method has been adopted to produce areca husk-glass fiber reinforced polyethylene composites.

3.4 Mechanical properties of areca-based hybrid composites

Explanation has been provided regarding the hybridization of areca fibers with other fibers for the manufacture of reinforced polymer composites. Compression molding technique has been adopted in the hybridization of areca husk-coir fiber reinforced unsaturated polyester and areca husk-sisal fiber reinforced epoxy composites [53]. On the other hand, the hot press method has been adopted in the production of areca husk-glass fiber reinforced polyethylene composites. Taking into account the drastic rise in the number of plastic wastes, which create an adverse effect on the ecosystem, environmental considerations have prompted a push in bio-composite studies. Studies have been conducted on the tensile, flexural, impact, and hardness of composites made by 20 wt% natural fiber loading comprising 10 wt% caustic-treated areca fiber, coir fiber, or a mixture of both dispersed in a polyester matrix.

The hybridization of natural fibers to reinforce polymer composites results in improved mechanical performance, in comparison with individual fiber-based polymer composites [54]. But it has been observed that, in certain instances, individual fiber-based polymer composites have shown superior mechanical properties as compared with hybrid composites because of the micromechanical behavior of the individual components of the reinforcement [55]. The areca husk reinforced polyester composites have been observed to be superior in comparison with hybrid areca/coir fiber reinforced polyester composites. Another research reported on 5% caustic treated areca fiber hybridized with glass fiber, in selected proportions, having 20% fiber loading in a thermoplastic matrix of polyethylene, and it has been investigated so as to study the effect of surface modification on the physico-mechanical properties of the composite. Depending on the comparison with the properties of polyethylene considered as a standard test sample, it has been found that the tensile and flexural properties have considerably improved for the formulations having selected proportions. The areca fiber coated with caustic showed a considerable enhancement in mechanical properties. With the rise in proportion of the glass fiber three times, it showed an improvement in tensile strength, Young’s modulus, flexural strength, and hardness but not in impact energy.

A work has reported on a study of the tensile, bending, and impact testing results for hybrid areca and jute reinforced epoxy composites, made with the hand lay-up method and consisting of a tri-layer, having areca fibers as surface layers and jute as a central layer. The tensile and bending strengths obtained at different levels, with epoxy LY 556 as the control specimen, have shown that the hybridization of areca and jute, with the epoxy matrix, considerably decreased the tensile and bending strengths of the composites.

However, work has been carried out on the hybridization of areca husk and sisal fiber, with a similar kind of epoxy, and it is observed that there is a slight decrease in tensile strength. However, there has been drastic rise in the flexural strength. It has been observed that there is a rise in the tensile and flexural strengths due to an increase in the content of betel nut fiber rather than that of sisal fiber. The effect of chemical modification with NaOH for composites comprising 20% areca frond, 20% sisal, and 60% of the same epoxy has been studied, and the findings show that the caustic-treated composites have revealed improved mechanical properties, like tensile and flexural strength, absorbed energy, and hardness, in comparison with the untreated specimen [56]. It has been observed that the entire spectrum of the composite properties is considerably influenced by the fiber content [57].

4. Evaluation of mechanical properties

Despite the modulus being dependent on the fiber properties, the tensile strength is sensitive to the grid properties. It is necessary to have a solid interface, low anxiety fixation, and fiber introduction so as to improve the strength. On the other hand, the elastic modulus is determined by fiber concentration [5, 6, 7, 58].

For certain tribological uses, treated betel nut fiber reinforced polymer composites have been regarded better in comparison with chopped strand mat glass fiber-reinforced polyester; betel nut polyester composite possesses mechanical properties identical to those of the glass-polyester composite. Thus, betel nut fibers possess a great prospect to replace glass fibers and for small load applications [59, 60, 61].

With regard to the high tensile strength applications, chemically treated areca fiber reinforced natural rubber composite, and also uses related to high dimensional stability, low-density property of raw betel nut husk fiber is used for lightweight applications [60, 61, 62]. Natural fibers have economy and biodegradability, can be reutilized, and are eco-friendly materials. Natural fibers can be a better choice over glass and carbon fibers owing to their eco-friendliness and biodegradable nature. Betel nut and Sansevieria cylindrical in PP (polypropylene) composites have found applications where strength and cost considerations are important [63].

Likewise, areca fiber and maize powder reinforced PF composites have been used in packing industries, low-cost housing, and domestic uses [64]. Areca sheath fiber is used in structural and non-structural areas like suitcases, post boxes, grain storage, automobile interiors, partition boards, and indoor uses [65].

4.1 Uses

From the aforesaid explanations, uses of naturally available, eco-friendly, renewable and reproducible, nontoxic, economical, and easily available reinforcing material (areca/betel nut fibers) composites, it can be summarized that areca fiber offers a good alternative for wood in indoor uses, and the following points have been listed that are present in the literature. Due to a rise in the volume fraction of fiber in the composite, there is a rise in dielectric strength of betel nut (Bn) composites. It is a rather uncommon phenomenon that has not been noticed in a number of natural fiber composites. Hence, based on the availability, cheaper and good dielectric strength of Bn fiber composite can certainly be considered for electrical insulation applications [66]. Further, hybrid composites with Bn and S. cylindrica in EP can be used in diverse applications as structural materials.

• Depending on the availability, cost-effectiveness, and good strength of areca fiber composites, they are utilized in the design of lightweight materials that are used in automobile body building, office furniture packaging industry, partition panels, and others compared to wood-based plywood or particle boards [67, 68, 69].

• Due to better outcomes with regard to wear of treated betel nut fiber reinforced polymer composites (T-BFRP) (98%) in comparison with chopped strand mat glass fiber reinforced polyester (CSM-GFRP) under dry and wet states, T-BFRP composite holds promise in certain areas of tribological uses.

• With regard to mechanical properties, the betel nut polyester composite is identical to the glass-polyester composite, and thus, betel nut fibers offer a very good substitute for glass fibers in mechanical end uses. Also, betel nut fibers offer superior support to the polyester matrix than other types of natural fibers.

• In the case of end uses related to a small load bearing, investigations have been conducted on caustic-treated areca fiber composites, which have been found to have enhanced mechanical properties to a certain extent in the areca fibers.

• In the case of end uses requiring high tensile strength, chemically treated areca fiber reinforced natural rubber composites have been considered.

• For end uses requiring high dimensional stability, low moisture and water uptake properties of dried BNH fibers are found to be advantageous for various applications, and low-density property of raw BNH fiber is used in applications requiring light weight.

• Certain investigations make it evident that areca fruit husk fibers are useful as a potential reinforcement in polymer composites due to their moderate tensile strength properties, better strength, and bonding properties with rough surface morphology in end uses requiring light weight.

• Hybrid composites with betel nut and S. cylindrical in PP (polypropylene) can be used in various areas like structural materials that are dictated by strength and cost aspects.

• In areas such as packing industries, low-cost housing, and domestic purposes, areca fiber and maize powder reinforced PF composite materials can be used as a communicative material for plywood.

• In the case of structural and non-structural uses like suitcases, post boxes, grain storage, automobile interiors, partition boards, and indoor uses, untreated chopped natural areca sheath fiber reinforced polymer matrix bio-composites are well adopted.

• In the case of end uses requiring high flexural strength, chemically treated areca fiber reinforced epoxy composites for applications where high impact strength is required, 60% fiber loading was considered.

5. Characterization

Natural fiber reinforced composites are found to offer resistance to electricity, possess good thermal insulating property, and are also resistant to corrosion [70]. It is found that as the volume fraction of the fiber increases, the tensile strength of natural polymer composites increases, as pointed by past research works on volume fraction [71]. It has been shown in the study of the tensile characteristic of the untreated areca sheath composite that the longer the fiber length, more is the strength of the composite. In comparison with untreated areca nut fibers, the fibers treated with caustic exhibit greater mechanical strength [72, 73]. The curing time of the composite also plays a vital role in determining the full potential strength of the composite. Studies have revealed that the strength of the composite increases with the curing time [7]. Investigations have been carried out with regard to other mechanical properties like impact strength, hardness, and flexural strength of the areca fiber composite, considering parameters like the influence of volume fraction, post curing time, and alkali treatment for effective bonding [14, 74]. The flexural strength increases with increase in fiber loading percentage. Fibers treated with caustic show a significant increase in flexural strength for references [8, 9, 68, 75]. Studies show that there is a rise in the impact strength due to the post-curing time, and it has been observed that with the rise in the curing time, the alkali-treated composites turned brittle [10, 57, 76, 77]. The finding aims on the tensile property of the non-chemically treated areca fiber sheaths that are immersed in water, hot pressed, and compressed with a thickness of 2.5 to 3 mm and are widely found in India as areca fiber plates. The study also aims to use this as a reinforcing agent in epoxy polymer composite to study its tensile properties and effects of the different combinations of the orientation angles of the fiber, which influences the tensile property of the composite.

6. Conclusion

Studies have been carried out with regard to the physical, mechanical, and thermal properties of areca fiber and its composites. The available literature shows that areca fiber holds the prospect for use as an optional reinforcement in polymer composites. On the other hand, it has been found that certain other species from the family of Arecaceae/Palmae have not been studied since natural fiber reinforcement in polymer composites either, hence showing further options of natural alternative reinforcements to be studied in terms of their potential for utilization in fiber-based composites for the automotive, aerospace, and construction sectors. Areca fibers can be used as an alternative natural resource and as a promising reinforcement of polymer matrices to produce lightweight composite structures. Different natural fibers have been used by many researchers for the development of bio-composites, but areca leaf fibers as a feasible fiber have seldom been researched or spoken about.