Progress in Adhesion and Adhesives, Volume 6

Preface xxi 1 Hot-Melt Adhesives: Fundamentals, Formulations, and Applications: A Critical Review 1 Swaroop Gharde, Gaurav Sharma and Balasubramanian Kandasubramanian 1.1 Introduction to Hot-Melt Adhesives (HMAs) 2 1.2 Formulation of Hot-Melt Adhesives 4 1.2.1 Theories or Mechanisms of Adhesion 4 1.2.1.1 Mechanical Interlocking Theory 4 1.2.1.2 Electrostatic Theory 5 1.2.1.3 Diffusion Theory 5 1.2.1.4 Physical Adsorption or Wetting Theory 5 1.2.1.5 Chemical Bonding 5 1.2.2 Intermolecular Forces between Adhesives and Adherend 5 1.2.3 Thermodynamic Model of Adhesion 6 1.2.4 Bonded Joints 7 1.2.5 Surface Preparation for HMA Application 8 1.2.5.1 Solvent Degreasing 9 1.2.5.2 Chemically-Active Surface 9 1.3 Fundamental Aspects of Adhesive Behavior of HMAs 10 1.3.1 Mechanical and Physical Behaviors 10 1.3.2 Blending Behavior and the Effects of Other Ingredients 11 1.3.3 Polymeric Behavior 12 1.4 Preparation of HMAs Using Various Polymers 12 1.4.1 HMAs by Grafting Acrylic and Crotonic Acids on Metallocene Ethylene-Octene Polymers 12 1.4.1.1 Solution Grafting 13 1.4.1.2 Melt Grafting 14 1.4.1.3 Preparation of HMAs 14 1.4.2 Cross-Linked Polyurethane Hot-Melt Adhesives (PUR-HMAs) 14 1.4.3 Soybean Protein Isolate and Polycaprolactone Based HMAs (SPIP-HMAs) 15 1.5 Mechanical Analysis of Hot-Melt Adhesives 16 1.5.1 Fracture Mechanics of HMAs 16 1.5.1.1 Fracture Energy Measurement 18 1.5.2 Stress-Strain, and Frequency-Temperature Sweep Tests for Viscoelasticity 18 1.6 Industrial Applications of Hot-Melt Adhesives 20 1.6.1 Medical Applications 20 1.6.2 Electronic Applications 21 1.6.3 Anticorrosion Applications 21 1.6.4 Food Packaging Applications 21 1.6.5 Textile Applications 22 1.7 Current Challenges and Future Scope of HMAs 22 1.8 Summary 23 Acknowledgment 24 References 24 2 Optimization of Adhesively Bonded Spar-Wingskin Joints of Laminated FRP Composites Subjected to Pull-Off Load: A Critical Review 29 S. Rakshe, S. V. Nimje and S. K. Panigrahi 2.1 Introduction 29 2.2 Finite Element Analysis of SWJ 31 2.2.1 Geometry and Configuration 31 2.2.2 Finite Element Modeling 32 2.2.3 Validation and Convergence Study 33 2.3 Taguchi Method of Optimization 34 2.3.1 Optimization of Material and Lamination Scheme 35 2.3.2 Geometrical Parameter 36 2.4 Results and Discussion 38 2.4.1 Material and Lamination Scheme 38 2.4.1.1 Analysis of Variance (ANOVA) 39 2.4.2 Geometrical Parameter 41 2.4.2.1 Analysis of Variance (ANOVA) 42 2.5 Conclusions 44 References 45 3 Contact Angle Hysteresis – Advantages and Disadvantages: A Critical Review 47 Andrew Terhemen Tyowua and Stephen Gbaoron Yiase 3.1 Introduction 47 3.2 Contact Angle and Hysteresis Measurement 49 3.2.1 Theoretical Treatment of Static Contact Angles 51 3.2.2 Modeling of Dynamic Contact Angles 53 3.2.3 Modelling Contact Angle Hysteresis 57 3.3 Advantages of Contact Angle Hysteresis 59 3.4 Disadvantages of Contact Angle Hysteresis 59 3.5 Summary 61 3.6 Acknowledgements 62 References 62 4 Test Methods for Fibre/Matrix Adhesion in Cellulose Fibre-Reinforced Thermoplastic Composite Materials: A Critical Review 69 J. Müssig and N. Graupner 4.1 Introduction 70 4.2 Terms and Definitions 70 4.2.1 Fibres 71 4.2.2 Fibre Bundle 71 4.2.3 Equivalent Diameter 72 4.2.4 Critical Length 72 4.2.5 Aspect Ratio and Critical Aspect Ratio 72 4.2.6 Single Element versus Collective 73 4.2.7 Interface and Interphase 75 4.2.8 Adhesion and Adherence 75 4.2.9 Practical & Theoretical Fibre/Matrix Adhesion 75 4.3 Test Methods for Fibre/Matrix Adhesion 76 4.3.1 Overview 76 4.3.2 Single Fibre/Single Fibre Bundle Tests 77 4.3.2.1 Pull-Out Test 77 4.3.2.2 Microbond Test 88 4.3.3 Test Procedures for Fibre/Matrix Adhesion 91 4.3.3.1 Pull-Out Test 92 4.3.3.2 Microbond Test 93 4.3.3.3 Evaluation of Characteristic Values from Pull-Out and Microbond Tests 94 4.3.3.4 Fragmentation Test 98 4.4 Comparison of IFSS Data 103 4.5 Influence of Fibre Treatment on the IFSS 107 4.6 Summary 118 Acknowledgements 119 References 119 5 Bioadhesives in Biomedical Applications: A Critical Review 131 Aishee Dey, Proma Bhattacharya and Sudarsan Neogi 5.1 Introduction 131 5.2 Theories of Bioadhesion 132 5.2.1 Factors Affecting Bioadhesion 134 5.3 Different Polymers Used as Bioadhesives 134 5.3.1 Collagen-Based Bioadhesives 135 5.3.2 Chitosan-Based Bioadhesives 137 5.3.3 Albumin-Based Bioadhesives 138 5.3.4 Dextran-Based Bioadhesives 139 5.3.5 Gelatin-Based Bioadhesives 140 5.3.6 Poly(ethylene glycol)-Based Bioadhesives 142 5.3.7 Poly(acrylic acid)-Based Bioadhesives 142 5.3.8 Poly(lactic-co-glycolic acid) (PLGA)-Based Bioadhesives 145 5.4 Summary 147 References 148 6 Mucoadhesive Pellets for Drug Delivery Applications: A Critical Review 155 Inderbir Singh, Gayatri Devi, Bibhuti Ranjan Barik, Anju Sharma and Loveleen Kaur 6.1 Introduction 155 6.2 Mucoadhesive Polymers 157 6.3 Pellets 159 6.3.1 Preparation and Evaluation of Pellets 160 6.3.2 Mucoadhesive Pellets for Drug Delivery Applications 161 6.4 Summary and Prospects 166 Conflict of Interest 166 References 166 7 Bio-Inspired Icephobic Coatings for Aircraft Icing Mitigation: A Critical Review 171 Liqun Ma, Zichen Zhang, Linyue Gao, Yang Liu and Hui Hu 7.1 Introduction 172 7.2 The State-of-the-Art Icephobic Coatings/Surfaces 174 7.2.1 Lotus-Leaf-Inspired Superhydrophobic Surfaces (SHS) with Micro-/Nano-Scale Surface Textures 176 7.2.2 Pitcher-Plant-Inspired Slippery Liquid-Infused Porous Surfaces (SLIPS) 177 7.3 Impact Icing Process Pertinent to Aircraft Inflight Icing Phenomena 179 7.4 Preparation of Typical SHS and SLIPS Coatings/Surfaces 181 7.5 Measurements of Ice Adhesion Strengths on Different Icephobic Coatings/Surfaces 182 7.6 Icing Tunnel Testing to Evaluate the Icephobic Coatings/Surfaces for Impact Icing Mitigation 184 7.7 Characterization of Rain Erosion Effects on the Icephobic Coatings 189 7.8 Summary and Conclusions 196 Acknowledgments 198 References 198 8 Wood Adhesives Based on Natural Resources: A Critical Review Part I. Protein-Based Adhesives 203 Manfred Dunky List of Abbreviations 203 8.1 Overview and Challenges for Wood Adhesives Based on Natural Resources 205 8.1.1 Definition of Wood Adhesives Based on Natural Resources 205 8.1.2 Motivation to Use Wood Adhesives Based on Natural Resources 207 8.1.3 Combined Use of Synthetic and Naturally-Based Wood Adhesives 208 8.1.4 Review Articles on Wood Adhesives Based on Natural Resources 209 8.1.5 Motivation for this Review Article in Four Parts in the Journal “Reviews of Adhesion and Adhesives” 211 8.1.6 Overview on Wood Adhesives Based on Natural Resources 212 8.1.7 Requirements, Limitations, and Opportunities for Wood Adhesives Based on Natural Resources 214 8.1.8 Synthetic and Natural Crosslinkers 214 8.1.9 Future of Wood Adhesives Based on Natural Resources 219 8.2 Protein-Based Adhesives 222 8.2.1 Introduction 222 8.2.1.1 Chemical Structure of Proteins 223 8.2.1.2 Proteinaceous Feedstock 224 8.2.1.3 Wood Bonding with Proteins 224 8.2.2 Plant-Based Proteins 228 8.2.2.1 Overview on Plant-Based Protein Sources and Types 228 8.2.2.2 Soy Proteins 228 8.2.2.3 Soy Protein as Wood Adhesive 239 8.2.2.4 Thermal Treatment of Soy Proteins 243 8.2.3 Animal-Based Proteins 246 8.2.3.1 Types and Sources of Animal-Based Proteins 246 8.2.3.2 Mussels (Marine) Proteins 246 8.2.3.3 Slaughterhouse Waste as Source of Proteins 257 8.2.3.4 Proteins from Specified Risk Materials (SRMs) 260 8.2.4 Properties of Protein-Based Adhesives 261 8.2.5 Denaturation and Modification of Proteins 261 8.2.5.1 Modification of Proteins 265 8.2.5.2 Crosslinking of Proteins 265 8.2.6 Proteins in Combination with Other Natural Adhesives and Natural Crosslinkers 286 8.2.7 Proteins in Combination with Synthetic Adhesive Resins and Crosslinkers 286 8.2.8 Application of Protein-Based Wood Adhesives 286 8.3 Summary 316 General Literature (Overview and Review Articles) for Wood Adhesives Based on Natural Resources 316 Protein-Based Adhesives 317 Plant Proteins (including Soy) 318 Animal Proteins and Other Sources 318 References 318 9 Wood Adhesives Based on Natural Resources: A Critical Review Part II. Carbohydrate-Based Adhesives 337 Manfred Dunky List of Abbreviations 337 9.1 Types and Sources of Carbohydrates Used as Wood Adhesives 338 9.2 Modification of Starch for Possible Use as Wood Adhesive 348 9.3 Citric Acid as Naturally-Based Modifier and Co-Reactant 348 9.4 Combination and Crosslinking of Carbohydrates with Natural and Synthetic Components 348 9.5 Degradation and Repolymerization of Carbohydrates 348 9.6 Summary 373 General Literature (Overview and Review Articles) for Carbohydrate-Based Adhesives 373 References 373 10 Wood Adhesives Based on Natural Resources: A Critical Review Part III. Tannin- and Lignin-Based Adhesives 383 Manfred Dunky List of Abbreviations 384 10.1 Introduction 385 10.2 Tannin-Based Adhesives 385 10.2.1 Chemistry of Condensed Tannins 386 10.2.2 Types of Condensed Tannins 390 10.2.3 Extraction, Purification, and Modification Methods for Tannins 390 10.2.4 Hardening and Crosslinking of Tannins 400 10.2.5 Hardening of Tannins by Hexamethylenetetramine (Hexamine) 418 10.2.6 Autocondensation of Tannins 419 10.2.7 Combination of Tannins with Natural Components 421 10.2.8 Combination of Tannins with Synthetic Components and Crosslinkers 421 10.3 Lignin-Based Adhesives 421 10.3.1 Chemistry and Structure of Lignin 430 10.3.2 Lignin as Adhesive 432 10.3.3 Analysis of Molecular Structure 437 10.3.4 Modification of Lignin 437 10.3.5 Lignin as Sole Adhesive and Chemical Activation of the Wood Surface 452 10.3.6 Laccase Induced Activation of Lignin 452 10.3.7 Pre-Methylolation of Lignin 469 10.3.8 Incorporation of Lignin into PF Resins 481 10.3.9 Reactions of Lignin With Various Aldehydes and Other Naturally-Based Components 481 10.3.10 Reaction of Lignin With Synthetic Components and Crosslinkers 481 10.4 Summary 481 General Literature (Overview and Review Articles) for Tannin and Lignin 499 References 501 11 Adhesion in Biocomposites: A Critical Review 531 Siji K. Mary, Merin Sara Thomas, Rekha Rose Koshy, Prasanth K.S. Pillai, Laly A. Pothan and SabuThomas 11.1 Introduction 531 11.2 Biocomposite Processing Methods 533 11.3 Factors Enhancing Adhesion Property in Biocomposites 536 11.3.1 Effect of Chemical Modification 537 11.3.2 Effect of Enzymatic Modification 539 11.3.3 Effect of Physical Modification 539 11.4 Physical and Chemical Characterization 542 11.5 Adhesion in Polymer Biocomposites with Specific Applications 545 11.5.1 Biomedical Applications 546 11.5.2 Dye Adsorption and Removal 547 11.5.3 Automotive Applications 548 11.6 Summary 549 References 549 12 Vacuum UV Surface Photo-Oxidation of Polymeric and Other Materials for Improving Adhesion: A Critical Review 559 Gerald A. Takacs, Massoud J. Miri and Timothy Kovach 12.1 Introduction 559 12.2 Vacuum UV Photo-Oxidation Process 561 12.2.1 VUV Background 561 12.2.2 VUV Radiation 561 12.2.2.1 Emission from Excited Atoms 561 12.2.2.2 Emission from High Pressure Rare Gas Plasmas 563 12.2.2.3 Emission from Rare-Gas Halides and Halogen Dimers 564 12.2.3 VUV Optical Filters 564 12.2.4 Penetration Depths of VUV Radiation in Polymers 565 12.2.5 Analytical Methods for Surface Analysis 565 12.2.6 VUV Photochemistry of Oxygen 565 12.2.7 Reaction of O Atoms and Ozone with a Polymer Surface 566 12.3 Adhesion to VUV Surface Photo-Oxidized Polymers 567 12.3.1 Fluoropolymers 567 12.3.2 Nafion® 568 12.3.3 Polyimides 569 12.3.4 Metal-Containing Polymers 569 12.3.5 Polyethylene (PE) 570 12.3.6 Polystyrene 571 12.3.7 Other Polymers 571 12.3.7.1 Polypropylene (PP) 571 12.3.7.2 Poly(ethylene terephthalate) (PET) 571 12.3.7.3 Poly(ethylene 2,6-naphthalate) (PEN) 571 12.3.7.4 Cyclo-Olefin Polymers 572 12.3.7.5 Polybenzimidazole (PBI) 572 12.4 Applications of VUV Surface Photo-Oxidation to Other Materials 573 12.4.1 Carbon Nanotubes and Diamond 573 12.4.2 Metal Oxides 574 12.5 Prospects 575 12.5.1 Sustainable Polymers 575 12.6 Summary 576 References 576 13 Bio- and Water-Based Reversible Covalent Bonds Containing Polymers (Vitrimers) and Their Relevance to Adhesives – A Critical Review 587 Natanel Jarach, Racheli Zuckerman, Naum Naveh, Hanna Dodiuk and Samuel Kenig List of Abbreviations 587 13.1 Introduction 588 13.1.1 RCBPs Classification 589 13.1.2 Reversible Bonds 590 13.1.2.1 General Reversible Covalent Bonds 590 13.1.2.2 Dynamic Reversible Covalent Bonds 590 13.1.3 RCBPs Applications 591 13.1.3.1 Recyclability 591 13.1.3.2 Self-Healing Materials 592 13.1.3.3 Shape-Memory Materials 592 13.1.3.4 Smart Composites 593 13.1.3.5 Adhesives 593 13.1.3.6 Dynamic Hydrogels and Biomedical Materials 594 13.2 Bio-Based RCBPs 595 13.2.1 Bio-Based Polymers 595 13.2.1.1 Classification of Bio-Based Polymers 596 13.2.1.2 Common Synthetic Bio-Based Polymers 596 13.2.2 Bio-Based RCBPs 599 13.2.2.1 Bio-Based DA RCBPs 600 13.2.2.2 Bio-Based Acylhydrazone-Containing RCBPs 601 13.2.2.3 Bio-Based Imine (Schiff-Base)-Containing RCBPs 601 13.2.2.4 Bio-Based β-Hydroxy Ester Containing RCBPs 604 13.2.2.5 Bio-Based Disulfide-Containing RCBPs 606 13.3 Water-Based RCBPs 607 13.3.1 Solvents in Polymer Industry 607 13.3.1.1 Organic and Inorganic Solvents Used in RCBPs Synthesis 608 13.3.1.2 Water-Based Polymers 608 13.3.2 Water-Based RCBPs 609 13.3.2.1 Acylhydrazone-Containing Water-Based RCBPs 609 13.3.2.2 Schiff-Base-Containing Water-Based RCBPs 609 13.4 Summary 611 13.5 Authors Contributions 611 13.6 Funding 611 13.7 Conflict of Interest 611 References 612 14 Superhydrophobic Surfaces by Microtexturing: A Critical Review 621 Anustup Chakraborty, Alan T. Mulroney and Mool C. Gupta 14.1 Introduction 622 14.1.1 Background 622 14.1.2 State-of-the-Art 626 14.1.2.1 Microtexture Geometry 627 14.1.2.2 Ice Adhesion 627 14.1.2.3 Optical Transparency 628 14.1.2.4 Anti-Condensation Surfaces 628 14.2 Fabrication of Microtextured Surfaces 628 14.2.1 Surface Materials 628 14.2.2 Methods of Fabrication of Superhydrophobic Surfaces 630 14.2.2.1 Plasma Treatment 630 14.2.2.2 Laser Ablation 631 14.2.2.3 Chemical Etching 632 14.3 Properties of Microtextured Surfaces 634 14.3.1 Antifogging 634 14.3.2 Antibacterial 634 14.3.3 Antireflection 634 14.3.4 Self-Cleaning 636 14.3.5 Effect of Temperature on Surface Properties 636 14.4 Applications 639 14.4.1 Anti-Icing 639 14.4.2 Drag Reduction 640 14.4.3 Anti-Corrosion 641 14.4.4 Solar Cells 641 14.4.5 Water-Repellent Textiles 641 14.5 Future Outlook 643 Acknowledgments 644 References 644 15 Structural Acrylic Adhesives: A Critical Review 651 D.A. Aronovich and L.B. Boinovich 15.1 Introduction 651 15.2 Compositions and Chemistries 653 15.2.1 Base Monomer 654 15.2.2 Thickeners and Elastomeric Components 656 15.2.3 Adhesive Additives 663 15.2.4 Initiators 665 15.2.5 Aerobically Curable Systems 670 15.2.6 Fillers 671 15.3 Physico-Mechanical Properties of SAAs 673 15.4 Adhesives for Low Surface Energy Materials 677 15.4.1 Initiators Based on Trialkylboranes 677 15.4.2 Alternative Types of Boron-Containing Initiators 686 15.4.3 Additives Modifying the Curing Stage 687 15.4.4 Hybrid SAAs 690 15.5 Comparison of the Properties of SAAs and Other Reactive Adhesives 693 15.6 Summary and Outlook 698 References 698 16 Current Progress in Mechanically Durable Water-Repellent Surfaces: A Critical Review 709 Philip Brown and Prantik Mazumder 16.1 Introduction 709 16.2 Fundamentals of Superhydrophobicity and SLIPs 710 16.2.1 Intermolecular Forces and Wetting 710 16.2.2 Young’s Contact Angle and Surface Chemistry Limitation 712 16.2.3 Superhydrophobicity by Texturing 715 16.2.4 Hysteresis and Tilt Angle 717 16.2.5 Slippery Liquid-Infused Porous Surfaces (SLIPs) 719 16.3 Techniques to Achieve Water-Repellent Surfaces 720 16.3.1 Superhydrophobic Composite Coatings 720 16.3.2 Superhydrophobic Textured Surfaces 724 16.3.3 Liquid-Impregnated Surfaces/SLIPs 728 16.4 Durability Testing 729 16.5 Future Trends 732 16.6 Summary 734 References 734 17 Mussel-Inspired Underwater Adhesives- from Adhesion Mechanisms to Engineering Applications: A Critical Review 739 Yanfei Ma, Bozhen Zhang, Imri Frenkel, Zhizhi Zhang, Xiaowei Pei, Feng Zhou and Ximin He 17.1 Introduction 740 17.2 Adhesion Mechanisms of Mussel and the Catechol Chemistry 741 17.2.1 Hydrogen Bonding and Metal Coordination 742 17.2.2 Hydrophobic Interaction 743 17.2.3 Cation/Anion/π-π Interactions 743 17.2.4 The Flexibility of the Molecular Chain 744 17.3 Catechol-Functionalized Adhesive Materials 744 17.3.1 Permanent/High-Strength Adhesives 745 17.3.2 Temporary/Smart Adhesives 748 17.3.2.1 pH-Responsive Adhesives 748 17.3.2.2 Electrically Responsive Adhesives 750 17.3.2.3 Thermally Responsive Adhesives 750 17.3.2.4 Photo-Responsive Adhesives 750 17.3.3 Applications 751 17.4 Summary and Outlook 753 References 754 18 Wood Adhesives Based on Natural Resources: A Critical Review Part IV. Special Topics 761 Manfred Dunky List of Abbreviations 762 18.1 Liquified Wood 765 18.2 Pyrolysis of Wood 769 18.3 Replacement of Formaldehyde in Resins 772 18.4 Unsaturated Oil Adhesives 791 18.5 Natural Polymers 793 18.5.1 Poly(lactic acid) (PLA) 793 18.5.2 Natural Rubber 795 18.6 Poly(hydroxyalkanoate)s (PHAs) 796 18.7 Thermoplastic Adhesives Based on Natural Resources 797 18.7.1 Polyurethanes (PURs) 798 18.7.2 Polyamides (PAs) 806 18.7.3 Epoxies 808 18.8 Cellulose Nanocrystals (CNCs) and Cellulose Nanofibrils (CNFs) 808 18.8.1 Cellulose Nanofibrils (CNFs) as Sole Adhesives 810 18.8.2 Cellulose Nanofibrils as Components of Adhesives 812 18.9 Cashew Nut Shell Liquid (CNSL) 812 18.10 Summary 819 General Literature (Overview and Review Articles) for Wood Adhesives Based on Natural Resources 820 References 820 19 Cold Atmospheric Pressure Plasma Technology for Modifying Polymers to Enhance Adhesion: A Critical Review 841 Hom Bahadur Baniya, Rajesh Prakash Guragain and Deepak Prasad Subedi 19.1 Introduction 842 19.2 Atmospheric Pressure Plasma Discharge 844 19.2.1 Corona Discharge 844 19.2.2 Dielectric Barrier Discharge (DBD) 845 19.2.3 Cold Atmospheric Pressure Plasma Jet (CAPPJ) 845 19.2.4 Polymer Surface Modification by CAPPJ 845 19.3 Experimental Setup for the Generation of Cold Atmospheric Pressure Plasma Jet 846 19.4 Methods and Materials for Surface Modification of Polymers 847 19.5 Direct Method for the Determination of Temperature of Cold Atmospheric Pressure Plasma Jet (CAPPJ) 848 19.6 Results and Discussion 848 19.6.1 Temperature Determination of Cold Atmospheric Pressure Plasma Jet (CAPPJ) 848 19.6.2 Electrical Characterization of the CAPPJ 849 19.6.2.1 Power Balance Method 849 19.6.2.2 Current Density Method 850 19.6.2.3 Determination of Energy Dissipation in the Cold Plasma Discharge per Cycle by the Lissajous Figure Method 851 19.6.3 Optical Characterization of CAPPJ 852 19.6.3.1 Line Intensity Ratio Method 852 19.6.3.2 Stark Broadening Method 856 19.6.3.3 Boltzmann Plot Method 858 19.6.3.4 Determination of the Rotational Temperature 859 19.6.3.5 Determination of the Vibrational Temperature 860 19.7 Surface Characterization/Adhesion Property of Polymers 862 19.7.1 Contact Angle Measurements and Surface Free Energy Determination 862 19.7.1.1 Poly (ethylene terephthalate) (PET) 862 19.7.1.2 Polypropylene (PP) 864 19.7.1.3 Polyamide (PA) 867 19.7.1.4 Polycarbonate (PC) 869 19.7.2 FTIR Analysis 871 19.7.2.1 Fourier Transform Infrared (FTIR) Analysis of PET 871 19.7.2.2 Fourier Transform Infrared (FTIR) Analysis of PP 872 19.7.3 SEM Analysis 872 19.7.3.1 SEM Images of the Control and APPJ Treated PET 872 19.7.3.2 SEM Images of the Control and APPJ Treated PP 872 19.8 Summary 873 Acknowledgements 874 Data Availability 874 Conflict of Interest 874 References 874