Page 19 - Handbook of Adhesives and Sealants

vi Contents

1.6.1.4 Forming an impervious joint 38
1.6.1.5 Joint design 39
1.6.1.6 Selection and control of materials and
manufacturing processes 39
1.6.2 Mechanism of bond failure 39
1.7 General materials and processes 42
1.7.1 Materials used for adhesives and sealants 42
1.7.2 Manufacturing processes for adhesives and sealants 44
1.7.3 End-use processes for adhesives and sealants 46
1.8 Sources of information 47

Chapter 2. Theories of Adhesion 49
2.1 Introduction 49
2.2 Forces involved in adhesion 49
2.2.1 Adhesive and cohesive forces 49
2.2.2 The concept of surface energy 51
2.2.3 Work of adhesion and cohesion 54
2.2.4 Bond failure energy 55
2.2.5 Surface attachment theory of joint strength 57
2.3 Theories of adhesion 59
2.3.1 Adsorption theory 59
2.3.2 Mechanical theory 62
2.3.3 Electrostatic and diffusion theories 64
2.3.4 Weak-boundary-layer theory 64
2.4 Stages in an adhesive’s or a sealant’s life 66
2.4.1 Application and Wetting 66
2.4.2 Setting or solidification 69
2.4.2.1 Localized stress 70
2.4.2.2 Setting stresses due to thermal expansion
differences 71
2.4.2.3 Setting stresses due to shrinkage of the
adhesive or sealant 74
2.4.3 Operation in service 75
2.4.3.1 Short term effects 75
2.4.3.2 Long term effects 77
2.5 Special mechanisms related to sealants 79
2.6 Polymer material interactions 81
2.6.1 Polymeric materials 82
2.6.2 Properties important for adhesives and sealants 82
2.6.2.1 Properties important for adhesion 82
2.6.2.2 Properties affecting cohesion 83
2.7 Surface and interface interactions 87
2.7.1 Boundary layer theory 88
2.7.2 Interphase region 89

Chapter 3. Joint Design 93
3.1 Introduction 93
3.2 Types of stress 94
3.2.1 Tensile and compressive stress 94
3.2.2 Shear stress 96
3.2.3 Cleavage and peel stress 97