5. Limitation and modification of nanocrystalline cellulose

There are several limitations when using natural fibers as reinforcement filler in the polymer matrix such as single-particle dispersion, barrier properties,

Figure 8. Limitation of nanocellulose. Adapted from Refs. [6, 7, 10].

permeability properties, and poor interfacial adhesion (Figure 8). Nanocrystalline cellulose has a strong propensity of self-association due to the interaction of abundance OH groups within its surface, which causes agglomeration and limits its potential applications. Besides, hydrophilic properties of nanocrystalline cellulose make it difficult to disperse homogenously within any medium and matrix. Therefore, in order to overcome the incompatible nature, poor interfacial adhesion, and difficult dispersion of nanocrystalline cellulose in a polymer matrix, surface modification of fibers or modification of matrix is introduced. Nanocellulose displays a high surface area valued more than 100 m<sup>2</sup> /g. This gives advantages to nanocellulose for surface modification in order to introduce any desired surface functionality. However, according to Postek et al. [98], the surface chemistry of nanocellulose is primarily controlled by the process of isolation that used to prepare these nanocelluloses from raw cellulose substrate. Figure 9 shows the most common surface chemical modifications of nanocrystalline cellulose. Surface modification of NCC can be categorized into three typical groups, namely, (1) polymer grafting based on "grafting onto" strategy with different coupling agents (as indicated with blue arrows in Figure 9), (2) substitution of hydroxyl group with small molecules (as indicated with red arrows in Figure 9), and (3) polymer grafting

based on the "grafting from" approach with a radical polymerization involving single-electron transfer-living radical polymerization (SET-LP), ring opening polymerization (ROP), and atom transfer radical polymerization (ATRP) (as indicated with yellow arrows in Figure 9). The enhancement of NCC-polymer matrix interaction is predicted to improve the stress transfer from the matrix to the dispersed phase and hence enhances the capability of load bearing material. Besides, the chemical modification of NCC can be dispersed in the low polarity of organic solvent and mixed with a polymer matrix solution or directly introduced into the polymer melt after drying. Nevertheless, two effects ascend from this process: (1) allow the improvement of dispersion of modified NCC in the polymer matrix and (2) limit the interaction between NNC and matrix through hydrogen bonding which is the basis of the outstanding mechanical properties of nanocellulose-based

Production, Processes and Modification of Nanocrystalline Cellulose from Agro-Waste: A Review

6. Applications of nanocrystalline cellulose from agro-waste fiber

The incorporation of nanocrystalline cellulose in biopolymers for the nanocomposite production provides huge advantages with superior performance which would extend their applications in various applications. This is due to their outstanding thermal and mechanical properties. NCC also can reduce the water vapor permeability of the composites due to its high gas permeability [26]. Besides that, NCC can be used to stabilize the encapsulated bioactive compounds in biopolymers for allowing better control in food applications which can improve the food quality, extend the shelf-life of food, and serve as active substance carriers such as antifungal, antioxidant compounds, antimicrobial, and insecticide.

The utilization of natural cellulose-based materials continues today as verified by the various industry players from forest product to make pulp and paper to the advanced technology used in biomedical applications. These uses have been

reported extensively as summarized in Table 4. NCC can be used as a drug delivery

Applications References

Interface melting [101]

Transparent, rubbery materials [102]

Optical devices [105]

[104]

Solution mixing Drug carrier [100]

Electrospinning Bone tissue engineering [103]

Solution casting Smart actuators and sensors [106]

Thermoreversible and tunable nanocellulose-based hydrogels

nanocomposites.

and forest by-products

DOI: http://dx.doi.org/10.5772/intechopen.87001

Polymer component Manufacturing

Methylcellulose Hydrogel by aqueous

PC Masterbatch melt

Cellulose esterified with lauroyl chloride

Ethyl acrylate; methylmethacrylate

Ethylene-co-vinyl acetate rubber

Maleic-anhydride grafted PLA

PC-based polyurethane

blend

101

technique

dispersion

extrusion process

Plasticized PLA Twin-screw extruder Film blowing, packaging [107] Plasticized starch Solution casting Transparent materials [108]

Solution casting and thermopressing

Solution mixing and vulcanization

#### Figure 9.

Schematic diagram illustrating nanocellulose surface functionalization modification. PEG, poly(ethylene glycol); PEO, poly(ethylene oxide); PLA, poly(lactic acid); PAA, poly(acrylic acid); PNiPAAm, poly(Nisopropylacrylamide); PDMAEMA, poly(N,N-dimethylaminoethyl methacrylate). Adapted from Ref. [99].

Production, Processes and Modification of Nanocrystalline Cellulose from Agro-Waste: A Review DOI: http://dx.doi.org/10.5772/intechopen.87001

based on the "grafting from" approach with a radical polymerization involving single-electron transfer-living radical polymerization (SET-LP), ring opening polymerization (ROP), and atom transfer radical polymerization (ATRP) (as indicated with yellow arrows in Figure 9). The enhancement of NCC-polymer matrix interaction is predicted to improve the stress transfer from the matrix to the dispersed phase and hence enhances the capability of load bearing material. Besides, the chemical modification of NCC can be dispersed in the low polarity of organic solvent and mixed with a polymer matrix solution or directly introduced into the polymer melt after drying. Nevertheless, two effects ascend from this process: (1) allow the improvement of dispersion of modified NCC in the polymer matrix and (2) limit the interaction between NNC and matrix through hydrogen bonding which is the basis of the outstanding mechanical properties of nanocellulose-based nanocomposites.

#### 6. Applications of nanocrystalline cellulose from agro-waste fiber and forest by-products

The incorporation of nanocrystalline cellulose in biopolymers for the nanocomposite production provides huge advantages with superior performance which would extend their applications in various applications. This is due to their outstanding thermal and mechanical properties. NCC also can reduce the water vapor permeability of the composites due to its high gas permeability [26]. Besides that, NCC can be used to stabilize the encapsulated bioactive compounds in biopolymers for allowing better control in food applications which can improve the food quality, extend the shelf-life of food, and serve as active substance carriers such as antifungal, antioxidant compounds, antimicrobial, and insecticide.

The utilization of natural cellulose-based materials continues today as verified by the various industry players from forest product to make pulp and paper to the advanced technology used in biomedical applications. These uses have been reported extensively as summarized in Table 4. NCC can be used as a drug delivery


permeability properties, and poor interfacial adhesion (Figure 8). Nanocrystalline cellulose has a strong propensity of self-association due to the interaction of abundance OH groups within its surface, which causes agglomeration and limits its potential applications. Besides, hydrophilic properties of nanocrystalline cellulose make it difficult to disperse homogenously within any medium and matrix. Therefore, in order to overcome the incompatible nature, poor interfacial adhesion, and difficult dispersion of nanocrystalline cellulose in a polymer matrix, surface modification of fibers or modification of matrix is introduced. Nanocellulose displays a

nanocellulose for surface modification in order to introduce any desired surface functionality. However, according to Postek et al. [98], the surface chemistry of nanocellulose is primarily controlled by the process of isolation that used to prepare these nanocelluloses from raw cellulose substrate. Figure 9 shows the most common surface chemical modifications of nanocrystalline cellulose. Surface modification of NCC can be categorized into three typical groups, namely, (1) polymer grafting based on "grafting onto" strategy with different coupling agents (as indicated with blue arrows in Figure 9), (2) substitution of hydroxyl group with small molecules (as indicated with red arrows in Figure 9), and (3) polymer grafting

Schematic diagram illustrating nanocellulose surface functionalization modification. PEG, poly(ethylene glycol); PEO, poly(ethylene oxide); PLA, poly(lactic acid); PAA, poly(acrylic acid); PNiPAAm, poly(Nisopropylacrylamide); PDMAEMA, poly(N,N-dimethylaminoethyl methacrylate). Adapted from Ref. [99].

/g. This gives advantages to

high surface area valued more than 100 m<sup>2</sup>

Nanocrystalline Materials

Figure 9.

100


Source Filler Polymer matrix Ref. MCC NCC PLA (5 wt% filler) [121] Potato pulp NFC Starch/glycerol (0–40 wt% filler) [122] Ramie NFC Unsaturated polyester resin [85] Ramie NCC Starch/glycerol (0–40 wt% filler) [87] Rutabaga NFC PVA (10 wt% filler) [120] Soy hulls NFC No attempts were made with composites [29]

Production, Processes and Modification of Nanocrystalline Cellulose from Agro-Waste: A Review

Tunicate NCC Styrene/butyl acrylate (6 wt% filler), starch/sorbitol

Wheat straw NFC No attempts were made with composites [29] Wheat straw NCC Wheat straw hemicelluloses [96]

Cassava bagasse NCC Cassava starch [62] Ramie NCC Wheat starch [87]

Flax fiber NCC PVA [83] Potato peel fiber NCC Starch [84]

Polymer References Cellulose acetate butyrate [58, 129] Cellulose [130] Chitosan [131–133] Poly(acrylic) acid, PAA [134] Poly-(allylmethylamine hydrochloride), PAH [135] Poly-(dimethyldiallylammonium chloride), PDDA [136] Poly(ethylene-co-vinyl acetate), EVA [137] Poly(hydroxyalkanoate), PHA [133, 138] Poly(hydroxyoctanoate), PHO [139]

Poly(lactic acid), PLA [118, 121, 140–144]

Poly(methyl-methacrylate), PMMA [145, 146] Poly(oxyethylene), PEO [147, 148]

Different nanocellulose sources of reinforcement fillers in polymer matrices.

Styrene/butyl acrylate (6 wt% filler) [123]

[94, 124– 126]

(25 wt% filler), waterborne epoxy (0.5–5 wt% filler)

NCC Yam bean starch [48]

NFC Yam bean starch [127]

NCC PVA [83]

PVA (10 wt% filler), PLA (5 wt% filler) [120, 128]

Sugar beet NFC/

Wood pulp NFC/

Water hyacinth

Water hyacinth

Phormium tenax (harakeke) fiber

Table 5.

103

fiber

fiber

NCC

DOI: http://dx.doi.org/10.5772/intechopen.87001

NCC

#### Table 4.

Polymer component reinforced NCCs and its manufacturing technique and applications.

excipient; Burt et al. [100] investigated the capability of pure NCC to bind watersoluble antibiotics (tetracycline and doxorubicin) and the potential of cationic NCC to bind non-ionized hydrophobic anticancer agents (docetaxel, paclitaxel, and etoposide). Moreover, besides direct use as drug delivery excipient, NCC can also be used as co-stabilizer to improve the physicochemical and flow properties of polymeric excipients. Acrylic beads prepared via emulsion polymerization using NCC as co-stabilizer were proven to be a suitable excipient.

Table 5 shows several nanocelluloses, NFCs, and NCCs that have been used as reinforcement fillers in polymer matrices. The polymer matrices used are from both synthetic and natural polymers. Table 6 shows examples of NCCs used as fillers in polymeric matrices.


Production, Processes and Modification of Nanocrystalline Cellulose from Agro-Waste: A Review DOI: http://dx.doi.org/10.5772/intechopen.87001


#### Table 5.

excipient; Burt et al. [100] investigated the capability of pure NCC to bind watersoluble antibiotics (tetracycline and doxorubicin) and the potential of cationic NCC to bind non-ionized hydrophobic anticancer agents (docetaxel, paclitaxel, and etoposide). Moreover, besides direct use as drug delivery excipient, NCC can also be used as co-stabilizer to improve the physicochemical and flow properties of polymeric excipients. Acrylic beads prepared via emulsion polymerization using

PVA Solution casting Food packaging [83] Chitosan Solution casting Food coating/packaging [70]

Polymer component reinforced NCCs and its manufacturing technique and applications.

Table 5 shows several nanocelluloses, NFCs, and NCCs that have been used as reinforcement fillers in polymer matrices. The polymer matrices used are from both synthetic and natural polymers. Table 6 shows examples of NCCs used as fillers in

Source Filler Polymer matrix Ref. Sugar palm NCC Sugar palm starch [117] Sugar palm NFC Sugar palm starch [115] Acacia mangium NCC PVA [56] Bacteria NCC CAB (0–10 wt% filler) [58] Cotton NCC PVA (0–12 wt% filler) [118]

> PVA (10 wt% filler), waterborne polyurethanes (0–30 wt% filler)

Hemp NFC PVA (10 wt% filler) [120] Kraft pulp NCC Waterborne acrylate [79]

NCC as co-stabilizer were proven to be a suitable excipient.

Polymer component Manufacturing

Nanocrystalline Materials

Starch Blending, solution

technique

casting

PU Solution casting High temperature biomedical devices [109] PVA Solution casting Stretchable photonic devices [110] PVA Solution casting Wound diagnosis/biosensor scaffolds [111] PVA Solution casting Conductive materials [112]

Starch Solution casting Food packaging [60] Cassava starch Solution casting Food packaging [62] Sugar palm starch Solution casting Food packaging [115] Wheat starch Solution casting Food packaging [87] Tuber native potato Solution casting Packaging [116] Cereal corn Solution casting Packaging [116] Legume pea Solution casting Packaging [116] Waterborne acrylate Solution mixing Corrosion protection [79]

Applications References

[113, 114]

[119, 120]

Air permeable, resistant, surfacesized paper, food packaging

Solution casting Packaging [96]

polymeric matrices.

Flax NFC/

102

NCC

Wheat straw hemicelluloses

Table 4.

Different nanocellulose sources of reinforcement fillers in polymer matrices.



Putra Malaysia Grant scheme Hi-CoE (6369107), FRGS/1/2017/TK05/UPM/01/1 (5540048) and iRMC UNITEN (RJO10436494). The authors are grateful to Dr. Muhammed Lamin Sanyang for guidance throughout the experiment.

Production, Processes and Modification of Nanocrystalline Cellulose from Agro-Waste: A Review

The authors also thank Dr. Rushdan Ibrahim for his advice and fruitful discussion.

, M.S.N. Atikah<sup>4</sup>

1 Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest

Engineering Materials and Composites Research Centre, Universiti Putra Malaysia,

3 Pulp and Paper Branch, Forest Research Institute Malaysia, Kepong, Selangor,

4 Department of Chemical and Environmental Engineering, Universiti Putra

5 Institute of Power Engineering, Universiti Tenaga Nasional, Kajang, Selangor,

6 Research Center for Chemical Defence, Universiti Pertahanan Nasional Malaysia,

© 2019 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,

Products, Universiti Putra Malaysia, Serdang, Selangor, Malaysia

\*Address all correspondence to: ahmadilyasrushdan@yahoo.com

2 Department of Mechanical and Manufacturing Engineering, Advanced

, A. Atiqah<sup>5</sup>

,

Author details

Malaysia

Malaysia

105

R.A. Ilyas1,2\*, S.M. Sapuan1,2, R. Ibrahim3

DOI: http://dx.doi.org/10.5772/intechopen.87001

M.N.M. Ansari<sup>5</sup> and M.N.F. Norrrahim<sup>6</sup>

Malaysia, Serdang, Selangor, Malaysia

provided the original work is properly cited.

Serdang, Selangor, Malaysia

Kuala Lumpur, Malaysia

Table 6.

NCC used as filler in polymeric matrices.

#### 7. Conclusion

Agro-waste is an unavoidable by-product that arises from various agricultural and agro-forest activities' operation. However, different kinds of agro-product industries, change of lifestyle, and population growth are assumed to be within the main factors that increase the rate of waste generation globally and locally. Therefore, proper waste management selections are very important based on the types of wastes and cost-effective factors in order to reduce the damage to the ecosystem. One of the alternatives to reduce agro-waste disposal is converting it to high-end value products such as nanocrystalline cellulose. In the present work, an overview of the production, processes, modification, and application of nanocrystalline cellulose from different agricultural wastes was proposed and leads to the following main concluding remarks: (1) it is important to select the proper raw material of agro-waste fiber, due to a broad variety of structure and chemical composition and its pretreatment process before the extraction process of nanocellulose begin; (2) the surface charge and morphology of nanocrystalline cellulose are affected by the production conditions such as hydrolysis time, temperature, and the acid-to-fiber ratio; and (3) nanocrystalline cellulose can be used in various applications including in hydrophobic polymer after some modification is made. The utilization of several lignocellulosic wastes from agricultural and forest by-product activities becomes the best proposal regarding cost/energy savings and economic development. The agricultural residue is available worldwide, abundant, cheap, and an unexploited source of cellulose that could be used as large-scale production of nanocellulose products.

#### Acknowledgements

The authors would like to thank Universiti Putra Malaysia for the financial support through the Graduate Research Fellowship (GRF) scholarship, Universiti Production, Processes and Modification of Nanocrystalline Cellulose from Agro-Waste: A Review DOI: http://dx.doi.org/10.5772/intechopen.87001

Putra Malaysia Grant scheme Hi-CoE (6369107), FRGS/1/2017/TK05/UPM/01/1 (5540048) and iRMC UNITEN (RJO10436494). The authors are grateful to Dr. Muhammed Lamin Sanyang for guidance throughout the experiment. The authors also thank Dr. Rushdan Ibrahim for his advice and fruitful discussion.
