1 Introduction

Increasing environmental consciousness motivates scientists to replace conventional nonbiodegradable materials using new biodegradable materials [1]. Manmade fiber–reinforced polymers are widely used nonbiodegradable materials in different domains, namely, construction, automobile, military, packaging, and electronics [2]. However, new guidelines and recommendations of environmental agencies have restricted the usage of manmade fiber–reinforced polymers. Cellulosic fiber-based fiber-reinforced plastics are partially biodegradable and have mechanical properties similar to synthetic fiber–reinforced composites [3]. So, consumption of plant-based cellulosic fibers is increasing daily, creating demand for plant fibers. Jute, coir, sisal, and banana are commonly used plant fibers in fabricating plant fiber–reinforced composites [4, 5]. However, the present demand for cellulosic fibers cannot be fulfilled by utilizing only conventional fibers. Searching for a new cellulosic fiber with suitable properties is the solution to meet the market demand. Fiber-yielding plants are abundantly available throughout the world. Studying the fundamental properties of fiber, namely, chemical composition, crystallographic information, mechanical properties, and thermal behaviors, is required. Cellulose, hemicellulose, lignin, and wax are common chemical constitutions present in fibers. Chemical composition of the fiber alters the fiber’s characteristics [6]. The binding between cellulosic fibers and polymer resin largely relies on the surface topography of plant fibers. Generally, lignin, hemicellulose, wax, and pollutions occur at the exterior of the fiber, which weakens the binding ability with the matrix. Eliminating amorphous fractions and impurities from the fiber’s surface may increase its binding ability with polymer resin [7]. Surface modifications are a proven method to remove the contaminants and amorphous fractions from the fiber surface [8]. Various researchers use sodium hydroxide treatment because of its low cost, simplicity, and effectiveness. Alkalization does not only eliminate the amorphous fraction in the fiber surface but also modify the chemical configuration of the fiber [9, 10]. These fluctuations in the chemical configuration may impact the fiber’s crystalline, tensile, and thermal properties. Optimal alkalization for the cellulosic fibers differs from one fiber to another fiber. So, the optimal alkalization of plant fibers needs to be studied [11]. Recently, Senthamaraikannan and Saravanakumar [12] extracted Mucuna atropurpurea stem fibers (MAF) and investigated their properties. They recommended performing surface treatment because of the existence of contamination on the external layer of the MAF. The impact of the alkalization depends on two important parameters: the alkali solution concentration and treatment timing. Recently, various researchers conducted the alkalization to the Ventilago maderaspatana, Ziziphus nummularia, Grewia flavescens, and Ficus religiosa root fiber by varying alkali treatment timing. By following this, in this article also alkali treatment was performed using 5% (w/v) NaOH solution, and alkalization duration varied from 15, 30, 45, 60, and 75 min. The influence of alkalization on various properties was examined.

2 Materials and methods

2.1 Materials

Matured M. atropurpurea stem, sodium hydroxide pellets, demineralized water, and hydrochloric acid were used in this study.

2.2 Extraction of raw MAF

Mucuna atropurpurea belongs to the climbing plants found in Asian countries. The matured stems of the M. atropurpurea plants were collected. For the retting procedure, the collected stems were submerged in water [13]. The fiber bundle was recovered after 7 days and rinsed with clean water. By warming the MAF for 1 day at 80 °C, the moisture was removed. The dried MAF was kept safely inside a zip cover to minimize biological infection and impurity deposition prior to composite fabrication [14].

2.3 Alkalization

Ten grams of NaOH pellets was dissolved in 200 ml demineralized water to prepare 5% (w/v) NaOH solution. Then, 5% (w/v) NaOH solution was prepared in five different beakers and dried MAFs (about 10 g) were submerged in the NaOH solution. The alkalization duration of the MAFs in the different beakers varied from 15, 30, 45, 60, to 75 min [15]. After the corresponding alkalization duration was completed, MAFs were removed from the NaOH solution. To avoid accumulation of extra sodium on the external layer of the fiber, the alkalized MAF were submerged for 5 min in a low-concentration HCl solution [16]. The HCl-treated MAF were placed in a drier at 70 °C for 2 days to eliminate the wetness. Alkalization process of Mucuna atropurpurea stem fiber is shown in Fig. 1.

Fig. 1
figure 1

a–d Alkalization process of Mucuna atropurpurea stem fiber

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2.4 Quantification of chemical composition

Using a process developed by Kurschner and Hoffer [17], we determined the cellulose fraction in the MAF. When determining the hemicellulose content of the fiber, neutral detergent fiber technique was used [18]. The APPITA P11s-78 protocol was followed to estimate the MAF lignin fraction [19]. The amount of wax in the fiber was measured according to a set of rules outlined by Conrad [20]. A moisture analyzer (Mettler Toledo, model HS153) determined the wetness in the MAF. The ash of the MAF was measured with the help of TAPPI protocols. Five replicas were taken for each analysis to obtain accurate outcomes [21].

2.5 Optimally NaOH-treated MAF

Table 1 shows the chemical analysis results for untreated and NaOH-treated MAF. The percentage of cellulose in the plant fibers is a determining factor of various properties, namely, mechanical, crystalline, and thermal properties. As a result, for usage as reinforcement in fiber-reinforced plastics, fibers with a larger cellulose content are preferred [22]. Compared with 60 min alkalized MAF, MAF alkalized for other timing (15, 30, 45, and 75 min) and raw MAF (RMAF) have a lower cellulose percentage. So, MAF immersed in alkali solution for 60 min was considered as Alkalized fiber (OAMAF) [23].

Table 1 Chemical compositions of raw and surface modified MAF
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2.6 Physical analysis

A liquid pycnometer was utilized to measure the density of RMAF and OAMAF. Toluene (pt = 866 kg/m3) was used as the density-known fluid [24]. The diameter of the fibers was determined via a Model 7 Auslese optical microscope. The diameter of the 25 single fibers was calculated using ImageJ software and found to be same at four places in each fiber [25]. The average values of the four measurements for each fiber were noted for statistical examination.

2.7 Crystallographic investigation

X-Ray diffraction (XRD) examination was conducted using an X’Pert PRO-make diffractometer. In the sample container, a powdered fiber sample was placed, and an X-ray was passed through it. An X-ray sensor was employed to record the X-rays after diffraction. The rotation of the detector was restricted from 2θ = 10 to 80°, and it was moving 2θ = 0.013° per 48.195 s. Using the following mathematical approach devised by Segal et al. [26], the crystallinity index (CI) of the RMAF and OAMAF was determined.

$$CI=\frac{{I}_{\mathrm{C}}-{I}_{\mathrm{A}}}{{I}_{\mathrm{C}}}\times 100$$
(1)

where IC is the altitude of the diffractogram at 22° and IA is the altitude of the diffractogram at 18°.

The fibers’ crystallite size (CS) was measured via Eq. (2) [27]:

$${\mathrm{CS}}_{22}=\frac{0.89\;\lambda}{{FWHM}_{22}\mathit{cos}\left(\frac{2\theta}2\right)}$$
(2)

where λ is the wavelength of X-ray (1.54178 Å) and FWHM22.42 is the full width at half maximum of the peak at 22°.

2.8 Determination of chemical functional groups

Fourier-transform infrared (FTIR) analysis of fiber was performed on a Jasco 6300 Type-A FTIR spectrometer [28]. Initially, powdered MAF and potassium bromide were finely blended at a ratio of 1:10. This blend was converted into a thin film by a hydraulic press. This film was exposed to infrared light at an incidence angle of 45°. Between the wavenumber of 4000 and 500 cm−1, infrared light passing through the film was recorded at a scanning speed of 2 mm/s.

2.9 Nuclear resonance spectroscopy

NMR is a precious method to differentiate raw and surface modified fibers by determining chemical groups. A solid-state NMR (model ECX400; JEOL) was used to perform the nuclear magnetic resonance (NMR) analysis of RMAF and OAMAF. First, 300 mg fine powder was taken for analysis, and 13C nuclei were chosen as the target. The experiment was run in the cross-polarization mode from 300 to − 100 ppm. The investigation was conducted at a resolution of 39.2824819 Hz and field strength was fixed as 399.7821 MHz [29].

2.10 Thermogravimetric analysis

The results of thermogravimetric analysis (TGA) may be utilized to determine the optimal processing temperature of a composite during fabrication and the optimal operating temperature of a composite made with the corresponding plant fiber [30]. TGA of the fibers were executed on an EXSTAR-6300 TGA machine. Initially, required quantities of fibers were taken into crucibles (alumina). Afterward, fiber-filled crucibles were placed in the heating chamber attached to the weighing machine. Temperature in the chamber was raised from 28 to 594 °C at a rate of 10 °C/min, while 200 ml/min of nitrogen gas was supplied constantly [31].

Calculation of kinetic activation (Ea) is an alternative way of understanding thermal behaviors of the fibers. In this investigation, Ea was determined using a simple graphical technique based on Eq. (3) established by Broido [32].

$$\mathrm{ln}\left[\mathrm{ln}\left(\frac{1}{y}\right)\right]=-\left(\frac{{E}_{a}}{8.32}\right)\left[\left(\frac{1}{T}\right)+K\right]$$
(3)

where T is the temperature of the fiber in Kelvin, y is the ratio of the mass of the fiber corresponding to the temperature (between 28 and 594 °C) and the mass of the MAF at 28 °C, and K is the reaction rate constant.

2.11 Surface morphological analysis

Surface modification of the plant fibers is mainly recommended to tailor the surface morphology to achieve improved binding between the plant fiber and matrix. Generally, during the alkalization, the external layer of the plant fibers is removed. This may improve the binding nature of the fiber [33]. On the other hand, alkalization for more than recommended timing may weaken the fiber’s mechanical properties.

2.11.1 Scanning electron microscopic (SEM) analysis

SEM investigation of fibers was done in a 200 FEG SEM machine (FEI Quantum model). During the analysis, 50-Pa pressure was maintained around the worktable. To find the minute particle, impurities, and other materials around the surface fiber, images were captured at lower and higher magnifications (200 × , 500 × , 1000 × , and 2000 ×). As plant fibers are nonconductive materials, a mild gold coating was applied on the fibers with the aid of sputter-coating equipment before being fixed onto the worktable. The accelerating voltage maintained for this investigation was 15 kV [34].

2.11.2 Energy-dispersive X-ray (EDX) analysis

This examination was conducted to find various elements existing around the fiber surface. It visualizes the difference between the surface of the surface modified and raw fiber. In this analysis, an EDX detector attached to the SEM machine recorded the different elements present on the RMAF and OAMAF. During the analysis, the current setting was modified to 25 pA [35].

2.11.3 Atomic force microscopic (AFM) analysis

AFM inspection provided 3D and 2D topographical pictures and surface morphological parameters, making it a more precise tool for evaluating the external surface of cellulosic fibers. By comparing surface morphological parameters of RMAF and OAMAF, the impact of surface modification can be easily understood. AFM analysis was conducted using an AFM machine (XE-70 type; Park) and operated in the non-conduct mode [13].

2.12 Tensile testing

In this study, the crosshead speed was operated with 2.5 mm per minute on a Zwick/Roell universal testing machine during single-fiber tensile testing. For testing, 25 fibers were chosen with the gauge length of 40 mm based on previous investigation [9, 12, 36]. The microfibril (α) angles of fibers were obtained via Eq. (4) [37].

$$\mathrm{Strain}\;\mathrm{rate}=\ln\left(1+\frac{\mathrm{Change}\;\mathrm{in}\;\mathrm{length}}{\mathrm{Gauge}\;\mathrm{length}}\right)=-\ln\;\left(\cos\;\alpha\right)$$
(4)

3 Result and discussion

3.1 Quantification of chemical composition

Table 2 shows the weight percentage of chemical constitutions of RMAF and OAMAF, and various cellulose-based plant fibers. Owing to the conversion of amorphous fraction into α-cellulose, the cellulose fraction of OAMAF was increased noticeably (58.74 ± 5.74 to 75.24 ± 5.26 wt.%) [44]. This increased cellulose fraction was considered helpful in modification because it might considerably improve cellulosic fibers’ mechanical and thermal stability [23]. The hemicellulose fraction in the OAMAF was reduced to 7.96 ± 3.11 wt.% from 16.31 ± 3.21. The same kind of reduction in the hemicellulose content was observed in the numerous alkalized plant fibers, namely, aerial root banyan fiber (13.46 wt.% from 10.74 wt.%) and Borassus fruit fiber (3.02 wt.% from 14.03 wt.%) [10]. Generally, all plant fibers have a considerable amount of lignin fraction. This lignin protects the plant parts from biological attacks [45]. However, when fibers are used as reinforcement, a higher lignin fraction is believed to be a detriment as it decreased the binding capability of the cellulosic fiber with matrix materials. The lignin fraction of the OAMAF was lowered to 6.72 ± 2.88 wt.% from 14.22 ± 3.36 wt.%. Wax is another element that increased hydrophilicity [46]. After optimal alkalization, wax also reduced from 0.38 ± 0.08 wt.% to 0.18 ± 0.11 wt.%. The ash content of OAMAF increased to 9.88 ± 1.98 wt.% from 7.66 ± 2.49 wt.% as a result of an increase in the α-cellulose percentage of OAMF. The moisture in the MAF decreased to 7.04 ± 1.78 wt.% from 11.12 ± 2.11 wt.% due to the effect of alkalization [47].

Table 2 Physical properties and chemical configurations of RMAF, OAMAF and other fibers
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3.2 Physical analysis

Usually, raw plant fibers have a lower density than alkalized plant fibers because of voids and cracks in the fibers. After alkalization, the holes and cracks in the fibers are filled by the crafted molecules, resulting in a substantial increase in fiber density. The calculated density of the OAMAF was 1136 ± 20.14 kg/m3, which was higher than that of the RMAF [16]. Because of the removal of the outermost surface in the OAMAF, fiber diameter fell from 289 ± 21 µm to 244.3 ± 14.38 µm. The diameter of various plant fibers, namely, Ziziphus nummularia fiber (209.064 ± 11 to 196.24 ± 10.2 µm), Ficus religiosa root fiber (25.62 ± 0.951 to 22.54 ± 1.152 µm), and Phaseolus vulgaris fiber (352 to 345 µm), was also reduced after optimal surface modification [38]. Figure 2 shows optical microscopy pictures of RMAF and OAMAF.

Fig. 2
figure 2

Optical microscopy pictures of a RMAF and b OAMAF

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3.3 Crystallographic investigation

The XRD spectra of RMAF and OAMAF are shown in Fig. 3. It highlights two rising peaks at 15° and 22° in RMAF and OAMAF, respectively. The peak with a Miller index of 1 1 0 indicated cellulose category I, whereas the peak with a Miller index of 0 0 2 indicated cellulose category IV [48]. After the alkalization, the height of both cellulose peaks was considerably enhanced because of the conversion of amorphous fraction to α-cellulose [49]. The measured CI value of the RMAF was 24.01%, whereas the CI value of the OAMAF was computed as 49.89%. It was found that the CI value of many alkalized plant fibers increased, i.e., Ziziphus mauritiana fiber (31.70 to 41.81%), Acacia planifrons bark fiber (65.38 to 74.78%), Symphirema involucratum fiber (28.22 to 33.33%), and Acacia concinna fiber (27.5 to 35.6%) [15, 23]. Another important crystallographic parameter of plant fiber is the CS, which is associated with the moisture-absorbing ability of the plant fiber [50]. Owing to crystallographic alterations, the CS value of the OAMAF reduced from 2.75 to 1.60 nm. This reduction was indicated in the previously investigated plant fibers, namely, Coccinia grandis L. (13.38 to 8.15 nm), Z. mauritiana fiber (43.5 to 33.9 nm), and S. involucratum fiber (5.10 to 3.21 nm) [42]. XRD, TGA, and tensile testing outcomes of RMAF, OAMAF and other cellulosic fibers are synopsized in Table 3.

Fig. 3
figure 3

X-Ray diffractograms of RMAF and OAMAF

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Table 3 XRD, TGA, and tensile testing results of RMAF, OAMAF and other plant-based cellulosic fibers
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3.4 Determination of chemical functional groups

Figure 4 shows the FTIR spectrograms of the RMAF and OAMAF. Ten significant peaks were observed for the RMAF, in which three peaks completely vanished after the alkalization. Table 4 contains the pertinent information on the existing peaks in the MAF. The OH stretching of α-cellulose is indicated as a first peak at 3277 cm−1 in the MAF spectra [51]. In both RMAF and OAMAF, the CH and CH2 peaks of α-cellulose (2921 cm−1) were also seen [52]. The C–H vibration of alkanes in α-cellulose was also revealed by a small peak at 2850 cm−1 [53]. After alkalization, two successive peaks at 2357 cm−1 (C–C stretching, wax, and other impurities) and 1730 cm−1 (carbonylic group C = O stretching) were eliminated of amorphous fraction in the MAF [30, 54]. C = O stretching of hemicellulose in the MAFs was revealed by the peak at 1608 cm−1 [55]. The peak at 1412 cm−1 revealed the existence of wetness in the MAF [13]. The OH bending vibration of cellulose was linked to a small peak at 1321 cm−1 in the RMAF and OAMAF [56]. Lignin and hemicellulose were considered absent from the optimally alkalized fiber because there was no peak at 1245 cm−1 [57]. It is the peak at 1026 cm−1 that could be used to identify the C–O–C pyranose ring vibrations (cellulose) in the fibers [58].

Fig. 4
figure 4

FTIR spectrogram of RMAF and OAMAF

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Table 4 Wavenumbers of noteworthy peaks in an FTIR spectrogram, linked chemical components, and associated functional groups in the RMAF and OAMAF
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3.5 Nuclear resonance spectroscopy

Figure 5 shows the NMR spectrums of the RMAF and OAMAF. The existence of cellulose in MAF is confirmed by 104.46 ppm of C-1 carbon. In the RMAF and OAMAF, the C-2, C-3, and C-5 are identified by the peak between 72 and 74 ppm [29]. C-1 and C-4 (cellulose) are present at 83 and 64 ppm, respectively, in both the RMAF and OAMAF [59]. In the RMAF, the carbonyl group is observed at 175 ppm, which is connected to the hemicellulose fraction of the fiber. In the OAMAF, the carbonyl peak disappeared, indicating the elimination of hemicellulose fraction from the OAMAF [28].

Fig. 5
figure 5

NMR spectrograms of RMAF and OAMAF

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3.6 Thermogravimetric analysis

TG and DTG patterns for RMAF and OAMAF are shown in Fig. 6. It is observed that the fiber loses around 10% of its weight from 30 to 200 °C owing to disappearance of wetness [60]. In the course of the alkalization, a significant quantity of hemicellulose was transformed to α-cellulose. Because of its crystalline structure, α-cellulose is more thermally stable than hemicellulose, which is reflected in the 200 to 500 °C segment [61]. The 200 to around 350 °C portion in the TG profile connected with the thermal decomposition of hemicellulose and cellulose. The wax and lignin fraction in the MAF are degraded in the 350–500 °C range. The quantity of fiber (about 5 wt.%) retained at 594 °C, which was believed as the residual mass.

Fig. 6
figure 6

TG and DTG diagrams of RMAF and OAMAF

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Three important peaks were observed in the DTG curve [62]. In both RMAF and OAMAF, the initial peak was located at 64 °C, indicating the abolition of wetness from the fiber. For RMAF, the cellulose degradation peak was found to be at 298 °C. In the OAMAF, this peak was shifted to 320 °C owing to the increase in the α-cellulose content. The same kind of improvement was reported in many plant fibers, namely, P. vulgaris fiber (322.1 to 346.6 °C), Musa acuminata peduncles fiber (337 to 350 °C), F. religiosa root fiber (325 to 356 °C), and Bahunia racemosa fiber (313–356 °C) after surface modification [21, 43]. A sharp peak witnessed around at 430 °C is linked to the degradation of the lignin in the MAFs.

Figure 7 shows Broido’s profile of the RMAF and OAMAF. The Ea of the OAMAF was improved from 68.08 to 72.46 kJ/mol. RMAF and OAMAF had kinetic activation energies in the middle of the recommended range for wood (60 to 150 kJ/mol) [63]. Thermal study showed that RMAF and OAMAF could be utilized as reinforcement in polymers. However, the processing temperature of the composites should be maintained below 200 °C.

Fig. 7
figure 7

Broido’s profiles of the RMAF and OAMAF 

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3.7 Scanning electron microscopic analysis

SEM pictures of the RMAF and OAMAF are shown in Fig. 8. Alkalization detached single fibers from the fiber bundles (Fig. 8e) whereas raw fibers were connected to the fiber bundles (Fig. 8a) [33]. Figure 8f shows that the surface roughness of OAMAF is improved, although the smoother surface of RMAF (Fig. 8b) is still present [64]. Figure 8c and d show the occurrence of wax and contaminants in the RMAF surface. Impurity-free fine fibers are seen in Fig. 8g and h [65].

Fig. 8
figure 8

SEM images of the RMAF (a–d) and OAMAF (e–h)

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3.8 Energy-dispersive X-ray analysis

EDX spectrum of the RMAF and OAMAF is revealed in Fig. 9a and b. In the EDX spectrum of the RMAF, many elements, namely, calcium (Ca), potassium (K), sulfur (S), phosphorus (P), aluminum (Al), and magnesium (Mg), are present along with carbon (C) and oxygen (O). Generally, impurity-free cellulosic fibers have only carbon (C) and oxygen (O) elements [66]. Presence of additional element indicated occurrence of contaminations on the RMAF surface. These unwanted elements vanished after the alkalization. This was indicated by the removal of a thin layer made up of contamination on the fiber [67]. In the OAMAF, a new element, sodium (Na), was observed, indicating the improper removal of sodium in the HCl treatment during the alkalization process. However, after alkalization, a small quantity of sodium content was observed in various plant fibers, namely, A. concinna, Pongamia pinnata L., S. involucratum, and Cissus vitiginea [67, 68].

Fig. 9
figure 9

EDX Spectrum of RAMF and OAMF

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3.9 Atomic force microscopic analysis

The recorded (a) three-dimensional and (b) two-dimensional images of AFM, (c) line profile of surface, and (d) morphological parameters are shown in Fig. 10. The average roughness (Ra) of the OAMAF was amplified to 77.373 nm from 27.113 nm. Because of alkalization, improvement in the Ra value of various plant fibers such as S. involucratum (6.647 to 15.826 nm), Eichhornia crassipes (101.84 to 112.84 nm), and ariel root Ficus amplissima fiber (8.225 to 15.387 nm) was reported in a previous investigation [69]. This enhanced Ra value indicated the existence of an impurity-free surface [49]. The roughness skewness (Rsk) values of the RMAF (− 1.747) and OAMAF (− 0.141) were negative, indicating cracks and pores in the fiber [15]. However, after alkalization, pores and cracks in the fibers were significantly reduced. The Rku value of the OAMAF was exceedingly reduced to below 3 (2.952 from 6.318), suggesting a high uneven surface in the fiber [70]. Other surface morphological parameters such as Rz, Rt, and Rq were enhanced considerably after optimal alkalization.

Fig. 10
figure 10

a 3D and b 2D AFM images, c line diagram of profile, and d surface morphological parameters of the RMAF and OAMAF

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3.10 Tensile testing

Alkalization enhanced the fiber tensile strength and modulus by improved the crystalline fraction. However, improper surface modification may lead to reduced tensile strength. OAMF showed improved tensile strength of 307.3 ± 24.12 MPa whereas tensile strength of the RAMF was 274.6 ± 29.5 MPa [71]. The tensile modulus of the OAMAF also increased from 2.88 ± 1.026 GPa to 4.633 ± 0.94 GPa. The strain rate of the OAMAF was decreased from 2.208 ± 0.654% to 1.776 ± 0.56%. The microfibril angle of the OAMAF was also decreased to 10.64 ± 1.65° from 11.87 ± 1.72°. The microfibril angle (α) of plant fibers improved as elongation percentages improved, and it dropped as the tensile strength and modulus increased. Owing to the variations in the shape of the fiber, maturity, and part that yields the fiber, tensile properties also differ. So, a statistical investigation method is needed to check the consistency of the mechanical property values. Figure 11 shows the Weibull distribution curves for the diameter and tensile characteristics of RMAF and OAMAF [14]. It showed that the tensile properties of the tested 25 RAMAF and OAMAFs are within the prescribed range, indicating their fitness to utilize as reinforcement in polymer matrixes.

Fig. 11
figure 11

Weibull analysis curves of tensile properties and diameter of the RMAF and OAMAF 

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4 Conclusions

The optimum alkalization duration for the MAF was optimized through chemical analysis. Owing to the removal of the outer most surface layer in the OAMAF, the diameter (289 ± 21 µm to 244.3 ± 14.38 µm) was reduced, whereas density (1082 ± 29 kg/m3 to 1136 ± 20.14 kg/m3) was slightly increased because of the filling of voids and cracks in the RMAF by grafted molecules. The CI value of the OAMAF revealed an increase in the crystalline fraction. Owing to alkalization, the hemicellulose component in the MAF was removed, as shown by the absence of peaks at 175 ppm in the NMR spectrum of OAMAF. Increases in the maximum degradation temperature and Ea of the OAMAF indicated a corresponding increase in its thermal consistency. The results of AFM showed that the Ra value amplified to 77.373 nm from 27.113 nm, designating that the surface roughness of the OAMAF increased. The results of this study indicated that OAMAF is a viable choice for consumption as reinforcement in polymers. In the future, RMAF and OAMAF-reinforced polymer composites can be developed and characterized to find suitable applications.