**3. Results and discussion**

### **3.1 Methods of obtaining pulp for preparation of nanocellulose**

Many factors determine the efficiency of the plant-based pulp production process, to which there has been a lot of research. These include technological, economic and environmental factors [31, 45, 57]. We are proposing to estimate efficiency of processes of delignification of plant raw materials by the diagram of dependence of pulp yield on the maintenance in it of residual lignin. For example, the dependence of pulp yield on the content of residual lignin for different methods of delignification of wheat straw is shown in **Figure 3**.

The proposed methodology for constructing diagram differs from the known lignin-carbohydrate diagrams of Ross, Geertz and Schmidt in the simplicity of construction, the essence of which is consists of the following [82]. On the y-axis the pulp yield

#### **Figure 3.**

*The dependence of the pulp yield on the residual lignin content for different methods of delignification of wheat straw: 1- line of "ideal" delignification; 2 - Acetic; 3 - Ester; 4 - Soda; 5 - two-stage alkali-alcohol; 6 - two-stage alkali-alcohol + AQ; 7 - Neutral-sulfite; 8 - Bisulfite; 9 - Alkaline- sulfite-alcohol + AQ; 10 - Peracetic; 11 - Ammonium-sulfite-alcohol; 12 - Ammonium-sulfite-alcohol + AQ.*

**67**

*Preparation, Properties and Use of Nanocellulose from Non-Wood Plant Materials*

the obtained pulp and thus delignification method is more efficient.

from various plants, which were used to obtain nanocellulose.

is indicated from 30% (for better visualization on the few percent lesser than cellulose content is in the plant raw material) to 100%. On the y-axis the point corresponding to holocellulose content is also indicated. On the x-axis, the percentage value of the lignin content in pulp is indicated from zero to maximum value in plant raw material. The intersection of horizontal axis at 100% yield and vertical axis of lignin content creates the point corresponding to initial composition of all plant components. The line, which links this point with the point of holocellulose content in plant raw material, can be considered as the line of ideal delignification‖. It characterizes maximal polysaccharide content for certain residual lignin content in pulp. Further, on the lignin-carbohydrate diagram, the dependencies of the yield on the residual content of lignin in the pulps obtained by different methods are plotted. So the closer the line of certain delignification method is to the line of ideal delignification, the higher is polysaccharide yield in

The dependencies presented in the diagram (**Figure 3**) allowed concluding that investigated delignification methods with approaching to the line of ideal delignification, i. e. with the increased efficiency of obtaining pulp from wheat straw, can be located in following sequence: Acetic – Ester – Soda – Neutral- sulfite – Bisulfite – two-stage alkali-alcohol – two-stage alkali-alcohol + AQ - Alkaline- sulfite-alcohol + AQ – Peracetic – Ammonium-sulfite-alcohol – Ammonium-sulfite-alcohol + AQ. This methodology is applicable to assess the efficiency of the processes of obtaining pulp from one type of raw material using different methods [83], and for a comparative assessment of the delignification of various types of plant raw materials by

To obtain cellulose with a minimum residual content of lignin and minerals, we used a two-stage method of delignification of NWPM [85–89]. Peracetic acid (PAA) was used as a reagent for the delignification of NWPM, which has bleaching properties. PAA leads to minimal fiber damage and is environmentally friendly [90]. We have already demonstrated the possibility of obtaining straw pulp by means of organosolv delignification in the system of isobutyl alcohol–H2O–KOH–hydrazine, which makes it possible to reuse the organic component and waste cooking liquor without regeneration [85]. At the same time, the waste liquor is divided into two layers: the upper organic solvent layer and the lower aqueous layer to which has moved the bulk of soluble minerals and organic substances from plant raw material (lignin, hemicelluloses, and extractives). The use of potassium and nitrogen compounds in the cooking liquor allows the use of waste liquor in the manufacture of fertilizers. **Table 1** shows the stages of preparation and indicators of the pulps

The data in **Table 1** show that carrying out the two-stage thermochemical treatment of NWPM makes it possible to almost completely remove lignin and minerals and obtain a pulp with a content of non-cellulose components of no more than 1%. The obtained organosolvent pulps are not inferior in quality, if not superior, to bleached sulphate pulp from softwood, and therefore were used for the production

We obtained nanofibrillated cellulose from air-dry bleached sulphate pulp of softwood using mechanochemical treatment [91]. It was carried out on grinding equipment, and hydrolysis with sulfuric acid solutions of various concentrations at temperatures from 20 to 60° C for 5–60 minutes. An increase of the acid concentration from 18–43% has led to an increase of the mechanical properties of the nanocellulose films. Further increase of the acid concentration above 50% leads to a sharp decrease of all strength properties and led to the formation of films with the

*DOI: http://dx.doi.org/10.5772/intechopen.94272*

one method [84].

of nanocellulose.

**3.2 Properties of nanocellulose**

#### *Preparation, Properties and Use of Nanocellulose from Non-Wood Plant Materials DOI: http://dx.doi.org/10.5772/intechopen.94272*

is indicated from 30% (for better visualization on the few percent lesser than cellulose content is in the plant raw material) to 100%. On the y-axis the point corresponding to holocellulose content is also indicated. On the x-axis, the percentage value of the lignin content in pulp is indicated from zero to maximum value in plant raw material. The intersection of horizontal axis at 100% yield and vertical axis of lignin content creates the point corresponding to initial composition of all plant components. The line, which links this point with the point of holocellulose content in plant raw material, can be considered as the line of ideal delignification‖. It characterizes maximal polysaccharide content for certain residual lignin content in pulp. Further, on the lignin-carbohydrate diagram, the dependencies of the yield on the residual content of lignin in the pulps obtained by different methods are plotted. So the closer the line of certain delignification method is to the line of ideal delignification, the higher is polysaccharide yield in the obtained pulp and thus delignification method is more efficient.

The dependencies presented in the diagram (**Figure 3**) allowed concluding that investigated delignification methods with approaching to the line of ideal delignification, i. e. with the increased efficiency of obtaining pulp from wheat straw, can be located in following sequence: Acetic – Ester – Soda – Neutral- sulfite – Bisulfite – two-stage alkali-alcohol – two-stage alkali-alcohol + AQ - Alkaline- sulfite-alcohol + AQ – Peracetic – Ammonium-sulfite-alcohol – Ammonium-sulfite-alcohol + AQ. This methodology is applicable to assess the efficiency of the processes of obtaining pulp from one type of raw material using different methods [83], and for a comparative assessment of the delignification of various types of plant raw materials by one method [84].

To obtain cellulose with a minimum residual content of lignin and minerals, we used a two-stage method of delignification of NWPM [85–89]. Peracetic acid (PAA) was used as a reagent for the delignification of NWPM, which has bleaching properties. PAA leads to minimal fiber damage and is environmentally friendly [90]. We have already demonstrated the possibility of obtaining straw pulp by means of organosolv delignification in the system of isobutyl alcohol–H2O–KOH–hydrazine, which makes it possible to reuse the organic component and waste cooking liquor without regeneration [85]. At the same time, the waste liquor is divided into two layers: the upper organic solvent layer and the lower aqueous layer to which has moved the bulk of soluble minerals and organic substances from plant raw material (lignin, hemicelluloses, and extractives). The use of potassium and nitrogen compounds in the cooking liquor allows the use of waste liquor in the manufacture of fertilizers. **Table 1** shows the stages of preparation and indicators of the pulps from various plants, which were used to obtain nanocellulose.

The data in **Table 1** show that carrying out the two-stage thermochemical treatment of NWPM makes it possible to almost completely remove lignin and minerals and obtain a pulp with a content of non-cellulose components of no more than 1%. The obtained organosolvent pulps are not inferior in quality, if not superior, to bleached sulphate pulp from softwood, and therefore were used for the production of nanocellulose.

#### **3.2 Properties of nanocellulose**

We obtained nanofibrillated cellulose from air-dry bleached sulphate pulp of softwood using mechanochemical treatment [91]. It was carried out on grinding equipment, and hydrolysis with sulfuric acid solutions of various concentrations at temperatures from 20 to 60° C for 5–60 minutes. An increase of the acid concentration from 18–43% has led to an increase of the mechanical properties of the nanocellulose films. Further increase of the acid concentration above 50% leads to a sharp decrease of all strength properties and led to the formation of films with the

*Novel Nanomaterials*

**3. Results and discussion**

10–60 nm in width, 500–2000 nm in length, and high aspect ratio L/D > 50 [77]. CNF is usually obtained by some kind of mechanical treatment of softwood pulp without any pretreatment or after chemical or enzymatic pretreatment. CNC particles are extracted from pulp, usually by hydrolysis, and have a diameter from 4

The hydrolysis of cellulosic materials remains the most common commercialscale CNC production method. The CNC yield after acid hydrolysis of pulp is 30–50% [62], and CNC films have brittle and rigid characteristics, which limits its use, for example, in flexible electronics. CNF has higher yield, good strength and good elasticity [79]. The combination of the intrinsic strength of CNF particles with the strong interaction between nanoparticles during drying makes it possible to

Typically, higher acid concentrations, longer reaction times, and higher temperatures lead to higher surface charge and narrow sizes, but to lower yield and decreased crystallinity and thermal stability of cellulose nanocrystals [81].

Many factors determine the efficiency of the plant-based pulp production process, to which there has been a lot of research. These include technological, economic and environmental factors [31, 45, 57]. We are proposing to estimate efficiency of processes of delignification of plant raw materials by the diagram of dependence of pulp yield on the maintenance in it of residual lignin. For example, the dependence of pulp yield on the content of residual lignin for different methods

The proposed methodology for constructing diagram differs from the known lignin-carbohydrate diagrams of Ross, Geertz and Schmidt in the simplicity of construction, the essence of which is consists of the following [82]. On the y-axis the pulp yield

*The dependence of the pulp yield on the residual lignin content for different methods of delignification of wheat straw: 1- line of "ideal" delignification; 2 - Acetic; 3 - Ester; 4 - Soda; 5 - two-stage alkali-alcohol; 6 - two-stage alkali-alcohol + AQ; 7 - Neutral-sulfite; 8 - Bisulfite; 9 - Alkaline- sulfite-alcohol + AQ; 10 -* 

*Peracetic; 11 - Ammonium-sulfite-alcohol; 12 - Ammonium-sulfite-alcohol + AQ.*

to 20 nm, a length 100–300 nm, and low aspect ratio L/D > 5 [78].

obtain a more rigid and flexible film from CNF than from CNC [80].

**3.1 Methods of obtaining pulp for preparation of nanocellulose**

of delignification of wheat straw is shown in **Figure 3**.

**66**

**Figure 3.**


*\* isobutanol: mixture of isobutanol-KOH–hydrazine, 120 min at 95 ± 2°C.*

*\*\*PAA: mixture of acetic acid and hydrogen peroxide in a volume ratio of 70:30%, 120 min, at 95 ± 2°C.*

*\*\*\*- solution 5% NaOH, 120 min, at 95 ± 2°C.*

#### **Table 1.**

*Indicators of pulps from various plant materials for the production of nanocellulose.*

brownish color. We recommended a reduced sulfuric acid concentration of 43% at 60°C during 60 minutes as the main process parameters for the production of NC by hydrolysis of organosolvent pulp from NWPM [87–89]. Such conditions agree well with data in [92] and are economically more favorable than traditional conditions for hydrolysis of cellulose with 60–65% sulfuric acid at 40–50°C for 1–2 h [93]. We used never-dried organosolvent pulps from NWPM to prepare NC. Never dried pulp is better than once dried sample, as the drying process leads to cornification of the fibers, which reduces the impregnation of the fibers with chemicals during their hydrolysis. Using of never-dried pulp does not require the consumption of energy for drying and grinding since dried cellulose fibers lose the ability to swell and percolate due to irreversible cornification.

Hydrolyzed NC was washed three times with distilled water by centrifugation at 8000 rpm, followed by dialysis to achieve a neutral pH and ultrasonic treatment during 30–60 min. As a result, the suspension took the form of a homogeneous gel-like dispersion and was stored in sealed containers for further research in order to determine the physical and mechanical characteristics of the NC. The prepared suspensions were poured into Petri dishes and dried in the air at a room temperature to obtain NC films. The structural change and crystallinity index of organosolvent pulps and NC were studied by means of SEM and XRD techniques. TEM and AFM methods were used to determine the particle size of nanocellulose **(Figure 4**). Transparency of the NC films was determined by electron absorption spectra, and tensile strength - according to ISO 527-1. The indicators of the obtained NC from NWPM is shown in the **Table 2**.

As can be seen from **Figure 4** and the data in **Table 2**, the process of hydrolysis and ultrasonic treatment of pulps leads to the formation of nanosized particles. NC had homogeneous and stable nanocellulose suspension. The nature of stabilization of the colloidal suspension is explained by the presence of charged groups on the surface of nanocellulose, which are formed by the interaction of cellulose with sulfate acid due to the esterification reaction. The structure of the NC films, according to SEM, TEM and AFM data, was similar to the structure of the film obtained from nanofibrillar cellulose [95]. The obtained NC had high tensile strength from 42.3 to 70 MPa and Young's modulus from 8.9 to 11.45 GPa. The obtained samples

**69**

**Figure 4.**

**3.3 Application of nanocellulose**

*projection (f) with definition of sample height tapping mode.*

*Preparation, Properties and Use of Nanocellulose from Non-Wood Plant Materials*

of NC from NWPM physical and mechanical parameters, comparable to the values obtained by other researchers. For instance, Young's modulus values of films generated from nanofibrillated bleached pulp, wheat straw, and recycled newspaper were between 6,0 and 9,0 GPa [96]. The positive results of obtaining NC from NWPM are given in other sources [97–99]. The properties of NC from NWPM exhibit great potential for their application to new nanocomposite materials and consumer goods.

*TEM images of nanocellulose prepared by hydrolysis from bleached sulphate pulp (a) and organosolvent wheat straw pulp (b); AFM images of nanocellulose from kenaf* (*c) and lateral size of its nanocellulose surface (d); and AFM images of nanocellulose from miscanthus: The lateral size of the nanocellulose surface (*e*) and 3D* 

Due to its unique properties, nanocellulose is widely used in various fields: in the production of electronic devices and composites, as a natural material for replacing synthetic reinforcing substances in the paper, chemical, pharmaceutical, cement

*DOI: http://dx.doi.org/10.5772/intechopen.94272*

*Preparation, Properties and Use of Nanocellulose from Non-Wood Plant Materials DOI: http://dx.doi.org/10.5772/intechopen.94272*

#### **Figure 4.**

*Novel Nanomaterials*

**obtaining**

Wheat straw, PAA\*\* [86]

Flax fiber, PAA [87]

Miscanthus, PAA [89]

Kenaf, PAA [88]

*\**

**Table 1.**

**Pulp from a plant and a method of** 

*\*\*\*- solution 5% NaOH, 120 min, at 95 ± 2°C.*

Wheat straw, isobutanol\* [85] I – isobutanol

Bleached sulphate softwood pulp I – grinding to

*isobutanol: mixture of isobutanol-KOH–hydrazine, 120 min at 95 ± 2°C.*

*Indicators of pulps from various plant materials for the production of nanocellulose.*

brownish color. We recommended a reduced sulfuric acid concentration of 43% at 60°C during 60 minutes as the main process parameters for the production of NC by hydrolysis of organosolvent pulp from NWPM [87–89]. Such conditions agree well with data in [92] and are economically more favorable than traditional conditions for hydrolysis of cellulose with 60–65% sulfuric acid at 40–50°C for 1–2 h [93]. We used never-dried organosolvent pulps from NWPM to prepare NC. Never dried pulp is better than once dried sample, as the drying process leads to cornification of the fibers, which reduces the impregnation of the fibers with chemicals during their hydrolysis. Using of never-dried pulp does not require the consumption of energy for drying and grinding since dried cellulose fibers lose the ability to swell and

*\*\*PAA: mixture of acetic acid and hydrogen peroxide in a volume ratio of 70:30%, 120 min, at 95 ± 2°C.*

**Stages of preparation of pulp**

II – PAA\*\*

I – NaOH\*\*\* II - PAA

I – PAA II - NaOH

I – PAA II - NaOH

I – PAA II - NaOH

> 93 o SR

**Yield, %**

> 49.0 41.5

54.9 51.1

68.2 52.8

61.2 51.2

50.7 57.0 **Lignin, %**

> 1.1 0.2

> 9.8 0.4

1.7 0.02

0.37 0.29

0.25 0.08

— 0.23 0.21

**Ash, %**

1.63 0.2

0.98 0.09

0.5 0.04

0.24 0.18

0.96 0.04

Hydrolyzed NC was washed three times with distilled water by centrifugation at 8000 rpm, followed by dialysis to achieve a neutral pH and ultrasonic treatment during 30–60 min. As a result, the suspension took the form of a homogeneous gel-like dispersion and was stored in sealed containers for further research in order to determine the physical and mechanical characteristics of the NC. The prepared suspensions were poured into Petri dishes and dried in the air at a room temperature to obtain NC films. The structural change and crystallinity index of organosolvent pulps and NC were studied by means of SEM and XRD techniques. TEM and AFM methods were used to determine the particle size of nanocellulose **(Figure 4**). Transparency of the NC films was determined by electron absorption spectra, and tensile strength - according to ISO 527-1. The indicators of the obtained NC from

As can be seen from **Figure 4** and the data in **Table 2**, the process of hydrolysis and ultrasonic treatment of pulps leads to the formation of nanosized particles. NC had homogeneous and stable nanocellulose suspension. The nature of stabilization of the colloidal suspension is explained by the presence of charged groups on the surface of nanocellulose, which are formed by the interaction of cellulose with sulfate acid due to the esterification reaction. The structure of the NC films, according to SEM, TEM and AFM data, was similar to the structure of the film obtained from nanofibrillar cellulose [95]. The obtained NC had high tensile strength from 42.3 to 70 MPa and Young's modulus from 8.9 to 11.45 GPa. The obtained samples

percolate due to irreversible cornification.

NWPM is shown in the **Table 2**.

**68**

*TEM images of nanocellulose prepared by hydrolysis from bleached sulphate pulp (a) and organosolvent wheat straw pulp (b); AFM images of nanocellulose from kenaf* (*c) and lateral size of its nanocellulose surface (d); and AFM images of nanocellulose from miscanthus: The lateral size of the nanocellulose surface (*e*) and 3D projection (f) with definition of sample height tapping mode.*

of NC from NWPM physical and mechanical parameters, comparable to the values obtained by other researchers. For instance, Young's modulus values of films generated from nanofibrillated bleached pulp, wheat straw, and recycled newspaper were between 6,0 and 9,0 GPa [96]. The positive results of obtaining NC from NWPM are given in other sources [97–99]. The properties of NC from NWPM exhibit great potential for their application to new nanocomposite materials and consumer goods.

#### **3.3 Application of nanocellulose**

Due to its unique properties, nanocellulose is widely used in various fields: in the production of electronic devices and composites, as a natural material for replacing synthetic reinforcing substances in the paper, chemical, pharmaceutical, cement


**Table 2.**

*The indicators of the obtained nanocellulose from NWPM.*

industries [100–104]. In the last few years, the cellulosic biopolymer-based green electronics is supplemented by lightweight, portable, flexible NC-based power generators to provide energy to wearable electronics through harvesting mechanical energy in triboelectric and piezoelectric appliances [105, 106]. Huge ecological advantage of the NC-based electronic and thermoelectric devices is their inherent biodegradability. As these devices have become ubiquitous in modern society, and are prevalent in every facet of human activities, and the lifetime of electronics get shorter and shorter, the pressure on electronic waste (e-waste) management systems is mounting with no abate insight. This poses a growing ecological problem, and an alternative to traditional electronics is biodegradable electronics as the most viable replacement to address the issue of uncontrollable e-waste to reduce the environmental footprint of devices [107, 108]. Recently, nanocellulose is used for the preparation of porous carbon that be used as a high-performance supercapacitor electrode [109–111].

The use of nanocellulose in energy harvesting is illustrated in the following articles [112–114]. We used conversion of solar energy into chemical energy of biomass of fast-growing perennial herb Miscanthus to fabricate via an environmentally friendly method of organosolvent delignification low-cost NC films used as substrates for the creation of new biodegradable thin film thermoelectric material [115]. To do this, we applied a 0.72-μm CuI film onto a 12-μm NC substrate using a low-temperature, low-cost and scalable sequential ion layer adsorption method and thus obtained a lightweight and flexible biodegradable CuI thermoelectric material CuI/NC. We found out that nanostructured p-type semiconductor CuI film in the CuI/NC thermoelectric material is quite dense and completely covers the NC surface. The determined value of the Seebeck coefficient (*S)* is about 228 μVK−1 more than an order of magnitude higher than the Seebeck coefficients that were measured earlier for the nanocellulose-derived organic and composite materials contained poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS), silver nanoparticles and carbon nanotubes [116]. The coefficient *S* obtained by us even exceeds the *S* values for the different thin-film composites of such well-known inorganic thermoelectric material as Bi2Te3 [117]. At that, *S* is constant in the temperature range 290–335 K, which is favorable for the use of CuI/ NC as new thermoelectric material for an in-plane design of biodegradable flexible thin film thermoelectric generator. The thermoelectric power factor of CuI/NC is about 36 μW·m−1·K−2 is higher than that of the best examples bacterial nanocellulose films with embedded highly dispersed carbon nanotubes networks (20 μW·m−1·K−2) in article [118]. At temperature gradient of 50 K, the single *p*-CuI thermoelectric

**71**

**Figure 5.**

*pulp (II) with different consumption (g/m2*

*dotted line - line of standards requirements.*

*Preparation, Properties and Use of Nanocellulose from Non-Wood Plant Materials*

leg made from CuI/NC generates Voc = 8.4 mV. It corresponds to the power density

friendly biodegradable flexible thin-film thermoelectric material can be effectively used to convert low-grade waste heat into electricity at temperatures close to room

The use of NC during paper formation or even coating of dry formed paper can improve interfiber bonding, softness and printability and, consequently, physicalmechanical properties [119–121]. **Figures 5**–**7** show the results of using NC from NWPM for the production of mass grades of paper and cardboard [122, 123].

As can be seen from the data in **Figures 5**–**7**, the application of NC to the surface of paper and cardboard has a positive effect on their physical and mechanical properties. Low consumption of NC allows production of the paper and cardboard with properties that meet the requirements to appropriate standards and replacement of synthetic reinforcing materials [123]. The increase in the values of the indicators of paper and cardboard occurs due to the creation of new hydrogen bonds between the fibers of cellulose and NC, which is confirmed by other authors [124, 125]. NC often replaces such well-known material, as glass and certain polymers, which are not biodegradable at ambient conditions. Modern technologies allow use NC

*Properties of paper for corrugating (a, b, c) and paper for bags (d, e, f) from waste paper (I) and unbleached* 

*) of nanocellulose from NWPM per paper surface; asterisk or* 

. Due to the complex of these properties, the developed environmentally

*DOI: http://dx.doi.org/10.5772/intechopen.94272*

10 μW/m2

temperature [115].

#### *Preparation, Properties and Use of Nanocellulose from Non-Wood Plant Materials DOI: http://dx.doi.org/10.5772/intechopen.94272*

leg made from CuI/NC generates Voc = 8.4 mV. It corresponds to the power density 10 μW/m2 . Due to the complex of these properties, the developed environmentally friendly biodegradable flexible thin-film thermoelectric material can be effectively used to convert low-grade waste heat into electricity at temperatures close to room temperature [115].

The use of NC during paper formation or even coating of dry formed paper can improve interfiber bonding, softness and printability and, consequently, physicalmechanical properties [119–121]. **Figures 5**–**7** show the results of using NC from NWPM for the production of mass grades of paper and cardboard [122, 123].

As can be seen from the data in **Figures 5**–**7**, the application of NC to the surface of paper and cardboard has a positive effect on their physical and mechanical properties. Low consumption of NC allows production of the paper and cardboard with properties that meet the requirements to appropriate standards and replacement of synthetic reinforcing materials [123]. The increase in the values of the indicators of paper and cardboard occurs due to the creation of new hydrogen bonds between the fibers of cellulose and NC, which is confirmed by other authors [124, 125]. NC often replaces such well-known material, as glass and certain polymers, which are not biodegradable at ambient conditions. Modern technologies allow use NC

#### **Figure 5.**

*Properties of paper for corrugating (a, b, c) and paper for bags (d, e, f) from waste paper (I) and unbleached pulp (II) with different consumption (g/m2 ) of nanocellulose from NWPM per paper surface; asterisk or dotted line - line of standards requirements.*

*Novel Nanomaterials*

Bleached sulphate softwood

*The indicators of the obtained nanocellulose from NWPM.*

pulp [91]

**Table 2.**

**Nanocellulose from plant Density,**

**g/cm3**

**Particle diameter, nm**

Wheat straw isobutanol [94] 1.3 10–40 42 72.2 70 Wheat straw PAA [86] 1.27 16–20 123 71.3 78 Flax [87] 1.37 20–60 70 62.0 60 Kenaf [88] 1.39 10–28 65 80.0 72 Miscanthus [89] 1.32 10–18 62 76.7 74

**Tensile strength, MPa**

1.38 15–30 88 79.8 78

**Crystallinity index, %**

**Transparency, %**

electrode [109–111].

industries [100–104]. In the last few years, the cellulosic biopolymer-based green electronics is supplemented by lightweight, portable, flexible NC-based power generators to provide energy to wearable electronics through harvesting mechanical energy in triboelectric and piezoelectric appliances [105, 106]. Huge ecological advantage of the NC-based electronic and thermoelectric devices is their inherent biodegradability. As these devices have become ubiquitous in modern society, and are prevalent in every facet of human activities, and the lifetime of electronics get shorter and shorter, the pressure on electronic waste (e-waste) management systems is mounting with no abate insight. This poses a growing ecological problem, and an alternative to traditional electronics is biodegradable electronics as the most viable replacement to address the issue of uncontrollable e-waste to reduce the environmental footprint of devices [107, 108]. Recently, nanocellulose is used for the preparation of porous carbon that be used as a high-performance supercapacitor

The use of nanocellulose in energy harvesting is illustrated in the following articles [112–114]. We used conversion of solar energy into chemical energy of biomass of fast-growing perennial herb Miscanthus to fabricate via an environmentally friendly method of organosolvent delignification low-cost NC films used as substrates for the creation of new biodegradable thin film thermoelectric material [115]. To do this, we applied a 0.72-μm CuI film onto a 12-μm NC substrate using a low-temperature, low-cost and scalable sequential ion layer adsorption method and thus obtained a lightweight and flexible biodegradable CuI thermoelectric material CuI/NC. We found out that nanostructured p-type semiconductor CuI film in the CuI/NC thermoelectric material is quite dense and completely covers the NC surface. The determined value of the Seebeck coefficient (*S)* is about 228 μVK−1 more than an order of magnitude higher than the Seebeck coefficients that were measured earlier for the nanocellulose-derived organic and composite materials contained poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS), silver nanoparticles and carbon nanotubes [116]. The coefficient *S* obtained by us even exceeds the *S* values for the different thin-film composites of such well-known inorganic thermoelectric material as Bi2Te3 [117]. At that, *S* is constant in the temperature range 290–335 K, which is favorable for the use of CuI/ NC as new thermoelectric material for an in-plane design of biodegradable flexible thin film thermoelectric generator. The thermoelectric power factor of CuI/NC is about 36 μW·m−1·K−2 is higher than that of the best examples bacterial nanocellulose films with embedded highly dispersed carbon nanotubes networks (20 μW·m−1·K−2) in article [118]. At temperature gradient of 50 K, the single *p*-CuI thermoelectric

**70**

**Figure 6.**

*Properties of cardboard for flat layers of corrugating cardboard with different consumption of sizing agents on 1 m2 : Without application (1); 7 g of glue (2); 3.5 g of nanocellulose (3); 3.5 g of glue and 3.5 g of nanocellulose (4); 7 g of nanocellulose (5); asterisk: Line of standard requirements.*

#### **Figure 7.**

*Properties of recycled cardboard with different nanocellulose consumption; asterisk: Line of standard requirements.*

in energy storage systems [126], biosensors [127], as well as in various electronic and optoelectronic devices [128, 129]. Among them, transparent transistors, light emitting diodes, solar cells, antennas and radiofrequency identification devices, high-performance loudspeakers, and lightweight actuators [130, 131].

Nano-sized cellulose fibers are considered as promising candidates for the production of nanocomposites. NC was added to polymer matrices to obtain reinforced composites with mechanical strengths from ten to one hundred times and to improve barrier properties [132–134].

Loading of structural materials with NC particles makes it possible to reduce their weight while maintaining the strength of the composites [135, 136]. For instance, addition of 6.5% nanofibrils improved the tensile strength and elongation at the break of the nanocomposite from cassava starch and polyvinyl alcohol by 24% and 51%, respectively. At the same time, the water vapor permeability and water solubility of the nanocomposite containing high contents of nanofibrils decreased up to 20% and 30%, respectively, in relation to the control blend [137]. A high effect of reinforcement was observed even at a low content of CNC when used to obtain nanocomposites with a matrix of natural rubber. With the addition of only 2.5 wt % CNC, which were isolated from soybean husks by acid sulfur hydrolysis, the elastic modulus of the composite was about 21 times higher than that of a pure rubber matrix [138]. In [139] it was shown that the addition of 10% NC from miscanthus to a composite based on epoxy resin Eposir-7120 with a polyethylene polyamine

**73**

**Author details**

this paper.

**Acknowledgements**

financial support.

**Conflict of interest**

Kyiv, Ukraine

Valerii Barbash\* and Olga Yaschenko

\*Address all correspondence to: v.barbash@kpi.ua

provided the original work is properly cited.

National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute",

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

The authors are grateful to the co-authors of the previous articles for carrying out our joint research and to the Ministry of Education and Science of Ukraine for

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in

*Preparation, Properties and Use of Nanocellulose from Non-Wood Plant Materials*

sion resistance values than the resistance of the original hydrogel [140].

hardener increases the elastic modulus of the composite by 12.2% with respect to the control mixture. Otherwise, adding 5% NC from Colombian fique to acrylic hydrogels made it possible to obtain a reinforced hydrogel with 2.5 times higher compres-

With the increasing requirements for environmental protection, there is a need to replace exhaustible sources - oil, gas, coal, and existing forest resources with biodegradable and renewable, including non-wood plant raw materials (NWPM). NWPM have the necessary reserves and properties to make up for a possible shortage of wood fiber for pulp production. To obtain pulp suitable for the production of nanocellulose (NC), a two-stage technology for delignification of NWPM with reagents that does not contain sulfur and chlorine has been proposed. NC has unique physical and mechanical properties and can replace well-known materials such as glass and some polymers, which are not biodegradable under ambient conditions. Methods for preparing nanocellulose are described. The influence of the main technological parameters of the cellulose hydrolysis process on the properties of nanocellulose is discussed. It is proposed to carry out the hydrolysis of cellulose using 43% concentration of sulfuric acid. Examples of the use of nanocellulose in various industries are given.

*DOI: http://dx.doi.org/10.5772/intechopen.94272*

**4. Conclusions**

hardener increases the elastic modulus of the composite by 12.2% with respect to the control mixture. Otherwise, adding 5% NC from Colombian fique to acrylic hydrogels made it possible to obtain a reinforced hydrogel with 2.5 times higher compression resistance values than the resistance of the original hydrogel [140].
