Effect of surface-modified makana fiber and Selenicereus undatus nanocellulose on the mechanical performance of vinyl ester composites under different service temperature conditions

Abstract

This study investigates the development of makana fiber-reinforced vinyl ester composites incorporated with crystalline nanocellulose derived from dragon fruit (Selenicereus undatus) to enhance mechanical performance and long-term durability. Composites were fabricated with 40 vol.% makana fiber and varying nanocellulose contents (0, 1, 3, and 5 vol.%), designated as VC0, VC1, VC2, and VC3. The incorporation of nanocellulose significantly improved tensile, flexural, impact, hardness, and interlaminar shear properties, with the VC2 composite (3 vol.%) exhibiting optimal performance, achieving a flexural strength of 187 MPa and impact energy of 4.98 J. These enhancements are attributed to improved interfacial adhesion and effective stress transfer between the matrix, fiber, and nanocellulose. However, a slight decline in properties at 5 vol.% was observed due to nanocellulose agglomeration. Fatigue and creep analyses demonstrated reduced crack propagation and lower time-dependent deformation, indicating enhanced durability under cyclic and sustained loading. Scanning electron microscopy revealed good nanocellulose dispersion, strong fiber–matrix interaction, and energy-absorbing mechanisms such as fiber pull-out. Overall, the results highlight the importance of optimizing nanocellulose content to achieve a balance between strength, toughness, and long-term stability, supporting the suitability of these composites for advanced engineering applications.

Keywords

composite cellulose creep behavior fatigue behavior mechanical properties

Introduction

Natural fiber-reinforced polymer composites, composed of high-strength plant fibers embedded in a polymer matrix, are gaining prominence across automotive, marine, and industrial applications due to their environmental and economic advantages.¹ Common natural fibers include flax, hemp, jute, ramie, sisal, and makana-the latter harvested from hemp 50%, linen 20%, lyocell 30%.^2,3 In this study, makana fiber was selected as a reinforcement in epoxy composites due to its favorable mechanical strength, low density, and good compatibility with polymer matrices, which promotes strong interfacial bonding and efficient stress transfer. Additionally, makana fiber remains relatively underexplored compared to other natural fibers, making it a promising candidate for developing sustainable and high-performance composite materials. Typically, Chanderasekaran et al.⁴ investigated the mechanical behaviour of natural Kenaf fiber reinforced polymer composite. The author of the study reported that reinforcement of 18 wt.% of fiber shows better tensile, flexural, behaviour, because of strong interfacial bonding adhesion between the fiber and matrix. Furthermore, Pachappareddy et al.⁵ studied the chemically treated Kenaf fiber and biofiller particle reinforced epoxy composite. The chemical treatment improves the tensile, and machining characteristics of the composite. Likewise, Ibhrahim et al.⁶ investigated the Kenaf fiber reinforced PLA/PBAT composite and their mechanical and morphological characteristics. The reinforcement of Kenaf fiber shows 68% improved tensile strength when compared to unreinforced composite.

The reinforcing qualities of composites are also contributed to by fillers and fibers. Fillers are the most crucial component of composites; they are also the most easily derived from biomass, which has many advantages such as being renewable, inexpensive, biodegradable, environmentally friendly, and less harmful to humans and the environment than fossil fuels. This waste biomass based plants sources are sturdy in part because their cell walls are filled with cellulose, a molecule that contains thousands of carbon, hydrogen, and oxygen atoms. Further, this cellulose have an increased potential for usage as a raw material or component in composite materials because their elasticity modulus.⁷ Other natural fillers extracted from biomass include lignin, wood, carbon, and cellulose. In this research, nanocellulose derived from Selenicereus undatus was chosen as a filler due to its high crystallinity, large surface area, and excellent mechanical properties, which enable effective reinforcement at the nanoscale. Furthermore, its extraction from agricultural waste enhances sustainability, while its fine structure improves dispersion within the matrix and contributes to improved composite performance. Compared to other biomass-derived fillers such as lignin and wood particles, nanocellulose offers superior reinforcing efficiency due to its unique structural characteristics. Scientists and researchers have explored cellulose’s mechanical properties and its use as a reinforcement in composite materials because of its many uses and benefits. The research relies on a number of literature reviews. The following is a list of them: Kaliappan et al.⁸ examined the mechanical behaviors of cellulose bambusa vulgaris fiber epoxy composites made from vitisvinifera stalks. Researchers found that adding cellulose improved the material’s load-bearing capacity. Lakshmaiya et al.⁹ reported that the composite with 3% cellulose reinforcement achieved the highest tensile (90 MPa) and flexural strength (143 MPa). In contrast, the 5% cellulose composite exhibited the greatest fracture toughness (30.29 MPa√m) and energy release rate (0.8267 MJ/m²), along with improved impact resistance, absorbing 12.5 J of energy.

In addition, fillers and fibers are treated with silane, to ensure that the resin is evenly distributed, to improve the bonding and adhesion of the matrix, to prevent coagulation, and so on. A popular silane coupling agent, 3-Aminopropyltrimethoxysilane (3-APTMS), was used to modify the nanocellulose’s surface. Amino silane improved the surface hardness, elastic modulus, and scratch resistance of the coated film, in addition to imparting the hydrophobic property and optical properties desired by the nanocellulose film.¹⁰ Here are a few works that have been studied over silane modified fiber and filler reinforced composite. Taib et al.¹¹ investigated thermal stability features of silane modified nanocellulose from natural plant reinforced PVA composite. The study reported the results that reinforcement of 2% of nanocellulose improves the thermal stability features of the composites. Further, Prabhu et al.¹² investigated the silane modified cellulose particle and banana fiber reinforced polymer composite behaviour. The resultant of the study concluded that addition of 4 vol. % of cellulose biopolymer along with fiber reinforcement improves the mechanical and structural properties, as well as hydrophobic characteristics of the composite. The aforementioned studies make it clear that cellulose can be extracted from a variety of biomass, however there is a dearth of study on dragon fruit cellulose extraction specifically.

The current investigation sought to address a knowledge gap by obtaining nanocellulose from the tropical herbaceous perennial climbing cactus known as dragon fruit.¹³ The disposal of the peels into the environment leads to pollution. The extraction of these fruit peels leads to the innovation of composite materials while simultaneously assisting nature in its degradation process, which in turn helps to replenish and prevent pollution and waste management. Moreover, to better understanding the durability performance of the composite research scientist are keen interested in studying prolonged temperature condition treatment on those materials.¹⁴ That is composites are under service temperature condition. However, there was not much studies are done on service temperature condition based polymer composite.

Natural fiber–reinforced polymer composites containing fillers are receiving increasing attention due to their sustainability and improved mechanical performance. Silane treatment is widely used to enhance fiber–matrix interfacial adhesion, thereby improving the overall properties of polymer composites. However, limited studies have explored the combined effect of silane-treated natural fibers and bio-derived nanocellulose, particularly from Selenicereus undatus, on the thermo-mechanical performance of vinyl ester composites under service temperature conditions. In this study, a hybrid reinforcement strategy is adopted by incorporating silane-treated makana fibers together with silane-treated nanocellulose into a vinyl ester matrix. The composites were fabricated with different nanocellulose loadings and evaluated to understand their thermo-mechanical behavior. The results show that the addition of nanocellulose significantly improves mechanical properties and durability, with the composite containing 3 vol.% nanocellulose exhibiting the best overall performance. The improved behavior is attributed to enhanced interfacial bonding and efficient stress transfer within the composite system, indicating the potential of these lightweight materials for applications such as automotive interior components and marine structural panels.

Experimentation

Raw material

The vinyl ester resin used in this study was sourced from Polychem, Chennai, India, and possesses a molecular weight of 368.7 g/mol, a viscosity of 200 cps, and a density of 1.04 g/cc. Methyl ethyl ketone peroxide (MEKP), procured from Orson Resins, Mumbai, India Ltd, served as the catalyst for vinyl ester curing and has a density of 1.18 g/cc with a molecular weight of 210 g/mol. The silane coupling agent 3-aminopropyltriethoxysilane (3-APTMS) was used for surface modification of fibers and nanocellulose, while ethanol served as the solvent for the silanization process. Makana fiber was supplied by Metro Composites, Chennai, and is characterized by GSM 140. Additionally, nanocellulose filler extracted from the epidermis of Selenicereus undatus peel was obtained from local markets in India and utilized as a reinforcing filler in the composite formulation. Figure 1 (a)–(f) presents the photograph of utilised materials.

Figure 1.

Photograph of (a) vinyl ester resin, (b) MEKP, (c) makana fiber, (d) Selenicereus undatus, (e) 3-APTMS, and (f) ethanol.

Cellulose extraction from Selenicereus undatus (SU)

In this study, crystalline nanocellulose was extracted from the peels of Selenicereus undatus (SU). The freshly obtained peels were first rinsed with distilled water to remove adhering impurities and then oven-dried at 130°C for 1 h. The dried material was mechanically ground into fine powder before undergoing alkali treatment using a 5 wt.% sodium hydroxide (NaOH) solution (5 g NaOH in 100 ml distilled water) with a solid-to-liquid ratio of 1:20, followed by magnetic stirring for 3 h to remove hemicellulose and impurities. The resulting mixture was filtered through Whatman filter paper and washed repeatedly with distilled water until neutral pH was attained, after which the solid fraction was oven-dried at 120°C for 20 min. Subsequently, the partially purified fibers were bleached by stirring in a solution containing 60 ml sodium hypochlorite (NaOCl) and 50 ml distilled water at 60°C for 1 h to remove residual lignin. The bleached cellulose was then washed thoroughly to remove residual chemicals and dried prior to further processing. The dried cellulose was subjected to ball milling for 35 min (at a constant speed) to obtain crystalline nanocellulose with particle sizes ranging from 100 to 300 nm. Finally, the obtained particles were repeatedly rinsed with distilled water to ensure neutral pH and removal of any remaining impurities.¹⁵ Figure 2 shows the preparation of cellulose particles derived from dragon fruit peel, while Figure 3 presents the XRD pattern illustrating the extracted nanocellulose from Selenicereus undatus. Two prominent diffraction peaks observed at 2θ values of 15.068° and 22.486° confirm the presence of cellulose I with a monoclinic crystalline structure, as identified through X-ray diffraction analysis.

Figure 2.

Synthesis of nanocellulose from Selenicereus undatus (dragon fruit peel).

Figure 3.

XRD pattern of Selenicereus undatus nanocellulose extract.

Silane treatment

Nanocellulose and makana fibers were individually subjected to silane treatment to enhance their interfacial compatibility with the polymer matrix. Initially, the fibers were dispersed in a 1:1 (v/v) mixture of distilled water and 90% ethanol at a fiber-to-solution ratio of 1:20 under continuous magnetic stirring at 400–500 rpm for 25 min to ensure uniform wetting and minimize agglomeration. The pH of the dispersion was adjusted to 4.5–5.0 using acetic acid to facilitate silane hydrolysis. A 3 wt.% solution of 3-APTMS, prepared with respect to the solvent volume, was then added drop-wise under constant stirring and maintained for an additional 25 min at room temperature (∼25°C) to promote hydrolysis and condensation reactions.¹⁶ Subsequently, the nanocellulose and makana fibers were immersed in the silane solution for 25 min to enable the formation of covalent bonds between silane molecules and hydroxyl groups on the fiber surfaces. After treatment, the fibers were thoroughly rinsed with ethanol to remove unreacted silane and prevent self-condensation. Finally, the treated fibers were oven-dried at 120°C for 2 h to complete curing and stabilize the silane layer. The overall process is illustrated in Figure 4.

Figure 4.

Surface modification process on reinforcements.

Composite fabrication

Vinyl ester composites were prepared by incorporating bio-extracted macromolecules at different weight fractions into silane-treated makana fibers using the hand layup technique. The macromolecules were first added to the vinyl ester resin and stirred magnetically at 300–400 rpm for 15 min to achieve uniform dispersion and prevent agglomeration. Following this, 0.5 wt. % cobalt naphthenate and 1–2 wt. % methyl ethyl ketone peroxide were introduced to the resin mixture as a promoter and initiator, respectively, to initiate the curing reaction. The mixture was stirred gently for an additional 2–3 min to ensure homogeneity without excessive air entrapment. The prepared resin-macromolecule mixture was poured into a wax-coated mold, and silane-treated makana fibers were placed in layers to form the composite structure. Each layer was carefully rolled using a cotton roller to remove excess resin, eliminate entrapped air, and achieve uniform fiber impregnation.¹⁷ The laminates were left to cure at room temperature (∼25°C) for 24 h, resulting in composite plates suitable for mechanical and physical testing. Formulation details for different composites are summarized in Table 1. To assess the durability and thermal stability of the composites, the cured plates were subjected to prolonged exposure at 50°C for 30 days. This treatment was intended to evaluate changes in mechanical performance and understand the effect of sustained elevated temperature on composite strength and long-term reliability.

Table 1.

Composition arrangements for composites.

Specimen name	Makana fiber (vol. %)	Matrix (vol. %)	Filler (vol. %)
V	100	-	-
VC0	40	60	-
VC1	40	59	1
VC2	40	57	3
VC3	40	55	5

Characterization

In order to evaluate the performance of the composite material, it is now being tested under different load and cyclic loading scenarios. Tensile, flexural, impact, fatigue, hardness, interlaminar shear strength (ILSS), and creep tests are among the several that are administered to the composite material. The testing was also carried out in accordance with the ASTM standard; Figure 5 shows the specimens that were tested. Table 2 testing details and procedures.

Figure 5.

Test specimen in accordance to ASTM standard.

Table 2.

Testing details and procedures.

Property	Test/Equipment	ASTM standard	Test parameters/Notes
Mechanical behaviour	INSTRON 4855 universal testing machine (UK)	D3039 (tensile), D790 (flexural), D2344 (ILSS)	Crosshead speed: 1.12 mm/s; specimens prepared per standards
Impact resistance	Zwick Roell impact tester (India)	D256	Process energy: 20 J; specimen prepared per standard
Hardness	Shore-D durometer	D2240	Measures surface strength of specimens
Fatigue behaviour	MTS bionic landmark 370 tension-fatigue machine (USA)	D3479	Frequency: 6 Hz; specimens cut per ASTM standard
Creep behaviour	Metro precision machine tools (India)	D7337	Temperature: 50°C; time: 15,000 s; load: 30% UTS; specimens cut per standard

Analysis and discussion

Strength and stiffness characteristics

Figure 6 (a) and (b) presents the stress strain curve and photograph of failed specimens, respectively. Figure 7 and Table 3 illustrates the enhanced mechanical performance of composites reinforced with crystalline nanocellulose from Selenicereus undatus. Tensile strength increased from 125 MPa (neat composite, V) to 131 MPa (VC0), 139 MPa (VC1), and 149 MPa (VC2) after service temperature exposure, driven by improved fiber-matrix adhesion and the intrinsic stiffness of cellulose.¹⁸ At the molecular level, hydroxyl groups on nanocellulose form hydrogen bonds and covalent interactions with silane-treated makana fibers and the vinyl ester matrix, enhancing interfacial bonding. Additionally, the high crystallinity of nanocellulose restricts polymer chain mobility locally, enabling more efficient stress transfer under load. Excessive filler in VC3 slightly reduced tensile strength compared to VC2, indicating an optimal loading threshold. This is likely due to nanocellulose agglomeration, which creates micro-voids and stress concentration sites that interfere with effective load transfer. Flexural strength followed a similar trend, rising from 148 MPa (V) to 160 MPa (VC0), 169 MPa (VC1), and 187 MPa (VC2), with VC3 showing a modest decline due to overloading.¹⁹ Molecularly, well-dispersed nanocellulose reinforces the fiber-matrix interface under bending by creating hydrogen-bonded networks that limit resin deformation and slippage. Impact and interlaminar shear strength (ILSS) were also enhanced, peaking in VC2 (4.98 J; 22 MPa) as nanocellulose improved energy dissipation and minimized micro-voids. At the nanoscale, the rigid crystalline domains resist crack propagation, while hydrogen-bonded networks redistribute stress effectively, improving fracture toughness. VC3 showed slightly lower values, reflecting filler aggregation that reduces stress dissipation efficiency. Hardness increased steadily with filler content, reaching 81 Shore-D for VC3, consistent with reduced porosity and densification of the matrix due to the network-forming effect of nanocellulose. Overall, nanocellulose effectively reinforced the composites, with optimal filler content crucial for maximizing mechanical performance.²⁰ At the molecular level, this is achieved through enhanced interfacial bonding, improved stress transfer, and suppression of microvoid formation, while overloading leads to filler agglomeration and localized weakening.

Figure 6.

(a) Stress-strain curve and (b) photograph of failed specimens.

Figure 7.

Mechanical characteristics of the developed composite formulations.

Table 3.

Recorded mechanical strength values of composites.

Specimen	Tensile (MPa)	% vs VC0	Flexural (MPa)	% vs VC0	ILSS (MPa)	% vs VC0	Impact (J)	% vs VC0	Hardness (Shore-D)	% vs VC0
V	125	-	148	-	18	-	3.5	-	74	-
VC0	131	-	160	-	19	-	3.7	-	76	-
VC1	139	+6.1%	169	+5.6%	20	+5.3%	4.2	+13.5%	77	+1.3%
VC2	158	+20.6%	187	+16.9%	22	+15.8%	5.0	+35.1%	78	+2.6%
VC3	150	+14.5%	175	+9.4%	21	+10.5%	4.6	+24.3%	81	+6.6%

Fatigue properties

Figure 8 and Table 4 illustrates that the addition of crystalline nanocellulose from Selenicereus undatus significantly improves the fatigue life of composites, and this improvement remains evident even after service temperature. Starting from the base composite (V), the fatigue cycles increase steadily with filler content. Specimens VC0 and VC1 demonstrated notable gains, while VC2 reached the highest values (35,250; 31,250; and 28,540 cycles at 25%, 50%, and 75% UTS, respectively). The improvement can be attributed to better crack deflection, energy dissipation, and a more uniform stress distribution provided by the nanocellulose, which delays crack initiation and propagation.²¹ Interestingly, specimen VC3 showed a slight decline compared to VC2, likely due to filler agglomeration and increased stiffness, which induced localized stress concentrations. Despite this minor drop, nanocellulose reinforcement consistently enhanced fatigue resistance across all specimens, further strengthened by the service temperature effect.

Figure 8.

Number of fatigue cycles endured by different composite samples.

Table 4.

Recorded fatigue cycle values of each composite type.

Specimen	25% UTS	% vs VC0	50% UTS	% vs VC0	75% UTS	% vs VC0
V	29,000	-	24,000	-	20,000	-
VC0	31,000	-	25,500	-	21,000	-
VC1	32,500	+4.8%	27,500	+7.8%	24,000	+14.3%
VC2	35,000	+12.9%	31,000	+21.6%	28,500	+35.7%
VC3	33,500	+8.1%	29,500	+15.7%	26,500	+26.2%

Creep behavior

Figure 9 and Table 5 presents the creep test results, showing that all specimens experienced an increase in creep strain, though resistance to long-term deformation improved with the incorporation of dragon fruit nanocellulose. For the base composite (V), creep strains of 0.0012, 0.0023, and 0.0041 were recorded at 5000 s, 10,000 s, and 15,000 s, respectively. With the addition of nanocellulose, specimen VC0 exhibited slightly lower creep (0.0010, 0.0024, and 0.0058), reflecting the role of fibers in delaying creep deformation. Specimen VC1 continued this trend, with moderate values of 0.0015, 0.0032, and 0.0063, benefiting from enhanced filler–matrix interactions. The best balance was achieved in specimen VC2, which showed creep strains of 0.0022, 0.0048, and 0.0077, attributed to the filler’s rigid yet flexible structure that effectively resists time-dependent deformation while improving load-bearing performance.²²

Figure 9.

Creep strain behaviour of prepared composite.

Table 5.

Calculated creep strain values.

Specimen	5000 s	% vs VC0	10,000 s	% vs VC0	15,000 s	% vs VC0
V	0.0012	-	0.0023	-	0.0041	-
VC0	0.0010	-	0.0024	-	0.0058	-
VC1	0.0015	+50.0%	0.0032	+33.3%	0.0063	+8.6%
VC2	0.0022	+120.0%	0.0048	+100.0%	0.0077	+32.8%
VC3	0.0034	+240.0%	0.0061	+154.2%	0.0081	+39.7%

However, specimen VC3, with the highest filler content, recorded the greatest creep strains (0.0034, 0.0061, and 0.0081), suggesting that excessive nanocellulose increases internal stresses and accelerates long-term deformation. Thus, while nanocellulose reinforcement consistently improves creep resistance under service temperature, overloading the matrix leads to diminished performance due to filler agglomeration and stress concentration.

ANOVA

The ANOVA results indicate that the null hypothesis (H_o) is rejected because the p-value is lower than the significance level (α) in Table 6 and Figure 10. This suggests that the mean values of some groups are significantly different, meaning the variation between certain sample averages is large enough to be considered statistically significant. The calculated p-value is 0.00000114751 which indicates an extremely low probability of committing a Type I error (rejecting a true null hypothesis), approximately 0.00011%. Such a small p-value provides strong statistical support for the alternative hypothesis (H₁). Furthermore, the calculated F-statistic is 19.4455 which lies outside the 95% acceptance region [0:2.8661]. Since the F value exceeds the critical limit, it confirms that there are significant differences among the group means.

Table 6.

One way ANOVA results showing the statistical significance of differences among composite groups including degrees of freedom (DF), sum of squares, mean squares, F-statistic and p-value.

Source	DF	Sum of square	Mean square	F statistic	p-value
Groups (between groups)	4	1613.2	403.3	19.4455	0.000001148
Error (within groups)	20	414.8	20.74	-	-
Total	24	2028	84.5	-	-

Figure 10.

Graphical representation of ANOVA results including confidence intervals for group means, F-distribution with rejection and acceptance regions, histogram of group data distribution and statistical power analysis for hypothesis test.

The statistical power of the test is relatively low (0.1212) however, the null hypothesis (H_o) is still rejected based on the obtained ANOVA results. Equality of variances among the groups was evaluated using Levene’s test which indicated that the population variances can be considered equal (p = 0.852). Nevertheless, the statistical power of Levene’s test is also weak (0.12). The group sizes are similar, with the ratio between the largest and smallest group equal to 1. Under such conditions, the ANOVA test is generally regarded as robust with respect to the homogeneity of variance assumption. Despite this robustness, the use of a non-parametric alternative such as the Kruskal-Wallis ANOVA test may also be considered for additional validation. The normality assumption was assessed using the Shapiro-Wilk test at a significance level of α = 0.05. Based on this evaluation, it is assumed that the data in all groups follow a normal distribution or that the sample size is sufficiently large to satisfy the normality requirement.

SEM analysis

Figure 11 illustrates the microstructural behavior of the composites as observed via SEM. In Figure 11(a), cracks initiate at the fiber-matrix interface, indicating localized stress concentrations due to imperfect bonding. Figure 11(b) shows a uniform distribution of makana fibers and filler particles within the matrix, suggesting effective dispersion that contributes to improved mechanical performance. Figure 11(c) confirms homogeneous fiber dispersion with no de-agglomeration, demonstrating strong interfacial bonding that enhances stiffness and strength while minimizing stress concentrations. Finally, Figure 11(d) reveals matrix cracking and flexural fiber fracture with pull-out events, highlighting energy absorption mechanisms, where some fibers remain partially embedded in the matrix even after failure, contributing to the composite’s toughness.

Figure 11.

Fractography SEM analysis of composite specimens after test.

Comparative analysis

Comparative analysis of the developed composites with previous studies, highlighting nanocellulose loading on mechanical performance (Table 7).

Table 7.

Comparative analysis of developed composites with previous studies.

Author	Investigation
Khan et al.²³	A sea urchin spike chitin–basalt encapsulated bamboo fiber epoxy composite was developed for prosthetic applications. The optimized composition demonstrated a tensile strength of 165 MPa, flexural strength of 224 MPa, compression strength of 198 MPa, interlaminar shear strength of 31.9 MPa, and impact energy of 5.8 J. Another formulation exhibited improved wear resistance, thermal conductivity of 0.72 W/mK, a low flame propagation rate of 5.72 mm/min, and hydrophobic behavior with a contact angle of 101°, indicating enhanced durability and environmental stability.
Prakash et al.²⁴	A hemp fiber–reinforced polyester composite incorporating lignin macromolecules derived from green pea pod waste was developed for lightweight UAV applications. Lignin addition enhanced load-bearing capacity, wear resistance, and flame retardancy. The composite with 4 vol.% lignin exhibited superior wear performance with a specific wear rate of 0.103 mm³/Nm and a coefficient of friction of 0.35, while 2 vol.% lignin achieved the highest fatigue life of 36,972 cycles at 25% UTS. The material also showed improved hydrophobicity and a reduced flame propagation speed of 11.90 mm/min, highlighting its potential for UAV and defense structures.
Alshahrani et al.²⁵	The study investigated polyester composites reinforced with silane-treated Sunn hemp fiber and nanocellulose extracted from pisum sativum sheath biomass. The optimized composite (PSC3), containing 2 vol.% nanocellulose, exhibited enhanced mechanical and dynamic performance, achieving a tensile strength of 141 MPa, flexural strength of 163 MPa, hardness of 84 Shore D, and an Izod impact strength of 6.6 J. It also showed improved fatigue resistance (50 MPa at 10³ cycles and 24 MPa at 10⁵ cycles) and a drop-load impact energy absorption of 18 J. Dynamic mechanical analysis indicated improved viscoelastic behaviour, with a storage modulus of 6.4 GPa at 91°C, reflecting increased stiffness, thermal stability, and stronger fiber–matrix interfacial bonding.

Conclusions

• Incorporation of dragon fruit (Selenicereus undatus) nanocellulose effectively improved the mechanical behavior of makana fiber-reinforced vinyl ester composites under service temperature conditions.

• Tensile and flexural strengths increased with nanocellulose addition, where the VC2 composite exhibited the highest flexural strength (187 MPa), indicating improved load transfer within the composite structure.

• Surface hardness also improved with filler incorporation, and the VC3 specimen achieved the maximum hardness value (81 Shore-D).

• The presence of nanocellulose enhanced fiber-matrix interfacial bonding, resulting in improved impact resistance and interlaminar shear strength due to better stress distribution.

• Fatigue and creep analyses indicated that moderate nanocellulose loading (VC2) provided the most balanced performance, whereas excessive filler content (VC3) caused slight reductions in fatigue life and increased creep deformation.

• Mechanical performance remained stable and in some cases improved under service temperature conditions, demonstrating the composite’s suitability for applications involving moderate thermal exposure.

• SEM observations revealed uniform dispersion of nanocellulose and fibers, strong interfacial adhesion, and energy-dissipating mechanisms such as controlled fiber pull-out, which supported the improved mechanical response.

• Overall, the results highlight that optimized nanocellulose content-particularly at the VC2 level provides the most effective balance between strength, fatigue resistance, and creep stability for makana fiber-reinforced vinyl ester composites.

Footnotes

ORCID iDs

Ashok Raj R

Suderson Krishna Pillai

Panneer Selvam Karuppiah

Author contributions

R.Ashok raj, K.Vinoth Kumar - Full research. SudersonKrishnaPillai and K. PanneerSelvam- Testing support.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

All data within the manuscript. No more additional data is available.*

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