Mechanical and Dynamic Properties of Biocomposites E-Book

• Herausgeber: Wiley-VCH GmbH
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 547

Veröffentlichungsjahr: 2021

Beschreibung

Mechanical and Dynamic Properties of Biocomposites

A comprehensive review of the properties of biocomposites and their applications

Mechanical and Dynamic Properties of Biocomposites offers a comprehensive overview of the mechanical and dynamic properties of biocomposites and natural fiber-reinforced polymer composites. This essential resource helps with materials selection in the development of products in the fields of automotive and aerospace engineering as well as the construction of structures in civil engineering.

With contributions from a panel of experts in the field, the book reviews the mechanical and damping properties of lingo-cellulosic fibers and their composites. The authors highlight the factors that contribute to the improved properties and their advancements in modern industrialization.

Besides, the book is designed to (a) introduce the mechanical and damping properties of lingo-cellulosic fibers and their composites, (b) factors that contribute to improvement in properties such as hybridization, chemical treatment of natural fibers, additive or fillers, etc. and (c) the real-time applications with case studies and future prospects.

Key features:

• Presents viable alternatives to conventional composites
• Examines the environmentally friendly and favorable mechanical properties of biocomposites
• Reviews the potential applications of biocomposites in the fields of automotive, mechanical and civil engineering
• Brings together in one comprehensive resource information found scattered across the professional literature

Written for materials scientists, polymer chemists, chemists in industry, civil engineers, construction engineers, and engineering scientists in industry, Mechanical and Dynamic Properties of BIocomposites offers a compreshensive review of the properties and applications of biocomposites.

Leseprobe

Table of Contents

Cover

Title Page

Copyright

1 Mechanical Behaviors of Natural Fiber‐Reinforced Polymer Hybrid Composites

1.1 Introduction

1.2 Concept of Natural Fibers and/or Biopolymers: Biocomposites

1.3 Hybrid Natural Fiber‐Reinforced Polymeric Biocomposites

1.4 Mechanical Behaviors of Natural Fiber‐Reinforced Polymer‐Based Hybrid Composites

1.5 Other Related Properties that Are Dependent on Mechanical Properties

1.6 Progress and Future Outlooks of Mechanical Behaviors of Natural FRP Hybrid Composites

1.7 Conclusions

References

2 Mechanical Behavior of Additive Manufactured Porous Biocomposites

2.1 Introduction

2.2 Human Bone

2.3 Porous Scaffold

2.4 Biomaterials for Scaffolds

2.5 Additive Manufacturing of Porous Structures

2.6 Design of Porous Scaffold

2.7 Mechanical Characterization of Additive Manufactured Porous Biocomposites

2.8 Conclusion

References

3 Mechanical and Dynamic Mechanical Analysis of Bio‐based Composites

3.1 Introduction

3.2 Mechanical Properties of Macro‐scale Fiber

3.3 Mechanical Properties of Nano‐scale Fiber

3.4 Dynamic Mechanical Analysis (DMA) of Biocomposites

3.5 Dynamic Mechanical Properties of Bionanocomposites

3.6 Conclusion

References

4 Physical and Mechanical Properties of Biocomposites Based on Lignocellulosic Fibers

4.1 Introduction

4.2 Major Factors Influencing Quality of Biocomposites

4.3 Conclusions

References

5 Machinability Analysis on Biowaste Bagasse‐Fiber‐Reinforced Vinyl Ester Composite Using

S

/

N

Ratio and ANOVA Method

5.1 Introduction

5.2 Experimental Methodology

5.3 Results and Discussion

5.4 Conclusions

References

6 Mechanical and Dynamic Properties of Kenaf‐Fiber‐Reinforced Composites

6.1 Introduction

6.2 Mechanical Properties of Kenaf‐Fiber‐Reinforced Polymer Composite

6.3 Dynamic Mechanical Analysis

6.4 Storage Modulus (E′) of Kenaf Fiber–Polymer Composite

6.5 Loss Modulus (E″) of Kenaf Fiber–Polymer Composite

6.6 Damping Factor (Tan δ)

6.7 Glass Transition Temperatures (Tg)

6.8 Conclusion

References

7 Investigation on Mechanical Properties of Surface‐Treated Natural Fibers‐Reinforced Polymer Composites

7.1 Introduction

7.2 Mechanical Properties of Natural Fibers

7.3 Drawbacks of Natural Fibers

7.4 Surface Modification of Natural Fibers

7.5 Maleated Coupling Agents

7.6 Summary

References

8 Mechanical and Tribological Characteristics of Industrial Waste and Agro Waste Based Hybrid Composites

8.1 Introduction

8.2 Materials and Methods

8.3 Result and Discussion

8.4 Conclusion

References

9 Dynamic Properties of Kenaf‐Fiber‐Reinforced Composites

9.1 Introduction

9.2 Manufacturing Techniques for Kenaf‐Fiber‐Reinforced Composites

9.3 Characterization

9.4 Overview of the Dynamics Properties of Kenaf‐Fiber‐Reinforced Composite

9.5 Conclusion

References

10 Effect of Micro‐Dry‐Leaves Filler and Al‐SiC Reinforcement on the Thermomechanical Properties of Epoxy Composites

10.1 Introduction

10.2 Materials and Methods

10.3 Results and Discussion

10.4 Conclusion

References

11 Effect of Fillers on Natural Fiber–Polymer Composite: An Overview of Physical and Mechanical Properties

11.1 Introduction

11.2 Influence of Cellulose Micro‐filler on the Flax, Pineapple Fiber‐Reinforced Epoxy Matrix Composites

11.3 Influence of Sugarcane Bagasse Filler on the Cardanol Polymer Matrix Composites

11.4 Influence of Sugarcane Bagasse Filler on the Natural Rubber Composites

11.5 Influence of Fly Ash on Wood Fiber Geopolymer Composites

11.6 Influence of Eggshell Powder/Nanoclay Filler on the Jute Fiber Polyester Composites

11.7 Influence of Portunus sanguinolentus Shell Powder on the Jute Fiber–Epoxy Composite

11.8 Influence of Nano‐SiO2 Filler on the Phaseolus vulgaris Fiber–Polyester Composite

11.9 Influence of Aluminum Hydroxide (Al(OH)3) Filler on the Vulgaris Banana Fiber–Epoxy Composite

11.10 Influence of Palm and Coconut Shell Filler on the Hemp–Kevlar Fiber–Epoxy Composite

11.11 Influence of Coir Powder Filler on Polyester Composite

11.12 Influence of CaCO3 (Calcium Carbonate) Filler on the Luffa Fiber–Epoxy Composite

11.13 Influence of Pineapple Leaf, Napier, and Hemp Fiber Filler on Epoxy Composite

11.14 Influence of Dipotassium Phosphate Filler on Wheat Straw Fiber–Natural Rubber Composite

11.15 Influence of Groundnut Shell, Rice Husk, and Wood Powder Fillers on the Luffa cylindrica Fiber–Polyester Composite

11.16 Influence of Rice Husk Fillers on the Bauhinia vahlii – Sisal Fiber–Epoxy Composite

11.17 Influence of Areca Fine Fiber Fillers on the Calotropis gigantea Fiber Phenol Formaldehyde Composite

11.18 Influence of Tamarind Seed Fillers on the Flax Fiber–Liquid Thermoplastic Composite

11.19 Influence of Walnut Shell, Hazelnut Shell, and Sunflower Husk Fillers on the Epoxy Composites

11.20 Influence of Waste Vegetable Peel Fillers on the Epoxy Composite

11.21 Influence of Clusia multiflora Saw Dust Fillers on the Rubber Composite

11.22 Influence of Wood Flour Fillers on the Red Banana Peduncle Fiber Polyester Composite

11.23 Influence of Wood Dust Fillers (Rosewood and Padauk) on the Jute Fiber–Epoxy Composite

11.24 Summary

11.25 Conclusions

References

12 Temperature‐Dependent Dynamic Mechanical Properties and Static Mechanical Properties of

Sansevieria cylindrica

Reinforced Biochar‐Tailored Vinyl Ester Composite

12.1 Introduction

12.2 Materials and Method

12.3 Results and Discussion

12.4 Conclusions

References

13 Development and Sustainability of Biochar Derived from Cashew Nutshell‐Reinforced Polymer Matrix Composite

13.1 Introduction

13.2 Materials and Methods

13.3 Results and Discussion

13.4 Conclusion

References

14 Influence of Fiber Loading on the Mechanical Properties and Moisture Absorption of the Sisal Fiber‐Reinforced Epoxy Composites

14.1 Introduction

14.2 Materials and Methods

14.3 Results and Discussion

14.4 Conclusion

References

15 Mechanical and Dynamic Properties of Ramie Fiber‐Reinforced Composites

15.1 Introduction

15.2 Mechanical Strength of Ramie Fiber Composites

15.3 Dynamic Properties of Ramie Fiber Composites

15.4 Conclusion

References

16 Fracture Toughness of the Natural Fiber‐Reinforced Composites: A Review

16.1 Introduction

16.2 Factors Affecting the Fracture Energy of the Biocomposites

16.3 Conclusion

Acknowledgments

References

17 Dynamic Mechanical Behavior of Hybrid Flax/Basalt Fiber Polymer Composites

17.1 Introduction

17.2 Materials and Methods

17.3 Result and Discussion

17.4 Conclusions

Acknowledgments

References

Index

End User License Agreement

List of Tables

Chapter 1

Table 1.1  Commonly used natural fibers and their mechanical behaviors.

Table 1.2 Commonly used natural fibers in hybrid composites and their chemica...

Table 1.3 Manufacturing processes of some hybrid (mainly natural) FRP composi...

Table 1.4  Benefits and drawbacks of natural FRP hybrid composites.

Table 1.5 Mechanical behaviors of bagasse/jute, bamboo/MFC, and banana/kenaf ...

Table 1.6 Mechanical behaviors of banana/sisal, coconut/cork, coir/silk, corn...

Table 1.7 Mechanical behaviors of cotton/kapok, cotton/ramie, and jute/oil pa...

Table 1.8 Mechanical behaviors of kenaf/PALF, roselle/sisal, and silk/sisal F...

Chapter 2

Table 2.1  Mechanical properties of human bone [18].

Table 2.2  Various porous biocomposites developed.

Table 2.3  Mechanical properties of additive manufactured porous structure.

Chapter 3

Table 3.1  Mechanical performances of various biocomposites.

Table 3.2  Bionanocomposites produced by extrusion and internal‐melt blending.

Table 3.3 Static mechanical properties of bionanocomposites reinforced by var...

Table 3.4  The single fiber reinforced biocomposites in DMA analysis.

Table 3.5  Summary of dynamic mechanical properties of hybrid biocomposites.

Table 3.6 Dynamic mechanical properties of bionanocomposites reinforced by va...

Chapter 4

Table 4.1 Physical and mechanical properties of some commercial natural fiber...

Table 4.2 Technological properties of polypropylene/wood composites depending...

Table 4.3 Mechanical properties of WPCs at 40% wood fiber or wood flour conte...

Table 4.4 Main mechanical properties of polypropylene/wood composites with or...

Table 4.5 Comparison of average tensile properties and cost of nanocrystallin...

Chapter 5

Table 5.1 Specifications of strain gauge drill tool dynamometer (PolyLab‐Make...

Table 5.2 Constant tool geometry of HSS twist drill bits utilized in this stu...

Table 5.3  Levels and factors of machining parameters.

Table 5.4  

L

9

orthogonal array and experimental values of torque and thrust fo...

Table 5.5  

S

/

N

ratio for torque/thrust force.

Table 5.6  ANOVA responses for thrust force.

Table 5.7  ANOVA responses for torque.

Table 5.8  Experimental confirmation and predicted torque and thrust force.

Chapter 6

Table 6.1  Peak height of tan 

δ

curve and

T

g

obtained from

E

″ and tan 

δ

...

Table 6.2  Storage modulus, loss modulus, and tan 

δ

values for different ...

Chapter 7

Table 7.1  Mechanical properties of natural fibers [7].

Table 7.2 Mechanical properties of different natural fibers with alkaline tre...

Chapter 8

Table 8.1  Details of fabricated composite.

Table 8.2  Crystallinity property of fiber.

Chapter 10

Table 10.1  Fabrication qualities of the epoxy composite samples.

Chapter 11

Table 11.1  Mechanical properties of PF/CMF hybrid fiber composites.

Table 11.2 Tensile strength of natural rubber, and raw and treated bagasse fi...

Table 11.3 Mechanical strength of different combinations of jute fiber compos...

Table 11.4  Mechanical properties of composites with filler contents.

Table 11.5  Comparison of results of various composite specimens.

Table 11.6 Summary of the effect of nano‐fillers on the physical and mechanic...

Chapter 12

Table 12.1  Composite designation.

Chapter 14

Table 14.1  Material specifications of the sisal fiber and epoxy resin.

Table 14.2  Tensile properties of the composites against the fiber loading.

Table 14.3  Flexural properties of the composites against the fiber loading.

Chapter 16

Table 16.1  Fracture modes in composites and their applications.

Table 16.2 ASTM standards to measure fracture toughness in composites based o...

Chapter 17

Table 17.1  Properties of flax and basalt fiber.

Table 17.2  Properties of polyester resin.

List of Illustrations

Chapter 1

Figure 1.1 Descriptive molecular structure of both (a) thermoplastic and (b)...

Figure 1.2 Schematic illustration of different orientations and stacking seq...

Figure 1.3 Improved mechanical properties of hybrid flax–basalt fibers FRP c...

Figure 1.4 Flowchart of preparation and characterization of the hybrid FRP c...

Figure 1.5 Frictional coefficients of (a) treated and (b) untreated sisal/gl...

Chapter 2

Figure 2.1  Schematic view of the bone.

Figure 2.2 Key requirements of a scaffold for osteochondral tissue engineeri...

Figure 2.3  Schematic diagram of Powder Bed Fusion process.

Figure 2.4  Schematic of Fused Deposition Modeling.

Figure 2.5 Porous scaffold with cubical pore. (a) Porous scaffold. (b) Detai...

Figure 2.6  Different topology of pore structure.

Figure 2.7 Porous scaffold specimen fabricated using biocomposite (polyamide...

Chapter 3

Figure 3.1  General schematic of a DMA instrumente.

Chapter 4

Figure 4.1  Classification of natural fibers.

Figure 4.2 (a) Flax sliver, (b) hemp sliver, (c) flax hackling tow, and (d) ...

Figure 4.3  Comparison of chemical composition of natural fibers.

Figure 4.4 (a) Specific modulus of commonly used plant fibers and E‐glass fi...

Figure 4.5 (a) Raw materials for WPC. (b) WPC compounding in the twin screw ...

Figure 4.6 Wood flour used in WPC production (for injection molding, wood fl...

Figure 4.7  Wood fibers used in WPC production.

Figure 4.8 Tensile strength of different fiber‐reinforced polypropylene comp...

Figure 4.9 Orientation of fibers in the composites of (a) aligned‐continuous...

Figure 4.10 The effect of fiber on the tensile strength and impact strength ...

Figure 4.11 Effect of processing method and filler loading on the flexural m...

Figure 4.12 Impact bending strength of the WPC depending on the fiber conten...

Figure 4.13 The changes in the relative properties of WPCs at different fibe...

Figure 4.14 Tensile stress versus strain curves for WPCs having different am...

Figure 4.15 The development of mechanical cracks caused by water or moisture...

Figure 4.16 Water absorption (a) and thickness swelling (b) for the water‐im...

Figure 4.17 (a) Reaction of coupling agent with natural fibres (PP: polyprop...

Figure 4.18 Effect of coupling agent on the interfacial bond of wood and pol...

Figure 4.19 The effect of birch fiber content and coupling agent (MAPP) on t...

Figure 4.20 The effect of coupling agents on the impact strength of composit...

Figure 4.21  Classification of polymer matrix.

Figure 4.22  (a) Structure of wood cell. (b) Nanocellulose.

Figure 4.23  Relationship between different kinds of nanocelluloses.

Figure 4.24 NCC at 5 wt.% solution; at 12% wt solution; and NCC powder (spra...

Figure 4.25  Nanocrystalline cellulose (NCC).

Figure 4.26 (a) Transparent film from nanocellulose. (b) Nanofiber paper‐der...

Chapter 5

Figure 5.1  Schematic layout of the drilling setup.

Figure 5.2 Influence of machining parameters on torque and thrust force for ...

Figure 5.3 Comparison graph of (a) thrust force, and (b) torque between pred...

Chapter 6

Figure 6.1 Different forms of kenaf fiber (a) non‐woven, (b) fiber strands, ...

Figure 6.2 Effect of nanofiller loading in kenaf/epoxy composites on loss mo...

Figure 6.3 Effect of nanofiller loading in kenaf/epoxy composites on damping...

Chapter 7

Figure 7.1  Flow chart representation of classification of natural fibers.

Figure 7.2 Alkaline treatment of natural fibers: (a) untreated and (b) alkal...

Figure 7.3 Effect of surface treatment of henequen fiber on interfacial shea...

Figure 7.4 Effect of alkaline treatment of ramie fiber on tensile strength....

Figure 7.5 Tensile strength of different alkaline‐treated kenaf fibers (T5–3...

Figure 7.6 Effect of different surface treatments on the tensile property of...

Figure 7.7 SEM images of tensile fracture of different fibers ((a) FIB/HDPE,...

Figure 7.8 (a) Tensile and (b) flexural strength of HDPE‐reinforced henequen...

Figure 7.9 SEM images of fracture surface of composite (a) with fibre withou...

Figure 7.10 (a) Flexural and (b) tensile strengths of hemp‐reinforced compos...

Figure 7.11 Mechanical properties: (a) tensile Strength (b) Young's Modulus ...

Figure 7.12 (a) Tensile and (b) impact strength properties of palm fiber–vin...

Figure 7.13 (a) Tensile strength and (b) Young's modulus of PVC/ENR/Kenaf co...

Figure 7.14 (a) Tensile strength and (b) impact strength of pandanwangi fibe...

Figure 7.15  The reaction of cellulose fibers with MAPP.

Figure 7.16 (a) Young's modulus and (b) tensile strength of the different fi...

Figure 7.17 Mechanical property and SEM images of recycled carbon fiber (RCF...

Figure 7.18 (a) Tensile strength and (b) flexural strength of wood–fiber PP ...

Figure 7.19  Reaction mechanism of plasma treatment.

Figure 7.20 SEM images of: (a), (b) untreated and (c), (d) plasma‐treated co...

Figure 7.21 (a) Tensile strength and (b) elastic modulus of untreated and pl...

Figure 7.22  Schematic representation of corona treatment.

Chapter 8

Figure 8.1 (a) Schematic representation of the erosion process. (b) Morpholo...

Figure 8.2  XRD pattern of fiber.

Figure 8.3 Hardness and tensile strength of composites (a) Hardness (b) Tens...

Figure 8.4 SEM image of tensile‐tested composites (a) Poor bonding (b) Red m...

Figure 8.5  Erosion exposure region at different impact angles.

Figure 8.6  Erosion rate at different impact angles.

Figure 8.7 (a) Crater development due to erodent impact. (b) Red mud hill fo...

Figure 8.8 Erosion behavior at different impact angles of treated and untrea...

Figure 8.9  (a) Micro cuts and ploughing (b) Crack developement.

Figure 8.10  Fiber damage due to erodent impact.

Chapter 9

Figure 9.1  Vibration testing scheme.

Figure 9.2  Experimental setup for acoustic testing.

Figure 9.3 Graph for the effect of various solutions of kenaf‐fiber‐reinforc...

Figure 9.4  At LPT (a) and HPT (b) composites compounded; storage modulus (

E

″...

Figure 9.5 Composites compounded at (a) LPT and (b) HPT; loss modulus graph....

Figure 9.6 Effects of varying fiber length on (a) storage modulus, (b) loss ...

Figure 9.7 Graphical representation of different fiber content loaded kenaf/...

Figure 9.8 Graph of sound absorption coefficient with various air gap thickn...

Chapter 10

Figure 10.1 Dry leaves fiber/Al‐SiC‐reinforced epoxy composites: (a) tensile...

Figure 10.2 Dry leaves fiber/Al‐SiC‐reinforced epoxy composites: (a) flexura...

Figure 10.3 Impact strength of dry leaves fiber/Al‐SiC‐reinforced epoxy comp...

Figure 10.4 Dynamic mechanical properties of dry leaves fiber/Al‐SiC‐reinfor...

Figure 10.5 Fracture SEM micrographs of dry leaves fiber/Al‐SiC‐reinforced e...

Chapter 11

Figure 11.1 Effect of fiber content on tensile strength of bagasse composite...

Figure 11.2  Effect of fiber content on hardness of bagasse composite.

Figure 11.3  Mechanical properties (a) CS

cylindrical

and (b) CS

cubic

.

Figure 11.4  Tensile strength of various composites.

Figure 11.5  Tensile stress–strain graph of various composites.

Figure 11.6  Hardness (Shore D) of various composites.

Figure 11.7 Tensile strength comparison of various combination specimens....

Figure 11.8  Hardness against the filler loading.

Figure 11.9  Tensile strength of various weight percentage specimens.

Figure 11.10  Impact strength.

Figure 11.11  Diagram of the scratch tester.

Figure 11.12 Effect of horizontal force on natural fiber‐filled epoxy compos...

Figure 11.13 (a) Tensile strength and (b) flexural strength of various compo...

Figure 11.14  Tensile strength comparison of various composites.

Figure 11.15  Flexural strength comparison of various composites.

Figure 11.16  Impact strength comparison of various composites.

Figure 11.17 Mean tensile strength comparison of RBPF and RBWF composites....

Figure 11.18 Tensile strength stress–strain graph of prepared composites....

Chapter 12

Figure 12.1  Ball‐milled biochar particle.

Figure 12.2  SEM micrograph of biochar particle.

Figure 12.3  SEM‐EDAX of

Zea mays

cob biochar.

Figure 12.4  SEM image of biochar after ball milling.

Figure 12.5  Particle size distribution of

Zea mays

cob biochar.

Figure 12.6  FTIR Spectrum of biochar particle.

Figure 12.7 Matching XRD pattern of Zea mays cob biochar and graphite (carbo...

Figure 12.8  Gaussian fit for the XRD pattern of

Zea mays

cob biochar using F...

Figure 12.9 Storage modulus plotted with respect to temperature for varying ...

Figure 12.10 (a) Loss modulus versus temperature for varying biochar wt.% an...

Figure 12.11  Cole–Cole plot for the biochar‐filled

Sansevieria cylindrica

‐re...

Figure 12.12 Tensile strength and tensile modulus for the biochar‐filled SCV...

Figure 12.13 SEM micrograph of tensile‐tested (a) 0 wt.% biochar‐filled SCVE...

Figure 12.14 Flexural strength and flexural modulus for the biochar‐filled S...

Figure 12.15 SEM Micrograph representing the three‐point bending on the (a) ...

Figure 12.16 Impact response of the biochar‐filled SCVEC for different bioch...

Figure 12.17 SEM images for impact tested specimens (a) 0 wt.% biochar‐fille...

Chapter 13

Figure 13.1 Cashew nutshell waste extracted biochar‐reinforced polyester com...

Figure 13.2 Tensile strength values of cashew nutshell waste extracted bioch...

Figure 13.3 Flexural strength values of cashew nutshell waste extracted bioc...

Figure 13.4 Impact strength values of cashew nutshell waste biochar‐reinforc...

Figure 13.5 Hardness values of cashew nutshell waste extracted biochar‐reinf...

Figure 13.6 Scanning electron microscopy images of tensile tested fractured ...

Figure 13.7 Scanning electron microscopy images of impact tested fractured c...

Figure 13.8 (a,b) SEM images of impact tested cashew nutshell waste extracte...

Chapter 14

Figure 14.1 Tensile load–elongation plot of the composites: (a) 15 wt.%, (b)...

Figure 14.2  Tensile failure in the composite.

Figure 14.3 Flexural load–deflection graph plot of the composites: (a) 15 wt...

Figure 14.4  Failure of the composite under flexural load.

Figure 14.5 Moisture absorption versus time graph as a function of fiber loa...

Chapter 15

Figure 15.1  Ramie fibers in different forms.

Figure 15.2 Ramie fabric fiber surface modification with a coupling agent....

Figure 15.3 (a) and (b) Ramie fabric fiber with 10 wt.%, (c) with 30 wt.%, (...

Figure 15.4 Storage modulus of hybrid composites with fiber ratio (a) 0 : 10...

Figure 15.5 Loss modulus of hybrid composites with fiber ratio (a) 0 : 100 a...

Figure 15.6 SEM fractography of ramie fiber‐reinforced epoxy composites; (a)...

Chapter 16

Figure 16.1  Common fracture modes.

Figure 16.2 Classification of fracture toughness test methodologies based on...

Figure 16.3 DCB test setup. (a) With piano hinges and (b) with loading block...

Figure 16.4 Specimens dimensions for compact tension fracture toughness test...

Figure 16.5  Test setup of the single‐edge notch bend (SENB) test.

Figure 16.6  End‐notched flexure (ENF) test setup.

Figure 16.7  Specimen dimension for the SCB test.

Figure 16.8  MMB test setup.

Figure 16.9 Mode‐I failure of composite from the DCB test. (a) Glass/phenoli...

Chapter 17

Figure 17.1  Tan 

δ

of flax/basalt fiber‐reinforced polyester matrix comp...

Figure 17.2 Storage modulus of flax/basalt fiber‐reinforced polyester matrix...

Figure 17.3 Loss modulus of flax/basalt fiber‐reinforced polyester matrix co...

Guide

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Mechanical and Dynamic Properties of Biocomposites

Edited by

Senthilkumar Krishnasamy

Rajini Nagarajan

Senthil Muthu Kumar Thiagamani

Suchart Siengchin

Editors

Dr. Senthilkumar Krishnasamy

Kalasalingam Academy of Research and Education

Department of Mechanical Engineering

Anand Nagar

626126 Krishnankoil, Tamil Nadu

India

Prof. Rajini Nagarajan

Kalasalingam Academy of Research and Education

Department of Mechanical Engineering

Anand Nagar

626126 Krishnankoil, Tamil Nadu

India

Dr. Senthil Muthu Kumar Thiagamani

Kalasalingam Academy of Research and Education

Department of Mechanical Engineering

Anand Nagar

626126 Krishnankoil, Tamil Nadu

India

Prof. Suchart Siengchin

King Mongkut's University of Technology North Bangkok

Department of Materials & Production Engineering

1518 Pracharat 1

Wongsawang Road, Bangsue

10800 Bangkok

Thailand

Cover

Cement plant © Muhammadfath/Shutterstock, Car manufacturer

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1Mechanical Behaviors of Natural Fiber‐Reinforced Polymer Hybrid Composites

Adelani A. Oyeniran1 and Sikiru O. Ismail2

1Cranfield University, Department of Advanced Mechanical Engineering, School of Water, Energy and Environment, Wharley End, Cranfield, Bedfordshire, MK43 0AL, UK

2University of Hertfordshire, Centre for Engineering Research, School of Engineering and Computer Science, Department of Engineering, College Lane Campus, Hatfield, Hertfordshire, AL10 9AB, UK

1.1 Introduction

The use of composites in industrial applications has evolved tremendously over the years, due to the quest for better material performance and cost reduction. They have been found to have exceptional properties in terms of their physical and mechanical properties. Simply put, composites describe a heterogeneous material that comprises two or more different materials that are combined within a single system such that the new material formed now has improved properties, which are suitable for an intended application. The materials that are combined to form a composite material are known as fiber and matrix, reinforcement and binder as commonly called, respectively. The matrix material could be either a natural or synthetic polymer, while fiber material could be glass, boron, or carbon, among others (synthetic type); hemp, jute, flax, among natural type; organic; or ceramic [1]. The increasing use of composite materials in industries has been traced to the fact that they have light weight, and possess high strength as well as exceptional corrosion resistance and acoustic properties, which make them preferred to metallic and alloy materials. Their applications now span into marine, power/energy, automobile, security, aerospace, telecommunications, sport/game, military industries, among others.

Biocomposite has been defined as a composite with at least one of its components derived from biological or natural sources [1]. Their main features that drive research interest are the fact that they are biodegradable, renewable, cheap, and have natural/sustainable resources. These features underscore their environmental friendliness. Some examples of natural fibers frequently used in biocomposites are caraua, sisal, jute, abaca, and kenaf, among others [2]. Other natural fibers used in biocomposites are hemp, agave, and flax, among others [3]. Some natural fibers have been identified in the literature to be used only for craft production and these include kenaf, agave, coir, ramie, and caraua fibers [3].

Table 1.1 Commonly used natural fibers and their mechanical behaviors.

Source: Nguyen et al. [4]. © 2017, Elsevier.

Fiber

Density (g/cm

3

)

Diameter (μm)

Elongation (%)

Tensile strength (MPa)

Young's modulus (GPa)

Bast

Flax

1.4–1.5

5–38

1.2–3.2

345–1500

27.6–80

Hemp

1.48

10–51

1.6

550–900

70

Jute

1.3–1.46

5–25

1.5–1.8

393–800

10–30

Kenaf

1.2

12–36

2.7–6.9

295

—

Ramie

1.5

18–80

2.0–3.8

220–938

44–128

Leaf

Abaca

1.5

—

3.0–10

400

12

Banana

1.35

13.16

5.3

355

33.8

Caraua

1.4

—

3.7–4.3

500–1150

11.8

Henequen

1.4

—

3.0–4.7

430–580

—

PALF

1.5

20–80

1–3

170–1627

82

Sisal

1.33–1.5

7–47

2.0–3.0

400–700

9–38

Seed

Cotton

1.5–1.6

12–35

3.0–10.0

287–597

5.5–12.6

Fruit

Coir

1.2

—

15.0–30.0

175–220

4–6

Oil palm EFB

0.7–1.55

19.1–25.0

2.5

248

3.2

Wood

Softwood kraft pulp

1.5

33

4.4

1000

40

Cane/grass

Bagasse

1.2

10–34

1.1

20–290

19.7–27.1

Bamboo

0.6–1.1

—

—

140–230

11–17

EFB and PALF denote empty‐fruit bunches and pineapple leaf fiber, respectively.

Some interesting mechanical behaviors of commonly used natural fibers and many more that are not aforementioned are shown in Table 1.1.

Biocomposites have found application in many different industrial sectors, including packaging, sports articles, and ship building, but most importantly in civil and automotive sectors for nonstructural applications: soundproofing, filling material, and lightening, among others [3]. They favor applications that require low cost and lightness as compared with any other synthetic fiber‐reinforced composites. They also demonstrate good thermal and acoustic insulation capacities [3]. Generally, biocomposites are randomly oriented with short fibers that are obtained through the extrusion or molding manufacturing process [3]. Essentially, the low specific weight as well as low cost of biocomposites is a function of the low weight and low cost of most natural fibers, in combination with the low cost of the automated manufacturing processes when mass‐producing them [3].

1.2 Concept of Natural Fibers and/or Biopolymers: Biocomposites

1.2.1 Natural Fiber‐Reinforced Polymer Composites or Biocomposites

Natural fiber‐reinforced polymer (FRP) composites or biocomposites are gaining widespread interest for many reasons. One such reason is the fact that they have shown a potential for replacement of synthetic fibers at a lower cost. They are also sustainable when compared with their synthetic counterparts [5].

Natural fibers refer to fibers whose origins are natural, that is, they are sourced from plants and animals. These origins give rise to three fundamental natural fiber types, viz:

Animal fibers

: These contain proteins, such as keratin, fibroin, and collagen. Other classifications in this category are animal wool/hairs (angora wool, alpaca, camel, mohair, lamb's wool, bison, yak wool, cashmere, horse hair, goat hair, and qiviut, among others), keratin fiber (chicken and bird feathers), and silk fibers (spider silk, tussah silkmoths, mulberry silk cocoons).

Plant fibers

: These are often referred to as cellulosic or lignocellulosic fibers. They are classified in six categories:

Seed/fruit fibers

: Coir, coconut, loofah, cotton, oil palm, kapok, sponge gourd, milkweed hairs.

Cane, grass, and reed fibers

: Bamboo, corn, albardine, esparto, bagasse, sabai, papyrus, rape, canary.

Bast or stem fibers

: Blax, jute, okra, rattan, paper mulberry, hemp, kenaf, isora, urena, ramie, kudzu, roselle hemp, wisteria, mesta and nettle, among others.

Wood fibers

: Hardwood and softwood, among others.

Leaf fibers

: Caraua, pineapple, abaca, raphia, agave, caroa, banana, fique, piassava, cantala, sansevieria, phormium, Mauritius hemp, sisal, date palm, istle and henequen, to mention but a few.

Stalk fibers

: Derivable from barley stalk, rice stalk, maize stalk, wheat stalk, oat stalk as well as other crops.

Table 1.2

shows the percentage weight (wt.%) of chemical compositions of the mostly used natural fibers.

Mineral fibers

: These fibers include fibrous brucite, asbestos group (amosite, chrysotile, anthophyllite, crocidolite, actinolite and tremolite) and wollastonite.

Table 1.2 Commonly used natural fibers in hybrid composites and their chemical compositions.

Source: Faruk et al. [6]. © 2012, Elsevier.

Fiber

Cellulose (wt.%)

Hemicellulose (wt.%)

Lignin (wt.%)

Waxes (wt.%)

Abaca

56–63

20–25

7–9

3

Bagasse

55.2

16.8

25.3

—

Bamboo

26–43

30

21–31

—

Coir

32–43

0.15–0.25

40–45

—

Curaua

73.6

9.9

7.5

—

Flax

71

18.6–20.6

2.2

1.5

Hemp

68

15

10

0.8

Jute

61–71

14–20

12–13

0.5

Kenaf

72

20.3

9

—

Oil palm

65

—

29

—

Pineapple

81

—

12.7

—

Ramie

68.6–76.2

13–16

0.6–0.7

0.3

Rice husk

35–45

19–25

20

14–17

Rice straw

41–57

33

8–19

8–38

Sisal

65

12

9.9

2

Wheat straw

38–45

15–31

12–20

—

1.2.2 Polymer Matrices

Polymer matrices serve as bonding agents to fibers. They bond the fibers together and help in load transfer to the fibers. Also, the polymer matrices allow for good‐quality finish of composite surfaces as well as protection of the reinforcing fibers from chemical attacks. Two common classifications of polymer matrices are thermosetting and thermoplastic resins. They are subsequently elucidated.

Thermosetting resins

: Curing process (chemical reaction) occurs with this type, thus linking polymer chains and connecting the whole matrix in a three‐dimensional (3D) network. It should be noted that once curing occurs, re‐melting or reforming becomes impossible. These resins are highly stable in dimension, resist high temperature as well as offer good resistance to solvents, due to their cross‐linked 3D structure [

4

]. Some thermosetting resins that are used frequently in composites are vinylesters, polyesters, phenolics, epoxies, bismaleimides (BMIs), and polyamides (PAs).

Thermoplastic resins

: These resins differ from thermosetting resins, because their thermoplastic molecules are not cross‐linked and can be melted when heated and made into solids and then cooled, thus allowing for reforming and reshaping repeatedly. Apart from being generally ductile, thermoplastic resins have more toughness than their thermosetting counterparts. They are broadly used for nonstructural applications without fillers and reinforcements. Their mechanical properties, which are factors of attraction, include good fatigue and compression strength, excellent tensile strength, excellent stiffness, high dimensional stability, excellent damage tolerance, and excellent durability. Furthermore, their flame‐retardant as well as wear‐resistant features broaden their applications and make them relevant, especially in an aerospace sector [

4

]. Common examples of thermoplastic resins include, but are not limited to, polyvinylidene fluoride (PVDF), polypropylene (PP), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polymethyl methacrylate (PMMA, also called acrylic), polyetherketoneketone (PEKK), and polyetherimide (PEI).

Figure 1.1 Descriptive molecular structure of both (a) thermoplastic and (b) thermoset polymers.

Source: Bergstrom [7]. © 2015, Elsevier

Figure 1.1a,b depicts the molecular structure of thermoplastic and thermosetting resins, respectively. The cross‐links in the molecular structure of the thermosetting resins (shaded molecules) are depicted in Figure 1.1b.

There are different categories that exist for the manufacturing process of polymer matrix composites (PMCs). These include squeeze flow methods, short‐fiber suspension methods, and porous media methods [4]. Table 1.3 depicts some partial and complete natural and synthetic hybrid FRP composites, their resins/matrices, and manufacturing methods.

It is well known that there is no single engineering material that can be all‐encompassing in terms of its applicability to operations and processes. Therefore, natural FRP composites have some limitations, despite their outstanding benefits. Table 1.4 presents some of the benefits as well as disadvantages of natural FRP composites.

The key elements that affect the mechanical response of natural FRP hybrid composites are subsequently identified [5]:

Fiber selection, which includes the type, method of extraction, time of harvest, natural fiber aspect ratio, content, as well as its treatment

Interfacial strength

Matrix choice

Fiber distribution

Composite manufacturing process

Fiber arrangement [

9

]

Void presence/porosity, among others.

Table 1.3 Manufacturing processes of some hybrid (mainly natural) FRP composites.

Source: Sathishkumar et al. [8]. © 2014, SAGE Publications.

Hybrid fiber

Resin

Curing agent Catalyst

Accelerator

Manufacturing methods

Pineapple/sisal/glass

Polyester

MEKP

Cobalt napthenate

Hydraulic press

Sisal/silk

Polyester

Hand lay‐up technique

Kenaf/glass

Polyester

Hand lay‐up and cold press

Woven jute/glass

Polyester

Hand lay‐up

Banana/Kenaf

Polyester

Hydraulic compression molding process

Banana/sisal

Polyester

Hand lay‐up method followed by compression molding

Glass/palmyra

Polyester

Hydraulic compression molding process

Jute/glass

Polyester

Hand lay‐up

Roselle/sisal

Polyester

Hand lay/up technique

Silk/sisal

Polyester

Hand lay‐up technique

Banana/sisal

Epoxy

Hydraulic compression molding process

Glass/glass

Epoxy

HY95 I hardener

Hand lay‐up technique

Carbon/glass

Epoxy

HY225 Hardener

Hand lay‐up technique

Oil palm/jute

Epoxy

Hardener

Compression molding process

Chicken feather/glass

Epoxy

n

‐

tert

‐Butyl peroxybenzoate

Hot press

Basalt/Hemp

Polypropylene

Hot pressing

Flax, Hemp, and jute

Polypropylene

Hydraulic press

Flax/wood fiber

HDPE

Twin screw extrusion

Banana/glass

Polypropylene

Twin screw extrusion

Cork/coconut

HDPE

Screw extrusion and compression molding

Kenaf/pineapple

HDPE

Mixing and compression molding

Bamboo/glass

Polypropylene

Injection molding

Cordenka/jute

Polypropylene

Injection molding

Bamboo/cellulose

Poly lactic acid

Injection molding

OPEFB/glass

Vinyl ester

Resin transfer molding

Aramid/sisal

Phenolic

Stirring, drying, compression

HDPE, high‐density polyethylene; MEKP, methyl ethyl ketone peroxide; and OPEFB, oil palm empty fruit punch.

Table 1.4 Benefits and drawbacks of natural FRP hybrid composites.

Source: Modified from Pickering et al. [5]. © 2014, SAGE Publications.

Benefits

Drawbacks

Renewable source of fibers/matrices and sustainability

Low danger/risk during manufacturing processes

Low density, stiffness, and high specific strength

Low process/production energy and environmental friendliness

Lower production cost when compared with synthetic fibers, such as carbon and glass

Low release of harmful fumes when heating and during end of life process (incineration)

Lower abrasive attack on processing tools, when compared with synthetic FRP composites

Possibility of predicting better balanced mechanical behaviors, such as toughness

Lower responses, especially impact strength in comparison with the synthetic FRP composites

Higher variability of behaviors, due to discrepancies in sources and qualities

Lower durability in comparison with synthetic FRP composites. However, it can be enhanced significantly using treatments

Poor fiber orientation and/or layer stacking sequence, causing weak fiber–matrix interfacial adhesion

High water/moisture absorption, consequently causes swelling effect

Lower processing parameters, such as degradability temperatures. Hence, it causes limiting matrix and fiber options and structural applications

1.3 Hybrid Natural Fiber‐Reinforced Polymeric Biocomposites

Fiber hybridization could offer a further alternative in composites. Hybrid composites are derived by a combination of two or more various fiber types in a common matrix [10]. The fibers can be arranged in different layer pattern/orientations and stacking sequences. Figure 1.2 presents some common arrangements (layering patterns) of natural FRP hybrid composites. This introduces wider spread in their properties than in the regular composite materials, which comprises only one kind of reinforcement. It also enables manufacturing engineers to channel the properties of the composite to the required structural properties. This can possibly be achieved once the hybrid composite behavior can be predicted from the constituent composites.

Operationally, producing hybrid natural FRP composites suggests an intermediate intervention to reduce the negative environmental impact of glass and carbon (synthetic) fibers on the environment, by partially replacing the glass and carbon fibers with such alternatives as the vegetable fibers jute, flax, hemp, kenaf, sisal, among others [12, 13]. In these substitutions, the limits are revealed by simulating the service performance in such a dynamic testing, including fatigue and impact [14, 15].

Figure 1.2 Schematic illustration of different orientations and stacking sequences of natural FRP hybrid composites.

Source: Refs. [9, 11]. © 2012; John Wiley and Sons.

Moreover, hybrid biocomposites refer to composites in which two or more different biofibers (natural fibers) are combined in a matrix, or a mixture of natural fibers with synthetic fibers in a matrix [4]. One synthetic fiber commonly used for improving the mechanical response in natural FRP composites is glass or carbon fibers. Several types exist for hybrid composites. These types are dependent on the material constituent mixture [16, 17].

For instance, Figure 1.3 shows higher mechanical properties of unaged hybrid flax/basalt FRP composite sample A, when compared with single or non‐hybrid flax FRP composite. However, the impact strength property of the aged hybrid counterpart samples B, C, D, and E changed insignificantly after 15, 30, 45, and 60 aging days of salt‐fog environment conditions (Figure 1.3c) of the hybrid types. Additional mechanical behaviors of some FRP hybrid biocomposites are presented later in Table 1.5 by considering their natural/natural fiber combined reinforcements.

In preparing hybrid FRP composites, the rule of mixture comes to play, while the volume fraction can be obtained using Eqs. (1.1)–(1.6) [8].

(1.1)

(1.2)

(1.3)

Figure 1.3 Improved mechanical properties of hybrid flax–basalt fibers FRP composites, depicting (a) stress–strain, (b) modulus–strain curves, and (c) impact strengths of aged and unaged biocomposites.

Source: Fiore et al. [18]. © 2016, Elsevier.

(1.4)

(1.5)

(1.6)

where Vf denotes total reinforcement volume fraction, Vc1 and Vc2 represent the first and second reinforcement relative volume fractions, Vf1 and Vf2 stand for the first and second fiber volume fractions, ρc and ρf designate the densities of the composites and fiber, while Wf indicates the weight of the fiber. The methodology for preparing and characterizing hybrid fiber‐reinforced PMCs as well as its applications is presented in Figure 1.4.

However, the present chapter does not cover all the methodologies shown in Figure 1.4 in detail, because the scope of this chapter is not manufacturing processes and techniques of natural FRP composite materials.

1.4 Mechanical Behaviors of Natural Fiber‐Reinforced Polymer‐Based Hybrid Composites

There are many properties of materials that determine where they function or are used in the engineering space. The required characteristics in a proposed design will determine what combinations of materials will be relevant and which of the various mechanical properties are of interest in such instances. Notable among the mechanical properties usually considered in engineering are tensile, compressive, flexural, and impact strengths, among others. These properties are discussed in Section 1.4.1.

Figure 1.4 Flowchart of preparation and characterization of the hybrid FRP composites.

Source: Sathishkumar et al. [8]. © 2014, SAGE Publications.

1.4.1 Hybrid Natural FRP Composites

This section discusses hybrid biocomposites in which their combined fibers are entirely natural (biofibers).

1.4.1.1 Bagasse/Jute FRP Hybrid Composites

Jute is a popular plant‐based fiber (vegetable) with dominant presence in tropical countries across the Asian continent, such as China, Brazil, Nepal, Bangladesh, India, and Thailand. They account for about 95% of jute fiber (JF) production worldwide [4]. Jute is considered as a lignocellulosic bast fiber, having comparative advantages with respect to renewability, biodegradability (which makes it eco‐friendly), high strength as well as high initial modulus over other fibers [11]. Bagasse, also called sugarcane bagasse, is a lingocellulosic by‐product of the sugar industry, mostly utilized as a fuel in boilers and sugar factories. Compared with other residues (by‐products), including wheat straw and rice, bagasse is preferred, because its ash content is lower [19].

A study of mechanical behavior of hybrid FRP composites with short JF and short bagasse fiber (BF) bundles reinforcement was carried out by Saw and Datta [20]. They used epoxidized phenolic novolac (EPN) as resin matrix and investigated various fiber surface treatments and fiber ratios. Sodium hydroxide (NaOH) alkali solution was used to treat the JF bundles. The BF bundles were either modified using chlorine dioxide (ClO2) and furfuryl alcohol (C5H6O2) or left untreated. The modification of the fiber surface was necessary for quinones creation in the lignin areas of the BF bundles. The created quinones then reacted with the furfuryl alcohol, and thereby improved the BF bundles' (modified) ability for better adhesion. Their result revealed greater mechanical responses (flexural, tensile and impact properties) for hybridized BF (modified) and JF bundles (alkali‐treated) in the EPN resin matrix than the BF bundles that were not modified. They obtained an optimum mechanical behavior at a BF/JF ratio of 50 : 50, as depicted in Table 1.5.

1.4.1.2 Bamboo/MFC FRP Hybrid Composites

Asian giants, India and China, are the chief producers of bamboo fiber with more than 80% of global production [21]. This biofiber is highly attractive, due to its renewable nature and low environmental impact. It grows rapidly and has comparative high strength to other biofibers, such as cotton and jute [22].

An unprecedented biocomposite (hybrid) that contained biodegradable poly‐lactic acid (PLA) matrix with microfibrillated cellulose (MFC) and bamboo fiber bundles reinforcements was developed by Okubo et al. [23]. Various nomenclatures have been used for describing MFC in the literature, such as microfibril, microfibrillar cellulose, microfibril aggregates, nanofibril, nanofibrillar cellulose, nanofiber, and fibril aggregates [24]. They conducted an investigation on how MFC dispersion influenced the responses of composites reinforced with bamboo fibers by dispersing MFC in a polymer matrix of PLA by a three‐roll mill calendering process. This calendering process helps to compress or smoothen a material. They used the PLA (bio‐based and biodegradable) polymer matrix for interfacial bonding enhancement with the MFC. The diameter of bamboo fiber bundles was about 200 μm, while that of MFC was just a few microns, which was much smaller. Using gap settings in decreasing order of 70, 50, 35, 25, 15, 10, and 5 μm, they processed the mixture of the MFC and PLA in the three‐roll mill. About 200% increase in the fracture energy was realized when they added 1 wt.% of MFC to the PLA matrix and milled the MFC/PLA composite at the smallest gap setting of 5 μm, which was quite significant. This hybrid composite combination of bamboo fiber and the PLA matrix with 1 wt.% MFC reinforcement was observed to prevent an abrupt crack channel through the bamboo fiber effectively, and thus produced a significant improvement in fracture strength. The results of other mechanical behaviors are presented in Table 1.5.

1.4.1.3 Banana/Kenaf and Banana/Sisal FRP Hybrid Composites

A good material for reinforcement in diverse polymer composites is the banana fiber. Its extraction is usually from the bark of banana trees [4]. Banana fiber has such advantaged mechanical properties, including good tensile strength and modulus, due to the high content of cellulose and low microfibrillar angle [25]. Kenaf fiber is a promising element of reinforcement in polymer composites, due to its interesting mechanical features such as eco‐friendliness and renewability. Kenaf is usually extracted from bast fiber (kenaf plants) [4]. Sisal, on the other hand, is known to be among the toughest materials for reinforcement. It is also well known for its durability. Sisal FRP composites possess moderate flexural and tensile behaviors and high impact strength, when compared with other composites of natural fiber reinforcements. It has relevant use in some industries, such as agriculture and marine to make twines, ropes, cords, rugs, and bagging, among others [26]. Sisal and kenaf fibers, similar to other natural fibers, have poor interfacial bonding with a polymer matrix, which shows their disadvantage [27].

Table 1.5 Mechanical behaviors of bagasse/jute, bamboo/MFC, and banana/kenaf FRP hybrid composites.

Source: Nguyen et al. [4]. © 2017, Elsevier.

Hybrid biocomposites

Fiber ratio (by weight or volume)

Flexural modulus (GPa)

Flexural strength (MPa)

Tensile modulus (GPa)

Tensile strength (MPa)

Impact strength (kJ/m

2

)

Natural fibers

Bagasse/jute

Bagasse fiber bundles (untreated) and jute fiber bundles (treated)

0 : 100

0.645

31.15

0.302

11.45

6.90

20 : 80

0.789

36.46

0.356

16.02

7.46

35 : 65

1.101

45.32

0.420

19.45

9.53

50 : 50

1.480

55.63

0.492

23.07

10.66

65 : 35

1.311

51.19

0.399

21.15

8.33

100 : 0

0.502

26.78

0.227

9.87

6.67

Bagasse fiber bundles (treated) and jute fiber bundles (treated)

20 : 80

1.178

42.72

0.526

18.72

10.00

35 : 65

1.484

54.57

0.635

22.57

13.33

50 : 50

1.748

65.22

0.753

26.77

15.93

65 : 35

1.518

60.12

0.704

23.54

10.93

100 : 0

0.632

30.78

0.286

11.20

8.66

Bamboo/MFC

MFC/PLA composites (milled to 5 μm)

1 wt.% of MFC

 —

—

4.61 ± 0.27

45.9 ± 4.1

—

2 wt.% of MFC

 —

—

3.95 ± 0.14

51.7 ± 2.3

—

Banana/kenaf

50 : 50, nonwoven hybrid

10% NaOH treatment

—

57.2

—

44

13

10% SLS treatment

60.8

50

16

50 : 50, woven hybrid

10% NaOH treatment

62.0

—

50

18

10% SLS treatment

—

68.0

54

21

MFC and PLA represent micro‐fibrillated cellulose and poly‐lactic acid, respectively.

Moreover, Thiruchitrambalam et al. [28] conducted a study on woven as well as non‐woven hybrids of banana/kenaf fiber with unsaturated polyester matrix reinforcement. They kept the fiber contents constant at 40% with equal ratio of banana and kenaf FRP composites (50 : 50 ratio) and treated the fibers with either 10% solution of NaOH or 10% of sodium lauryl sulfate (SLS) for 30 minutes. They observed that the SLS‐treated specimen had better improvement with respect to mechanical behavior than the alkali‐treated specimen, showing for both woven and non‐woven cases of the banana/kenaf hybrid composites enhanced impact, flexural, and tensile strengths, as shown in Table 1.5.

Furthermore, Venkateshwaran et al. [29] evaluated the mechanical properties of banana/sisal FRP epoxy matrix hybrid composite and found out that hybridization increased the flexural, tensile, and impact strengths by 4%, 16%, and 35% respectively. They also reported that the 50 : 50 fiber ratio by weight enhanced the mechanical response of the banana/sisal FRP hybrid composite and decreased the uptake of moisture, as presented in Table 1.6.

1.4.1.4 Coconut/Cork FRP Hybrid Composites

A natural coconut fiber, also known as coir, is usually extracted from coconut trees. These trees are mainly grown in tropical regions of Asian countries, such as Vietnam, India, and Thailand [4]. Cork fiber is usually obtained from cork oak trees (Quercus suber). There is a specific species of the tree from whose bark the cork fiber is harvested. The cork oak tree is a renewable resource, as new cork bark regrows naturally [4].

Hybrid composites containing high‐density polyethylene (HDPE) with reinforcements of cork powder and short coconut fibers that were randomly distributed was prepared by Fernandes et al. [30]. The interfacial bonding and compatibility between the matrix and fiber was improved by maleic anhydride, a coupling agent (CA). Their results showed 27% and 47% rise in elastic moduli and tensile strengths of the coconut/HDPE/cork hybrid composites, respectively (Table 1.6), when compared with the cork/HDPE composite. Also, they observed that using CA resulted in enhancement of the elongation at break and tensile behaviors of the hybrid composites. As a recommendation for better mechanical responses of the cork‐based composites, 10 wt.% of short coconut fibers and 2 wt.% of CA were proposed.

Table 1.6 Mechanical behaviors of banana/sisal, coconut/cork, coir/silk, corn husk/kenafm and cotton/jute FRP hybrid composites.

Source: Nguyen et al. [4]. © 2017, Elsevier.

Hybrid biocomposites

Fiber ratio (by weight or volume)

Flexural modulus (GPa)

Flexural strength (MPa)

Tensile modulus (GPa)

Tensile strength (MPa)

Impact strength (kJ/m

2

)

Banana/sisal

100 : 0

8.920

57.33

0.642

16.12

13.25

75 : 25

9.025

58.51

0.662

17.39

15.57

50 : 50

9.130

59.69

0.682

18.66

17.90

25 : 75

9.235

60.87

0.703

19.93

20.22

0 : 100

9.340

62.04

0.723

21.20

22.54

Coconut/cork

10 : 44 : 44 : 2 (wt.% of coconut/cork/HDPE/coupling agent)

—

—

0.599 ± 0.02

20.4 ± 0.3

—

Coir/silk

Alkali treatment

10 mm fiber

—

39.53

—

15.01

—

20 mm fiber

—

45.07

—

17.24

—

30 mm fiber

—

42.02

—

16.14

—

Corn husk/kenaf

0 : 30 (PLA 70 wt.%)

—

—

2.117

—

—

15 : 15 (PLA 70 wt.%)

—

—

1.547

—

—

30 : 0 (PLA 70 wt.%)

—

—

1.221

—

—

Cotton/jute

23.7 : 76.3 (jute fabric type III)

Test angle, 0°

9.9 ± 0.8

136.7 ± 4.0

7.1 ± 0.3

59.4 ± 1.7

9.3 ± 0.9

Test angle, 45°

8.4 ± 0.7

84.6 ± 4.7

4.6 ± 0.1

21.1 ± 1.4

7.5 ± 1.0

Test angle, 90°

7.2 ± 0.7

58.3 ± 5.4

4.1 ± 0.1

14.6 ± 0.5

5.5 ± 1.0

HDPE = high‐density polyethylene.

1.4.1.5 Coir/Silk FRP Hybrid Composites

Silk is a continuous protein fiber characterized by its soft, light, and thin nature and produced by different insects. The silkworm and spun synthesize silk fiber, such as silk cocoon. Large quantities of silk proteins (sericin and fibroin) are produced by the silkworm at the last stage of larval development [31]. These silk proteins are key components of the silk cocoons. Silk fiber, with its huge specific strength and stiffness, have wonderful luster and excellent drape. It prides itself as the strongest material in nature. It however has poor resistance when exposed to sunlight [4].

Using unsaturated polyester matrix, Noorunnisa Khanam et al. [32] in an investigation into the coir/silk fiber hybrid composites used various fiber lengths of 10, 20, and 30 mm. Sodium hydroxide (NaOH) solution was used to treat the coir fibers in order to eliminate their lignin and hemicellulose, thereby causing better bonding of the fiber with the matrix. Composites of 20 mm fiber length showed higher tensile and flexural strengths than the 10 and 30 mm counterparts, as shown in Table 1.6. The tensile, flexural, and compressive strengths were improved significantly in the coir/silk hybrid composites, owing to the NaOH treatment that facilitated the bonding at the coir fiber–polyester matrix interface.

1.4.1.6 Corn Husk/Kenaf FRP Hybrid Composites

Several agricultural wastes such as rice straw, corn husk, and rice husk form a huge quantity of raw natural fibers that are used in polymer composites as materials for reinforcement. Corn husks contain fibers that are rich in cellulose. They are the thin and leafy sheaths that surround corn cobs [33]. Kenaf fiber is important in paper as well as other industrial sectors, as a fiber source.

Kwon et al. [34] used PLA matrix and prepared kenaf fiber and corn husk flour hybrid biocomposites, using a constant fiber to matrix ratio of 30 : 70 by weight (Table 1.6). Different kenaf/corn husk flour ratios were examined. Before and after extrusion, the aspect ratio was measured for kenaf fibers and its influence on the mechanical behavior was investigated. The result showed that the aspect ratio post‐extrusion had no influence on the values predicted from the Halpin–Tsai equation. Note that the Halpin–Tsai model for predicting elastic response of composites assumes that there is no fiber–matrix interaction and works on the basis of the orientation (geometry) as well as elastic behavior of the matrix and the fibers. They found out that the variation in the Young's modulus of fibers affected the transfer of stress from the matrix to the fiber and reported that a factor of control to optimize mechanical behavior in hybrid biocomposites could be the reinforcements' scale ratio in various aspect ratios.

1.4.1.7 Cotton/Jute and Cotton/Kapok FRP Hybrid Composites

Cotton fibers have been considered as fibers with the greatest importance across the globe. They usually do not have branches and the seed hairs have a single cell (unicellular). They are also rich in cellulose and can elongate up to 30 mm. The wall of cotton fiber does not contain lignin, as distinct from the secondary cell walls of most plants [35]. Cotton fibers are used widely in the textile industry. They possess some advantages, which include excellent drape, high absorbency, as well as good strength.

In the study conducted by De Medeiros et al. [36], the mechanical behavior of woven fabrics of hybrid cotton/jute with phenolic matrix (novolac type) reinforcement was investigated. The results showed strong dependence on the mechanical behaviors on fiber content, fabric characteristics, fiber–matrix adhesion, and fiber orientation. The anisotropy of the composites increased when the test angle was increased and showed dependence on fiber roving/fabric characteristics. There was an inverse proportionality between the mechanical properties and the test angle as the best performance was obtained in the specimen tested at zero degree (that is, jute roving direction). Brittle failure, though controlled, was displayed in the composites that were tested at angles of 45° and 90° as jute fiber directions (Table 1.6), while at 0° to the longitudinal direction, the tested composites exhibited an uncontrollable catastrophic failure. Jute fiber was identified as a strong material for reinforcement and when combined with cotton could prevent catastrophic failure in the fabric composites. In addition, the results obtained from mechanical behaviors of cotton/kapok FRP hybrid composites are depicted in Table 1.7, showing the effects of accelerated and non‐accelerated weather conditions of alkaline‐treated and untreated specimens. The results of cotton/ramie FRP hybrid composites, with ramie fibers placed longitudinally to the mold length and various ratio, are also shown in Table 1.7.

Table 1.7 Mechanical behaviors of cotton/kapok, cotton/ramie, and jute/oil palm empty‐fruit bunches (OPEFB) FRP hybrid composites.

Source: Nguyen et al. [4]. © 2017, Elsevier.

Hybrid biocomposites

Fiber ratio (by weight or volume)

Flexural modulus (GPa)

Flexural strength (MPa)

Tensile modulus (GPa)

Tensile strength (MPa)

Impact strength (kJ/m

2

)

Cotton/kapok

3 : 2

Untreated (

V

f

 = 60%)

—

—

0.884

55.70

110.53

Alkali treatment (

V

f

 = 43%)

—

—

1.635

52.87

119.25

Non‐accelerated weather condition (

V

f

 = 46.6%)

0.709

52.40

—

—

—

Accelerated weather condition (

V

f

 = 46.6%)

0.703

39.55

—

—

—

Cotton/ramie (ramie fibers placed longitudinally to the mold length)

10.8 : 41.1 (0° composite)

—

—

—

90.9 ± 12.7

—

11.9 : 45.5 (0° composite)

—

—

—

117.3 ± 13.3

—

11.9 : 45.1 (0° composite)

—

—

—

118.0 ± 6.5

—

Jute/OPEFB

1 : 4

OPEFB/Jute/OPEFB

—

—

2.39

25.53

—

Jute/OPEFB/Jute

—

—

2.59

27.41

—

Pure OPEFB

—

—

2.23

22.61

Pure jute

—

—

3.89

45.55

1.4.1.8 Jute/OPEFB FRP Hybrid Composites

Oil palm (Elaeis guineensis) is a perennial crop known for its high‐value fruits from which oil is produced. It mostly grows in tropical regions, such as Southeast Asia and West/Southwest Africa. Oil is extracted by stripping the fruits (nuts) from the bunches, a process that leaves the empty‐fruit bunches (EFBs) as waste material [37]. Fibers of oil palm are usually derived from the oil palm empty‐fruit bunches (OPEFB) as well as mesocarp. In composite materials, the OPEFB fibers are mostly used, as they contain the highest hemicellulose content in comparison with pineapple, coir, banana, as well as soft and hardwood fibers [11].

A three‐ply hybrid sample of jute/OPEFB fibers composites with epoxy resin reinforcement was prepared by Jawaid et al. [38], fixing the jute/OPEFB ratio (by weight) at 1 : 4. They investigated the void content, chemical resistance, as well as tensile behaviors of the hybrid composites. From the results obtained, the OPEFB/jute/OPEFB and jute/OPEFB/jute composites showed great resistance to chemicals: toluene (C7H8), benzene (C6H6), water (H2O), 40% of nitric acid (HNO3), carbon tetrachloride (CCl4), hydrochloric acid (HCl), 5% of acetic acid (CH3COOH), 20% sodium carbonate (Na2CO3), 10% of sodium hydroxide (NaOH), and 10% of ammonium hydroxide (NH4OH). A lower void content was displayed in the jute/OPEFB/jute than pure OPEFB as well as OPEFB/jute/OPEFB composites, because the mats of the jute fiber adhered better to the epoxy resin with higher compatibility. At the outer ply, the jute fibers withstood the tensional stress due to their high strengths, and the core (OPEFB fiber) absorbed and distributed the stresses evenly within the composite sample systems. Also, it was evident from Table 1.7 that the jute/OPEFB hybrid exhibited higher tensile responses (both strength and modulus) as well as improved adhesion bond between the fiber and the matrix, when compared with pure OPEFB composite.

1.4.1.9 Kenaf/PALF FRP Hybrid Composites

A tropical plant, pineapple (Ananas comosus) belongs to the family of bromeliad (Bromeliaceae). In South America, it is next in line to banana and mango in total production across the globe [39]. Pineapple leaf fibers (PALFs) are waste products when cultivating pineapples and are extracted from pineapple leaves. It has a significant mechanical behavior, because it is high in cellulose (70–82%) as well as in crystallinity (44–60%) [40]. Combining these properties with that of Kenaf fiber, excellent tensile and flexural strengths from FRP composite are obtained, which promises a good material for different applications [4].

Aji et al. [41] studied hybridized Kenaf/PALF specimens with HDPE reinforcement, using 1 : 1 fiber ratio. They investigated into how the size of fiber and its loadings affected the mechanical responses of the hybrid biocomposites (Table 1.8). The four reinforcement lengths considered at a fiber loading range of 10–70% were 0.25, 0.50, 0.75, and 2.00 mm. The smallest of these fiber lengths (0.25 mm) yielded the best result in terms of its flexural and tensile properties, while both 0.75 and 2 mm exhibited enhancement in impact strength. As observed further, an increase in the fiber length reduced some of the mechanical behaviors, which is credited to the entanglement in fibers as against fiber attrition. An inverse proportionality was established between the tensile and impact properties, as the rule of mixture was satisfied by flexural strength. The adhesion between the fiber and the matrix interface was good, as evaluated by scanning electron microscopy (SEM).

Table 1.8 Mechanical behaviors of kenaf/PALF, roselle/sisal, and silk/sisal FRP hybrid composites.

Source: Nguyen et al. [4]. © 2017, Elsevier.

Hybrid biocomposites

Fibre ratio (by weight or volume)

Flexural modulus (GPa)

Flexural strength (MPa)

Tensile modulus (GPa)

Tensile strength (MPa)

Impact strength (kJ/m

2

)

Kenaf/PALF

1 : 1 (At 0.25 mm fiber length and 60% fiber loading)

4.114

34.01

0.874

32.24

6.167

1 : 1

Sisal/roselle

Dry condition, fiber length = 15 cm

—

76.5

—

58.7

1.30

Wet condition, fiber length = 15 cm

—

62.9

—

44.9

1.28

Sisal/silk

1 : 1, fiber length = 20 mm

Untreated

—

46.18

—

18.95

—

Alkali treatment

—

54.74

—

23.61

—

1.4.1.10 Sisal/Roselle and Sisal/Silk FRP Hybrid Composites

Sisal (Agavesisalana), from the Agavaceae family, is a hard‐fiber plant with wide cultivation in the tropical countries of Africa, America, and Asia, though it has its origin in Mexico and Central America. Their fibers are strong and tough, and extracted from sisal plant leaves. Sisal fibers are widely utilized in composites and plastic/paper industries. The nativity of roselle (Hibiscus sabdariffa) can be traced to West Africa. It is a species of Hibiscus, whose plant is naturally abundant and majorly used for fruits and bast fibers. Roselle fibers have extensive applications in the textile industry and in composites, because they exhibit greater mechanical behaviors in comparison with some other naturally occurring fibers, such as jute and kenaf.

Moreover, Athijayamani et al. [42