A Review on False Banana (Enset Ventricosum) Fiber Reinforced Green Composite and Its Applications

ABSTRACT

The composites industry is advancing towards producing green composites as sustainability is quickly becoming a global focus across numerous industries. Natural fiber-based composites have emerged as materials of interest in important industries, such as packaging, automobiles, and construction. False banana fiber-reinforced composite is a promising area of research owing to their partial or full biodegradability, easy availability, low cost, and considerable mechanical properties. However, more research is required to understand the full potential of false banana fiber on its composites. As a result, this review gives a basic overview of several researchers work and explain in terms of how they are prepared, what features they have, and how they are used. Particularly in regards to the mechanical and water absorption capabilities of composites, the use of false banana fibers as reinforcements in different matrices has produced interesting results. The study also found that preparation, hybridization and treatment of fiber influence the properties of false banana fiber composites. Furthermore, the development of these composites has promoted the use of environmentally friendly materials and the development of a sustainable world. This review also provides a strong and holistic outlook on the potential of false banana fibers for use as a partially or fully biodegradable composite and has not been reviewed earlier.

摘要

随着可持续性迅速成为众多行业的全球焦点，复合材料行业正朝着生产绿色复合材料的方向发展. 天然纤维基复合材料已成为包装、汽车和建筑等重要行业中备受关注的材料. 假香蕉纤维增强复合材料由于其部分或全部可生物降解性、易得性、低成本和可观的机械性能而成为一个有前途的研究领域. 然而，还需要更多的研究来了解假香蕉纤维在其复合材料上的全部潜力. 这篇综述详细介绍了不同研究人员在制备假香蕉纤维增强复合材料时采用的不同加工技术及其对复合材料性能的影响. 此外，这篇综述强调了这些复合材料在可持续应用中发挥重要作用的潜力. 研究发现，假香蕉纤维复合材料的制备和处理对其性能有影响. 此外，这种复合材料的开发促进了环保材料的使用和可持续世界的发展. 这篇综述对假香蕉纤维作为一种部分或完全可生物降解的复合材料的潜力提供了一个强有力的、全面的展望，此前尚未对其进行综述.

KEYWORDS:

• Composite industries
• natural fiber
• false banana fiber reinforced composites
• biodegradable
• green composite
• mechanical properties
• water absorption
• sustainable applications

关键词:

• 复合工业
• 天然纤维
• 假香蕉纤维
• 能进行生物降解的
• 绿色复合材料
• 可持续应用

Introduction

Natural fibers from agricultural waste can be used to create sustainable lightweight materials and composite structures (Balcha et al. 2021; Dahy 2017; Dungani et al. 2016; T; Taj, Ali Munawar, and Khan 2007). Composite materials are increasingly being used in applications due to their unique properties and adaptability (Singh et al. 2022).

Natural fibers are favored over synthetic fibers by engineers, researchers, professionals, and scientists worldwide as an alternative reinforcement because of their superior properties, such as high specific strength, low weight, low cost, good mechanical properties, nonabrasiveness, eco-friendliness, and biodegradability (Balcha et al. 2021; Bos, Van Den Oever, and Peters 2002). Additionally, due to their naturally renewable nature and the reduced energy required for their manufacturing and processing (4 MJ/kg of natural fiber against 30 MJ/kg of glass fiber or 130 MJ/kg of carbon fiber), the use of natural fibers enables the reduction of environmental effect (Monzón et al. 2019).

Natural fibers may include wood, sisal, hemp, coconut, thread, kenaf, flax, jute, abaca, banana leaf fibers, bamboo, wheat straw, or other fibrous materials that are used as reinforcement because of their good mechanical properties (Joshi et al. 2004; Taj, Ali Munawar, and Khan 2007). These natural fiber composite materials are being increasingly used in the automotive and building industries, but their potential is estimated to be only 10% (Dungani et al. 2016; Joshi et al. 2004). However, natural fiber composites have the highest specific performance per price compared to other materials such as steel, aluminum, and FRP (Kazmierski 2012).

However, natural fiber composites have drawbacks such as variations in properties, poor compatibility with the matrix, high moisture absorption, and lower thermal stability. To overcome these, natural fibers are subjected to surface modifications such as alkali treatments. Natural fiber composites could be an alternative engineering material to synthetic fiber composites for non-load-bearing construction elements and structural elements (Balcha et al. 2021; Tarno et al. 2011).

One of the suitable plants with great potential for the production of natural fibers is Ensete (Ensete ventricosum) also known as false banana (Mizera et al. 2017). Enset (Ensete ventricosum) is a perennial monocarpic plant belonging to the Musaceae family. It can be obtained for manufacturing purposes, but the know-how in using it is not matured in Ethiopia. Previous research focused on food components (Balcha et al. 2021; Mohammed, Gabel, and Karlsson 2013; Nurfeta et al. 2008; Singha and Rana 2012; Tuffa et al. 2017). Enset fiber has a tensile strength of 352 MPa, fracture strain of 3.2%, crystallinity index of 64.9%, and moisture content of 12.2%. These properties of enset fiber indicate its competitive candidate to make natural fiber-based biocomposites (Teli and Terega 2017). After determining the mechanical and physical properties of fibers from the Ensete ventricosum plant, Mizera et al. have also suggested the potential of enset fibers to be used as construction material (Mizera et al. 2017; Negawo et al. 2020). In previous study, the surface modified enset fiber‐unsaturated polyester composites have shown comparable mechanical and dynamic mechanical properties for further production and its marketing as promising green composites (Negawo et al. 2018, 2020).

However, there are promising limited review works on enset fiber, which provide insight that it can be used as an alternative to synthetic and other natural fibers. This review article provides a comprehensive overview of the current state-of-the-art false banana fiber-reinforced green composites, including their properties and applications. This provides insight into the potential of enset fiber as an alternative to synthetic and other natural fibers.

Review methodology

Studies specifically devoted to the production of biodegradable materials are urgently needed right now. There may be effective solutions to address the issue of synthetic fiber composites being used extensively across a variety of applications. To the best of our knowledge, no review articles have examined false banana fiber reinforced composites that are partially or completely biodegradable composites, depending on the matrix. As a result, this work gives a basic overview of several researchers' work and explains in terms of how they are prepared, what features they have, and how they are used. The false banana fiber reinforced composite is therefore reviewed in an organized and thorough manner for readers. Thus, we provide readers with an organized and comprehensive review of false banana fiber reinforced composite which is partially and fully biodegradable depending on the matrix. This review also highlights issues and potential directions for the future that could help to enhance the performance and characteristics of composites made of false banana fibers. The literature review was planned and conducted keeping the following points:

• False banana fiber and its properties were highlighted based on earlier researchers.

• Enumerate the key methods used in false banana fiber reinforced composite production

• Provide a brief overview of recent studies on false banana fiber reinforced composite and its mechanical as well as water absorption properties implication on potential application area.

• Provide the existing limitation and potential areas for further research

Sustainability of natural fibers reinforced composite

Sustainable development is development that meets the needs of the present without compromising future generations’ needs (Saptarshi et al. 2022; Teli and Terega 2017). Integrating economic, environmental, and social concerns into decision-making is essential for long-term economic and environmental stability (Teli and Terega 2017).

Recently, there has been increased interest in natural fibers since natural fibers are renewable, carbon-neutral, versatile, biodegradable, and low-cost (Ashik and Ramesh 2015; Begum and Islam 2013). Based on their origin, natural fibers are classified into plant, animal, and mineral fibers, and they are mainly composed of cellulose, proteins, and mineral substances, respectively. Plant fibers are further subdivided into several types according to the part of the plant used for their generation; the major types are bast fibers, leaf fibers, seed fibers, and fruit fibers. Except for a few fibers such as cotton (about 90% cellulose), all plant fibers occur as a natural composite consisting mainly of cellulose (α-cellulose), hemicellulose, lignin, pectin, and waxes (Dunne et al. 2016; Teli and Terega 2017).

False banana (Enset ventricosum) fibers

Physical structure and chemical composition

Enset (Ensete ventricosum (Welw.) Cheesman) is a herbaceous, perennial, monocarpic plant, belonging to the family Musaceae. Morphologically, enset resembles the banana plant (Musa spp.) (Figure 1) although it is not cultivated for its fruits, but for its underground corm and pseudostem base which are mainly processed into starchy food products. The cultivation of enset only occurs in the south and south-western highlands of Ethiopia where it is a staple food for ~24 million people (~20% of the Ethiopian population) (Blomme et al. 2023; Borrell et al. 2019). This process yields solid agricultural residual byproducts with fibrous nature, commonly called fibers. These fibers are sun-dried and used traditionally to make sacks, bags, ropes, mats, and sieves, but these applications only use a small fraction of the material and very large quantities of these residues are left without commercial value (Berhanu et al. 2021). Thus, the proper valorization of these agricultural remnants for more added value products is the eco-friendly approach for agricultural waste management because it prevents the need for their disposal (Berhanu et al. 2021; Kaur, Kant Bhardwaj, and Kumar Lohchab 2017).

Figure 1. Ensete ventricosum plant (left) and cross-section of enset pseudo stem (right) (Berhanu et al. 2018).

Enset (Ensete ventricosum) plant is also found in sub-Saharan Africa and grows wild in many countries. It is the main crop of a sustainable indigenous African system, providing food security and drought resistance. It is also used for fiber production, animal forage, and construction materials, as an ornamental, and for its medicinal value. Ensete fiber is a plant fiber extracted from the pseudostem and leaf parts of the plant. It is strong and flexible enough to be used for many applications, and there is potential to extract and utilize fibers from the leaf stalk and fallen-sheath parts of the plant (Teli and Terega 2017). Cellulosic fibers are widely used for many purposes, for example, in textile industries, papermaking and packaging industries, pharmaceutical applications, and the preparation of innovative materials, such as “green” composites (Berhanu, Kiflie, and Yimam 2019) and flame retardant textiles (Dejene, Belachew Fenta, and Godana Korra 2022).

The chemical structure of banana fiber is complex and multilayered, with three main components that determine its physical and mechanical properties. These components were cellulose, hemicellulose, and lignin (Singh et al. 2022). Cellulose is a structural component of plants and is often surrounded by matrices of other structural polymers such as lignin and hemicellulose (Berhanu, Kiflie, and Yimam 2019). Investigations of the chemical composition of the enset fiber revealed that it consisted of 64.46% cellulose, 22.47% hemicellulose, 6.88% acid-insoluble lignin, 5.66% ash, and 0.54% solvent extractives (Table 1).

Table 1. Chemical composition of EV fiber (Teli and Terega 2017).

Enset ventricosum fiber	Cellulose	Hemi cellulose	Lignin	Extractives	Ash
Composition (%)	64.46	22.47	6.88	0.54	5.66

The combined weight of the two major components that make up holocellulose (i.e. cellulose plus hemicellulose) was 87%, which can also be used for various applications. In another interesting study by (Berhanu et al. 2018), the enset crop residual products remaining from the food production were analyzed in view of their valorization and the holocellulose was 87.47% which is higher than the result found by (Teli and Terega 2017). These results (of fiber composition) were compared with those of some important natural fibers (Table 2). It is evident that the enset fiber showed a higher cellulose content than bamboo, banana, and coir fibers (Teli and Terega 2017).

Table 2. Comparison of the chemical composition and tensile properties of EV fiber with other natural plant fibers (Dunne et al. 2016; Teli and Terega 2017).

Fiber	Cellulose (%)	Hemicellulose (%)	Lignin (%)	Tensile strength (MPa)	Elongation (%)
Abaca	56–70.2	17.5–25	7–15.1	12–980	3–10
Bamboo	26–43	20.5–30	21–31	140–230	-
Banana	57.6–62.5	19–29.1	5–13.3	180–914	5.9
Coir	32–46	0.15–0.3	40–45	106–175	30
Cotton	82–96	2–6.3	0.5–1	300–700	7
Flax	71–75.2	8.6–20.6	2.2–4.8	345–1500	2.7–3.2
Hemp	68–81	2–22.4	3.5–10	690	1.6
Jute	61–71	14–20	12–13	393–773	1.5–1.8
Kenaf	53.5–72	2.1–20.3	9–17	930	1.6
Pineapple	80.5	17.5	8.3	1020	14.5
Ramie	68.6–76.2	13–16	<0.7	560	2.5
Sisal	47.6–78	10–17	10–14	317.5	3–7
Enset	57.2–64.46	22.47	6.88	351.7	3.2
Enset	69.51	-	5.7	-	-
Enset (leave)	37.96	-	18.93	-	-

Table 3. Comparison of mechanical properties of natural fiber hybrid composites (Bekele, Lemu, and Jiru 2022; Biresaw, Sirahbizu Yigezu, and Gloria 2022).

Hybrid composite	Tensile strength (MPa)	Flexural strength (MPa)	Impact strength
Sisal/Enset/Polyester	114.02	61.21	22.21 KJ/m^2
Jute/Sisal/Epoxy	66.77	114.01	332 J/m
Banana/Jute/Polyester	25.83	182.34	20.1 kJ/m^2
Hemp/Flax/Epoxy	44.17	44.61	4.18 kJ/m^2
Flax/Enset/Polyester	113.4	167.88	-
Jute/Sisal/Epoxy	15.91	29.65	0.55 J

Table 4. Effects of alkali treatment on mechanical behaviors of natural fiber-reinforced hybrid composites (Bekele, Lemu, and Jiru 2023).

Hybrid composite	Tensile strength (MPa)		Flexural strength (MPa)		Impact strength
	Untreated	Treated	Untreated	Treated	Untreated	Treated
Enset/sisal/unidirectional	90.23	116.12	38.77	60.92	22.21 J/m^2	23.33 J/m^2
Enset/Sisal/woven	115.67	122.56	105.23	116.3	22.77 J/m^2	24.11 J/m^2
Jute/sisal	70.39	74.78	67.56	54.67	332 J/m	588 J/m
Jute/Curaua	66.77	63.9	97.67	80.86	388 J/m	288 J/m
Sugarcane leaves/almond shell	12.86	17.16	39.91	40.68	0.78 J	1.06 J

Table 5. Consolidated observations of manufacturing techniques, mechanical properties and application of false banana fiber reinforced composites.

Composite specification	Manufacturing technique	Mechanical properties	Application	Reference
The characterization of natural fiber epoxy composites	Hand lay-up	The mechanical properties are increased with the similar proportion as amount of epoxy increased.		(Mehamud et al. 2016)
Manufactured the composite material using gypsum resin and false banana fiber.	Hand lay-up	The addition of false banana fiber has improved the mechanical properties of gypsum resin	Interior decoration	(Abuye and Molla 2020)
Developed a biodegradable composite of (Enset) fiber as reinforcement with polyester resin	Hand lay-up	The study showed that fiber orientation has a significant effect on mechanical properties		(Wondmagegnehu et al. 2022)
Developed a one-way enset fiber-reinforced polypropylene (PP) composite	Film stacking and hot pressing	The treated unidirectional enset fiber woven mat showed the highest tensile strength.	Automotive, construction	(Dessie et al. 2022)
Fabricated false banana and bamboo fibers reinforced epoxy composites with varying fiber concentration.	Hand lay-up	False banana and bamboo fibers reinforcement in the epoxy matrix has improved the mechanical properties of composite structure.		Gebre and Raj [35]
Investigated the mechanical properties of false banana/glass fiber reinforced hybrid composite materials at different fiber volume fractions and orientation of hybrid	Hand lay-up	The results showed that both volume fraction and fiber orientation significantly affect the mechanical properties of the hybrid composite.		(Batu and Lemu 2020)
Developed new material from flax and false banana fiber hybrid reinforced polymer composite using polyester resin as a matrix	Hand lay-up	The hybrid composites of 25% of flax, 15% of false banana, and unidirectional orientation have shown the maximum tensile and flexural strength.	Automotive interior bodies	(Biresaw, Sirahbizu Yigezu, and Gloria 2022
Produced bio composite profiles that consisting of polyester resin glue and banana fibers as a filling material and glass ropes binding.	Compression molding and hand lay-up	The results showed that the the highest and lowest bending strengths for the double layers specimens were 18.196 N/mm^2 and 16.834 N/mm^2, respectively.	Decoration for garden furniture	(Hoyur and Çetinkaya 2012)
Studied false banana fibers were used as reinforcement to obtain composites with melted waste polyethylene bottled as matrix phase	Compression molding	It was observed that the mechanical strength of treated false banana reinforced PE increased linearly with increment of fibers loadings.	block board and construction	(Kimutai, Siagi, and Kiptarus 2014)
Weaved enset fiber into the mat and treated with 1.5 wt% Si69 and 5 wt% GPS	Compression molding and film stacking	The treated enset fiber unidirectional reinforced PP composite achieved a remarkable improvement of property	long-term performance applications	(Dessie et al. 2022)
Designed and developed false ceiling board from polyvinyl-acetate composite reinforced with false banana fibers and filled with sawdust	Hand lay-up and compression molding	The optimum results obtained were tensile strength of 12.54 N/mm2, compressive strength of 7.03 N/mm^2, and flexural strength of 5.13 N/mm^2.	Ceiling board	(Yerdawu, Rotich, and Caggiano 2021)
The effects of alkali treatment and fiber orientation on mechanical properties of enset/sisal polymer hybrid composite	Hand lay-up	The treated and woven fiber orientation hybrid composites exhibit better mechanical properties than untreated and unidirectional enset/sisal hybrid composites	Industrial application	(Bekele, Lemu, and Jiru 2023)

EV fibers have a higher cellulose content and lower lignin content than other fibers, making them a potential source for textiles and other technical products (Teli and Terega 2017). The false banana fiber bundles have been used as natural fibers reinforcement in composite materials. Their structural and chemical features also suggested their use as a fiber source for paper pulp production, but the high hemi-cellulose content advised them to apply pre-treatments for their previous removal, namely by using low chemical input processes such as hydrothermal treatments (Berhanu et al. 2021).

Physical and tensile properties

The physical and tensile properties of the EV fibers are expressed in terms of diameter, linear density, moisture content, tensile strength, and elongation at break. According to (Teli and Terega 2017) study, the results revealed that the individual fibers had an average diameter of 128 μm, linear density of 8.8tex, tensile strength of 352 MPa, and elongation at break of 3.2%. Moreover, the fibers had a moisture content of 12.2% and a moisture regain of 13.8%. The enset fiber showed tensile properties comparable to those of most commercially available fibers, and its tensile strength (MPa) was similar to that of the abaca, banana, cotton, and flax fibers. Moreover, the enset fiber was stronger than the sisal, bamboo, and coir fibers. The elongation at break of the enset fiber was similar to that of the abaca, flax, and sisal fibers, and better than that of the hemp, jute, kenaf, and ramie fibers. The significantly good tensile properties of the enset fibers are attributed to their high cellulose content and good crystallite orientation. The hemicellulose component in the fiber creates a barrier between the cellulose polymer chains, which causes them to dissociate from each other. As a result, strain develops and remains intact in the cellulose polymer chains. This, in effect, causes the fibers to have high tensile strength and elongation at break. Moisture adsorption measurements depend on the chemical composition of the fibers and their molecular structures (Baltazar-Y-Jimenez and Bismarck 2007). Therefore, the high moisture content and regain of EV fibers are attributed to the presence of abundant hydroxyl and other oxygen-containing groups in the amorphous regions of hemicellulose and cellulose (Teli and Terega 2017).

Processing techniques for false banana fiber composites

Methods for extracting and preparing false banana fibers

Stripping

Tuxying is the most widely used and oldest method of removing fiber from leaf sheaths. It involves separating the fibrous outer layer from each leaf sheath and stripping or cleaning the fiber strands from the tuxy. Tuxying operations must be performed immediately after the stalk is felled (Temesgen 2019).

Decortications

False banana fibers were also cleaned using a decorticator. Manually or small spreader machines are used to separate the fibers from the stem of the plant (Figure 2) (Temesgen 2019).

Figure 2. Extraction of false banana from enset plant manually a). Enset plant b). Manual extraction on plane wood c). Extracted false banana fiber (Batu and Lemu 2020).

Techniques for fabricating false banana fiber composites

Different manufacturing techniques are used to produce epoxy-based natural fiber composites, depending on the component material properties, size, and cost (Beyene et al. 2021).

The hand lay-up technique

The most popular method to produce bio-composite epoxy in small- and large-scale manufacturing. The mold is coated with a gel to facilitate the removal of the composite, and the fibers are manually placed in the mold and the resin containing the hardener is applied. A uniform distribution of the resin mixture is achieved using a roller to ensure that the entrapped air is removed from the composite mat. Sufficient curing time is allowed, and the composite is removed from the mold for further processing (Figure 3) (Beyene et al. 2021).

Figure 3. Schematic diagram of hand layup technique (Alsuwait et al. 2023).

Different researchers have used hand lay-up techniques to produce false banana fiber-reinforced composite. The work of (Mehamud et al. 2016) explained the characterization of different weights of composite, natural fiber epoxy composites, using a hand lay-up technique and a mechanical testing machine. In the study of (Abuye and Molla 2020), an effort was made to manufacture a composite material using gypsum resin and false banana fiber to improve the mechanical and physical properties. (Wondmagegnehu et al. 2022) developed a biodegradable source of false banana (Enset) fiber as reinforcement with polyester resin composite material. (Dessie et al. 2022) develop a one-way enset fiber-reinforced polypropylene (PP) composite. In this study, long and aligned enset fibers were interlaced with PP yarns to form a woven mat. The mat was surface-treated, and the film-stacking method was applied to develop the composite via hot pressing. The mechanical properties of the composites were also investigated. (Gebre and Raj 2016) fabricated false banana and bamboo fiber-reinforced epoxy composites with varying fiber concentrations. The composites were fabricated using the hand lay-up method, which is one of the simplest methods for fabricating composites.

(Dessie et al. 2022) looks into the physical and mechanical properties of Enset fibers, which are controlled by the position of the leaf sheath, and is used as an input to optimize their variation for unidirectional composite applications. (Batu and Lemu 2020) investigated the mechanical properties of false banana/glass-fiber-reinforced hybrid composite materials at different fiber volume fractions and the orientation of the hybrid (false banana and glass) fibers. False banana/glass fiber-reinforced hybrid composites were designed considering the effects of fiber orientation and volume fraction and then manufactured according to ASTM standards using the hand-layup technique. (Biresaw, Sirahbizu Yigezu, and Gloria 2022) developed a new material from flax and false banana fiber hybrid-reinforced polymer composites using polyester resin as a matrix to replace synthetic fiber-reinforced polymer composites for automotive interior bodies. The composite samples were fabricated based on the weight percentage of fibers and matrix and the orientation of the fibers, which were combined with Taguchi’s experimental design using the hand layup fabrication process. Furthermore, Enset and sisal fibers are among the most widely used reinforcements to fabricate natural fiber-based composite materials. Hand lay-up techniques were employed in (Bekele, Lemu, and Jiru 2022) study to fabricate enset – sisal (E/S) hybrid fiber composites with volume ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 and constant polyester resin.

In the study by (Hoyur and Çetinkaya 2012), composite profiles with dimensions of 40 × 40 x 1100 mm were produced. Biocomposites consisting of polyester resin glue and banana fibers as a filling material and glass rope binding were prepared by compression molding at 400 bar pressure and 70°C temperature using a hydraulic press. Glass fiber and polyester binding were used to increase the strength of the outer surfaces of the produced profiles. One and two glass fibers were laid in two different orientations. One of them was laid using the hand lay-up method, which was used to increase the strength of the outer surfaces. Similarly, (Temesgen et al. 2021) was used hand lay-up composite manufacturing technique to manufacture the composite using acacia-frankincense bio resin and enset fabric with resin to enset fabric weight ratio of 80:20 wt.% and 70:30 wt.%.

Compression molding

Compression molding is a simple and versatile process for epoxy/natural fiber component manufacturing, where a mixture of resin and fiber is placed in the mold cavity and compressed with pressure (Dayo et al. 2017). High-volume, high-pressure epoxy bio-composites can be produced, but the yield is limited by press size and labor intensity (Beyene et al. 2021).

Different researchers have used hand compression molding for producing false banana fiber reinforced composite (Figure 4). According to (Kimutai, Siagi, and Kiptarus 2014), false banana fibers were used as reinforcements to obtain composites with melted waste polyethylene bottles as the matrix phase. The composites were prepared by compression molding, and the effects of fiber loading on mechanical properties, such as impact strength, flexural strength, and wear resistance, were investigated. (Dessie et al. 2022) was weaved enset fiber into the mat and treated with 1.5 wt% Si69 (triethoxysilyl propyl tetrasulfide) and 5 wt% GPS (Glycidoxypropyl trimethoxy silane) after which it was used to reinforce PP composites through the film stacking method followed by the compression molding. In the (Hoyur and Çetinkaya 2012) study, bio composite profiles, in the dimensions of 40 × 40 x 1100 mm, were produced. Biocomposites consisting of polyester resin glue and banana fibers as filling materials and glass rope binding were prepared by compression molding. (Yerdawu, Rotich, and Caggiano 2021) designed and developed a false ceiling board from polyvinyl-acetate (PVAc) composite reinforced with false banana fibers and filled with sawdust. The aim was to develop a lightweight false ceiling board with good strength performance using raw materials that are fully biodegradable, including sawdust, and thus solving the problem of its disposal. The false banana fibers were characterized by their tensile strength, elongation, and moisture content because these parameters affect the composite properties. The hand lay-up method combined with compression molding followed by curing has been utilized in the manufacture of false ceiling composites. (Chaka et al. 2022) carried out compression molding of composite materials developed from natural fibers reinforced with recycled polyethylene terephthalate.

Figure 4. Schematic diagram of compression molding technique (Alsuwait et al. 2023).

Properties of false banana fiber-reinforced composites

Mechanical properties

The mechanical properties of sustainable fiber-reinforced composites are the most important factors determining their potential applications in various sectors, including automobiles, aerospace, households, and sports (Saptarshi et al. 2022). This section discusses briefly about the mechanical performance studies on the false banana fiber-reinforced various polymer matrix composites and their applications. In addition, the effect of hybridization in banana fiber reinforcing with other natural fibers and synthetic fibers is also discussed.

Enset fiber-reinforced thermoplastic composites

The use of natural fibers in recycled plastics resulted in the production of cheaper, effective floor tile composites, and a reduction in environmental pollution. The waste polyethylene bottles reinforced with false banana composite mechanical property studies were performed by (Kimutai, Siagi, and Kiptarus 2014) with fiber weight percentage and it was evident that the flexural modulus, compressive strength, and flexural strength increased linearly with increasing fiber loading, and the water absorption increased with increasing fiber loading. The study has demonstrated that the optimum fiber loading for the best performance of the composite achieved was 30 wt%. Using sisal and false banana fibers at a ratio of 3 weight percent each as reinforcement in melted recycled PET matrix with 22 weight percent of gypsum added as fillers to improve shrinkage on molding.

(Chaka et al. 2022) conducted a study on composite materials used for floor tiles, which showed that natural fiber-based composites were lightweight and had poor compressive strength. Chemical treatment of natural fibers resulted in the removal of certain functional groups, while composites made of recycled PET and sisal fibers had a maximum compressive strength of 3.1 MPa. The findings of this study support the idea that melted PET wastes can be combined with natural fibers like sisal and false banana to create composites that are lightweight and have a low compressive strength. Additionally, Ethiopian banana fibers that are highly flexible and with better surface of materials (plate of composite) can be created and can be easily produced for other purposes by reinforcing them with epoxy resin. Also, with a higher percentage of banana fiber, the composites have better mechanical properties (Mehamud et al. 2016).

Further research has been conducted to improve false banana fiber-reinforced composites, focusing on their suitability for construction and automotive applications. (Dessie et al. 2022) developed a one-way enset fiber-reinforced polypropylene composite, which showed the highest tensile strength and flexural strength, respectively, relative to pure PP. Therefore, the developed composite samples confirm that the enset fiber can be effectively reinforced with PP for applications in the automotive and construction industries. Additionally, (Dessie et al. 2022) studied the effects of surface treatment on the properties of unidirectional enset fiber-reinforced polypropylene (PP) composites. They found the 1.5 wt% Si69-treated enset fiber unidirectional reinforced polypropylene composite achieved a remarkable improvement in properties and can be used for high mechanical and long-term performance applications. (Yerdawu, Rotich, and Caggiano 2021) developed a false ceiling board from PVA composite reinforced with false banana fibers and filled with sawdust. The optimum proportions of raw materials were 40% sawdust, 40% binder, and 20% fibers. The optimum results were 12.54 N/mm², 7.03 N/mm², and 5.13 N/mm².

Alkaline treated Enset fibers satisfactorily and effectively improved mechanical, morphological, and dynamic properties of thermoplastic matrix for various engineered and hi-tech applications. Alkali (NaOH) treated 2.5%, 5.0%, and 7.5 wt% Ensete stem fiber reinforced unsaturated polyester composites underwent surface morphology and structural composition studied by (Negawo et al. 2018). 5.0 wt.% treated Ensete fibers/UP composites showed 14.5% and 43.5% increases in flexural strength, Young’s modulus, storage and loss modulus, and glass transition temperature, indicating better interfacial interaction. Similarly, (Adiraro et al. 2020) investigated the use of natural Enset fiber as reinforcement in Polyester resin matrix for non-load bearing structural elements. The results showed that NaOH solution treatment had a positive effect on impact strength and water absorption properties of the composite. Optimum impact strength was recorded at 20 wt% fiber content, while water absorption was highest at 30 wt% fiber content.

Enset fiber-reinforced cement composites

Enset fiber-reinforced cement composites have been progressively studied in recent years. The study of (Abuye and Molla 2020) showed that 20 wt. % of false banana fiber mixed with gypsum gave optimum properties. This improved the tensile, flexural, and impact properties of the gypsum resin, increasing its water absorption. False banana fibers can be a potential candidate for use in natural fiber-reinforced composites to improve their mechanical and physical properties. An effort has been made to manufacture the composite material using gypsum resin and false banana fiber to improve mechanical and physical properties. The false banana fiber as a suitable reinforcement in cement and polymer-based composites and its performance has been done by (Beyene et al. 2021) and was assessed the mechanical performance of aligned enset ventricosum fiber reinforced cementitious composites and particularly the influence of the fiber volume fraction on the flexural performance of the composite. The post-cracking stiffness, toughness, and flexural strength of the enset ventricosum fiber-reinforced specimens increased with increasing fiber content. These results are promising for the development of an enset-ventricosum fiber-based green composite.

Hybrid enset fiber-reinforced composites

The mechanical properties are largely dependent on the volume fraction of the fibers in the matrix. Generally, when there is an increase in the fiber volume fraction up to an optimum level, there is a greater distribution of load among the fibers, and the applied force can be carried even after fiber fracture, which can lead to a higher tensile strength (Saptarshi et al. 2022). (Wondmagegnehu et al. 2022) investigated the mechanical and physical properties, such as tensile, flexural, impact strength, and water absorption. In the composites, the fiber orientations were 0°, 90°, 45°/45°, 0°/90°, and chopped at a 40% fiber volume fraction. The study showed that fiber orientation has a significant effect on mechanical properties. Another interesting study has been done by (Müller, Valášek, and Ruggiero 2017) was described basic mechanical properties (tensile strength, strain at the break, modulus of the elasticity, and impact strength) of the composite material reinforced with fibers of the false banana plant. The addition of fibers increased the modulus of elasticity and impact strength, whereas the tensile strength and strain at break decreased.

Further research has been conducted to improve the mechanical properties of false banana fiber-reinforced composites by focusing on their hybridization with other fibers. (Bekele, Lemu, and Jiru 2022) fabricated an enset-sisal hybrid fiber composite with volume ratios of 100/0, 75/25, 50/50, 25/75, and 0/100. Results showed that hybrid composites excel in mechanical properties, with tensile and flexural strengths enhanced by 47.3% and 41.03%, respectively, at 50/50 E/S volume ratio. Enset ensured impact strength, while sisal fiber helped reduce water absorption. Similarly, (Batu and Lemu 2020) designed false banana and glass fiber-reinforced hybrid composites by considering the effects of fiber orientation and volume fraction. The results showed that both volume fraction and fiber orientation significantly affected the mechanical properties of the hybrid composite of false bananas and glass fibers (Figure 5).

Figure 5. Influence of fiber volume fraction on (a) tensile and compressive strength and (b) modulus of elasticity in tension of banana/glass-fiber-reinforced hybrid composite materials at different fiber volume fractions and the orientation of the hybrid (Batu and Lemu 2020).

Another interesting study has been done by (Biresaw, Sirahbizu Yigezu, and Gloria 2022) on a new material from flax and false banana fiber hybrid-reinforced polymer composites using polyester resin as a matrix to replace synthetic fiber-reinforced polymer composites for automotive interior bodies. False banana fiber hybrid-reinforced polymer composites showed better flexural strength than synthetic fiber-reinforced polymer composites, with maximum tensile and flexural strength. As shown in the (Table 3), the enset hybrid composite outperforms the other hybrid composites in terms of tensile and flexural strength.

Further review study on the use of hybrid false banana natural fiber especially the banana and bamboo fiber as hybrid composites reinforced epoxy matrix was performed by (Gebre and Raj 2016) with varying fiber concentrations. The experimental analysis showed that false banana and bamboo fiber reinforcements in the epoxy matrix improved the mechanical properties of the composite structure. According to (Boset 2019) false banana fiber reinforced by epoxy increases mechanical properties. From the results and comparisons, it is concluded that the fabricated false banana epoxy composite is lightweight and has good mechanical properties.

Further research has been conducted to improve the mechanical properties of hybrid false banana fiber-reinforced composites. (Bekele, Lemu, and Jiru 2023) studied the effects of alkali treatment and fiber orientation on the mechanical properties of enset/sisal polymer hybrid composites. The result showed that treated and woven fiber orientation hybrid composites exhibit better mechanical properties than untreated and unidirectional E/S hybrid composites. The tensile and flexural strengths and impacts of 5% NaOH-treated composites were improved by 5.21%, 9.25%, and 5.98%, respectively, over untreated E/S hybrid composites.

The 5% alkali treated enset/sisal hybrid composites have comparable, acceptable, and satisfactory mechanical and physical properties to other hybrid fiber-reinforced polymer composites (Table 4) due to strong adhesion between the matrix and the reinforcement, which govern some promising and potential applications with the benefits of the environment, renewable resources, accessibility, and sustainability.

Enset fiber-reinforced bio resin composites

(Yohannes et al. 2022) studied the enhancement of mechanical properties of bioplastic films by reinforcing them with false banana fiber. The bioplastic films showed good tensile strength and extensibility when reinforced with false banana fiber, potentially substituting petroleum-based synthetic plastics. Additionally, fibrous structures are some of the most commonly used materials for sound absorption applications, and very interesting research done on the reduction of noise. (Temesgen et al. 2021) studied the acoustic property of enset fabric and its green composite material. The sound absorption coefficient of enset fabric could only reach 0.5 level with five layers, and composite structures with increasing number of fabric layers decreased sound absorption frequency interval. Increased ratio of bio resin to enset fabric caused sound absorption behavior to shift from higher to medium frequency regions. (Bekele, Lemu, and Jiru 2023) carried out extraction and characterization of avocado seed starch, and its blend with enset cellulosic. As a result, avocado seed starch and enset cellulosic blend can be used as alternative raw materials to develop biodegradable plastics.

Water absorption properties

Water absorption is an important test for natural particles and fiber-reinforced composites to determine their potential for outdoor working (Gebre and Raj 2016). Moisture absorption by natural fiber-reinforced polymer composites decreases mechanical properties and accelerates microbial deterioration, leading to poor stress transfer and specimen fracture (Yerdawu, Rotich, and Caggiano 2021). The results of water absorption test of (Yerdawu, Rotich, and Caggiano 2021) composite sample manufactured with an optimum percentage of the constituents (sawdust 40%, resin 40%, and false fiber 20%) are shown in Figure 6 after 2-hour and 24-hour immersion in water. It is shown that as the immersion time increased, the amount of water absorbed in the composite also increased, which followed Fick’s diffusion law.

Figure 6. Water absorption test of polyvinyl-acetate (PVAc) composite reinforced with false banana fibers and filled with sawdust for 2 hours and 24 hours, respectively (Yerdawu, Rotich, and Caggiano 2021).

This could be because the raw materials used for the composite manufacturing were inherently hydrophilic owing to the presence of hydroxyl groups on their surfaces. This indicates that the developed composite should not be used for applications that are exposed to water. Figure 6 also shows that the tensile strength of the composite reduced as the water absorbed increased. This is probably because the absorption completely terminates the bonding force between the fiber and matrix to a greater extent (Kimutai, Siagi, and Kiptarus 2014). It was observed that the rate of water absorption in the composite increases as the percentages of fibers increases. Composite materials have more tied bonding and fewer pores than wooden portioning boards, and the fiber content affects water absorption values. PE filler reduces water absorption of fiber portioning boards.

Further research has been conducted on the effect of surface treatment of false banana fiber-reinforced composites (Dessie et al. 2022). Investigations indicated that, surface treatment of false banana fiber-reinforced composites reduced equilibrium water up take up by 64.3% and 30.9%, respectively, due to strong interfacial adhesion and condensed – OH groups on the surface of the fibers.

Applications of false banana fiber-reinforced composites

Natural FRP composites are popular due to their mechanical performance, economic production, and biodegradability (Saptarshi et al. 2022). False banana fiber composites are increasingly being used in diverse applications due to their exceptional mechanical properties and potential for sustainability (Table 5). They are eco-friendly, biodegradable, and have a high strength-to-weight ratio, making them ideal for building and construction applications. However, their limited availability could increase their cost, but they are expected to grow as people become more environmentally conscious and demand eco-friendly building materials.

(Dessie et al. 2022) developed a one-way enset fiber-reinforced polypropylene (PP) composite for the application of automotive and construction industries. (Abuye and Molla 2020) manufactured a composite material using gypsum resin and false banana fibers to improve the mechanical and physical properties. These composites can be applied to interior decoration such as false ceilings and wall partitioning for domestic and industrial purposes as construction materials.

(Batu and Hirpa 2021) studied the hybridization of natural fibers and synthetic fiber-reinforced composite materials, particularly for wind turbine blade applications, to reduce the problems that exist in the wind energy sector, such as higher cost, higher density, and environmental pollution. The results obtained from the designed hybrid composite for turbine blades indicated a reduction in weight and improvement in fatigue life compared to synthetic fiber glass-reinforced epoxy composites for turbine blades. (Biresaw, Sirahbizu Yigezu, and Gloria 2022) developed new material from flax and false banana fiber hybrid reinforced polymer composite using polyester resin as a matrix to replace synthetic fiber-reinforced polymer composites for automotive interior bodies. (Yerdawu, Rotich, and Caggiano 2021) designed and developed a false ceiling board from polyvinyl-acetate (PVAc) composite reinforced with false banana fibers and filled with sawdust.

Processing composites made of false banana fibers: current issues and prospects

The pseudo-stem and leaves of the Enset plant are used to produce fibers that are used to create a variety of domestic goods, including ropes, bags, and composites. However, there are some persistent problems with false banana fiber composite manufacturing that must be resolved. These include the absence of standardization and contemporary processing methods for the extraction and processing of fiber. However, there are a number of opportunities for composites composed of false banana fibers, including the rising global demand for sustainable and eco-friendly goods. False banana fiber composites have strong, stiff, and impact-resistant mechanical characteristics that make them appropriate for a variety of applications, including those in the construction and automotive industries. Market expansion for false banana fiber-based composites is highly anticipated. However, currently, in terms of polymer composites hybridization with conventional fiber, the enset fibers are not adequately studied. Similarly, false banana fiber composites are a possible replacement for conventional synthetic composites due to the increased interest in employing sustainable materials in a variety of industries. The recent research by (Dejene and Mamo Geletaw 2023) directed that use of plant mediated ZnO for self-cleaning composite applications, especially for food packaging purpose. False banana fiber composites have undergone more research and development as a result, and new applications may yet be found. Future research studies will explore green fiber extraction techniques.

Conclusion

This review paper discusses the processing techniques for creating composites with false banana fibers and any matrix, whether it is biodegradable or not. It has been effectively stated by several researchers how to prepare these fibers using various methods to get the optimum qualities. Particularly in regard to the mechanical and water absorption capabilities of composites, the use of false banana fibers as reinforcements in different matrices has produced interesting results. False banana fiber composites are currently being used in a variety of industries, from packaging and construction to biodegradable composites. Despite the potential of false banana fiber-reinforced composites as sustainable alternatives, several challenges still need to be addressed to fully realize their potential and few manufacturing techniques were addressed. The investigation of novel uses and markets for false banana fiber composites, notably in biomedical engineering and energy storage systems, is one of the major research needs in this area. The opportunity to investigate the potential of false banana fiber-reinforced composites as sustainable substitutes is abundantly provided by these research gaps for researchers, engineers, and manufacturers. In order to realize the potential of banana fiber composites as adaptable and sustainable materials, several issues must be resolved.

Highlights

• The mechanical characteristics, biodegradability, and low cost of false banana fiber-reinforced composites make them a viable field for further investigation.

• However, to the best of our knowledge there is no comprehensive review.

• As a result, this work gives a basic overview of several researchers' work and explains in terms of how they are prepared, what features they have, and how they are used.

• Particularly in regard to the mechanical and water absorption capabilities of composites, the use of false banana fibers as reinforcements in different matrices has produced interesting results.

• This review also highlighted issues and potential directions for the future that could help to enhance the performance and characteristics of composite made of false banana fibers

Acknowledgements

The author expresses gratitude to the current and previous groups of researchers in the field of composites at the department of textiles.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The reviewers received no financial support to review the authorship or publication of the article.