Characterization of Natural Fiber Extracted from Corn (Zea mays L.) Stalk Waste for Sustainable Development

Abstract

Corn stalk fibers were extracted from corn stalk using sodium hydroxide for textile application. The extraction conditions were optimized on the basis of the quality and quantity of extracted fibers. The optimum conditions were obtained by treating corn stalk with 5 g/L concentration of sodium hydroxide for 60 min at boiling temperature using a 1:50 material-to-liquor ratio. Extracted fibers were bleached and tested for different physical and chemical properties. Besides these properties, the characterization of extracted fibers was carried out by a scanning electron microscope (SEM), X-ray diffraction analysis (XRD) and Fourier–transform infrared (FTIR) analysis. SEM was used to study the morphological changes in the raw and bleached fibers. The crystallinity changes of the raw and bleached samples were measured with an X-ray diffractometer by peak height method. FTIR was used to examine the compositional changes in the bleaching process. It was found that raw fibers contained the cellular residues such as lignin and hemicelluloses, which cement the fibers together. The chemical treatments such as alkali and bleaching partially removed hemicelluloses, lignin, and amorphous fractions of cellulose. This led to the gradually increasing crystallinity of the treated fiber. Peak height values were obtained by measuring the transmittance of the spectra through FTIR analysis. Different physical and chemical properties of the extracted corn stalk fibers indicated that it can be used for making biodegradable composite materials.

1. Introduction

Indian agriculture generated approximately 696.38 million tons (Mt) per year of crop residues [1] either left in the agricultural field or orchard after harvested residues (stalks, stubble, leaves, and seed pods) or left after the crop residues (molasses and sugarcane bagasse) [2,3], and out of these about 85 Mt of crop residues are burnt on-farm as per estimated by the Indian Ministry of New and Renewable Energy [4,5] and Inter-Governmental Panel on Climate Change [6,7]. Among all the crops, corn (Zea mays L.) is one of the most versatile crops having the highest genetic yield potential, wider adaptability under diverse agro-climatic conditions [8], and a variety of food and industrial products [9,10,11]. Globally, corn is known as the queen of cereals because it has been cultivated in over 170 countries with 1219.76 million tons of grain production [12], and it emerged as a potential remunerative crop, especially among progressive farmers in India. The natural fiber comes from stalks, leaves, and seeds such as wheat straw, corn straw, cotton, jute, hemp, kenaf, and sisal [13,14,15]. In general, the utility of corn stalk is very limited for domestic fuel, livestock feed, and industrial fuel [16], and the remaining straw was burned in fields by factors such as labor scarcity, low nutritive value [17], ignorance of cultivators towards the public health issue [18,19], and socio-economic constraints [20] in the past [21,22,23,24,25], which led to a loss of valuable soil nutrients [26,27], waste of resources, and serious pollution of the environment [28,29,30,31], and poses a challenge to production and life [32]. Therefore, utilization of such cereal crop residue is of great importance not only for minimizing the environmental impact and risk to human health, but also for obtaining a higher profit through natural fiber. In such circumstances, it has led to several deaths as well as significant economic losses [21,22,33,34]. To get the strong, smooth, and suitable natural fiber, there is need for optimization of the extraction process. Optimization of various fiber extraction processes by varying the chemical concentration, time, temperature of treatment, and material-to-liquor ratio (MLR) can help in maximizing the recovery of fibers from these residues [12,35]. The mechanical properties of reinforced polyester and epoxy composites of corn stalk fiber, 100% corn stalk three-layered composite samples have better mechanical properties than the other layered composites and can be used in high-strength applications if the fiber loading is increased in appropriate amount [36]. The chemical analysis of corn stalk fiber such as bundle strength, elongation, scouring, and bleaching of fiber, and removal of extra non-cellulosic material parameters was inversely proportion to the concentration of hydrogen peroxide and temperature [37]. However, only a few research works concerned with the use of fibers from waste corn stalks in the production of fiber-cement have been published and there is a complete lack of data on the characterization of these fibers.

In many studies conducted on many natural fibers for extraction by water retting and alkalization processes followed by enzymatic treatment [38]), sodium hydroxide is the most commonly used alkali for fiber extraction [39,40]. Acids such as sulphuric acid and oxalic acid in combination with a detergent have also been used for fiber extraction [41,42]. Chemical concentration, temperature, and duration of treatment are the main factors determining the quality of chemically extracted fibers [42]. Natural fibers are renewable, show higher tenacity, and high abrasion resistance as compared to glass fibers [43,44,45,46]. Alkalized fibers had higher elongation and lower stiffness values than the other conventional fibers [35]. These natural fibers have properties of lingo-cellulosic and cellulosic; therefore, these are used for textile bio-composites with non-biodegradable matrices [47,48,49,50,51]. However, in the above studies, conditions were optimized in isolation and fewer studies showed its applicability other than composite making.

The technical fibers have breaking tenacity and breaking elongation higher than those of fibers obtained from wheat straw and sorghum stalk and leaves, but lower than that of cotton. Overall, the structure and properties of the technical fibers obtained from corn stalk indicates that the fibers could be suitable for use in textiles, composites, and other industrial applications [49,52,53]. Isolated cellulose whiskers from rice husk by means of an environmentally friendly process for cellulose extraction and bleaching were analyzed. Techniques of infrared absorption spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) showed that the overall process is adequate to obtain cellulose with high purity and crystallinity [54,55]. Morphological investigation of rice husk fiber using scanning electron microscopy (SEM) was found to be useful in its suitability for textile application [54,56]. Technical fibers obtained from corn stalk have high cellulose content but low percent crystallinity [57]. In view of this, a study was planned for the optimization of alkali extraction parameters of corn stalk fibers from corn stalk and analysis of various physicochemical properties of extracted fiber. This approach can increase the overall utilization of corn stalk fiber through a low-cost, energy saving method without causing secondary pollution and reduce the dependence on natural resources for building materials in rural areas of India.

2. Materials and Methods

• Collection of corn straw

Stalks of the corn variety HQPM-1(high quality protein maize-1) after harvesting were collected from fields of the Indian Institute of Maize Research, New Delhi. This variety is suitable for growing in all seasons, viz., kharif, post-monsoon and rabi. The details of the experimental work methodology are given in the form of a flow diagram (Figure 1).

• Preparation of corn straw for fiber extraction

The corn straw was dried in the open ground in the natural sun rays until the moisture content had decreased to about 15 percent for effective recovery of fiber. To calculate the moisture content (MC) we used the following formula:

MC = (w − d)/w ∗ 100

where, MC is the moisture content (%); w is the weight while wet; and d is the weight while dry.

The corn stalk was cleaned manually after sun drying to remove all the dried leaves and any other impurities such as roots, mud, etc. These cleaned stalks were cut into 5–6 inches at the nodes present in the corn stalk (Figure 2).

• Extraction of fiber using alkali treatment and assessment of properties

Dried and cut stalks were treated with alkali for partial delignification. The delignification process using alkali was standardized by varying one parameter and keeping other parameters such as concentration of alkali, process temperature, treatment duration, and MLR constant. The physicochemical properties such asfiber length tenacity, fineness, and fiber elongation were measured on Vibroscope. Ash content (IS 199), wax content (IS 199), and moisture content (IS 199) were assessed using standard test methods.

• Structural analysis of corn stalk fiber samples

Various techniques were used to evaluate surface characteristics and morphology of extracted fibers. These techniques were scanning electron microscopy (SEM), FTIR, X-ray diffraction, etc.

• Microscopic analysis of sample

SEM (scanning electron microscope) was used to study the morphological changes in the raw and bleached substrate. The samples were ground into a powder and dehydrated with gradually increasing concentrations of acetone (10–100%). Specimens were molded into a I1 cm diameter stab having the aluminum tape, having glue on one side. Then, those specimens were taken into a sputter coater and the specimens were coated with gold and platinum alloy up to the thickness 32 nm. Later on, those specimens were taken to SEM ZEISS EVM 10, then imaging was done in high volume with a 20 KV detector was used.

• X-ray diffraction analysis

The crystallinity changes of the corn stalk raw and bleached samples were measured with an X-ray diffractometer by peak height method (PW1729 Philips X-ray generator). Diffraction patterns were recorded by using Cu-Kα radiation at 40 kV and 20 mA. Diffracted intensity was measured in a range of 2θ between 50° and 4° with a step size of 0.1. The Segal method with the pragmatic equation as given below was adopted to estimate cellulose crystallinity.

C (%) = (I₀₀₂ − I_am)/I₀₀₂ × 100

where, C (%) is the relative degree of crystallinity, I₀₀₂ is the maximum intensity of the 002 lattice diffraction, and I_am is the intensity of diffraction in the same units at 2θ = 18°.

• Fourier–transform infrared (FTIR) analysis

FTIR was used to examine the compositional changes of extracted and bleached corn stalk fibers using a Perkin–Elmer spectrum BX FTIR. Peak height values were obtained by measuring the transmittance of the spectra.

3. Results and Discussions

• Optimization of fiber extraction parameters

The main aim of these experiments was to optimize various process parameters used for the extraction of fiber from corn stalk such as treatment time duration, treatment temperature, and concentration of alkali. The details of the optimization of these parameters are discussed below:

• Alkali concentration

To optimize the corn stalk extraction parameters, first of all, raw materials were treated with 2, 3, 5, and 7 g/L NaOH concentration. The other parameters (temperature: 100 °C, treatment duration: 60 min, and MLR: 1:50) were kept constant (Table 1). When the sample was treated with 2 g/L NaOH, there was no effect on corn stalk. Then, when the sample was treated with 3 g/L, there was a slight opening of the fiber. Complete fiber opening and fiber extraction from corn stalk occurred when the sample was treated with 5 g/L NaOH concentration with the highest fiber recovery However, at a 7 g/L NaOH concentration, damage of fibers was observed. Therefore, the 5 g/L concentration was selected for further study.

• Optimization of temperature parameter

Temperature plays an important role in the extraction of fiber from corn stalk. For the optimization of temperature parameters, raw corn stalk was treated separately at 60, 80, and 100 °C similarly in a concentration of alkali (5 g/L, optimized in Table 2) and other parameters such as MLR (1:50) and time treatment duration (60 min) were kept constant. It was observed that there was no significant change in fiber extraction till 80 °C. However, with increases in temperature around 100 °C, the fiber opened and extracted completely. Therefore, a temperature of 100 °C was selected for further study. Similar results were observed in a study [58] carried out on the extraction of fibers from corn husk. The highest tensile performance was obtained in 5–10 g/L NaOH concentration and 60–90 min duration ranges. The result was in accordance with the findings of other researchers’ studies [59], who have also reported extraction of fibers from corn husk at boiling temperatures.

• Optimization of time

In this study, the process’s temperature (around 100 °C), concentration of NaOH (5 g/L), and MLR (1:50) were kept constant, and time was varied (Table 3). It was observed that at 30 min treatment time, the stalk did not open up much and only thick strands were obtained. As a result, there was no significant change in the fiber extraction. However, with the increase in treatment time up to 60 min, the fibers were opened and extracted completely. Further increases in time for 90 min pulping of corn stalk fibers have been started. Therefore, the 60 min time was optimized and selected for further study. Similar studies [57,60] carried out on corn husk also indicated similar processing parameters for complete extraction of fibers.

• Optimization of MLR

In this study, the process’s temperature (around 100 °C), NaOH concentration (5 g/L), and time (60 min) were kept constant, and MLR was varied (Table 4). The results showed that with MLR (1:30), corn stalk samples were not dipped in solution completely because of drying of solution during the process. Due to this, fiber extraction was not optimum. With the further increase in MLR (1:50), the extraction process done completely as the raw materials were also dipped completely in solution. The further increase in MLR, i.e., 1:80, did not result in any change in extraction process. Therefore, 1:50 MLR was selected for further study.

Based on the experiments conducted in the laboratory of NITRA, it was found that the optimum concentration of NaOH for fiber extraction was5 g/L. It was also observed that, temperature, process time duration, and MLR were 100 °C, 60 min, and 1:50, respectively. With this optimized condition, the average weight of fiber was 2.28 g/5g sample weight of corn stalk. Similar results were found for fiber extraction in switch grass stems, leaves, and soya bean agro-biowaste, where optimized conditions were determined based on the fineness of the fibers and fiber yield obtained [57].

• Assessment of composition and physicochemical properties

The fiber properties, such as fineness, crimp, strength, elongation, modulus, and moisture regain properties estimated to compare one fiber’s performance with another. Various properties of extracted fibers are discussed below along with similar types of fibers.

• Fiber fineness and tenacity

The fineness of a natural fiber is a major factor in ascertaining quality as finer fibers are softer, more pliable, and have better drapability. The results showed (Table 5) that the corn stalk fibers were coarse fibers with a linear density of 85.96. This could be because corn stalk fibers were not separated to individual fibers and were in fact, a bundle of fibers. Similar results were also with corn husk having a fiber fineness of 130 denier with a tenacity of 1.51 g/d [61].

Tenacity is defined as the specific stress corresponding with the maximum force on a force extension curve and indicates the load that a fiber can bear before it breaks. Generally, natural fibers have a characteristic higher tenacity and lower elongation or vice versa. The tenacity of corn stalk fibers is 2.49 g/denier. It is higher in comparison to other cellulosic fibers except linen and jute.

• Elongation and moisture regain

Elongation at break is the amount of stretch a fiber can take before it breaks. Among all other cellulosic fibers, viscose has very high elongation at break. Elongation at break of corn stalk fibers was 22.7% which was comparable to bamboo fibers. The lower orientation and higher amorphous regions are responsible for the increased elongation, because when the fiber is stretched, molecules in these regions can align themselves to become more oriented to the fiber axis without rupture. Due to elongation, fibers have elasticity which is very useful for the bendable properties of fiber or fabric, and without elasticity, the fiber would hardly be usable.

The ability of bone dry fiber to absorb moisture is called moisture regain and in corn stalk fibers, it was similar to viscose, but lower than jute, linen, bamboo, and viscose fibers [62,63,64]. Corn stalk fibers have higher moisture regain due to the presence of non-cellulosic substances, especially hemicelluloses, which are hydrophilic. The higher amount of accessible regions, surface area, and capillary effect contribute to the higher regain. The high moisture regain of corn stalk fibers suggests that apparel made from that would be comfortable to wear.

• Wax content and ash content

The percentage of wax content in corn stalk fibers was lower than other cellulosic fibers. Among all other cellulosic fibers, cotton and bamboo have a higher wax content followed by linen, jute, and viscose. The low percentage of wax content in corn stalk fibers may be because of its treatment with alkali during extraction which removes wax. However, the percentage of ash content was lower than other cellulosic fibers.

• Structural analysis of corn stalk fiber sample

Raw and bleached corn stalk fiber samples were subjected to SEM, XRD, and FTIR analysis to study the changes in the biomass during the pre-treatment and post-treatment process.

• Microscopic analysis of sample

The structure of the stem comprised of an outer epidermis, a cellular inner region, and a central void or lumen. SEM was used to study the morphological changes in the raw and bleached substrate. The morphology of alkali-extracted corn stalk fibers before bleaching and bleached with hydrogen peroxide is shown in the SEM micrographs (Figure 3). The surface of bleached fiber was more uniform and homogenous while the raw fiber (without bleaching) showed more surface irregularities. Raw fibers still contained the cellular residues such as lignin and hemicelluloses, which might have cemented the fibers together. A similar study also reported that one-fourth of the inner cellular structure comprised of sclerenchyma or vascular bundles [65,66].

• X-ray diffraction analysis

The degree of crystallinity of the extracted corn stalk fiber and the bleached corn stalk fiber was 40.88% and 45.37%, respectively, as shown in Figure 4. Due to partial removal of the hemicellulose, lignin, and the amorphous fraction of cellulose during chemical treatment, the crystallinity degree increased gradually from the raw fibers to the bleached fibers (Figure 5). The rigidity of the bleached fiber increased with an increase in the number of crystallinity regions [67]. It is quite obvious that lower crystallinity is attributed to poor crystal orientation and the presence of a bundle of single cells which contributed to the lower strength of the raw corn stalk fiber. Hence, it was evident from the study that after bleaching, the crystallinity of corn stalk fiber increased. It indicates that the strength of the bleached fiber will be higher than the extracted corn stalk fiber, i.e., raw fiber. Therefore, the higher crystallinity of the bleached fiber can be used in higher tensile strength applications [68].

• Fourier–transform infrared (FTIR) analysis

The FTIR spectroscopy of the corn stalk fibers showed that there is a slight difference in chemical structures of the FTIR spectra for the raw and treated corn stalks fibers (Figure 6). The broad band absorbance peak of corn stalk fibers observed around 3400 cm⁻¹ corresponds to the O–H stretching. The peak at 2925 cm⁻¹ was due to the C–H stretching. The peak at 1599 cm⁻¹ was due to the C=O carbonyl stretching which is attributed to the carbonyl groups (–C=O) stretch, confirming the formation of new acetyl groups in cellulose. This peak is due to an esterification reaction that results in an increased stretching vibration of the C=O group of the ester linkage [69].

The absorption in this region is attributed to both the C=O groups in the acid and ester groups attached to the corn stalk. The 1317 cm⁻¹ absorbance peak is attributed to the C–H bending vibration of the aromatic ring in polysaccharides. The peak at 1161 cm⁻¹ was due to the anti-symmetrical deformation of C–O–C band in cellulose and hemicelluloses [70]. The peak at around 1033 cm⁻¹ is due to C–O and O–H stretching, and the peak at 897 cm⁻¹ is interpreted as C–O–C stretching at the beta-(1–4)- glycosidic linkage in cellulose.

The peak at 1044 cm⁻¹ is less intense for the 5 g/L alkaline extracted fiber compared to that of the other fibers (Figure 5). This can be explained by the fact that the O–H and C–O functions are higher in cellulose than in hemicellulose [71]. The cellulose content is lower and the hemicellulose content is higher in 5 g/L alkaline extracted fiber as compared to the other fibers. The peak at 1254 cm⁻¹, associated with C–O stretching in lignin, is more intense in 5 g/L alkaline extracted fibers than that in the remainder of the fibers. This can be explained by the partial removal of lignin with alkalization. These IR findings agreed with the thermal gravimetric analysis.

4. Conclusions

The extraction conditions were optimized by 5 g/L NaOH solution in 1:50 MLR at 100 °C for 60 min. Overall, all the properties of corn stalk fiber in terms of elongation, tenacity, denier, and moisture content were favorable for valuable textile applications. The surface of bleached fiber was more uniform and homogenous, while the raw fiber without bleaching showed more surface irregularities. It was evident from the study that after bleaching, the crystallinity of corn stalk fiber increased significantly which can be used for higher tensile strength applications. It was concluded that the alkali extracted corn fiber after bleaching can be used for textile application for making biodegradable materials. Corn stalks have been used to extract natural cellulose fibers with characteristics halfway between cotton and linen and suited for a variety of industrial uses. Food, clothes, and other key industrial products can all be produced using high-quality cellulosic fibers derived from corn stalks without the use of any extra natural resources. Utilizing corn stalk for fibrous purposes would reduce the need for non-renewable petroleum resources and the amount of land and natural resources needed to grow fiber crops. Future agriculture, fiber, food, and energy demands will benefit greatly from using corn stalk as a source of natural cellulose fibers and overall, this will also benefit the environment.

Author Contributions

Conceptualization, S.D. and A.T.; methodology, V.K.; software, A.G.; validation, V.K., P.K.P. and R.K.M.; formal analysis, A.G.; investigation, S.D.; resources, P.K.P.; data curation, S.D.; writing—original draft preparation, S.D.; writing—review and editing, V.K., U.K. and M.K.A.-S.; visualization, A.G.; supervision, P.K.P.; project administration, V.K.; funding acquisition, M.K.A.-S. All authors have read and agreed to the published version of the manuscript.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Acknowledgments

The authors would like to extend their sincere appreciation to the Researchers Supporting Project Number (RSP2022R410), King Saud University, Riyadh, Saudi Arabia.

Conflicts of Interest

The authors declare no conflict of interest.

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures and Tables

Figure 1. The flow chart showing the experimental work methodology.

Figure 2. Process of the corn stalk fiber extraction.

Figure 3. Scanning electron microscopic (SEM) images of extracted pre-bleached (a) and bleached (b) corn stalk fibers.

Figure 4. Crystallinity percentage analysis of pre-bleached and bleached corn stalk fiber.

Figure 5. X-raydiffraction (XRD) profile of the raw (C) and bleached (B) corn stalk fiber.

Figure 6. Fourier–transform infrared (FTIR) analysis of corn stalk fiber: (a) Bleached corn stalk fiber and (b) Pre-bleached fiber.

Table 1

Optimization of concentration of alkali treatment.

NaOHConcentration (g/L)	Temperature Constant(°C)	Time Duration(min.)	Materials-to-Liquor Ratio (MLR)	Observations	Weight of Fiber (g)
2	100	60	1:50	-	-
3	100	60	1:50	Slight opening of fiber	3.12 ± 0.02
5	100	60	1:50	Extraction of fiber	2.97 ± 0.19
7	100	60	1:50	Damage of fibers	2.93 ± 0.03

Table 2

Optimization of treatment temperature for fiber extraction from corn stalk.

Temperature(°C)	NaOHConcentration (g/L)	Materials-to-Liquor Ratio (MLR)	Time(min)	Observations	Weight of Fiber (g)
58 to 62	5	1:50	60	No opening of fiber	-
78 to 82	5	1:50	60	Slight opening of fiber	3.34 ± 0.24
98 to 102	5	1:50	60	Extraction of fiber	2.25 ± 0.20

Table 3

Optimization of time.

Time(min)	Temperature(°C)	NaOHConcentration (g/L)	Materials-to-Liquor Ratio (MLR)	Observations	Weight ofFiber (g)
30	100	5	1:50	No opening of fiber
60	100	5	1:50	Extraction of fiber	2.36 ± 0.19
90	100	5	1:50	Degradation of fiber	2.26 ± 0.21

Table 4

Optimization of materials-to-liquor ratio (MLR).

MLR	Time (min)	Temperature (°C)	NaOH Concentration (g/L)	Results	Weight of Fiber	Results
1:30	60	100	5	Not done, water dry before extraction of fiber	-	Not done, water dry before extraction of fiber
1:50	60	100	5	Extraction complete, no extra water	2.29 ± 0.18	Extraction complete, no extra water
1:80	60	100	5	Done, but extra water remaining	2.27 ± 0.18	Done, but extra water remaining

Table 5

Physicochemical properties of corn stalk and other cellulosic fibers.

S. No.	Test Parameter	Corn Stalk Fiber	Bleached Corn Stalk Fiber	Cotton	Viscose	Linen	Jute	Bamboo	Milkweed
1.	Fiber fineness (denier)	86.72	85.96	3.6	1.5	1.5	18	1.3–5.6	1.0
2.	Tenacity (g/denier)	2.76	2.49	2.1	2.3	6.0	3.3	2.3	2.4
3.	Elongation at break (%)	23.1	22.7	6.7	30	2.5	1.2	21.8	1.3
4.	Wax content (%)	0.7	0.2	0.6	0.5	0.3	0.2	0.6	0.4
5.	Ash content (%)	0.5	0.3	1.2	1.5	0.8	0.6	1.9	2.4
6.	Moisture regain (%)	12.92	12.95	6.9	13.1	12.0	13.8	13.3	10.5

References

1. Venkatramanan, V.; Shah, S.; Prasad, S.; Singh, A.; Prasad, R. Assessment of Bioenergy Generation Potential of Agricultural Crop Residues in India. Circ. Econ. Sustain.; 2021; 1, pp. 1335-1348. [DOI: https://dx.doi.org/10.1007/s43615-021-00072-7]

2. Agamuthu, P. Challenges and Opportunities in Agro-waste Management: An Asian Perspective. Proceedings of the Meeting of First Regional 3R Forum in Asia; Tokyo, Japan, 11–12 November 2009.

3. Obi, F.O.; Ugwuishiwu, B.O.; Nwakaire, J.N. Agricultural Waste Concept, Generation, Utilization and Management. NIJOTECH; 2016; 35, pp. 957-964. [DOI: https://dx.doi.org/10.4314/njt.v35i4.34]

4. Ministry of New and Renewable Energy (MNRE). 2012; Available online: http://www.fiber2fashion.com (accessed on 20 August 2022).

5. NPMCR. Available online: http://agricoop.nic.in/sites/default/files/NPMCR_1.pdf (accessed on 6 March 2019).

6. Watson, R.T.; Zinyowera, M.C.; Moss, R.H. IPCC 1997; Cambridge University Press: Cambridge, UK, 1997; 517.

7. Jonoobi, M.; Harun, J.; Mathew, A.P.; Hussein, M.Z.B.; Oksman, K. Preparation of cellulose nanofibers with hydrophobic surface characteristics. Cellulose; 2009; 17, pp. 299-307. [DOI: https://dx.doi.org/10.1007/s10570-009-9387-9]

8. Kumar, S.; Basavanneppa, M.A.; Koppalkar, B.G.; Umesh, M.R.; Gaddi, A.K. Precision nitrogen management in maize (Zea mays L.) through leaf colour chart tool in Tunga Bhadra Command area. Bull. Environ. Pharmacol. Life Sci.; 2018; 7, pp. 43-46.

9. Naik, G. Closing the Yield Gap: Maize in India. Technology, Adaptation and Exports: How Some Developing Countries Got It Right; Chandra, V. The World Bank: Washington, DC, USA, 2006; pp. 275-300.

10. Parihar, C.M.; Kumar, B.; Jat, S.L.; Singh, A.K.; Jat, M.L.; Chaudhary, V.; Dass, S. Specialty Corn for Nutritional Security and Dietary Diversification; Biofortification of Food Crops; Springer: Berlin/Heidelberg, Germany, 2016; [DOI: https://dx.doi.org/10.1007/978-81-322-2716-8_28]

11. Kumar, T.K.; Venkateswarlu, B. Baby corn (Zea mays L.) performance as vegetable-cum fodder in intercropping with legume fodders under different planting pattern. Range Manag. Agroforest.; 2013; 34, pp. 137-141.

12. Doraiswamy, I.; Chellamani, P. Pineapple-leaf fibers. Text. Prog.; 1993; 24, pp. 1-25. Available online: http://www.fao.org/faostat/en/#data/QC (accessed on 7 June 2022). [DOI: https://dx.doi.org/10.1080/00405169308688859]

13. Shanks, R.A.; Hodzic, A.; Wong, S. Thermoplastic biopolyester natural fiber composites. J. Appl. Polym. Sci.; 2004; 91, pp. 2114-2121. [DOI: https://dx.doi.org/10.1002/app.13289]

14. García, M.; Garmendia, I.; García, J. Influence of natural fiber type in eco-composites. J. Appl. Polym. Sci.; 2008; 107, pp. 2994-3004. [DOI: https://dx.doi.org/10.1002/app.27519]

15. Qin, L.; Qiu, J.; Liu, M.; Ding, S.; Shao, L.; Lü, S.; Zhang, G.; Zhao, Y.; Fu, X. Mechanical and thermal properties of poly (lactic acid) composites with rice straw fiber modified by poly(butyl acrylate). Chem. Eng. J.; 2011; 166, pp. 772-778. [DOI: https://dx.doi.org/10.1016/j.cej.2010.11.039]

16. Devi, S.; Gupta, C.; Jat, S.L.; Parmar, M. Crop residue recycling for economic and environmental sustainability: The case of India. Open Agric.; 2017; 2, pp. 486-494. [DOI: https://dx.doi.org/10.1515/opag-2017-0053]

17. Singh, Y.; Sidhu, H. Management of cereal crop residues for sustainable rice-wheat production system in the Indo-Gangetic Plains of India. Proc. Indian Natl. Sci. Acad. USA; 2014; 80, pp. 95-114. [DOI: https://dx.doi.org/10.16943/ptinsa/2014/v80i1/55089]

18. Bhuvaneshwari, S.; Hettiarachchi, H.; Meegoda, J.N. Crop Residue Burning in India: Policy Challenges and Potential Solutions. Int. J. Environ. Res. Public Health; 2019; 16, 832. [DOI: https://dx.doi.org/10.3390/ijerph16050832] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/30866483]

19. Chawala, P.; Sandhu, H. Stubble burn area estimation and its impact on ambient air quality of Patiala & Ludhiana district, Punjab, India. Heliyon; 2020; 6, e03095. [DOI: https://dx.doi.org/10.1016/j.heliyon.2019.e03095] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/31970295]

20. Lopes, A.A.; Viriyavipart, A.; Tasneem, D. The role of social influence in crop residue management: Evidence from Northern India. Ecol. Econ.; 2020; 169, 106563. [DOI: https://dx.doi.org/10.1016/j.ecolecon.2019.106563]

21. Barbier, B.; Yacouba, H.; Karambiri, H.; Zoromé, M.; Somé, B. Human Vulnerability to Climate Variability in the Sahel: Farmers’ Adaptation Strategies in Northern Burkina Faso. Environ. Manag.; 2009; 43, pp. 790-803. [DOI: https://dx.doi.org/10.1007/s00267-008-9237-9]

22. Bakhsh, K.; Rauf, S.; Zulfiqar, F. Adaptation strategies for minimizing heat wave induced morbidity and its determinants. Sustain. Cities Soc.; 2018; 41, pp. 95-103. [DOI: https://dx.doi.org/10.1016/j.scs.2018.05.021]

23. Lohan, S.K.; Jat, H.; Yadav, A.K.; Sidhu, H.; Jat, M.; Choudhary, M.; Peter, J.K.; Sharma, P. Burning issues of paddy residue management in north-west states of India. Renew. Sustain. Energy Rev.; 2018; 81, pp. 693-706. [DOI: https://dx.doi.org/10.1016/j.rser.2017.08.057]

24. Raza, A.; Razzaq, A.; Mehmood, S.S.; Zou, X.; Zhang, X.; Lv, Y.; Xu, J. Impact of climate change on crops adaptation and strategies to tackle its outcome: A review. Plants; 2019; 8, 34. [DOI: https://dx.doi.org/10.3390/plants8020034]

25. Niu, B.; Kim, B.H. Method for Manufacturing Corn Straw Cement-Based Composite and Its Physical Properties. Materials; 2022; 15, 3199. [DOI: https://dx.doi.org/10.3390/ma15093199]

26. Jat, H.; Jat, R.; Nanwal, R.; Lohan, S.K.; Yadav, A.; Poonia, T.; Sharma, P.; Jat, M. Energy use efficiency of crop residue management for sustainable energy and agriculture conservation in NW India. Renew. Energy; 2020; 155, pp. 1372-1382. [DOI: https://dx.doi.org/10.1016/j.renene.2020.04.046]

27. Fahad, S.; Chavan, S.B.; Chichaghare, A.R.; Uthappa, A.R.; Kumar, M.; Kakade, V.; Pradhan, A.; Jinger, D.; Rawale, G.; Yadav, D.K. et al. Agroforestry Systems for Soil Health Improvement and Maintenance. Sustainability; 2022; 14, 14877. [DOI: https://dx.doi.org/10.3390/su142214877]

28. Wang, D.; Yu, K.; Chen, Z. Otimized test of running parameter on rind-pith separation equipment for corn stalk. Nongye Gongcheng Xuebao/Trans. Chin. Soc. Agric. Eng.; 2013; 29, pp. 26-32.

29. Qin, L.; Wang, Y.; Wu, Y.; Wang, Q.; Luo, L. Assessment of nitrate leakage and N₂O emission from five environmental-friendlyagricultural practices using fuzzy logic method and empirical formula. Environ. Monit. Assess.; 2015; 187, 371. [DOI: https://dx.doi.org/10.1007/s10661-015-4569-4] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/26003184]

30. Jallow, M.F.A.; Awadh, D.G.; Albaho, M.S.; Devi, V.Y.; Thomas, B.M. Pesticide risk behaviors and factors influencing pesticide useamong farmers in Kuwait. Sci. Total Environ.; 2017; 574, pp. 490-498. [DOI: https://dx.doi.org/10.1016/j.scitotenv.2016.09.085] [PubMed: https://www.ncbi.nlm.nih.gov/pubmed/27644027]

31. Adekola, U.A.; Eiroboyi, I.; Yerima, Y.; Akinmoji, T.E.B.; Uti, L.O. Improved biogas production from corn stalks, pg manure and eggshell. J. Adv. Biol. Biotechnol.; 2021; 24, pp. 39-47. [DOI: https://dx.doi.org/10.9734/jabb/2021/v24i430210]

32. Xuan, L.; Hui, D.; Cheng, W.; Wong, A.H.H.; Han, G.; Tan, W.K.; Tawi, C.A.D. Effect of Preservative Pretreatment on the Biological Durability of Corn Straw Fiber/HDPE Composites. Materials; 2017; 10, 789. [DOI: https://dx.doi.org/10.3390/ma10070789]

33. Abbas, A.; Amjath-Babu, T.; Kächele, H.; Mueller, K. Non-structural flood risk mitigation under developing country conditions: An analysis on the determinants of willingness to pay for flood insurance in rural Pakistan. Nat. Hazards; 2014; 75, pp. 2119-2135. [DOI: https://dx.doi.org/10.1007/s11069-014-1415-x]

34. Zhao, H.; Zhang, X.; Zhang, S.; Chen, W.; Tong, D.Q.; Xiu, A. Effects of agricultural biomass burning on regional haze in China: A review. Atmosphere; 2017; 8, 88. [DOI: https://dx.doi.org/10.3390/atmos8050088]

35. Reddy, N.; Thillainayagam, V.A.; Yang, Y. Dyeing Natural Cellulose Fibers from Cornhusks: A Comparative Study with Cotton Fibers. Ind. Eng. Chem. Res.; 2011; 50, pp. 5642-5650. [DOI: https://dx.doi.org/10.1021/ie200217w]

36. Devi, S.; Gupta, C.; Parmar, M.S.; Jat, S.L.; Sisodia, N.; Kapil, N. Impact analysis of chemicals on properties of corn stalk fibre during different process. Pharma Innov. J.; 2019; 8, pp. 414-417.

37. Devi, S.; Gupta, C.; Parmar, M.S.; Jat, S.L.; Sisodia, N.; Kapil, N. Mechanical properties of reinforced polyester and epoxy composites of corn (Zea mays) stalk fibre. Indian J. Agric. Sci.; 2019; 89, pp. 873-876.

38. Yilmaz, N.D.; Michielsen, S.; Banks-Lee, P.; Powell, N.B. Effects of material and treatment parameters on noise-control performance of compressed three-layered multifiber needle-punched nonwovens. J. Appl. Polym. Sci.; 2011; 123, pp. 2095-2106. [DOI: https://dx.doi.org/10.1002/app.34712]

39. Herlina Sari, N.; Wardana, I.N.G.; Irawan, Y.S.; Siswanto, E. Characterization of the chemical, physical and mechanical properties of NaOH—Treated natural cellulosic fibers from corn husks. J. Nat. Fibers; 2018; 15, pp. 545-558. [DOI: https://dx.doi.org/10.1080/15440478.2017.1349707]

40. Chand, N.; Fahim, M. 1-Natural fibers and their composites. ‘Tribology’ of Natural Fiber Polymer Composites; 2nd ed. Woodhead Publishing Series in Composites Science and Engineering; Woodhead Publishing: Sawston, UK, 2021; pp. 1-59.

41. Sinha, M.K.; Ghosh, S.K. Processing of pineapple leaf fibers in jute machine. Indian Textile J.; 1977; 88, pp. 105-110.

42. Henriksson, G.; Akin, D.E.; Hanlin, R.T.; Rodriguez, C.; Archibald, D.D.; Rigsby, L.L.; Eriksson, K. Identification and retting efficiencies of fungi isolated from dew-retted flax in the United States and Europe. Appl. Environ. Microbiol.; 1997; 63, pp. 3950-3956. [DOI: https://dx.doi.org/10.1128/aem.63.10.3950-3956.1997]

43. Jawaid, M.; Abdul Khalil, H.P.S. Cellulosic/synthetic fiber reinforced polymer hybrid composites: A review. Carbohydr. Polym.; 2011; 86, pp. 1-18. [DOI: https://dx.doi.org/10.1016/j.carbpol.2011.04.043]

44. Arpitha, G.; Sanjay, M.; Senthamaraikannan, P.; Barile, C.; Yogesha, B. Hybridization Effect of Sisal/Glass/Epoxy/Filler Based Woven Fabric Reinforced Composites. Exp. Tech.; 2017; 41, pp. 577-584. [DOI: https://dx.doi.org/10.1007/s40799-017-0203-4]

45. Madhu, P.; Sanjay, M.R.; Senthamaraikannan, P.; Pradeep, S.; Saravanakumar, S.S.; Yogesha, B. A review on synthesis and characterization of commercially available natural fibers: Part II. J. Nat. Fibers; 2017; 16, pp. 25-36. [DOI: https://dx.doi.org/10.1080/15440478.2017.1379045]

46. Girijappa, Y.G.T.; Rangappa, S.M.; Parameswaranpillai, J.; Siengchin, S. Natural Fibers as Sustainable and Renewable Resource for Development of Eco-Friendly Composites: A Comprehensive Review. Front. Mater.; 2019; 6, 226. [DOI: https://dx.doi.org/10.3389/fmats.2019.00226]

47. Reddy, N.; Yang, Y. Biofibers from agricultural byproducts for industrial applications. Trends Biotechnol.; 2005; 23, pp. 22-27. [DOI: https://dx.doi.org/10.1016/j.tibtech.2004.11.002]

48. Huda, M.S.; Drzal, L.T.; Mohanty, A.K.; Misra, M. Effect of fiber surface-treatments on the properties of laminated biocomposites from poly (lactic acid) (PLA) and kenaf fibers. Compos. Sci. Technol.; 2008; 68, pp. 424-432. [DOI: https://dx.doi.org/10.1016/j.compscitech.2007.06.022]

49. Summers Cales, J. Durability of Composites in the Marine Environment. Durability of Composites in a Marine Environment; Solid Mechanics and Its Applications; Davies, P.; Rajapakse, Y. Springer: Dordrecht, Switzerland, 2014; Volume 208, [DOI: https://dx.doi.org/10.1007/978-94-007-7417-9_1]

50. Rao, P.V.; Subbaiah, G.; Veeraraghavaiah, R. Agronomic response of maize to plant population and nitrogen availability. Int. J. Plant Anim. Environ. Sci.; 2014; 4, pp. 107-116.

51. Karimah, A.; Ridho, M.R.; Munawar, S.S.; Adi, D.S.; Ismadi,; Damayanti, R.; Subiyanto, B.; Fatriasari, W.; Fudholi, A. A review on natural fibers for development of eco-friendly bio-composite: Characteristics, and utilizations. J. Mater. Res. Technol.; 2021; 13, pp. 2442-2458. [DOI: https://dx.doi.org/10.1016/j.jmrt.2021.06.014]

52. Liu, D.J.; Tao, X.Z.; Gao, L.X. Dry corn stalk nutrient distribution and palatability selection. J. Shenyang Agric. Univ.; 2019; 2, pp. 740-743.

53. Chen, Z.; Chem, Z.; Yi, J.; Feng, D. Preparation menthod of Corn stalk fiber material and its performance investigation in Asphalt concrete. Sustainability; 2019; 11, 4050. [DOI: https://dx.doi.org/10.3390/su11154050]

54. Johara, N.; Ahmad, I.; Dufresnec, A. Extraction, preparation and characterization of cellulose fibers and nanocrystals from rice husk. Ind. Crops Prod.; 2012; 37, pp. 93-99. [DOI: https://dx.doi.org/10.1016/j.indcrop.2011.12.016]

55. Kataki, S.; Hazarika, S.; Baruah, D.C. Investigation on by-products of bioenergy systems (anaerobic digestion and gasification) as potential crop nutrient using FTIR, XRD, SEM analysis and phyto-toxicity test. J. Environ. Manag.; 2017; 196, pp. 201-216. [DOI: https://dx.doi.org/10.1016/j.jenvman.2017.02.058]

56. Rosa, S.M.; Rehman, N.; de Miranda, M.I.G.; Nachtigall, S.M.; Bica, C.I. Chlorine-free extraction of cellulose from rice husk and whisker isolation. Carbohydr. Polym.; 2012; 87, pp. 1131-1138. [DOI: https://dx.doi.org/10.1016/j.carbpol.2011.08.084]

57. Reddy, N.; Yang, Y. Properties and potential applications of natural cellulose fibers from the bark of cotton stalks. Bioresour. Technol.; 2009; 100, pp. 3563-3569. [DOI: https://dx.doi.org/10.1016/j.biortech.2009.02.047]

58. Yılmaz, N.D. Effect of chemical extraction parameters on corn husk fibers characteristics. Indian J. Fiber Text. Res.; 2013; 38, pp. 29-34.

59. Reddy, N.; Yang, Y. Wiley Inter Science. 2007; Available online: www.interscience.wiley.com (accessed on 8 October 2022).

60. Reddy, N.; Yang, Y. Properties and potential applications of natural cellulose fibers from cornhusks. Green Chem.; 2005; 7, pp. 190-195. [DOI: https://dx.doi.org/10.1039/b415102j]

61. Segal, L.G.; Creely, J.J.; Martin, A.E., Jr.; Conrad, C.M. An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer. Text. Res. J.; 1959; 29, pp. 786-794. [DOI: https://dx.doi.org/10.1177/004051755902901003]

62. Mwaikambo, L. Review of the history, properties and application of plant fibres. Afr. J. Sci. Technol.; 2006; 7, 121.

63. Hearle, J.W.S.; Morton, W.E. Physical Properties of Textile Fibres; Elsevier: Amsterdam, The Netherlands, 2008; [DOI: https://dx.doi.org/10.1533/9781845694425]

64. Murthy, H.V. Fibre characteristics. Introduction to Textile Fibres; 1st ed. Murthy, H.V. Woodhead Publishing India in Textiles; Woodhead Publishing: Cambridge, UK, 2016; pp. 1-24.

65. Hornsby, P.R.; Hinrichsen, E.; Tarverdi, K. Preparation and properties of polypropylene composites reinforced with wheat and flax straw fibers: Part I fiber characterization. J. Mater. Sci.; 1997; 32, pp. 443-449. [DOI: https://dx.doi.org/10.1023/A:1018521920738]

66. Panthapulakkal, S.; Zereshkian, A.; Sain, M. Preparation and characterization of wheat straw fibers for reinforcing application in injection molded thermoplastic composites. Bioresour. Technol.; 2006; 97, pp. 265-272. [DOI: https://dx.doi.org/10.1016/j.biortech.2005.02.043]

67. Alemdar, A.; Sain, M. Isolation and characterization of nanofibers from agricultural residues—Wheat straw and soy hulls. Bioresour. Technol.; 2008; 99, pp. 1664-1671. [DOI: https://dx.doi.org/10.1016/j.biortech.2007.04.029]

68. Pereira, A.L.S.; Nascimento, D.M.D.; Filho, M.D.S.M.S.; Morais, J.P.S.; Vasconcelos, N.F.; Feitosa, J.P.; Brígida, A.I.S.; Rosa, M.D.F. Improvement of polyvinyl alcohol properties by adding nanocrystalline cellulose isolated from banana pseudostems. Carbohydr. Polym.; 2014; 112, pp. 165-172. [DOI: https://dx.doi.org/10.1016/j.carbpol.2014.05.090]

69. Williams, T.; Hosur, M.; Theodore, M.; Netravali, A.; Rangari, V.; Jeelani, S. Time Effects on Morphology and Bonding Ability in Mercerized Natural Fibers for Composite Reinforcement. Int. J. Polym. Sci.; 2011; 2011, 192865. [DOI: https://dx.doi.org/10.1155/2011/192865]

70. Mothé, C.; de Miranda, I. Characterization of sugarcane and coconut fibers by thermal analysis and FTIR. J. Therm. Anal. Calorim.; 2009; 97, pp. 661-665. [DOI: https://dx.doi.org/10.1007/s10973-009-0346-3]

71. Rachini, A.; Le Troedec, M.; Peyratout, C.; Smith, A. Chemical modification of hemp fibers by silane coupling agents. J. Appl. Polym. Sci.; 2012; 123, pp. 601-610. [DOI: https://dx.doi.org/10.1002/app.34530]