Progress in Adhesion and Adhesives, Volume 2
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Preface xiii
1 Surface Modification of Natural Fibers for Reinforced Polymer Composites 1
M. Masudul Hassan and Manfred H. Wagner
1.1 Introduction 1
1.1.1 Natural Fibers (NFs): Sources and Classification 2
1.1.2 Composition of NFs 2
1.1.3 New Trends in the Chemistry of Cellulose 3
1.1.4 Action of Reducing and Oxidizing Agents 6
1.1.5 Drawbacks of Natural Fibers 7
1.2 Modifications of Natural Fibers 9
1.2.1 Physical Modifications of Natural Fibers 9
1.2.2 Chemical Modifications of Natural Fibers 11
1.3 Composites 16
1.3.1 Hybrid Composites 17
1.3.2 Compatibilization 17
1.3.3 Effect of Radiation on Fiber Composites 19
1.3.4 Initiative in Product Development of NF Composites 20
1.4 Properties Evaluation 20
1.4.1 Lantana-Camara Fiber 20
1.4.2 Tea Dust-Polypropylene (TDPP) Composite 23
1.4.3 Water Absorption Test 27
1.4.4 Jute Fiber Reinforced Vinylester Composites 27
1.4.5 Coir Fiber Reinforced Polyester Composites 29
1.4.6 Effect of Alkali Treatment on Hemp, Sisal and Kapok for Composite Reinforcement 31
1.4.7 DSC Analysis of Mercerized Fibers 34
1.4.8 XRD Analysis of Mercerized Fibers 34
1.4.9 SEM Analysis of Alkalized Fibers 34
1.5 Conclusions 36
Acknowledgements 37
References 37
2 Factors Influencing Adhesion of Submicrometer Thin Metal Films 45
A. Lahmar, A. Assaf, M.J. Durand, S. Jouanneau, G. Thouand and B. Garnier
2.1 Introduction 46
2.2 Experimental Details 47
2.2.1 Film Deposition 47
2.2.2 Measurement of the Critical Load 48
2.3 Results and Discussion 50
2.3.1 Scanning Electron Microscopy Observations 50
2.3.2 Effects of Film Thickness and Substrate Bias on the Mean Critical Load 51
2.3.3 Effects of Ion Bombardment Etching of Substrate Surface 54
2.3.4 Effect of Ageing Treatment after Deposition 55
2.3.5 Effect of Roughness of the Substrate Surface 56
2.3.6 Dependence of Critical Load and Thermal Resistance on Deposition Conditions 58
2.3.7 Correlation Between Adhesion and Thermal Contact Resistance 60
2.4 Summary 63
References 63
3 Surface Treatments to Modulate Bioadhesion 67
D.G. Waugh, C. Toccaceli, A.R. Gillett, C.H. Ng, S.D. Hodgson and J. Lawrence
3.1 Introduction 67
3.1.1 The Role of Wettability in Biological and Microbiological Adhesion 69
3.2 Various Surface Treatments 70
3.2.1 Laser Surface Treatment 70
3.2.2 Lithography 75
3.2.3 Micro/Nano Contact Printing 77
3.2.4 Plasma Surface Treatment 79
3.2.5 Radiation Grafting 81
3.2.6 Ion Beam and Electron Beam Processing 82
3.3 Prospects 85
3.4 Summary 89
References 89
4 Hot-Melt Adhesives from Renewable Resources 101
P. Utekar, H. Gabale, A. Khandelwal and S.T. Mhaske
4.1 Introduction 101
4.2 Potential Renewable Base Polymers 103
4.3 Lactic Acid Based Polymers as Hot-Melt Adhesives 104
4.4 Soy Protein Based Polymers as Hot-Melt Adhesives 106
4.5 Bio-Based Polyamides as Hot-Melt Adhesives 107
4.6 Starch Based Polymers as Hot-Melt Adhesives 109
4.7 Summary 111
References 111
5 Relevance of Adhesion in Particulate/Fibre-Polymer Composites and Particle Coated Fibre Yarns 115
V.B. Mohan, K. Jayaraman and D. Bhattacharyya
5.1 Introduction 115
5.1.1 Mechanisms of Adhesion 118
5.1.2 Tests for Interfacial Adhesion in Composites 120
5.2 Theory of Interaction 124
5.2.1 Adhesion Mechanism in Fibre Yarns and Polymer Systems 125
5.2.2 Surface Modification Techniques 126
5.2.3 Adhesion Properties of Fibres 130
5.2.4 Morphological Evaluation of Fibre Yarns Coated with Nanoparticles 131
5.2.5 Interfacial Adhesion in Particle and Polymer Blends 138
5.3 Summary 140
References 142
6 Study and Analysis of Damages in Functionally Graded Adhesively Bonded Joints of Laminated FRP Composites 147
S.K. Panigrahi and Rashmi Ranjan Das
6.1 Introduction 148
6.2 Damage Analysis of Adhesively Bonded Laminated Composite Joints 149
6.2.1 Damage Analysis of Adhesively Bonded Flat FRP Composite Joints 149
6.2.2 Damage Analysis of Adhesively Bonded Tubular FRP Composite Joints 151
6.3 Effect of Adhesive Property on Damages in Adhesively Bonded Joints 152
6.4 Effect of Functionally Graded Adhesives on Damages in Adhesively Bonded Joints 153
6.5 Conclusion 156
References 156
7 Surface Modification Strategies for Fabrication of Nano-Biodevices 161
Ankur Gupta, Vinay Kumar Patel, Rishi Kant and Shantanu Bhattacharya
7.1 Introduction 161
7.2 Interfacial Interactions for Proper Functioning of Nano-biodevices 164
7.3 Strategies for Surface Modification of Polymers in Nano-biodevices 167
7.3.1 Surface Modification of Polymers Through Plasma Treatment 168
7.3.2 Surface Modification of Surfaces Through Chemical Route 168
7.3.3 Surface Modification Through Silanization of Surfaces 169
7.3.4 Surface Modification of Polymers with SAMs by Micro-contact Printing Technique 170
7.3.5 Other Surface Modification Strategies 171
7.4 Benefits of Surface Modifications to Nano-Biodevices 176
7.5 Summary 177
References 177
8 Effects of Particulates on Contact Angles and Adhesion of a Droplet 187
Youhua Jiang, Wei Xu and Chang-Hwan Choi
8.1 Introduction 187
8.2 Theoretical Background of Contact Angles and Adhesion of a Droplet 189
8.3 Effects of Particulates on Static Contact Angles 191
8.3.1 Deposition of Particulates on Solid-liquid Interface 192
8.3.2 Adsorption of Particulates on Liquid-Gas Interface 194
8.3.3 Adsorption of Surfactants on Solid-Gas Interface 195
8.4 Effects of Particulates on Droplet Pinning 197
8.4.1 Flows Within a Droplet 199
8.4.2 Interactions amongst Particulates, Solid Substrates, and Liquid-Gas Interfaces 201
8.4.3 Structural Disjoining Pressure 204
8.5 Effects of Particulates on Droplet Motion 205
8.5.1 Contact Line Velocity 205
8.5.2 Stick-Slip Behavior 206
8.6 Summary 210
8.7 Prospects 210
Acknowledgements 211
References 211
9 Thermal Stresses in Adhesively Bonded Joints/Patches and Their Modeling 217
M. Kemal Apalak
9.1 Introduction 217
9.2 Thermal Stresses 219
9.2.1 Bi-material Strips 219
9.2.2 Linear Analyses 220
9.2.3 Nonlinear Analyses 225
9.3 Thermal Residual Stresses 230
9.3.1 Residual Stresses - Adhesive Curing 233
9.3.2 Residual Stresses - Hygrothermal Ageing 246
9.4 Viscoelastic Analyses 250
9.5 Fracture and Fatigue 255
9.6 Summary 263
References 264
10 Ways to Mitigate Thermal Stresses in Adhesively Bonded Joints/Patches 271
M. Kemal Apalak
10.1 Introduction 271
10.2 CFRP Strengthened Beams and Plates 273
10.3 Weld-Bonded Joints, Cutting Tools 276
10.4 Adhesive Joints Under Cryogenic Temperatures 279
10.5 Low and High-Temperature Adhesives 285
10.6 Fillers and Electrically-conductive Adhesives 289
10.6.1 Adhesive Layer with Fillers or Voids 289
10.6.2 Electrically-conductive Adhesives 292
10.7 Microelectronics, Optics and Nuclear Applications 296x Contents
10.8 Dental Applications 307
10.9 Summary 312
References 314
11 Laser-Assisted Electroless Metallization of Polymer Materials 321
Piotr Rytlewski, Bartomiej Jagodzi?ski and Krzysztof Moraczewski
11.1 Introduction 321
11.2 Application of Lasers in the Metallization of Polymer Materials 323
11.2.1 Modification in a Gaseous Medium 324
11.2.2 Modification in Solutions 326
11.2.3 Modification of Thin Films 327
11.2.4 Modification of Composite Materials 328
11.3 Modification of Polymer Composite Materials 328
11.3.1 Polyamide Composites 328
11.4 Summary 346
Acknowledgement 347
References 347
12 Adhesion Measurement of Coatings on Biodevices/Implants 351
Wei-Sheng Lei, Kash Mittal and Zhishui Yu
12.1 Introduction 352
12.2 Mechanical Test Methods of Adhesion Measurement 354
12.2.1 Cross-Cut Test 354
12.2.2 Peel Test 355
12.2.3 Scribe (Scratch) Test 356
12.2.4 Pull-Off (Tensile) Test 360
12.2.5 Single-Lap Shear Test 363
12.2.6 Blister Test 364
12.2.7 Micro- and Nano- Indentation Tests 365
12.2.8 Small-Punch Test 369
12.2.9 Micro- and Nano- Scale Tensile Testing 369
12.2.10 Four-Point Bending Test 371
12.2.11 Other Test Methods 372
12.3 Summary and Remarks 373
References 374Contents xi
13 Cyanoacrylate Adhesives 381
P. Rajesh Raja
13.1 Introduction 381
13.2 Synthesis and Processing 382
13.3 Applications 386
13.3.1 Industrial and Consumer 386
13.3.2 Medical 390
13.3.3 Forensics 393
13.3.4 Recent Advances in Cyanoacrylate Adhesives 393
13.4 Summary 394
References 394
14 Promotion of Adhesion of Green Flame Retardant Coatings onto Polyolefins by Depositing Ultra-Thin Plasma Polymer Films 399
Moustapha E. Moustapha, J"rg F. Friedrich, Zeinab R. Farag, Simone Kr?ger, Gundula Hidde and Maged M. Azzam
14.1 Introduction 400
14.2 Role of Adhesion in the Use of Thick Fire-Retardant Coatings 400
14.3 Strategies for Adhesion Promotion of Flame-Retardant Coatings 406
14.4 Plasma Polymerization 409
14.5 Adhesion Improvement by Plasma Polymer Layers 412
14.5.1 Inorganic Flame Retardant Layers (Water Glass Layers) 412
14.5.2 Coating with Prepolymer of Melamine Resin 414
14.5.3 Curing of the Melamine Prepolymer 414
14.6 Results of Adhesion Improvement Using Adhesion-Promoting Plasma Polymers 415
14.6.1 Results of Adhesion Promotion 415
14.6.2 Locus of Adhesion Failure 418
14.7 Flame Retardancy Tests 420
14.8 Thermal Behavior 421
14.9 Summary 423
Acknowledgement 424
References 424
Chapter 1
Surface Modification of Natural Fibers for Reinforced Polymer Composites
M. Masudul Hassan1* and Manfred H. Wagner2
1Department of Chemistry, M C College, National University, Sylhet-3100, Bangladesh
2Berlin Institute of Technology (TU Berlin), Institute of Materials Science and Technology, Polymer Engineering/Polymer Physics, D-10623 Berlin, Germany
*Corresponding author: msdhasan@yahoo.com
Abstract
Recent advances in engineering, natural fibers development and composites science offer significant opportunities for new, improved materials which can be biodegradable and recyclable and can also be obtained from sustainable resources at the same time. The combination of bio-fibers like betel nut, banana, coir, jute, rice straw, tea dust and various grasses with polymer matrices from both non-renewable (petroleum based) and renewable resources to produce composite materials that are competitive with synthetic composites such as glass fiber reinforced polypropylene or epoxide has been getting increased attention over the last decades. This article provides a general overview of natural fibers and bio-composites as well as the research on and application of these materials. A special emphasis is placed on surface modification of natural fibers to attain desired composite properties. The roles of compatibilizers and radiation on the natural fiber-polymer composites are also included. A discussion about chemical nature, processing, testing and properties of natural fiber reinforced polymer composites completes this article.
Keywords: Natural fiber, surface modification, compatibilizer, radiation, hybrid composite, mechanical properties
1.1 Introduction
The demand for natural fiber reinforced polymer composites is growing rapidly due to their high mechanical properties, significant processing advantages, low cost and low density. Natural fibers are renewable resources in many countries of the world; they are cheaper, pose no health hazards and finally provide a solution to environmental pollution by finding new uses over expensive materials and non-renewable resources. Furthermore, natural fiber reinforced polymer composites form a new class of materials which seem to have great potential in the future as a substitute for scarce wood and wood based materials in societal applications [1].
Lignocellulosic natural fibers like jute, sisal, coir, and pineapple have been used as reinforcements in polymer matrices. Natural fibers of vegetable origin include bast, leaves, and wood fibers. They may differ considerably in their physical appearance but they have, however, many similarities that identify them as one family. The characteristics of the fibers depend on the individual constituents and the fibrillar structure. The fiber is composed of numerous elongated fusiform fiber cells. The fiber cells are linked together by means of middle lamellae, which consist of hemicellulose, lignin and pectin. Growing environmental awareness has spurred the researchers worldwide to develop and utilize materials that are compatible with the environment. In this process natural fibers have become suitable alternatives to traditional synthetic or man-made fibers and have the potential to be used in cheaper, more sustainable and more environmentally-friendly composite materials [2-3].
1.1.1 Natural Fibers (NFs): Sources and Classification
Natural organic fibers can be derived from either animal or plant sources. The majority of useful natural textile fibers are plant derived, with the exception of wool and silk. All plant fibers are composed of cellulose, whereas fibers of animal origin consist of proteins. Natural fibers, in general, can be classified based on their origin, and the plant-based fibers can be further categorized based on part of the plant they are recovered from. An overview of natural fibers and some photographs of NFs are presented in Figures 1.1 and 1.2, respectively [4-5].
Figure 1.1 Overview of natural fibers.
Figure 1.2 Photographs of some natural fibers.
Plant fibers are a renewable resource and have the ability to be recycled. The plant fibers leave little residue if they are burned for disposal, returning less carbon dioxide (CO2) to the atmosphere than is removed during the plant's growth.
Chemically the lignocellulosic fibers comprise cellulose, hemicellulose, lignin, pectin and small amounts of waxes and fat. Several important sources of lignocellulosic materials are listed [6] in Table 1.1, Dinwoodie [7] summarizes the polymeric state, molecular derivatives and function of cellulose, hemicellulose, lignin and extractives (see Table 1.2).
Table 1.1 Chemical compositions of various lignocellulosic materials.
Lignocellulose source Cellulose (%) Hemicellulose (%) Lignin (%) Other constituents (%) Hardwood 43-47 25-35 16-24 2-8 Softwood 40-44 25-29 25-31 1-5 Coir 32-43 10-20 43-49 4.5 Cotton 95 2 0.9 0.4 Hemp 70.2 22.4 5 5.7 Henequen 77.6 4.8 13.1 3.6 Jute 71.5 13.6 13.1 1.8 Kenaf 36.0 21.5 17.8 2.2 Ramie 76.2 16.7 0.7 6.4 Sisal 73.1 14.2 11.0 1.7Table 1.2 Cellulosic component, polymeric state, derivatives and function.
Component Polymeric state Derivatives Function Cellulose Crystalline highly oriented large molecule Glucose "Fiber" Hemicelluloses small molecules Semi-crystalline mannose, xilose Galactose "Matrix" Lignin Amorphous large 3-D molecule Phenyl propane "Matrix" Extractives Some polymeric; Other nonpolymeric polyphenols Terpenes1.1.2 Composition of NFs
Natural plant fibers are composed of cellulose fibers, made of helically wound cellulose micro-fibrils, bound together by an amorphous lignin matrix. Lignin keeps the water in the fibers acts as a protection against biological attack and as a stiffener to give stem its resistance against gravity forces and wind. Hemicellulose found in the natural fibers is believed to be a compatibilizer between cellulose and lignin. The cell wall in a fiber is not a homogeneous membrane [8-9]. Each fiber has a complex, layered structure consisting of a thin primary wall which is the first layer deposited during cell growth encircling a secondary wall. The secondary wall is made up of three layers and the thick middle layer determines the mechanical properties of the fiber. The middle layer consists of a series of helically wound cellular micro-fibrils formed from long chain cellulose molecules. The angle between the fiber axis and the micro-fibrils is called the microfibrillar angle. The characteristic value of microfibrillar angle varies from one fiber to another. These micro-fibrils typically have a diameter of 10-30 nm and are made up of 30-100 cellulose molecules in an extended chain conformation and provide mechanical strength to the fiber. Study on jute cellulose, hemicellulose and lignin [10-11] suggests that these consist of units as shown in Figures 1.3-1.5.
Figure 1.3 Structure of cellulose.
Figure 1.4 Structure of hemicellulose.
Figure 1.5 Structure of lignin.
1.1.3 New Trends in the Chemistry of Cellulose
The chemistry of cellulose now under development will make possible the use of cellulose, the most important and widespread polymer, for manufacturing a great variety of materials with new structures and endowed with valuable properties quite different from those of ordinary cellulose products. The transformation of natural cellulose containing one type of reactive groups (primary and secondary alcohol groups) into high molecular weight compounds which, depending on processing conditions, will contain almost any...
