Mechanical Characteristics of Sugarcane Bagasse Fibre Reinforced Polymer Composites: A Review

Abstract

The increasing concern for ecological preservation has prompted the development of new and innovative green materials that produce minimal environmental pollution. In this context, natural polymers have gained significant attention in recent times. Sugarcane Bagasse fibre, in particular, has undergone several chemical modifications, which have greatly enhanced its potential for various fields of interest. The advantages of sugarcane bagasse fibres are numerous and noteworthy. These fibres are a valuable by-product with qualities such as abundance, biodegradability, flexibility during processing, minimal health hazards, relatively high tensile and flexural modulus, low density, affordability, and recyclability. The chemical modification is done either by introducing a certain functional group on its surface or by modifying the chemistry of bagasse. These chemical structural changes reported to improve the matrix adherence and improving the composites mechanical properties. This review provides information on the application of surface-modified sugarcane bagasse and their materials from packaging to fillers. Also, this review article aims to give a detailed overview of the research on the use of sugarcane bagasse in reinforced composites, as well as its advancements and applications.

Keywords:

• Sugarcane bagasse fibre
• natural fibre reinforced composites
• polymeric composites
• sustainable materials
• bio-materials

Public interest statement

Natural fibre composites are gaining traction as a viable alternative to conventional plastics, primarily because they are easy to biodegrade and are environmentally sustainable. In this paper, we present findings that demonstrate the enhanced mechanical properties of natural fibre composites. Our research focuses on sugarcane bagasse fibres reinforced with various polymer matrix materials, including thermosets, thermoplastics, and elastomers. We detail the resulting improvements in mechanical properties, such as tensile strength, flexural strength, and impact resistance, among others. Moreover, we explore the diverse applications of these composites in sectors such as automotive, cement, packaging, healthcare, household, and military. Our findings provide a glimpse of the immense potential of natural fibre composites in various industries and highlight their growing importance as a sustainable material choice.

1. Introduction

Natural fibre reinforced polymer composite materials are a type of material that aim to solve majority of the environmental and economic problems associated with synthetic fibre-reinforced composites (Saber & Abdelnaby, 2022; Thakur & Thakur, 2014). In a composite the reinforcement could be of material which is fibrous, particulate or laminate. For fabrications of NFRCs, natural fibres derived from plants, animals, and minerals are mostly used (Singh et al., 2017). Natural fibres like fibres from sugarcane, bamboo, jute, coir, banana, oil palm, kenaf, and other plants are frequently used as reinforcement in polymeric matrixes (Dinesh et al., 2020; Ku et al., 2011; Yashas Gowda et al., 2018). The fibres have excellent mechanical qualities, provide greater thermal and acoustic insulation, and are biodegradable (Lodha & Netravali, 2005; Prabhu et al., 2022).

Sugarcane Bagasse is one such lignocellulose that is relatively inexpensive, biodegradable, light in weight, and widely available. Long-term sustainability of such Natural Fibre Reinforced Composites can be considered as an advancement in the field of polymer composites and bio-composites (D. G. Devadiga, K. S. Bhat, G. Mahesha, et al., 2020; Islam et al., 2022). For the fabrication of new Natural Fibre Reinforced Composites (NFRC), Sugarcane bagasse fibres have the potential to replace glass-reinforced composites as the core material. Since they are readily available, ecologically benign, recyclable, and biodegradable, NFRP composites are a feasible alternative to synthetic fibre-reinforced polymeric composites and have high mechanical strength (Vidyashri et al., 2019). Sugarcane bagasse fibre research has expanded primarily due to environmental concerns and the rising expense of synthetic materials (Saheb & Jog, 1999). There are many attractive features for sugarcane bagasse fibre like biodegradability, lightweight, high specific modulus, low cost and renewability (Kumar et al., 2022). Sugarcane bagasse fibres can be chosen accordingly, depending on the features needed in the newly fabricated reinforced composites.

The matrix in composites could be metal, polymer or ceramic to hold the different reinforcing agents (Parameswaran et al., 2021). The polymer as a binder for natural fibres not only protects them from chemical and environmental damage but it serves as a load carrier for applied loads and gently absorbing created stresses via the matrix, which also enhances the characteristics of pure polymers. The small weight, high rigidity, and great strength in the direction of their reinforcements are few benefits of Polymer as matrix (Brabazon, 2021). Thermosets and thermoplastics, both biodegradable and non-biodegradable, are the two primary categories of polymers (O’Donnell et al., 2004). As a matrix, synthetic or biopolymer, thermosetting, thermoplastic and elastomers, can be employed (Bin Bakri et al., 2022; Boparai K & Kumar, 2021; Motsoeneng et al., 2021; Panwar & Pal, 2022; Thomas et al., 2012). Epoxy, Polyester resins, Vinyl ester, polyethene, PLA, and other polymers are some examples which are commonly employed in the construction of Fibre Reinforced Polymer (FRP) composites (Ilczyszyn et al., 2014).

The mechanical characteristics of different polymeric composites are examined in this article, with an emphasis on sugarcane bagasse fibres as reinforcement. The purpose of this review article is to give beginners an in-depth examination and complete understanding of reinforcing bagasse fibres with different kind of polymers (thermosets, thermoplastic and elastomer). Also, better understanding of mechanical properties of fabricated sugarcane fibres reinforced composites.

2. Physiochemical Properties of Sugarcane bagasse

Following the extraction of the juice, crushed sugarcane is used to create sugarcane bagasse, a fibrous substance. Both the inner pith and the outer rind make up the stalk. The rind is primarily composed of a strong fibrous structure that protects the interior soft spongy substance. The stem featured long finer threads distributed randomly and kept together by hemicelluloses and lignin, while the inner region had tiny fibres with sucrose as the major component. Sugarcane bagasse is chemically made up of cellulose, hemicellulose, and lignin. Depending on the environment and situations, these components’ contents may change. Dry sugarcane bagasse consists mostly of cellulose, hemicellulose, and lignin, with only a little amount of ash and wax (around 40–50% and 28.–55%, respectively) (John & Anandjiwala, 2008). Table 1 illustrates the chemical compositions percentage of sugarcane bagasse fibres.

Table 1. Chemical composition of sugarcane bagasse fibres (Alokika et al., 2021)

Bagasse Fibres Content	Chemical Composition (%)
Cellulose	32–45
Hemicellulose	20–32
Lignin	17–32
Pectin	NA
Ash	1.0–9.0
Moisture	NA

Except for material, all of these components are fundamentally identical to natural lignocellulose constituents. The products that may be used as reinforcing fillers in different polymer matrices will only be a subset of the sugarcane bagasse and products that can be described in the next paragraph. Furthermore, carbonized sugar bagasse can be produced by alkali treatment at a higher temperature (>500°C) followed by burning in a furnace that creates ashes. In a variety of polymers, these particles can be employed as a source of reinforcement. They are principally made of SiO₂, Al₂O₃, Mg, and Fe₂O₃ and have a solid appearance in nature with irregular finer forms (D. G. Devadiga, K. S. Bhat, G. T. Mahesha, et al., 2020). Figure 1 illustrates the principal components of the sugarcane bagasse.

Figure 1. a) the sugarcane plant, the sugarcane bagasse, and its principal components (cellulose, hemicellulose, and lignin) (Da Silva & Frollini, 2020) b) Pectin Structure (Tezara et al., 2016).

In contrast to cellulose, hemicellulose is a polysaccharide with a lower molecular weight. This amorphous, hydrophilic, heterogeneous, and heavily branched biomass accounts for around 30% of the total biomass weight. These serve as a bonding agent between hydrophilic cellulose and hydrophobic lignin & have a lesser degree of polymerization. Mannose, arabinose, methyl ether, and glucose are the residues of hemicellulose.

Lignin is a thermoplastic, amorphous polymer that is slightly friable at high temperatures. It has chemically related substances having a complex network of different molecular weights due to its aromatic nature. The structural rigidity of lignin is higher because the residues of hemicellulose are covalently bonded. Impermeability, tolerance to oxidative stress, and microbial attack are all benefits of its amorphous-heterogeneous existence. Alkyl-alkyl, alkyl-aryl, and aryl-aryl bonding can occur in lignin (Chen et al., 2017). The flexural modulus of bagasse fibre and biodegradable resin composites rose when the volume fraction of bagasse fibre was raised up to 65%. Fibre length and volume fraction of bagasse fibre can impact flexural modulus, flexural strength, and compression ratio (Shibata et al., 2005). Table 2 illustrates the physical properties of sugarcane bagasse fibre.

Table 2. Physical properties of sugarcane bagasse fibre (Balaji et al., 2018)

Physical Properties	Values
Diameter (µm)	300–400
Density (gm/cc)	0.55–0.70
Aspect Ratio (L/D)	100–140
Elongation at break (%)	3–7
Young’s modulus (GPa)	15–19
Tensile strength (MPa)	170–290
Microfibrillar angle (°)	10–22

3. Evaluation of Mechanical Properties of Bagasse Fibre Polymer Composite

3.1. Pre-Treatment of Bagasse Fibres

3.1.1. Alkali treatment

The mechanical property of the 1% NaOH solution-treated bagasse fibre composite showed improved mechanical properties (Cao et al., 2006). The enhancement occurred because of an increase in the strength and aspect ratio. Scanning electron microscopy (SEM) confirmed the increase in the fibre matrix adhesion (Onésippe et al., 2010). The thermal property of alkali-treated fibre in terms of macroscopic density and porosity determined the thermal conductivity of the fibres with alkali treatment. Table 3 illustrates the Mechanical properties enhancement after alkali treatment.

Table 3. Mechanical properties enhancement after alkali treatment (Onésippe et al., 2010)

Mechanical Property	Improvement (%)
Impact strength	30
Flexural strength	14
Tensile strength	13

The outcome demonstrated that the specific heat of the bagasse fibres after alkali treatment had increased. Alkaline fibres have a lower heat conductivity than rectified fibres. The thermal conductivity of composites made with modified bagasse fibre is lower than that of composites made with an alkaline treatment. Alkaline treatment, known as mercerization, is one of the most used chemical processes for natural fibres used to strengthen thermoplastics and thermosets (Elmeniawy et al., 2021).

3.1.2. Effect of acrylic acid, mercerization, isocyanate and washing with an alkaline solution

Work was carried out by Vazquez A. et al. 1999 (Vázquez et al., 1999) processing of bagasse fibres polypropylene composites. To increase fibre adherence to the matrix, four distinct chemical treatments were used: acrylic acid, mercerization, isocyanate, and washing with an alkaline solution. Infrared spectroscopy was used to observe the effects of each chemical treatment. The infrared spectroscopy revealed that the mercerization process produces a heavily fibrillated surface. The impact of each chemical treatment on the composite’s tensile characteristics was investigated. The composite loses tensile strength and elongation at break when the fibres are not chemically treated. The tensile strength of the composite is improved by mercerization and isocyanate treatments. (Figure 2)

Figure 2. FTIR spectra of treated and untreated fibres a) isocyanate treatment b) acrylic acid treatment c) mercerization d) Mechanical properties of PP/bagasse composite with 20% of fibres (Vázquez et al., 1999).

3.1.3. Effect of alkali and acid treatment

Another pre-treatment of bagasse fibre was carried out by Motaung et al. 2015 (T. E. Motaung & Anandjiwala, 2015) whereby sugarcane bagasse was washed with tap water, then rinsed in deionized water, and finally dried for a whole night at 50 degrees Celsius. When the pH was neutral, it was washed with deionized water and dried for the night at 50°C after being immersed for an hour at 80°C in a solution of 2% alkali. After being thoroughly cleaned with deionized water, it was pH-neutralized for 40 minutes at 80°C by submerging it in 5 per cent (v/v) sulfuric acid. As shown in Table 4, the highest concentration of hemicellulose was discovered in sugar cane bagasse that had not been treated, followed by samples that had been exposed to alkali, and samples that had been exposed to acid. The cellulose content of SB increased following alkali and acid treatments. Sulphuric acid-treated SB, on the other hand, had the greatest cellulose concentration, nearly 18% more than untreated SB. After acid treatment, the considerable shift in readings might suggest faster defibrillation of SB fibres.

Table 4. Sugar cane bagasse’s main components in fractions before and after exposure to alkali and acid (T. E. Motaung & Anandjiwala, 2015)

Sample	Lignin (%)	Cellulose (%)	Hemicellulose (%)
Sulphuric acid treated SB	1.49 ± 0.51	66.0 ± 0.11	32.80 ± 0.12
NaOH treated SB	2.51 ± 0.12	54.90 ± 0.18	39.80 ± 1.81
Sugar cane bagasse (SB)	2.78 ± 1.34	48.75 ± 0.14	± 0.75

3.1.4. Maleic anhydride treatment (coupling agents)

A common agent for strengthening composites with fillers and reinforcements is maleic anhydride. A malleated coupling agent and mercerization treatment, change the surface and matrix to strengthen interfacial bonding. The process of this treatment may be explained by first activating the copolymer and then esterifying the cellulose (S. Mishra & Naik, 2005; Saber et al., 2023).

Mishra et al. 2003 worked on the Effect of Different Anhydrides on Cane Bagasse Pith and Melamine—Formaldehyde-Resin Composites (S. Mishra & Patil, 2003). Bagasse was treated with three different anhydrides: maleic, succinic, and phthalic & then reinforced with thermoset melamine-formaldehyde-resin. Promising results were seen in the mechanical properties of treated bagasse fibres. (Figure 3)

Figure 3. a) flexural characteristics of melamine-formaldehyde composites filled with cane bagasse pith and various anhydrides. b) Tensile strength of composite wood materials made using melamine-formaldehyde resin and cane bagasse pith (S. Mishra & Patil, 2003).

4. Thermosets Polymeric Composites:

4.1. Bagasse fibre/Phenolic resin composite

A comparative work was carried out between hybrid and pure composites and the tensile strength and tensile modulus of pure SCB/phenolic resin composites were evaluated and obtained value was 4.51 MPa and~470 MPa respectively (Table 5). (Ramlee et al., 2019) There is poor interfacial bonding between pure SCB/Phenolic resin in comparison to hybrid composites. Hence the mechanical property values were supposed to be less than other hybrid composites due to the low density of single fibres.

Table 5. Mechanical Characteristics of a Composite of Bagasse and Phenolic Resin (Ramlee et al., 2019)

Material	Tensile Strength (MPa)	Tensile Modulus (MPa)
Pure SCB/Phenolic Formaldehyde Resin	4.51	~470

(Trindade et al., 2005) Another work was carried out where thermoset phenolic matrices reinforced with unmodified and surface-grafted furfuryl alcohol sugar cane bagasse fibres were studied. Bagasse fibre was oxidised before the final composites fabrication and it showed tensile strength up to 238 MPa and elongation of 0.9% (Table 6). (Trindade et al., 2005)

Table 6. Tensile strength and elongation for untreated and treated sugar cane, expressed as a percentage (Trindade et al., 2005)

Material	Tensile Strength (MPa)	Elongation ε (%)
Oxidized sugar cane bagasse reacted with FA	238	0.9
Oxidized sugar cane bagasse	126	0.7
Unmodified sugarcane bagasse	222	1.1

4.2. Bagasse/Jute hybrid reinforced epoxy composites

(Sudhir at el. 2014) Chemical alteration of jute and sugarcane bagasse fibers for an epoxy matrix was used by to generate novel hybrid composites (Table 7) Such hybrid composites have superior mechanical characteristics than single matrix composites. The treated jute and bagasse taken in 1:1 ratio, resulted in better values of mechanical properties in comparison to untreated jute and bagasse fibres (Kumar Saw & Datta, 2009).

Table 7. Studies of Mechanical Behaviour of Enhanced JF Bundles Reinforced Epoxy Hybrid Composites Combined with Modified BF Bundles (Kumar Saw & Datta, 2009)

Unmodified BF bundles with modified JF bundles reinforced epoxy hybrid composites.	Bagasse %	Tensile Strength (MPa)	Tensile Modulus (MPa)	Flexural Strength (MPa)	Flexural Modulus (MPa)
	0	11.45	302	31.15	645
	20	16.02	356	36.46	789
	35	19.45	420	45.32	1101
	50	23.07	492	55.63	1480
	65	21.15	399	51.19	1311
	100	9.87	227	26.78	502
Modified BF bundles with modified JF bundles reinforced epoxy hybrid composites	20	18.72	526	42.72	1178
	35	22.57	635	54.57	1484
	50	26.77	753	65.22	1748
	65	23.54	704	60.12	1518
	100	11.2	286	30.78	632

4.3. Bagasse fibre/Epoxy resin composites

Here the 5 % NaOH pre-treated Bagasse fibre was taken into consideration. The type of resin used was Araldite LY556 which was taken together with the hardener H×951. The usual hand lay-up process was used to process the composite (Kumar Acharya et al., 2011). A calculated amount of resin and the hardener was poured into the mould which is followed by a uniform distribution of bagasse fibre over the mixture. The required amount of pressure was applied and curing was done at room temperature for about 12 hours (P. Mishra & Acharya, 2010). As shown in Table 8, the flexural strength was evaluated for BF/Epoxy Resin’s flexural strength in different environment.

Table 8. BF/Epoxy Resins Flexural Strength in a different environment (P. Mishra & Acharya, 2010)

BF/Epoxy resin composite	Normal	Steam	Saline	Sub zero
Flexural Strength	7.67%	23.34%	17.43%	17.56%

In the other case combination of bagasse fibre with oil palm fibre was rinsed and washed with hot water several times to remove the impurities. The fibre was used as filler and was uniformly mixed with Phenolic resin for 15 mins which were poured into a hot, pressing, moulding machine at 150 °C. Compression and curing of the composite specimen were done. Finally, the composite prepared was cold-pressed for 5 mins and the composite plates obtained were cut according to the ASTM standard.

The hybrid composite (7OPEFB:3SCB) has a better mechanical property which is due to the high cellulosic content. (Table 9) The bagasse fibre has helped in reducing the water content and void (Ramlee et al., 2019).

Table 9. Mechanical characteristics of composites made of BF and epoxy with different fillers (Ramlee et al., 2019)

Material	Tensile Strength (MPa)	Elongation break (%)	Young’s Modulus (GPa)
SCB Fibre	20–50	0.9–1.1	2.7
Oil Palm Fibre	-	8–18	1–9
7OPEFB: 3SCB	20–50	-	-

4.4. Bagasse-glass fibre/Epoxy resin composites

(Tewari et al., 2012) blended 15 weight %, 20 weight %, 25 weight %, and 30 weight % bagasse fibre with 5 weight % glass fibre in resin to generate a bagasse-glass fibre reinforced composite material. The maximum tensile strength is diminished when fibres made of bagasse are added. Glass fibre, however, improves ultimate tensile strength considerably more when contrasted to widely viable bagasse-based composites. Bagasse-glass reinforced fibres boost the impact strength of epoxy composites because they are more flexible than matrix materials. The capacity to absorb water is increased by the inclusion of fibres. This test is necessary when composites are used in damp environments. The bending toughness is impacted by the inclusion of bagasse fibre. The addition of glass fibre, however, increases the strength properties even more when compared to widely viable bagasse-based hybrids. (Table 10)

Table 10. Mechanical characteristics of composites made of bagasse, glass fibre, and epoxy resin (Tewari et al., 2012)

Properties	15 wt% BG 5 wt% GF	20 wt% BG 5 wt% GF	25 wt% BG 5 wt% GF	30 wt% BG 5 wt% GF	Epoxy	10 wt% BG
Tensile strength (MPa)	4.69	4.33	2.87	1.56	35.79	-
Impact strength (Nm)	24.01	25.56	26.21	27.01	22.07	20.42
Flexural strength (MPa)	3.96	3.53	1.41	0.82	5.09	3.26

4.5. Bagasse fibre/Polyester composite

Bagasse fibre loading was done in several weight %’s, such as 20%, 30%, and 40%, with unsaturated polyester resin (UP). It was then treated with various concentrations of NaOH such as 0%, 20%, 30% and 40%. The results obtained show good enhancements in Modulus elasticity, Flexural modulus, Flexural strength and Tensile Strength of Bagasse Fibre reinforced polyester composites (Zakaria et al., 2020). (Figure 4)

Figure 4. a).The impact of various NaOH solution concentrations on the tensile strength of composites reinforced with unsaturated polyester and sugarcane fibre at various fibre loadings. b) the impact of various NaOH solution concentrations on the flexural modulus of unsaturated polyester composites reinforced with sugarcane fibres and various fibre loadings. c) the impact of various NaOH solution concentrations on the flexural strength of unsaturated polyester composites reinforced with sugarcane fibres and various fibre loadings. d) the impact of various NaOH solution concentrations on the elastic modulus of unsaturated polyester composites reinforced with sugarcane fibres and various fibre loadings (Zakaria et al., 2020).

Similar work was carried out by (Vilay et al., 2008) There was another treatment of acrylic acid done on bagasse fibre before the final fabrication of composites. It shows when more fibre is added to the bagasse fibre–reinforced polyester composite, the tensile and flexural characteristics improve. (Figure 5) shows treated fibre composites had better tensile and flexural characteristics than untreated fibre-based composites, with AA-treated fibre-based composites showing a significant trend.

Figure 5. The untreated and treated fibre composites’ (a) tensile strength (b) tensile modulus (c) flexural strength and (d) flexural modulus at various fibre loadings (Vilay et al., 2008).

(Lee & Mariatti, 2008) carried out another work on unsaturated polyester composites using rind and pith components of bagasse fibre. The volume bagging method was used for the fabrication of such composites. For rind fibre composites, the flexural strength is raised by 127% (at 15% volume of fibre content), while for pith fibre composites, it increases by 70%. Similarly, for the flexural modulus, the rind fibre composites clearly showed an increasing trend as their fibre content rose. (Figure 6)

Figure 6. Unsaturated polyester composites reinforced with rind and pith fibres at various filler loadings were studied for their (a) flexural strength and (b) flexural modulus (Lee & Mariatti, 2008).

5. Thermoplastic Polymeric Composites

5.1. Bagasse fibre/Polypropylene composite

(Luz et al., 2007) carried out work on sugarcane bagasse fibres reinforced polypropylene composites in which combined 8.7–10 wt% bagasse and 6.7 wt% cellulose from bagasse with Polypropylene. The optimum moulding method is vacuum injection, which results in a uniform dispersion of fibres and eliminates blisters. The (Figure 7) given below shows enhancement in the mechanical properties of fabricated composite using bagasse fibre. The amount of reinforcement applied had no effect on the tensile and flexural moduli variations. As Young’s modulus of fibres is larger than the thermoplastic modulus, their insertion can help to enhance the modulus.

Figure 7. A)tensile and Flexural Strength; b) Tensile and Flexural Modulus: Mechanical characteristics of composite materials (Luz et al., 2007).

Another work on the similar composites was carried out by (Cerqueira et al., 2011) Bagasse fibre was pre-treated into 1% alkali solution and 10% sulphuric acid solution. Later these treated bagasse fibres were reinforced with polypropylene polymer. As the wt% of bagasse fibre increases from 5%, 10% and 20%, the mechanical properties also show an enhancement in fabricated polymer composite material. (Table 11)

Table 11. Mechanical properties of Bagasse Fibre/polypropylene composite (Cerqueira et al., 2011)

Material	Tensile strength (MPa)	Tensile modulus (MPa)	Flexural strength (MPa)	Flexural modulus (MPa)	Impact strength (kJ/m^2)
PP	19.3 ± 1.1	955.6 ± 93.3	27.5 ± 0.9	906 ± 35.8	36.1 ± 1.1
PP/FSB (5%)	22.9 ± 1.4	1105.5 ± 22.6	34.8 ± 2.9	1047.3 ± 234.5	32.7 ± 6.0
PP/FSB (10%)	23.0 ± 0.6	1027.1±82.9	35.5 ± 3.6	960.7 ± 139.2	45.0 ± 0.1
PP/FSB (20%)	22.3 ± 0.8	1442.5 ± 68.7	37.2 ± 2.1	1200.8 ± 112.9	52.5 ± 0.6

Note: (Reinforcement in wt%)

(T. E. Motaung et al., 2015) worked on silane-treated cane bagasse fibre reinforcing with recycled polypropylene. Injection moulding was used to prepare rPP/SB composite. In a mechanical study of that composite, it was found that there was a persistent increase in the modulus with an increase in the fibre content. Also, it was found that stress during break increased at the lowest SB concentration and then declined somewhat to a nearly constant value as SB content increased. (Figure 8) A dispersion of the fibre and a significant interfacial adhesion might account for the first rise. The reported drop might be due to fibre end clustering and pull-outs. The rPP/SB composites’ elongation at break reduces as the SB content increases, however, the impact is less pronounced in the SB composite with the greatest concentration.

Figure 8. A)young’s modulus b) Stress and c) Elongation at break of rPP composites (T. E. Motaung et al., 2015).

Development of another composite was reported using modified and unmodified bagasse fibre and recycled high-density polypropylene by (Carvalho Neto AGV et al., 2014) Injection moulding technique was used for the fabrication of the composite. The bagasse fibres went under different pre-treatments like mercerization and acetylation which is then referred to as modified bagasse fibre. A later comparison study was done on the mechanical properties of treated and untreated bagasse fibre reinforced with high-density polypropylene wt% of 5, 10 and 20. (Table 12)

Table 12. For recycled polyethene and various composites, the following properties have been studied: tensile strength, tensile modulus, flexural strength, flexural modulus, and Izod impact strength (Carvalho Neto AGV et al., 2014)

Sample	Tensile strength (MPa)	Tensile modulus (MPa)	Flexural strength (MPa)	Flexural modulus (MPa)	Izod impact strength (J/m^2)
PEr	20.2 ± 0.3	450 ± 20	23 ± 0.6	822 ± 50	42 ± 3
PEr/5SCw	19.8 ± 0.3	472 ± 10	25.4 ± 0.6	914 ± 55	46 ± 6
PEr/5SCac	20.1 ± 0.6	489 ± 22	26.2 ± 0.9	996 ± 65	46 ± 5
PEr/10SCw	19.5 ± 0.4	515 ± 25	27.5 ± 0.9	1010 ± 90	44 ± 4
PEr/10SCac	19.8 ± 0.2	547 ± 45	27.9 ± 0.7	1094 ± 70	51 ± 5
PEr/20SCw	18.0 ± 0.9	533 ± 80	29.9 ± 0.9	1290 ± 70	45 ± 4
PEr/20SCac	18.9 ± 0.1	574 ± 75	33.4 ± 0.6	1467 ± 80	47 ± 3

In another work (Lila et al., 2021) investigated the thermal post-processing of bagasse fibres-based polypropylene composites. Extrusion injection moulding has been used to create a polypropylene composite made from bagasse fibre with varying fibre weight fractions (10%, 20%, and 30%). The specimens were exposed for varying lengths of time to temperatures below their softening point. Tensile strength increased by 4.2 %, 7.6 %, 8.4 %, 9.0 %, 9.7 %, and 10.2 % during time periods of 15 minutes, 30 minutes, one hour, 3 hours, 4 hours, and 6 hours respectively, as compared to untreated specimens. In comparison to unexposed specimens, the increase in flexural strength was observed to be 6.2 %, 9.08 %, 13.93 %, 14.19 %, 16.90 %, and 17.76 % longer thermal post-processing times. In contrast, the increase in flexural modulus was observed to be 17.67 % and 21.97 % longer thermal post-processing times (Lila et al., 2021).

5.2. Bagasse fibre/Polystyrene Composites

Sugarcane bagasse fibre was first modified with dichloro-methyl vinyl silane and grafted using polystyrene. The grafted bagasse with polystyrene showed higher thermal stability (examined through TGA) than those of untreated fibre. This showed a significant increase in young’s modulus but there was a slight loss in the tensile strength. The effective improvement in the mechanical property is due to the better interfacial adhesion between the fibres and the polymer matrix.

The PS composite of bagasse was prepared by in-situ polymerization and the mechanical properties like tensile strength, Flexural strength and wear rate was measured for different size varying from 75 µm to 350 µm (Table 13). (AB et al., 2013)

Table 13. Composites made of polystyrene and bagasse fibre’s mechanical characteristics (AB et al., 2013)

Material	Tensile strength (MPa)	Flexural strength (MPa)
Virgin PS	4.51	43.5
PS-SFB	27.05–18.05	52.0–50.3

In conclusion, as the mechanical property of PS-SFB increases, it also depends on the filler size. For the alkali pre-treatment, sugarcane bagasse was submerged in NaCl solution, and the resin was made by swirling polystyrene with Methylethylketone at the ratios of 60:40, 70:30, and 80:20 for about 1 hour. The bagasse fibre (short fibre Granule) and polystyrene solvent were mixed and dried in a 70°C oven for 15 minutes. The composite was prepared using the hot press process (AB et al., 2013). The results were clear that the binding strength and compressive strength were increased with decreasing the bagasse fibre (short fibre Granule). (Tables 14–Table 15)

Table 14. ~tc~

SCB/Polystyrene	60:40	70:30	80:20
Compressive strength	43.5 MPa	42 MPa	41.8 MPa
Binding Strength	25 MPa	20 MPa	18 MPa

Table 15. ~tc~

Material	Young’s modulus (MPa)
Virgin PS	1900
PS composite	2300

5.3. Bagasse fibre/Polyethylene Composites

At 160°C, 30 revolutions per minute, and 12 minutes, the HDPE-SFB was made using the melt-mixed process over a roll mill. According to the TGA investigation, the composites are much less thermally stable than the polymer matrix separately. Due to enhanced interfacial adhesion between both the fibre and the polymer matrix, the ultimate tensile and modulus were increased while the elongation at break & the impact strength was decreased (El-Fattah et al., 2015).

In an extruder screw, sugarcane bagasse was combined with HDPE polymer matrix. The fibre composition was taken as 10%. The temperature set for 4 different zones were 120°C, 130°C, 140°C, and 150°C and the screw speed rate was 50RPM. They are later compressed in moulds for mechanical testing. There was no improvement in the elongation break and the tensile strength but there was an improvement in the tensile modulus. (Tables 16, 17)

Table 16. Mechanical properties of Bagasse/Polyethylene Composites (Mulinari, Voorwald, Cioffi, DASILVA, et al., 2009)

Material	Tensile modulus (MPa)	Tensile strength (MPa)	Elongation break (%)	Impact strength (KJ/m^2)
HDPE	850–870	15–25	2.0	11
HDPE-SFB (10%)	940–950	25–28	2.8	8

Table 17. Mechanical characteristics of materials produced by compression moulding (Mulinari, Voorwald, Cioffi, DASILVA, et al., 2009)

Material	Elongation Break (%)	Tensile Modulus (MPa)	Tensile strength (MPa)
HDPE	1.96 ± 0.087	850.9 ± 28.2	16.7 ± 0.15
HDPE-SFB composite	1.62 ± 0.097	880.01 ± 63.5	14.4 ± 0.58

Another composite was made by using low-density polyethylene and bagasse fibre by (T. Motaung et al., 2017). Before fabrication with melt compounding methods, bagasse fibre was treated mechanically by passing it through a 1 mm. sieve and then kept in deionised water for 24 hours. Bagasse fibre was passed through the sieves at different numbers of times (100, 200 and 500 times). Then composite was developed using mechanically treated fibres in 95/5 as LDPE/SB and its mechanical properties were studied. (Table 18)

Table 18. Mechanical results of pure LDPE and its composites (T. Motaung et al., 2017)

Sample (95/5 w/w LDPE/SB)	Elongation at break(%)	Stress at break(MPa)	Young’s modulus(MPa)
LDPE	8.6±2.1	45±6.3	151±2.0
LDPE/SB	8.7±5.1	36±5.1	330±8.4
LDPE/SB100	8.9±3.0	17±3.7	280±7.2
LDPE/SB200	9.3±2.4	75±2.1	130±4.1
LDPE/SB500	10.6±1.5	129±1.1	440±6.1

Similar work was carried out by (Moubarik et al., 2013) using low-density polyethene but native Moroccan sugarcane cellulose fibre. Before the fabrication of the composite by Screw Extruder Method, it was pre-treated in 3 steps with hot water, alkali, and bleaching. After fabrication mechanical properties of composites were tested containing 10%, 15%, 20% and 25% of bagasse fibre in composites.

In another work by (Mulinari, Voorwald, Cioffi, da Silva, et al., 2009) they fabricated composite using injection moulding and described the mechanical and morphological characteristics of composites made of high-density polyethene, processed sugarcane bagasse cellulose, and reform leftovers. In comparison to untreated bagasse cellulose, the zirconium oxychloride modification of bagasse cellulose with HDPE demonstrated greater tensile strength. (Figure 9) Because the modified cellulose has better fibre-to-matrix adhesion and tensile strength than the original cellulose does, it has been demonstrated that zirconium oxychloride modification of cellulose enhances that adherence.

Figure 9. A)the mechanical characteristics of the materials produced by injection moulding. b) the percentage of elongation at break for composite specimens (Mulinari, Voorwald, Cioffi, da Silva, et al., 2009).

5.4. Bagasse fibre/PLA Composites

(Nampitch et al., 2016) worked on to create composite PLA/bagasse fibre foams with varying fibre contents of 0%, 5%, 10%, 15%, and 20% wt percent and a fixed foaming agent with an additional 2 wt % added for all composites. Investigations were conducted into the shape and mechanical characteristics of clean PLA and PLA/bagasse fibre composite foams. Tensile testing revealed that whereas plain PLA had a tensile strength of 25.63 MPa, the greatest fibre content at 7 wt % was 45.27 MPa. Impact strength showed a tendency to decline as fibre content rose. (Figure 10)

Figure 10. a) the tensile strength and Young’s modulus of PLA foams that were either neat or composited with varied amounts of bagasse fibre. b) Izod impact resistance of pure PLA and PLA/bagasse fibre composite foams with varying bagasse fibre contents (Nampitch et al., 2016).

5.5. Bagasse fibre/PVC Composites

Compression moulding was used to create the pre-treated PVC composite with benzoic acid. For around 7 minutes, two roll mills were used to compound the BF and PVC. The temperature was held between 150 and 170 degrees Celsius. The matrix was first created, then the fibre was put to it upon reaching a stable plastifying condition (which will take almost 3 mins). In order to create specimens that may be utilised for evaluating mechanical properties, it is mixed for an additional 3–4 minutes before being put into a compression mould (Zheng et al., 2007). Two varieties of specimens were prepared; the dog-shaped specimen was used for the tensile testing and the rectangular shape was used for the Impact test (Kokta et al., 1990).

The result reached was that benzoic acid is an excellent adhesion promoter for BF/PVC composites, increasing the dispersion of BF in the PVC matrix (as evidenced by SEM analysis) and thereby increasing the composite’s tensile strength (Kokta et al., 1990). (Table 19)

Table 19. Mechanical characteristics of composites made of bagasse and PVC (Zheng et al., 2007)

Composite	Tensile Modulus (MPa)	Elongation break (%)	Impact strength (kJ/m^2)	Tensile strength (MPa)
Pure PVC	495	150	>20	57.18
Untreated BF/PVC	971	3.45	7.49	38.53
Benzoic acid pre-treated BF/PVC	750	7.73	10.63	42.30

The BF/PVC composites can also be prepared using the virgin polyvinyl chloride by the Screw Extruder Method. The BF/PVC composite here was prepared using 41.2%, 50%, 2%, 6%, and 0.8% by wt. of PVC, Bagasse, Lubricant, & heat stabilisers. The mechanical properties were studied at different temperatures (Xu et al., 2010). (Table 20)

Table 20. Variation in Mechanical properties on Increasing temperature for BF/PVC composite (Xu et al., 2010)

Composite	T (°C)	E1(MPa)	E2(MPa)	Ƞ1 (Pa s)	Ƞ2 (Pa s)
BF/PVC	35	2994.0	18518.5	3.62E + 12	3.2E + 13
	45	2475.2	7462.7	1.97E + 12	1.62E + 13
	55	1960.8	4338.4	1.26E + 12	6.86E + 12
	65	1398.6	1162.8	4.69E + 11	2.63E + 12

The temperature showed a large effect on the creep activity of the composite. At low temperatures, the creep resistance showed was compared to the high stress-strain behaviour and the 30 min creep data was collected.

Another work of bagasse/PVC composite was carried out by (Huang et al., 2012) where Mechanical activation (MA) and surface modification of sugarcane bagasse (SCB) were carried out utilizing a self-designed stirring ball mill and aluminate coupling agent, (ACA) respectively. SCBs were used to create composites with a matrix material of polyvinyl chloride, both unmodified and differentially treated (PVC). After being compounded with PVC, the mechanical properties of both unaltered and ACA-modified SCB (40-weight % of SCB and PVC matrix) were examined. (Figure 11)

Figure 11. a) the impact of milling time on the unaltered SCB/PVC composites’ flexural and tensile strengths. b) Flexural strength and tensile strength of ACA-modified SCB/PVC composites as a function of milling time (Huang et al., 2012).

6. Elastomer Polymeric Composites

6.1. Carbonized bagasse filler/natural rubber composites

The objects were put through a variety of tests, including those for tensile strength, compression test, abrasion resistance, hardness, and elongation at break. As the filler loading grew, so did the material’s tensile strength, abrasion resistance, and hardness properties. Reduced filler loading also enhanced properties such as elongation at break and compression set. As a result, in Figure 12 the bagasse filler seems to be reinforcing in nature and has intrinsic reinforcing potential. This is because when more filler is introduced into the rubber matrix, the rubber chain’s flexibility is diminished, resulting in a stiffer vulcanizate (Osarenmwinda & Abode, 2010).

Figure 12. a) effect of filler loading on compression set b) effect of filler loading on tensile strength c) effect of filler loading on elongation at break d) effect of filler loading on hardness (Osarenmwinda & Abode, 2010).

6.2. Bagasse fibre/Starch Composite

Starch-based matrix and bagasse fibres were used to create environmentally friendly, biodegradable “green” composites by (Mehanny et al., 2012). Native corn starch was emulsified with glycerin and water before being applied to bagasse fibres that had already been processed and treated with NaOH. The composite was warmed before being pressed at 5 MPa and 170°C for 30 minutes. SEM revealed strong adhesion between fibres and matrix, with up to 60% of fibres adhering to the matrix. As the fibre weight percentage climbed from 0% to 60%, the tensile and flexural strengths improved as well. (Figure 13)

Figure 13. a) Experimental and theoretical tensile strength of composite with different fibre weight content. b) Flexural strength of composite with different fibre weight content (Mehanny et al., 2012).

7. Applications

Sugarcane bagasse fibre was widely available, making it easy to employ as a natural fibre and reinforcing polymer in a variety of applications. The hydrophilic character may affect the overall property but proper chemical modifications can overcome this limitation. The thermal degradation behaviour will be altered while the thermal and mechanical characteristics will be improved. The studies on the usage of bagasse as a filler material in composites showed the betterment of such mechanical properties. The aging studies on the bagasse composites showed that the bagasse ash as a binder in concrete gave an improvement in the thermal stability of the concrete at elevated temperatures (Table 21).

Table 21. Application of Sugarcane bagasse fibre reinforced composites in different sectors

Application	Observation	Reference
1. Used as fillers in the cement and plastic industry.	The fibre surface treatment reduced filler moisture absorption and enhanced matrix wettability.	(Díaz-Ramírez et al., 2019)
2. Used in Reinforced cement composites.	The thermal behaviour of these cement composites was enhanced when reinforced with bagasse fibre.	(Potiron et al., 2010)
3. Sugarcane bagasse is used as a fibre-cement composite with 0%, 1.5%, and 5% by volume.	The introduction of larger fibre increased the tenacity (TM); higher the number of macrospores (0.1 to 1 µm). Fibre degradation occurred at 200 cycles.	(Teixeira et al., 2012)
4. Uses in Automotive light weighting	Natural fibre-reinforced polymeric composites are the primary material in the automobile industry used in making seat backs, door panels, boot liners, seat padding, interior insulation, bumper, windshield etc.	(Pervaiz et al., 2016)
5. Uses of bagasse fibre composites.	1. Transport sector (Railway Coach and Vehicle): (a) Flooring (b) Ceiling (c) Seat and backrest 2. Building Materials: (a) Doors (b) Window (c) Wall partition (d) Ceiling 3. Wooden Furniture: (a) Tables (b) Chairs (c) Kitchen cabinet, etc.	(Lila et al., 2021)
6. Uses of NFRCs in Natural Disasters.	In prefabricated structures that may be used in the case of natural catastrophes like hurricanes, pandemic and earthquakes, NFRCs are finding a variety of uses.	(Chandramohan, 2014; Saber & El-Aziz K, 2022)
7. Uses of NFRCs in the household, military, and food packaging industry	The applications include transportation aerospace, marine, sporting products, construction industries, electronic industries, packaging, and so on.	(Ali et al., 2021; Sanjay et al., 2016)
8. Natural fibres (Wheat, hemp, sisal, bagasse, flax, wood, etc.) as thermoplastic composite	Composites and Hybrid Composites of thermoplastic polymer reinforced with natural s are used in building Engine covers, Oil pans, Cam covers, Battery trays, and Door Cladding. Many components in the automobile industry are made from natural fibre composite materials. These materials, which incorporate fibres like flax, hemp, and jute, are mostly based on polypropylene or polyester matrices.	(Panthapulakkal et al., 2017; Patil & Kalagi, 2015)

8. Conclusion

This review concludes with the different composites prepared from thermosets, thermoplastic, and elastomers polymers reinforcing with sugarcane bagasse fibre. Also, study of the mechanical properties of the different composites has been carried out in comparison with the polymer matrix alone. This is due to the better interfacial adhesion between the fibres and polymer matrix. The size of the filler material is responsible for its thermal and mechanical properties. Loading of up to 20% will improve the mechanical properties of the composite material. Reinforcement of sugarcane bagasse fibre with different polymers leads to enhancements in their mechanical properties such as Tensile strength (MPa), Tensile modulus (MPa), Flexural strength (MPa), Flexural modulus (MPa). Natural fibre Composites can be prime examples of sustainable materials and sustainable development with more emphasis giving on fabrication of novel materials, causing lesser pollution to the environment. Due to the large pool of examples of polymers, there are still some unexplored composites to be fabricated using bagasse depending on suitable mechanical properties. If all the limitations are addressed using appropriate polymers and natural fibres, along with further research into the surface chemical modification, and mechanical properties, then improvements pertaining to current composites can be made and successfully implemented in an environmental friendly way. Composites with natural materials have gained popularity in machine implementations, leading manufacturers to explore their potential in reducing waste and associated carbon costs. These composites, which incorporate agricultural fibres to reinforce thermoplastics, are particularly appealing to the vehicle manufacturing sector for producing lightweight, cost-effective, and strong automobile interiors. This approach not only upgrades fuel efficiency but also addresses the public’s demand for eco-friendly vehicles. Natural Fibres composites as biomaterials in field of packaging still trending topic for many researchers to explore it further.

Acknowledgments

The authors thankfully acknowledge Manipal Academy of Higher Education, Manipal, India for providing funding to support open access publication of this article.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Mohd. Khalid Zafeer

Mohd Khalid Zafeer completed his post-graduation in Analytical Chemistry from Aligarh Muslim University, Aligarh (2019-2021). Ms. Roopa Prabhu completed her post-graduation in Chemistry from Manipal Academy of Higher Education (2019-2021). Ms. Sithara Rao doing her post-graduation in Chemistry from Manipal Academy of Higher Education (2021-2023). Dr. Bhat works as an Additional Professor in the Department of Chemistry, Manipal Institute of Technology, Manipal, India. His research interests include synthetic chemistry and, Physics and Chemistry of Materials. He authored about 70 research papers, two patents, and co-edited a book on nanocomposites. G T Mahesha, presently Professor in the department of Aeronautical and Automobile Engineering. His research interests focused on development of natural fibre composites and their applications.