Rubber Curing and Properties

Chapter 1: Bird’s Eye View of the Cure Process, First Attempts

1.1 Method Based on the Capacity of Liquid Absorption

1.1.1 Principle of the Method

1.1.2 Experimental

1.1.3 Experimental Results and Discussion

1.1.4 Calculation of the State of Cure

1.1.5 Temperature Dependence and Reference Temperature

1.1.6 New Model Built by Hands and Horsfall

1.1.7 Verification of the Method on Thick Rubber Samples

1.1.8 Conclusions on This Method

1.2 Numerical Evaluation of the State of Cure

1.2.1 Principle of the Method

1.2.2 Theoretical

1.2.3 Results

1.3 Heat Conduction and Vulcanization in Molds

1.3.1 Principle of the Method

1.3.2 Theoretical

1.3.3 Theoretical and Experimental Results

1.3.4 Remarks on the Calorimetry Studies

1.4 Evaluation of Temperature and Extent of Cure during the Process

1.4.1 Scheme of the Method

1.4.2 Theoretical

1.4.3 Kinetic Study Using Isothermal Calorimetry

1.4.4 Results and Applications

1.4.5 Conclusions

1.5 Expression of the Cure Reaction

1.5.1 S-Shaped SOC–Time Curves and Scorch Period at the Beginning of the Cure

1.5.2 Cure Reaction Defined by a Complex Reaction System

1.6 General Conclusions

References. 

Chapter 2: General Study on Heat Transfer

2.1 Various Means of Heat Transfer

2.1.1 Heat Conduction

2.1.2 Heat Convection

2.1.3 Heat Radiation

2.2 Heat Conduction

2.2.1 Principle of Heat Conduction

2.2.2 Differential Equation of Heat Conduction

2.2.3 General Solution of Heat Conduction (Separation of Variables)

2.2.4 Initial and Boundary Conditions

2.2.4.1 Initial Conditions

2.2.4.2 Boundary Conditions

2.3 Heat Convection

2.3.1 Forced Heat Convection

2.3.2 Natural (Free) Heat Convection

2.4 Solutions of the Equations of Heat Transfer

2.4.1 Sheet Heated on Both Sides with Infinite Heat Transfer at the Interface

2.4.2 Heat Transfer through a Rubber Sheet Immersed in a Large Volume of Fluid

2.5 Thermal Properties of Rubbers

2.5.1 Specific Heat

2.5.2 Thermal Conductivity

2.5.3 Thermal Diffusivity

2.5.4 Surface Heat Transfer Coefficient

2.5.5 Conclusions on Gum Rubbers

2.6 Heating or Cooling Stages without Cure Reaction

2.6.1 Cooling Stage of a Perfectly Cured Rubber Sheet in Motionless Fluid

2.6.1.1 Case of Motionless Air at Room Temperature in Laminar Mode

2.6.1.2 Case of Motionless Air at Room Temperature in Turbulent Mode

2.6.2 Cooling of Perfectly Cured Rubber in Stirred Fluid

2.6.2.1 Case of Stirred Air in a Vertical Position

2.6.2.2 Case of Stirred Water in a Vertical Position

2.6.3 Heating Stage of the Cured Rubber in the Mold

2.7 Conclusions on Heat Transfer Boundary Conditions

References. 

Chapter 3: Kinetics of the Cure Reaction

3.1 Calorimetry: Principle, Theory, and Techniques

3.1.1 Principle of Calorimetry

3.1.2 Theoretical Considerations in Calorimetry

3.1.2.1 Case of the Calorimeter with a Cylindrical Sample

3.1.2.2 Case of the Calorimeter with a Horizontal Sensible Detector, Plane in Shape

3.1.3 Isothermal Calorimetry Techniques

3.1.3.1 Measure of the Cure Enthalpy under Isothermal Conditions

3.1.3.2 Kinetics of the Overall Cure Reaction

3.1.4 Calorimetry in Scanning Mode

3.1.4.1 Measure of the Cure Enthalpy in Scanning Mode

3.1.4.2 Kinetics of the Cure Reaction

3.1.5 Conclusions on Calorimetry Techniques

3.2 Increase in Stiffness during Cure: Isothermal MDR

3.2.1 Presentation of the Technique

3.2.2 Process of Cure in Isothermal MDR

3.2.2.1 Experimental

3.2.2.2 Theoretical Treatment

3.2.2.3 Results Obtained by Calorimetry

3.2.2.4 Results Obtained by Using Either MDR or Calorimetry

3.2.3 Conclusions on the Process in Isothermal MDR

3.3 MDR in Scanning Mode with Constant Heating Rate

3.3.1 Presentation of the Technique

3.3.2 Theoretical Treatment

3.3.2.1 Assumptions

3.3.2.2 Mathematical Treatment

3.3.3 Results Obtained with MDR in Scanning Mode

3.3.3.1 Material and Apparatus Used for the Study

3.3.3.2 Calculation of the Torque–Temperature Curve

3.3.3.3 Profiles of Temperature and State of Cure in the Rubber Sample

3.3.3.4 Evaluation of the Kinetic Parameters from the Curves Obtained in Scanning Mode

3.3.4 Conclusions on the MDR in Scanning Mode

3.4 Improvements for MDR in Scanning Mode

3.4.1 MDR Scanned with Change in Heating Rate

3.4.2 MDR with Square-Root Time–Temperature Dependence

3.4.2.1 Theoretical Treatment of the Process

3.4.2.2 Materials and Apparatus

3.4.3 Results Calculated with the MDR Run with This Method

3.5 Conclusions

References.

Chapter 4: Cure of Rubber in Mold

4.1 Rubber–Mold Relation

4.1.1 Process of Heating and Cure

4.1.1.1 Mathematical Treatment

4.1.1.2 Numerical Treatment of the Problem

4.1.2 Effect of the Position of the Heating System

4.1.2.1 Mold–Rubber System

4.1.2.2 Results Obtained for the Cure of the Rubber Sheet

4.2 Effect of the Thickness of the Rubber Sheet

4.3 Effect of the Enthalpy of Cure

4.4 Effect of the Temperature on the Cure

4.5 Effect of the Kinetic Parameters of the Cure

4.5.1 Effect of the Order of the Overall Reaction

4.5.2 Effect of the Activation Energy

4.6 Effect Postcure of a Rubber Sheet

4.7 Cure of Rubber–Metal Sandwiches

4.7.1 Theoretical Study of the Process of Cure

4.7.2 Results

4.8 Simultaneous Cure of Various Kinds of Rubbers

4.8.1 Theoretical Approach of the Process

4.8.2 Results for Bilayer Rubber Compounds

4.9 General Conclusions

References.

Chapter 5: Cure of Rubber with Injection Molding

5.1 Principles of the Technique

5.2 Evaluation of the Operational Conditions in the Injection System

5.2.1 Theory

5.2.1.1 Heating Stage in the Reservoir before Injection

5.2.1.2 Injection Stage of the Rubber in the Mold

5.2.2 Results for the Heating Stage in the Reservoir

5.3 Heating Stage and Cure in the Mold

5.3.1 Theoretical for the Stage of Cure in the Mold

5.3.2 Results Obtained by Calculation

5.4 Conclusions on Injection Molding

References.

Chapter 6: Mechanical Properties of Rubbers

6.1 Mechanical Properties of Unvulcanized Rubbers

6.1.1 Principle of Viscoelastic Behavior

6.1.2 Measure of Plasticity and Flow Rate with Plastimeters

6.1.2.1 Compression Plastimeters: Plate Test and Disc Test

6.1.2.2 Rotation Plastimeters: Mooney Viscometer

6.1.2.3 Extrusion Plastimeters and Die Swell

6.1.2.4 Miscellaneous Processibility Tests

6.1.2.5 Correlation between Plastimeters

6.1.3 Scorch Time Measure

6.2 Mechanical Properties of Vulcanized Rubbers

6.2.1 Tests Run under Static Conditions

6.2.1.1 Hardness of Rubber

6.2.1.2 Tensile Stress/Strain

6.2.1.3 Compression Stress/Strain

6.2.1.4 Shear Stress/Strain

6.2.1.5 Tear Tests

6.2.2 Dynamic Stress and Strain Properties

6.2.2.1 Dynamic Compression Property of Vulcanized Rubber

6.3 Conclusions on the Mechanical Properties of Rubbers

6.3.1 Conclusions Concerned with Unvulcanized Rubber

6.3.2 Conclusions Concerned with Vulcanized Rubber

References. 

Chapter 7: Resistance of Rubber to Liquids

7.1 Effect of Liquids on Rubber and Its Measures

7.1.1 Measurement of the Swelling

7.1.2 Standard Tests

7.2 Liquid Transport by Diffusion

7.2.1 Principle of Diffusion

7.2.2 Differential Equations of Diffusion

7.2.2.1 Case of a One-Dimensional Diffusion through a Thin Sheet

7.2.2.2 Radial Diffusion through the Plane Section of a Cylinder or a Sphere

7.2.3 Initial and Boundary Conditions

7.2.4 General Solution of the Equations of Diffusion in Sheets

7.2.5 Solution of Diffusion in Sheets with Infinite Coefficient of Convection

7.2.6 Case of Rubber Sheets in Contact with a Liquid

7.2.7 Determination of the Parameters of Diffusion

7.2.8 Equation of Radial Diffusion with Change in Dimension of the Sphere

7.2.9 General Equation of One-Dimension Diffusion

7.3 Diffusion of the Curing Agent during the Cure

7.4 Examples of Diffusion of Liquids in Rubbers

7.4.1 Diffusion of Liquids through a Sheet with Change in Dimensions

7.4.1.1 Experimental Procedures

7.4.1.2 Results and Conclusions

7.4.2 Diffusion of Liquids in EPDM Sheets with Different Percentages of Peroxide

7.4.2.1 Experimental

7.4.2.2 Results on Kinetics of Absorption and Discussion

7.4.2.3 Anisotropic Swelling of EPDM Rubber Discs

7.5 Drying of Rubbers Containing a Liquid

7.5.1 Operational Conditions

7.5.2 Experimental Results and Discussion

7.6 Permeability of Rubbers to Vapors and Gases

7.6.1 Principle of the Transfers

7.6.2 Theoreticals of the Process

7.6.3 Measurements of the Permeability of Gases

7.6.3.1 Constant Volume Method

7.6.3.2 Constant Pressure Method

7.6.3.3 Carrier Gas Method

7.6.4 Measurements of the Permeability of Vapors

7.7 Conclusions on Rubber Resistance to Liquids

References.

Chapter 8: Methods of Recycling Waste Tire Rubber

8.1 General Consideration

8.2 Scrap Tire Disposal in Previous Studies before 1974

8.2.1 Problems Set Down by Scrap Tire Disposal in 1974

8.2.2 Physical Applications

8.2.3 Fuel Value and Incineration

8.2.4 Chemical Applications

8.2.4.1 Reclaiming

8.2.4.2 Pyrolysis

8.2.4.3 Carbon Black Manufacture

8.2.4.4 Biodegradation

8.3 Reclaiming Processes in Progress

8.3.1 Artificial Reefs and Highway Abutments

8.3.2 Asphalt Component and Road Base

8.3.3 Cure of Scrap Rubber Powder with Addition of New Rubber

8.3.4 Cure of Scrap Rubber Powder without Addition of New Rubber

8.3.4.1 Vibration Isolation Rubber Sheets

8.3.4.2 Rubber Sheets Absorbing Impact Noises in Houses

8.3.5 Concrete Component

8.3.6 Pyrolysis of Scrap Rubber

8.3.7 Distribution of Scrap Rubber into Polymers

8.4 Tentative Conclusions on Tire Rubber Recycling

References.

Chapter 9: Rubber: Cure and Properties

9.1 Conclusions

9.1.1 Evaluation of the State of Cure and Kinetics of Cure

Appendix

Suggested Reading

Index