Enhancement of crystallinity of jute fibers through surface modification and gamma irradiation

Abstract

Jute fiber’s intriguing qualities have made it a natural material with significant promise for use in many sectors. Compared with its synthetic rivals, this natural fiber offers the unique benefit of being readily available. It also has a CO₂-neutral life cycle, is renewable, and is biodegradable. This study examines how the crystallinity of jute fibers can be improved using surface modification and gamma irradiation approaches. After receiving chemical surface treatments to enhance their characteristics, the jute fibers were exposed to various gamma radiation dosages. After treatment, XRD examination showed a significant rise in the crystallinity index, suggesting molecular structural changes. Additional confirmation of the modifications in functional groups linked to increased interchain interactions came from FTIR spectroscopy. This research provides insightful information on how surface modification and gamma irradiation work together to enhance the performance and crystallinity of jute fibers. The results indicate that integrating surface modification with gamma irradiation notably enhances the crystallinity of jute fibers, which may lead to improvements in their mechanical properties and expanded uses in composites and various industries. This study emphasizes a promising method for improving natural fibers to satisfy the requirements of sustainable material uses.

Keywords

Jute jute fiber chemical treatment gamma irradiation surface modification

Crystallinity is examined comprehensively, encompassing the degree of crystallinity and the entire intricate structure of jute fibers. The percentage of crystallinity in raw jute fibers can vary based on factors like the source of the jute, processing, and environmental conditions.^1,2 Jute fibers have lower crystallinity than synthetic fibers like glass or carbon fibers, which limits their mechanical properties, durability, moisture resistance, dimensional stability, thermal stability, compatibility with composite, sustainability, cost-effectiveness, and utility in specific industrial applications.³ Natural fibers are preferable to artificial fibers in many ways, along with being more affordable, environmentally friendly, lightweight, biodegradable, and having perfect mechanical qualities.^4,5 The crystallinity of raw jute fibers typically falls within 30% to 60%, although this range can vary. Temperature, retting duration, and the alkali content of the material all promote crystallinity. The fiber’s tensile power and linear density are made more suitable via chemical retting treatment.⁶ The low crystallinity of jute fiber can be attributed to a combination of factors, including its fiber composition, growth conditions, harvesting and retting, mechanical and chemical processing, and genetic variability. Achieving a high percentage of crystallinity in jute fibers, particularly above 70–75%, remains a significant challenge.⁷ Besides this, jute fiber includes crystalline and amorphous regions, and the amorphous region is responsible for low crystallinity; the dissolution and reduction of the amorphous zone without compromising the structural integrity of jute fiber remains a challenge.⁸ However, jute fiber-strengthened composites are afflicted by decreased mechanical and destructive interfacial properties because of the reduced crystallinity and hydrophilicity delivered through the large quantities of non-cellulosic substances of their structure.

Moreover, jute fibers are inherently electrically insulating, which limits their utility as multifunctional composites when electric conductivity is required.¹ Some methods, such as alkali treatment, oxidative modification, and acid hydrolysis, for example, peracetic acid treatment, can reduce the amorphous zone. Therefore, the dissolution of the crystallinity of cellulose fibers in the amorphous zone can be increased. The pretreatment makes the fibers more cellulose-, lignin-, and crystallinity-rich, and thermally stable, making them useful for further chemical alterations.^9,10 It is noted that no research has previously been conducted that explicitly considered crystallinity. Though cellulose jute fibers’ mechanical and thermal properties can be increased through acid hydrolysis, water and moisture absorption are significant limitations due to the hydrophilic properties of hydrolyzed cellulose jute fibers. It has been reported that there is a prospect of using gamma (1 kGy) radiation dosing to improve the mechanical properties and water and moisture resistance of the jute crystalline cellulose bio-composite film.¹¹

Gamma irradiation doses of different intensities were applied to the surface of jute composite materials to optimize the intensity of doses for this particular weave structure, and γ-radiation of 5 kGy gave the optimum tensile properties. The increase in the tensile properties of jute with increasing gamma radiation dose may be due to the intercrosslinking between the neighboring cellulose molecules, which increased the strength of the natural fiber. It was observed that the tensile properties increased with γ-pretreatment up to a specific limit (5 kGy), and then decreased due to two opposing phenomena, photo-crosslinking and photodegradation, simultaneously under γ-radiation. Additionally, it has been noted that gamma radiation is a potent form of ionizing radiation that can reorganize a material’s internal structure and decrease its hydrophilic properties. This, in turn, facilitates improved crosslinking between the natural fiber and matrix.¹²

X-ray diffraction (XRD) is a standard analytical method for identifying crystalline material phases and measuring unit cell size. The fundamental principle of XRD techniques is based on a crystal’s unique capacity to diffract X-rays, which enables an accurate examination of the crystalline phases’ structure. A sample’s micro- and macrostructural characteristics contribute to recorded diffraction patterns.¹³ For homogeneity, the specimen under study is extensively mixed and crushed. Calculating average values determines composition. XRD is commonly used to study crystal formations and measure atomic distances. XRD relies on constructive interference between monochromatic X-rays and crystalline materials.¹⁴

Fourier transform infrared spectroscopy (FTIR) provides scientists with a wide range of solutions for comprehending natural fibers and the technologies and products associated with their modification, including chemical compositions, microstructures, fiber architectures, interface characterization, and properties of both natural fibers and related composites. FTIR can also be used to identify changes in the chemical compositions, effective interfaces, and properties of natural fibers and composites.

The novelty of this work is to increase the crystallinity of jute fibers through chemical treatment and gamma irradiation, which other researchers have not used earlier. Previous researchers worked to decrease lignin content and increase cellulose content in jute fibers. This study focuses on chemical treatments and gamma irradiation to improve the crystallinity of jute fibers, which will be used to produce composites in aerospace and automotive applications where the contribution of crystalline jute will be significant. It is noted that better properties and performances are obtained than traditionally modified jute fibers when used as reinforcing materials in composites.

Materials and methodology

Materials

The jute fiber was received from the nearby marketplace in Natore, Bangladesh, located in a tropical weather sector at a range of 24.26 levels north and a longitude of 89.9 degrees. Despite the sweltering atmosphere, this district is one of the harshest areas in Bangladesh. The majority of precipitation takes place in the region during the monsoon season. The relative humidity commonly reaches 90% on average from July to September and drops to at least 71% on average from January to April. Types of soil: Alluvial soils are sedimentary soils that can be determined in geological zones characterized by the deposition of sediments through flowing water. Most soil sorts include loam or clay loam and feature a low-content material of natural matter.

Sodium hydroxide sodium chlorite was purchased from Merck, Germany, and other analytical grade chemicals, peracetic acid and acetic acid, were purchased from Labtex, Dhaka-1217. Every step of this experiment used demineralized water (pH: 5.5 to 7.5, conductivity: <1 μS/cm, Silica: 0.1 ppm, Iron: 0.01 ppm, Hardness: Nil) purchased from PureTech, Dhaka-1203, Bangladesh.

Methodology

This work converted untreated jute fiber into cellulose using alkaline and oxidative chemical treatments. Sodium hydroxide (NaOH) was used for alkali treatment of jute fibers. Alkalization reduces the number of hemicelluloses in fiber, thus resulting in better mechanical properties than untreated fiber. Alkali modifications with NaOH solution at room temperature were completed to achieve selective hemicellulose removal and to remove impurities, oils, and other contaminants from the raw jute fibers.^14,15

Oxidative modifications were performed with NaClO₂ solution at pH 4–4.5 and boiling temperature. The NaClO₂ bleaching process enhances cellulose purification by eliminating any remaining hemicellulose, pectin, or other impurities that may have been left behind after the initial alkali treatment.

The general reaction mechanism can be simplified as follows:

C_{6} H_{9} O_{4} (ONa) + {NaClO}_{2} + H_{2} O \to C_{6} H_{10} O_{5} + Soluble lignin derivatives + NaCl

where C₆H₉O₄(ONa) represents the alkali cellulose, and C₆H₁₀O₅ represents the purified cellulose.

Peracetic acid is usually prepared by reacting acetic acid and hydrogen peroxide with a strong acid catalyst like sulfuric acid (H₂SO4). The reaction usually goes like this:

{CH}_{3} COOH + H_{2} O_{2} \to {CH}_{3} COOOH + H_{2} O

This reaction’s molar ratio of acetic acid to hydrogen peroxide is 1:1.

The appropriate concentration of peracetic acid is used to immerse the jute fibers and time and temperature maintained.

A radiation beam emitted by a C_o60 gamma source from the Atomic Energy Commission of Bangladesh was employed to examine the crystalline structure of jute fibers at 3 kGy and 6 kGy of radiation exposure. The various samples of jute fiber were positioned on the collimator for experimental assessment. The qualities of the jute fibers in various % of crystallinity samples after surface modification and gamma irradiation were measured. The experimental conditions and sampling of raw and treated jute fibers have been further analyzed. Figure 1 shows the methodology used.

Chemical treatment process

The NaOH solution used for alkali treatment of jute fibers had a concentration of 1%. This concentration was chosen to balance the need for effective treatment with the risk of fiber destruction that can occur with more significant concentrations.¹⁶ Additionally, the duration and temperature of the alkali treatment bath impact the treatment’s efficacy. A temperature of 30°C and time of 30 min were utilized in this experiment. In general, elevated temperatures and times hasten the process but may also heighten the danger of fiber injury.^17,18 The fibers should be neutralized with an acid solution (acetic acid) following the alkali treatment to halt the alkaline reaction. Further rinsing with demineralized water is required to eliminate any remaining alkali in the fibers.

This experiment utilized oxidative modification with 0.7% NaClO₂, with a time and temperature of 80 minutes and 80°C, as a chemical treatment approach to modify jute fibers. The process can add oxygen-containing functional groups to the surface of the jute fibers. Oxidation can change the chemical composition of the fibers, resulting in modifications to their properties, such as those found in cellulose jute fibers.¹⁴

An acid hydrolysis process will eliminate the amorphous region where peracetic acid is used, producing a highly crystalline substance known as microcrystalline cellulose.¹⁹ However, it is essential to maintain a chemical concentration of 1.5 molality, 50°C temperature, and time 120 min for this process.

Figure 2 shows the chemical treatment process.

Gamma irradiation

Gamma irradiation is a widely employed method for sterilizing, altering, and interconnecting different substances, such as natural fibers like jute, flax, hemp, banana, ramie, and kenaf.²⁰

This study exposed raw jute fibers and cellulose and those treated with peracetic acid to gamma irradiation (Figure 3). The resulting impacts varied depending on the dosage received. The 3 kGy and 6 kGy dosages specified are considered large doses of gamma radiation and can cause considerable changes in the crystallinity of jute fibers.

Measurement technique of crystallinity

We detected, processed, and calculated X-ray scattering. We scanned the sample through the 2θ 2-angle range to capture all lattice scattering orientations caused by random powder material orientations.²¹ Nine types of samples were prepared for the examination of crystallinity.

Crystallinity is usually measured using XRD by comparing the sample’s diffraction peak intensity with an amorphous baseline or reference standard. The following formula can be used to determine a sample’s crystallinity:

\begin{matrix} % o f Crystallinity (X_{c}) \\ = \frac{\begin{matrix} Area o f crystalline peaks \\ (A c = A c_{1} + A c_{2} + A c_{3} + \dots) \end{matrix}}{\begin{matrix} Area o f Crystalline peaks (A c) \\ + Area o f amorphous peaks (A a) \end{matrix}} \times 100 \end{matrix}

In Origin software, peak intensities and locations in the XRD pattern are used to measure crystallinity. First, the XRD data are loaded into Origin and then the XRD pattern is plotted using the right parameters. Plot counts or intensity (a.u.) are on the y-axis and 2θ (theta) on the x-axis. We then check that data peaks match diffraction peaks. Background noise is removed by correcting the XRD pattern baseline. Origin software generally includes baseline correction tools. Peaks are manually detected using their 2θ locations and intensities. Origin software may automate peak detection. Recognized peaks are fit using relevant functions. Gaussian functions are often utilized. We ensure that the peak fitting matches the data peaks, and measure the area under the fitting peaks. Amorphous and crystalline phase integrated peak areas contributed to the XRD pattern’s overall integrated peak area. Integrated peak areas were calculated according to the crystallinity formula and % crystallinity values computed for 09 (nine) samples, as shown in Figure 4.

Measurement of other crystallographic parameters

One very beneficial method for deciding the crystallographic properties of substances is XRD. Although its principal use is in analyzing crystal structure, segment composition, and lattice parameters,²² it can also yield valuable insights into additional factors such as crystallite size, microstrain, dislocation density, and stress. The extraction of these characteristics from XRD data can be achieved as follows.

Using the Scherrer formula, the crystallite size (D) along the prominent peak was determined²³:

D = 0.9 λ / β \cos θ

(1)

where λ denotes the wavelength of XRD, β is the full width at half maximum, and θ is the diffraction angle.

The strain values (ε) of the synthesized thin films were determined using the equation:

ε = β \cos θ / 4

(2)

The following formula was applied to compute the dislocation density (δ)²⁴:

δ= 1 / D^{2}

(3)

The below equation was used to calculate the stress (σ) created in the jute fibers²⁵:

σ = - 232.8 \times ε

(4)

The different calculated parameters from XRD are listed in Table 1. These include the full width at half maximum (FWHM), crystallite size (D), dislocation density (δ), microstrain (ε), stress (σ), and peak shift. The crystallite size gradually decreased in relation to the enhancement of the crystallinity of various treated jute fibers. In addition, there are increases in the microstrain, dislocation density, and stress with the rising value enhancement of crystallinity.

Table 1.

Crystallographic Data of Jute Fibers

Sl no.	Experimental condition	% of crystallinity	Average crystal size D (nm)	Average micro strain (ε) ×10⁻³ (dimensionless)	Average dislocation density ×10⁻³, nm⁻²	Average compressive stress, GPa
1	Raw JF	60.30	1.74	109.75	331.39	25.54
2	Raw JF_6kGy	67.90	1.77	89.34	319.58	20.79
3	Raw JF_3kGy	71.30	1.88	81.21	280.85	18.90
4	Cellulose JF	65.95	2.21	71.42	204.68	16.63
5	Cellulose JF_6kGy	70.09	2.26	69.54	195.46	16.19
6	Cellulose JF_3kGy	73.10	2.56	61.45	151.75	14.30
7	PAA Treated JF	75.34	3.34	38.72	89.49	9.01
8	PAA Treated JF_6kGy	77.16	4.96	33.69	40.56	7.84
9	PAA Treated JF_3kGy	79.15	5.16	31.30	37.46	7.28

The intrinsic strain is precipitated inside the jute fibers using the deposition parameters, which consist of increased temperature, gas pressure, laser electricity, and pulse duration. The signal obtained describes the compressive intrinsic strain.

Results and discussion

FTIR analysis

Different IR sampling methods for research on natural fibers have been made easier by FTIR. In general, FTIR spectra of jute fibers can be separated into two characteristic regions: The vibrational modes in the 3500 to 2800 cm⁻¹ range are usually connected with the O-H and C-H stretching modes; in the 2000 to 800 cm⁻¹ region, cellulose, hemicellulose, and lignin compounds exhibit many peaks.²⁶

Cellulose, hemicellulose, and lignin are the primary components of jute fiber. The FTIR analysis of raw, gamma-irradiated, cellulose, and peracetic acid-treated jute fiber are shown in Figure 5(a) and (b). The following wave numbers and corresponding functional groups were found in treated and untreated jute. The strong and broad peak at 3319 cm⁻¹ corresponds to –OH stretching vibration. This extensive peak signifies the hydroxyl (–OH) groups in cellulose and hemicelluloses.²⁷ The peak at 1634 cm⁻¹ in the FTIR spectrum of jute fiber is typically associated with the H-O-H stretching vibration of absorbed water in carbohydrates, as well as the C=O stretching vibrations of carbonyl groups present in lignin or hemicelluloses.²⁸ This absorption band at 1634 cm⁻¹ shows a noticeable difference in intensity between raw and treated samples. This suggests that the amount of lignin and hemicelluloses in the treated samples has decreased compared with the raw samples. The reduction in these components is likely due to chemical treatments that have selectively removed or altered the lignin and hemicellulose content. The wavenumber 1011 cm⁻¹ was assigned for C-O stretching vibration. This intense peak indicates polysaccharides, particularly hemicellulose, cellulose, and lignin.²⁹ A peak at 1334 cm⁻¹ for all samples in the FTIR spectra indicates –CH₂ bending. Based on the analysis of the FTIR spectra, the peak detected at 2890 cm⁻¹ emerged solely in the three treated samples (3, 8, and 9). This peak suggests the existence of C–H stretching vibrations, which are likely owing to the presence of ether groups.²⁶ For the other six samples, a peculiar peak at 2337 cm⁻¹ was noticed, ascribed to the absorption of CO₂, often originating from atmospheric CO₂ present during the measurement.

Crystallographic analysis of jute fibers

XRD analysis is essential to investigate a material’s crystalline properties. XRD tests were undertaken to analyze the raw and treated jute fibers and measure the percentage of crystallinity of raw, cellulose, and peracetic acid-treated jute fibers. The XRD curves of raw, cellulose, and treated jute fibers are shown in Figures 6, 7, and 8.

Figures 6 –8 illustrate the XRD examination of jute fibers treated with peracetic acid under nine distinct circumstances. The figure shows that the sample labeled PAA Treated JF-3 kGy has the highest crystallinity fraction, as indicated by the peak intensity. The samples of PAA Treated Jute Fiber from Figure 8 hold the second highest rank. The PAA Treated JF-6 kGy sample achieved the third highest position out of the nine samples. Furthermore, it was observed that the crystallinity percentages of the samples labeled as cellulose JF, PAA cellulose JF-3 kGy, and cellulose JF-6 kGy in Figure 8 are noteworthy, with increasing values in sequential order.

Conversely, the sample pack from Figure 6 resembles the first two samples based on their closely aligned values. Among the nine experimental settings, the lowest values observed on RAW JF-6 kGy can be considered noteworthy, as shown in Figure 6. Nevertheless, the intensity values exhibit substantial variation among the samples depicted in Figure 6 and Figure 7 despite their apparent similarity in Figure 8.

Gamma irradiation’s effects on raw, cellulose, and peracetic acid-treated jute fibers include rearranging polymer chains inside the fibers due to the energy from the radiation that enhances crystallinity. By eliminating contaminants, cellulose treatment can increase the cellulose’s structural susceptibility to gamma-irradiation-induced structural changes, which may result in a higher rise in crystallinity.

Figure 9 illustrates the relationship between the crystallinity and gamma radiation dose of three types of jute fiber: raw jute fiber, cellulose jute fiber, and acid hydrolysis-treated jute fiber. Observations indicate that the proportion of crystallinity rises as the treatment duration increases to a specific point. During the time intervals, the level of crystallinity exhibited a steady growth until it reached a gamma radiation dose of 3 kGy. At this point, the rate of increase experienced a minor acceleration. Gamma irradiation decreases the degree of crystallinity in jute fibers.³⁰ In Figure 9, the percentages of crystallinity increase to a specific range (3 kGy). Similarly, as the gamma radiation dose increases further, there is a noticeable decline in crystallinity. It is seen that the crystallinity of all three types of fiber was reduced at the same rate as the dose increased.

The precise percentage increase in crystallinity caused by gamma irradiation is contingent upon several parameters, including the starting crystalline structure of the fibers, the dosage of radiation administered, and the specific treatments, such as cellulose or peracetic acid, applied to the jute fibers. Quantifying the precise increase in crystallinity percentage for each type of jute fiber treatment under 3 kGy and 6 kGy irradiation settings would require conducting experimental research.

Based on Figure 8, a dose of 3 kGy is an ideal energy level. Irradiation can promote crystal formation and assist structural rearrangements that improve crystallinity. Higher doses, such as 6 kGy, may cause significant harm or disturbance and alteration, or creation of defects in the structure of the jute fiber, resulting in a decrease in crystallinity. Figure 10 illustrates the most significant and minor percentage increases in crystallinity compared with raw jute fibers. The treatments that resulted in these enhancements were peracetic acid treatment with 3 kGy irradiation and cellulose jute fibers.

Figure 11 depicts the percentage of crystallinity of jute fiber under six different experimental conditions. It is evident from the image that the sample labeled Raw JF_3kGy exhibits the most significant increase in crystallinity. Subsequently, the samples labeled Raw JF_6kGy exhibit the second highest value, while the ones labeled cellulose JF_3kGy demonstrate nearly identical values to the Raw JF_6kGy sample. Conversely, the sample labeled PAA Treated JF_6kGy exhibits the lowest value. Similarly, the samples labeled cellulose JF_6kGy and PAA Treated JF_3kGy display nearly identical values, approximately 4%.

Gamma-irradiated raw jute fibers’ crystallinity enhancement range is higher than of treated jute fibers, as shown in Figure 11. Surface modification causes structural changes in cellulose chains, promoting their reorganization into more ordered crystalline arrangements. This reorganization can have a low impact on cellulose and peracetic acid-treated jute fibers. The complicated increase in crystallinity in gamma-irradiated raw jute fibers compared with treated fibers may be due to the irradiation procedure, the fibers’ treatment history, and the material’s inherent qualities. More research and experiments are needed to understand and fully maximize fiber crystallinity enhancement.

Enhancement of the crystallinity range is lower in control (non-irradiated), 3 kGy and 6 kGy dose raw jute fibers to cellulose compared with cellulose to peracetic acid -treated jute fibers, as shown in Figure 11. Peracetic acid treatment enhances the crystalline zone and reduces the amorphous zone from the cellulose fibers. This process could increase the relative proportion of crystalline zones in the fibers, thus increasing the crystallinity index. Additionally, removing the amorphous zone may result in better alignment and packing of cellulose chains of the peracetic acid-treated jute fibers, further contributing to increased crystallinity range.

Figures 12 –15 show the percentage of crystallinity for various types of fiber based on crystal size, average microstrain, average dislocation, and average compressive stress. The rate of crystallinity, determined by crystal size, initially showed a modest increase, then increased again at an intensity of 3 kGy for both raw jute fiber and cellulose jute fiber. However, this increase was not observed in peracetic acid-treated jute fiber. Here, the inverse situation occurred. Initially, there was a quick surge, but then the rate of increase slowed down. The percentage of crystallinity for the average microstrain consistently decreased during the entire period for jute fibers treated with 3 kGy Raw, cellulose, and PAA. However, the significant observation is that in Figure 12(a), there is a consistent decline in the rate of crystallinity over time. The same phenomenon occurred in the average compressive curve of 6 kGy raw jute fiber’s crystallinity. However, it is seen that the crystal size reached its highest point on the jute fiber treated with 3 kGy PAA, as shown in Figure 15(a), and its lowest point on the raw jute fiber, as shown in Figure 13(a). The same phenomenon was observed on the average microstrain line for all three types of jute fibers. The impact of compressive stress on crystallinity is distinct for the three fiber types, but it consistently decreases in raw jute fiber.

The correlation between crystallinity and crystallite size is complex. It can be influenced by multiple factors, such as the composition of the material, the method of manufacturing, and the circumstances of processing.^19,31 As crystallite size decreases, crystallinity often increases. Several reasons are that crystallinity increases as crystallite size falls, surface area to volume ratio increases, and surface energy increases with surface area. Crystallinity increases as more atoms or molecules form an organized crystalline structure to minimize energy. Smaller crystallites have larger surface-to-volume ratios, which might limit atom or molecule mobility. This can prevent non-crystalline or amorphous regions and help atoms or molecules form a crystalline lattice.³² Smaller crystallites can increase strain caused by differences in lattice structure or imperfections at the borders between grains. To relieve this strain, crystallite atoms or molecules may reorganize into a more organized crystalline structure, increasing crystallinity. Depending on the material system and experimental conditions, this relationship may only sometimes be accurate. Characterization methods for crystallinity and crystallite size can affect the relationship.

The percentage of crystallinity in jute fiber and the rise in microstrain have a complicated relationship that depends on several variables, including the fiber’s structure and characteristics. Microstrain enhances nucleation sites for fiber crystalline areas. These strain areas promote crystallization and increase crystallinity by arranging atoms or molecules into organized crystalline structures. Microstrain can alter the fiber’s crystal lattice, increasing structural disorder. Although this seems counterintuitive, microstrain-induced disorder can promote the creation of smaller, more frequent crystalline domains, increasing crystallinity. Higher microstrain may impact the fiber’s thermodynamic stability, making a more crystalline structure energetically advantageous. Microstrain-induced stress in the fiber may cause atoms or molecules to rearrange into a more ordered crystalline lattice, increasing crystallinity. Microstrain affects grain growth kinetics during crystallization. High microstrain may impede grain growth, forming more minor, more numerous crystalline domains in the fiber.³¹ The crystallinity % may increase with a decrease in average microstrain. It’s crucial to note that the link between crystallinity and microstrain can be complex and depends on several aspects, including the jute fiber’s qualities, processing circumstances, and measurement methods. Understanding the relationship between these characteristics in jute fiber requires more research and experimentation.

The link between jute fiber crystallinity and dislocation density depends on several parameters; thus, context is crucial. The proportion of crystallinity in a substance indicates how orderly the polymer chains are. A less disordered crystal lattice is generally indicated by decreasing dislocation density. Dislocations in a material’s crystal structure can prevent orderly crystalline development. The crystal lattice gets more regular and organized as dislocation density decreases. Jute fibers are mostly cellulose; a lower dislocation density may indicate better cellulose chain alignment and crystalline structure. This enhanced polymer chain order can promote crystallinity. The link between crystallinity and dislocation density is complicated and depends on processing, thermal history, and additives. XRD and infrared spectroscopy are also employed to assess fiber crystallinity and structure. Jute fibers’ behavior depends on their circumstances and treatment.³² A material’s crystal lattice has dislocations. A lower dislocation density indicates a more organized crystal lattice.

Organized polymer chains create crystalline areas in polymers like cellulose, a significant component of jute fibers. Improved chain alignment: Dislocations can misalign polymer chains. A decrease in dislocation density reduces cellulose chain alignment disruptions. Improved chain alignment makes the fiber more ordered and crystalline. Increased crystallinity measures a material’s crystalline structure. A highly organized polymer chain arrangement increases crystallinity.^21–23,32 Jute fiber polymer chains can become more organized with lower dislocation density, increasing crystallinity. Fiber crystallinity is often assessed using XRD and infrared spectroscopy. These methods can reveal structural changes in jute fibers as dislocation density reduces, suggesting the link between fewer dislocations and higher crystallinity.

The increased structural order in crystalline areas of jute fibers reduces compressive stress. Jute fiber polymer chains align more consistently as crystallinity rises, providing a neat, solid structure. This increased structural order helps fibers distribute and withstand compression. The crystalline areas’ higher load-bearing capability and deformation resistance improve stress distribution, reducing compressive stress. Higher crystallinity in jute fibers creates a more ordered and durable interior structure, reducing compressive stress by improving the fibers’ capacity to bear and distribute compressive pressures. Table 1 shows the crystallographic data of the developed jute fibers. Table 2 compares the obtained data with the data available in the literature. It is seen that most researchers have performed chemical treatment to improve the crystallinity of jute fibers. The commonly used chemicals are sodium carbonate, acetic acid, sodium acetate, sodium chlorite, sodium metabisulfite, chloroform, toluene, acrylonitrile, diphenylmethanediisocyanate, sulfuric acid, polyvinyl chloride, ethanol, dimethylformamide, dimethylsulfoxide, toluene, and tetrahydrofuran. Having higher crystallinity is beneficial for jute fibers as it increases their potential for use in more mechanical applications.

Table 2.

Comparison with the Data Available in the Literature

Materials	Technology used	Obtained crystallinity (%)	References
Sodium carbonate, acetic acid, sodium acetate, sodium chlorite, sodium metabisulfite, chloroform, toluene, acrylonitrile, and diphenylmethanediisocyanate	Chemical treatment	73.07	[33]
NaOH, NaClO₂, H₂SO₄, PVA	Chemical treatment	74.90	[34]
NaOH, CH₃COOH, NaClO₂	Chemical treatment	70.12	[35]
ethanol, dimethylformamide, dimethylsulfoxide, toluene, tetrahydrofuran	Chemical treatment	75.00	[36]
NaOH	Alkali treatment	62.60	[37]

Conclusions

The crystallinity of jute fibers has been improved in this research work through surface modification and gamma irradiation. To improve the crystallinity, the jute fibers were chemically treated first and then exposed to different doses of gamma radiation. The crystallinity improved by the treatment due to molecular structure change. The modification of those functional groups that helped to improve crystallinity has been confirmed by FTIR analysis.

Footnotes

Data availability statement

Data will be made available on request.

Declaration of conflicting interests

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

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Nayem Hossain

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