Rubber Recycling

Author : S K De | Edition : 1st | 2005 | 514 pages

The safe disposal and reuse of industrial and consumer rubber waste continues to pose a serious threat to environmental safety and health, despite the fact that the technology now exists for its effective recycling and reuse. Mountains of used tires confirm the belief that chemically crosslinked rubber is one of the most difficult materials to recycle. That coupled with a long history of failed attempts to create quality products from crumb rubber has resulted in such a resistance to new ideas concerning rubber recycling that very little literature on the subject has even seen the light of day

Rubber Recycling is one of those rare books that have the potential to directly impact our ecological well-being. The editors of this important volume have filled a void in technological responsibility by bringing together a group of international experts who, using substantial research evidence, prove that the utilization of recycled rubber is not just desirable, but is also quite feasible and profitable.

This text provides a thorough overview of the fundamentals of rubber and the challenges of recycling. However, the heart of the book lies in its detailed explanation of the various processes currently available to break down, recycle and reuse crosslinked rubber. These include:

  • Unconventional Polymer Recycling

  • High Pressure, high Temperature Sintering

  • Ultrasonic and Non-Ultrasonic Devulcanization

  • The use of tire particles as replacement aggregates for low-strength concrete material.

  • The utilization of powdered rubber waste in the production of rubber compounds

  • The future potential for recycling waste rubber by blending it with waste plastics

Never forgetting that these technologies are meaningless without industry participation, the book concludes with a highly practical discussion on how present market demands can be met with recycled rubber.

Table of Contents

MANUFACTURING PRACTICES FOR THE DEVELOPMENT OF CRUMB RUBBER MATERIALS FROM WHOLE TIRES – Abstracts, Background, The Tire, Other Sources of Tire Shredding Components and Systems, Size Reduction Relationships, Applications, Testing and Quality Assurance, CRM Plant Demand, support Equipment, Primary, Secondary & Tertiary Processing, Major CRM Processes, Overall Concept, A Market-Driven Approach, Economics, Other Considerations.

QUALITY PERFORMANCE FACTORS FOR TIRE-DERIVED MATERIALS – Abstract, The Average, Standard and Bound of Measurements, The TDM Challenge, Identifying the TDM, Tests for the various CRM and TDM Materials, Contamination. The Tire Processors Commitment, Management’s Direction, Lean Manufacturing, Quality Assurance and Quality Control (Continual Improvement), Analyzing the Outcomes, An Overall Strategy for Success and Perception, Implementation.

UNTREATED AND TREATED RUBBER POWDER – Grinding Technologies – Cutting and Shearing – Cutting, Milling, Extrusion, Disk Grinding, Grinding in a Pellet Press. Grinding by Impact – Grinding in the Rubber State (Ambient and Wet Grinding), Grinding in the Glassy State (Cryogenic Grinding), Grinding by Physical or Chemical Processes. Applications of Untreated Particulated Rubber – Rubber Products - Products from Pure Rubber Crumb and Untreated Rubber Granulate and a Binder, Use of Untreated Rubber Powder in Rubber Compounds, Blends with Thermoplastic Materials (Polyblends). Surface Treatment of Rubber Powder – Chemical Activation – Addition of a Polymer and /or a Curing, Grafting, Swelling, Halogenation, Physical Activation, Microbial Treatment, Superfacial Devulcanisation. Applications of Surfact Treated Rubber Powders in Rubber Products.

TIRE RUBBER RECYCLING BY MECHANOCHEMICAL PROCESSING – Brief Review of Existing Tire Rubber Recycling Processes, Principles of Size Reduction, Mechanochemical Processes for Rubber Recycling.

RECYCLING CROSS LINKED NETWORKS VIA HIGH PRESSURE, HIGH TEMPERATURE SINTERING – High Pressure, High Temperature Sintering – History of Polymer Sintering, Schematic of Sintering Process, Influence of Molding Parameters on Mechanical Properties, Influence of Rubber Backbone – Natural Rubber, Styrene Butadiene Rubber, Polysulfide Rubber. Mechanisms of Sintering (Bond Rupture and Reformation)- Continuous and Intermittent Stress Relaxation, Correlation to Sintering, Time Temperature Superposition, Mechanical Conclusions. Use of Additives to increase Mechanical Propeties - Reversion in Rubbers, Additive Results.

POWDERED RUBBER WASTE IN RUBBER COMPOUNDS – Grinding Methods, Preparation of Powdered Rubber – Ambient ,Cryogenic and Wet Grinding, Extrusion, Abrasion. Comparison of Grinding Techniques, Characterization of Powdered Rubber, Modifications of Ground Rubber Rubber – Surface Modificaiton by Mechanical Means and by Chemical Methods, Irradiation. Devulcanization – Using Chemical Probes, High Energy Excitation, High Shear Mixing, Microbial Desulfurization, High Pressure Steam. Revulcanizatin of Powderes Rubber and Application of Revulcanizates, Mixing and Processing of Rubber Compounds Containing Powdered Rubber, Effect of Addition of Ground Rubber on Rheological Behavior of Fresh Rubber Compounds, on the Curing Characteristics of Fresh Rubber Compounds, on the Mechanical Properties of Rubber Vulcanizates, Effect of Addition of Powdered Rubber on the properties of Rubber Blends.

RUBBER RECYCLING BY BLENDING WITH PLASTICS - Advantages of Rubber Recycling by Blending with Plastics, Compatibilization. Mechanical Compatibilization – Chemical Compatibilization, Reactive and Nonreactive Compatibilization, Surface Characteristics of Ground Rubber and Their Influence of GRT/Plastic Blends. Product and Process Development – Rubber Thermoplastic Composites – Thermoplastic Elastomers, Rooffing and miscellaneous Products, Rheological Studies, Processes, Rubber Thermoset Composites.

STRATEGIES FOR REUSE OF RUBBER TIRES - Disposal of Tires. Solutions to the Rubber Disposal Problem – Retreading and Splitting, Rubber Reclaiming, Pyrolysis, Tire Derived Fuel, Reefs and Erosion Structures, Rubberized Asphalt & Concrete, Rubber Treatment, Miscellaneous Applications.

ULTRASONIC DEVULCANIZATIN OF USED TIRES AND WASTE RUBBERS – Abstracts. Development of Technology – Equipment, Application of Technology. Process Characeristics – Processing Parameters, Die Pressure and Power Consumption. Cure Behaviour – Tire Rubber, Various Types of Rubbers. Gel Fraction and Cross Link Density. Rehological Properties – Experimental Observations, Theoretical Description. Molecular Effect in Devulcanization – Sulfur Cured Rubbers, Peroxide Cured Rubber, Molecular Mobility and Diffusion. Mechanical Performance of Revulcanized Rubbers – Tire Rubber, Various Types of Rubbers, Blends of Devulcanized & Virgin Rubbers.

DEVULCANIZATION BY CHEMICAL AND THERMOMECHANICAL MEANS – Devulcanization. Early Methods of Devulcanization – Thermal Process, Heater or Pan Process, Digester. Later Methods od Devulcanization – Thermal, Chemical & Mechanical Devulcanization, Chemomechanical, Thermomechanical & Thermochemical Devulcanisation. Equipments. Materials and Chemicals. Compounding with Devulcanized Rubber. Biotreatment.

CONVERSION OF USED TIRES TO CARBON BLACK AND OIL BY PYROLYSIS – Abstract, Vacuum Pyrolysis Process, Properties of the Pyrolysis Products – Pyrolytic Carbon Black – Proximate and Elemental Analysis, Specific Surface Area and Structure, CBp Demineralzation & Surface Chemistry & Applications. Pyrolysis Oil – Whole Oil, Oil Fractions, Pyrolysis Gases, Data on Economics.

MARKETS FOR SCRAP TIRES AND RECYCLED RUBBER – The Marke in the US and Europe, markets elsewhere in the world. Market analysis : The Practical Approach – Marketing’s four Ps, The Concept of Product/Service Value, The Value Tires of Recycled Tires and Rubber – Substitute Virgin Rubber, Use Recycled Rubber for its Rubber Character in Bound Systems, flexible and Low Cost Fillers, Use of Larger Size Particles of Rubber, Whole Tires or Parts of Tires, Energy Value.

Financial Evaluation – Opportunity Cost, Payback Period, Net Present Value Method, Internal Rate of Return Method. Where to Get Market Information. A Handy List : Use of Scrap Tires and Recycled Rubber – Substitute Virgin Rubber, bound Systems Utilizing Rubber Characteristics of Recycled Rubber, flexible and Low Cost Fillers, Use of Larger Size Particles of Rubber, Whole Tires or Parts of Tires, Energy Use. INDEX