Chemistry and Processing,

Transcription

1 Recycled Polymers: Chemistry and Processing, Volume 1 Editor: Vijay Kumar Thakur SMITHERS R A P R A A Smithers Group Company Shawbury, Shrewsbury, Shropshire, SY4 4NR, United Kingdom Telephone: +44 (0) Fax: +44 (0)

2 C" 1 State-of-the-Art of Thermomechano-chemical Rubber Regeneration Introduction Rubber Structure: Formulation and Vulcanisation Regeneration: Goal and Methods Biotechnological Methods Classical Methods Wet Methods Wet Methods using Supercritical Fluids Thermomechanical Methods Thermomechano-chemical Methods Methods using Radiation Methods using Ultrasound Methods using Microwaves Regeneration Evaluation Composition and Homogeneity of Rubber Powders Thermomechanical Regeneration Processes Mechano-chemical Regeneration Processes Proposed Regeneration Mechanisms Conclusion and Future Work 28 2 The Recycling of Polymers as Feedstock in Coke Manufacture and Ironmaking Introduction The Polymer-waste-feedstock Chain 38 IX

3 Recycled Polymers: Chemistry and Processing, Volume Plastic Waste Management Saving Plastic Materials and Energy Mechanical Recycling Energy Recovery Feedstock Recycling Feedstock Recycling of Plastic Wastes in Cokemaking Metallurgical Coke for the Blast Furnace Interactions between Plastic Wastes and Coal during Co-carbonisation Effect of Plastic Wastes on the Generation of Coking Pressure Effect of Plastic Wastes on the Coke Quality Current Status in Industrial Cokemaking Feedstock Recycling of Plastic Wastes in Ironmaking Environmental Benefits in Greenhouse Gas Emissions 71 3 Preparation of Coating Powder from Postconsumer Polyethylene Terephthalate Packaging Introduction Main Components of Powdered Paints Thermoplastic Resins Thermosetting Resins Pigments Curing Agents Other Additives Steps in the Production of Powdered Paints Premixture Dispersion Cooling Micronisation Methods to Apply Powdered Paints 86 x

4 Application Contents Simple Systems Simple Fluidised Beds Flame Spray Systems Electrostatic Systems Electrostatic Fluidised Beds Electrostatic Spraying Corona Electrostatic Spray Guns Triboelectric Spray Guns Degradation of Polyethylene Terephthalate to obtain Paints Methods for the Hydrolysis Studied Polyethylene Terephthalate Degradation Determination of Viscosity Melt Flow Index Measurement Differential Scanning Calorimetry Particle Size Profile Size Exclusion Chromatography Production of the Powdered Varnishes Formulation Mixing Dispersion of the Components by Extrusion Micronisation Obtaining the Test Panels - of the Varnishes Application Process Melting the Varnish Cooling of the Panels Characterisation of the Film Determination of Gloss Impact Resistance Determination of Film Hardness (Scratch Resistance) 97 xi

5 Recycled Polymers: Chemistry and Processing, Volume Determination of Adherence Determination of the Cupping Index Results for the Hydrolysis Studies Degradation and Characterisation of the Polyethylene Terephthalate Analysis by Viscometry Differential Scanning Calorimetry Size Exclusion Chromatography Formulation of the Varnishes Particle Size Profile Application and Characterisation of the Film Viscometry by Solution Intrinsic Viscosity by Melt Flow Index Size Exclusion Chromatography Performance of the Varnishes Determination of Gloss Impact Resistance Cupping Index Hardness Adherence Final Considerations Effective Screw-disc Extrusion in the Processing of Recycled Polymers and its Composites Principles of Disc and Screw-disc Extrusion A Review of Screw and Screw-disc Extruder Construction Movement of Polymer Particles in the Disc Zone of the Screw-disc Extruder Effect of Multiple Screw-disc Extrusion on the Rheological Properties of Low-density Polyethylene Research on the Properties of Polymer Mixtures Extruded in a Screw-disc Plasticising System 137 xn

6 Contents Microscopic Studies of Mixtures Tensile Properties of Mixtures Processing Parameters of Mixtures Experimental Verification of the Trajectory of a Plastic Particle in the Disc Zone Wood-polymer Composites Evaluation of the Stage of Composite Mixing Extrusion of Mixtures Containing a 50% Wood Phase Summary Plastics Flotation Introduction Historical Development of Plastics Flotation The Principle of Plastics Flotation Gamma Flotation Adsorption of Wetting Agents Surface Treatment Flotation Modulated by Frothers Flotation Behaviour Mechanism of Action of Frothers Flotability of Plastics Modulated by Frothers Flotation Modulated by Wetting Agents Flotation Behaviour Mechanism of Action of Wetting Agents Interfacial Interactions Adsorption Model of Wetting Agents onto a Plastic Surface Wetting Ability, Adsorption Intensity and Desorption Effects of Additives on the Flotability of Plastics 188 xiu

7 A Recycled Polymers: Chemistry and Processing, Volume The Effects of Additives on the Surface of Polyvinyl Chloride Plastics Surfaces of Plastic Particles in a Flotation System The Effects of Additives on the Surface Free Energy of a Mixed Surface Interactions between the Mixed Surface and Water Interactions between the Mixed Surface and a Bubble The Natural Flotability of Polyvinyl Chloride Plastics Flotation Separation of Plastic Mixtures Flotation Separation of Waste Plastics without.. Reagents Flotation Separation of Waste Plastics using Frothers Flotation Separation of Waste Plastics using Wetting Agents Recycling of Natural Rubber-based Waste Tyres - Green Environment for the Future Introduction Recycling of Rubber Scrap Tyre or Waste Tyre Types of Scrap Rubber Recycling Methods Grinding of Rubber Material Recycling Technologies Ambient Mechanical Grinding Cryogenic Grinding Microwave/Pyrolysis Reclaiming Microwave Reclaiming Pyrolysis Reclaiming Burning Scrap Tyres for Energy 220 xiv

8 Contents 6.5 Proposed Reaction Mechanism of the Reclamation of Vulcanised Rubber Classification of Reaction Mechanisms Chain and/or Crosslink Scission using a Disulfide Reclaiming Agent Main Chain Scission by a Reclaiming Agent Phenylhydrazine-iron (II) Chloride Crosslink Scission (Triphenylphosphine) Main Chain and Crosslink Scission (Thiols and Disulfides) Opening of Sulfur Crosslinks Applications Tyre-derived Fuel Ground Rubber Applications Civil Engineering Applications Technical and Economic Barriers to Recycling Tyres Conclusion Magnetic Density Separation of Polymer Wastes Polymers in Europe Polyolefins Packaging Waste Car Waste Magnetic Density Separation The Principle of Magnetic Density Separation Magnetic Density Separation Layout Factors affecting the Magnetic Density Separation Process Polyolefin Recycling Quality of Magnetic Density Separation Products Rheological Property 264 xv

9 Recycled Polymers: Chemistry and Processing, Volume Mechanical Properties Modelling of Magnetic Density Separation Turbulence Magnetic Field Errors Size of the Flakes Combined effect of all Factors Recycling of Postconsumer Engineering Thermoplastics: Acrylonitrilebutadiene-styrene and Polycarbonate Introduction Acrylonitrile-butadiene-styrene Effect of Impurities Effect of Thermal Processing Improving Properties of Recycled Acrylonitrilebutadiene-styrene Polycarbonate Effect of Impurities Effect of Thermal Processing Improving the Properties of Recycled Polycarbonate Use of Virgin Materials and Impact Modifiers Use of Reinforcing Materials Use of Nanoclays Flammability Properties of Recycled Acrylonitrile-butadienestyrene and Polycarbonate Conclusions 298 Abbreviations 301 Index 309 xvi