Mixing of Rubber Compounds

Table of Contents

1 Internal Mixer – Configuration and Design

1.1 Machine Design

1.1.1 Overall Features

1.1.2 Mixing Chamber

1.2 Types of Internal Mixers

1.2.1 Tangential Rotors

1.2.2 Intermeshing Rotors

1.2.3 Technological Comparison

1.2.4 Intermeshing Rotors with Variable Clearance (VIC)

1.2.5 Tandem Mixing

1.3 Feeding Hopper

1.3.1 Design Considerations

1.3.2 Pneumatic Feeding Hopper

1.3.3 Hydraulic Feeding Hopper

1.3.4 Comparative Aspects

Low Noise Levels

Rapid Ram Movement

Precise Ram Force Adjustment

Reproducible Pro­cess Conditions

Reduced Operating Costs

1.4 Digital Ram Position Control

1.5 Mixing Chamber

1.5.1 Hard-Coating

1.5.2 Dust Sealing

1.5.3 Spring Loaded Dust Seals

1.5.4 Hydraulic Dust Seals with Yoke

1.5.5 Hydraulic Dust Seals with Cylinders (CH)

1.5.6 Comparison of Spring Loaded and Hydraulic Dust Seal Systems

1.6 Temperature Sensor

1.7 Plasticizer Oil Injection

1.8 Rotors

1.8.1 Assembly and Cooling

1.8.2 Rotor Bearings

1.8.3 Rotors for Tangential Internal Mixers

Basics

Two-Wing Rotors

Four-Wing Rotors

N-Rotor (Normal Rotor

Full-4-Wing (F-4-W)-Rotor

ST®-Rotor (Synchronous Technology)

ZZ 2-Rotor

HDSC-Rotor (High Dispersion Super Cooled)

MDSC-Rotor (Maximum Dispersion Super Cooled) [10]

Six-Wing Rotor [11]

1.8.4 Rotors for Intermeshing Internal Mixers

History of Development

Interlocking Technology

PES-Technology

1.9 Mixer Base Plate

1.9.1 Design

1.9.2 Drop Door and Latch Assembly

1.9.3 Drop Door and Toggle

References

2 Processing Aspects of Rubber Mixing

2.1 Mixing Principles

2.2 Pro­cess Description

2.3 Influence of Raw Material Properties

2.4 Influences of Process Parameters

2.5 Basic Considerations for the Development of a Mixing Cycle

References

3 Mixing Characteristics of Polymers in an Internal Mixer

3.1 Natural Rubber (NR)

3.2 Ethylene Propylene Diene Rubber (EPDM)

3.3 Chloroprene Rubber (CR)

3.4 Styrene Butadiene Rubber (SBR)

3.5 Butadiene Rubber (BR)

3.6 (Acryl)Nitrile Butadiene Rubber NBR

3.7 Butyl Rubber

3.8 Fluor Rubber

3.9 Resins

3.10 General Considerations

References

4 Internal Mixer – a Reaction Vessel

4.1 The Silica Network

4.2 Influence of Mixing Time and ­Temperature on Hydrophobation

4.3 Chemistry of the Silica-Silane Reaction

4.4 Temperature Limits

4.5 Summary and Consequences

References

5 Effect of Process Parameters on Product Properties

5.1 Introduction

5.1.2 Quality Para­meters of Raw Material

5.1.2.1 Quality Para­meters of EPDM Polymers

5.1.2.2 Quality Para­meters of Carbon Black

5.2 Raw Material Changes in the Rubber Mixing Room

5.2.1 Increase of Carbon Black Fines Content during the Conveying Process

5.2.2 Baking Behavior of Carbon Black in Conveying Pipes

5.3 Effect of Variations in Raw Material Quality Parameters on the Mixing Process

5.3.1 EPDM Long Chain Branching

5.3.2 Carbon Black Fines Content

5.3.3 Carbon Black Pellet Hardness

5.4 Delivery Form of Sulphur

5.5 Weighing Accuracy

5.6 Predicting Product Quality

5.7 The Quality Assurance Concept “Future Mixing Room”

References for Section 5.1 to 5.7

5.8 Rubber Compounding and its Impact on Product Properties

5.9 Testing Methods for Rubber Compounds

5.9.1 Mooney Viscometer

5.9.2 Vulcameter

5.9.3 Rubber Process Analyzer

5.9.4 Carbon Black Dispersion Measurement

5.10 Factors Influencing Rubber Part Properties

5.11 The Mixing Process

5.11.1 The Mixing Process and its Tasks

5.11.2 Further Processes

5.12 Factors Influencing the Mixing Process

5.12.1 Influence of Plasticizer Addition on the Mixing Process and Compound Properties

5.12.2 Influences of the Mixing Process on the Injection Molding Process

5.12.3 Influence of the Mixing Process on Extrusion

5.12.4 Influence of the Milling Process on Compound and Part Properties

The Purpose of Roll Mills within the Mixing Process

The Batch-Off

5.13 Summary

References for Section 5.8 to 5.13

6 Dispersion and Distribution of Fillers

6.1 Dispersive and Distributive Mixing

6.1.1 Dispersive Mixing

6.1.2 Distributive Mixing

6.1.3 Quality or “Goodness” of Mixes

6.2 Mechanism of Filler Dispersion

6.2.1 Theoretical Approach

6.2.2 Phases of Mixing Process

6.2.3 Polymer-Filler versus Filler-Filler Interactions

6.3 Dispersion Measurements

6.3.1 Macro-Dispersion

6.3.1.1 Optical Transmission Microscopy

6.3.1.2 Optical Roughness Measurements

6.3.1.3 Mechanical Scanning Microscopy

6.3.1.4 Reflectometry

6.3.2 Micro-Dispersion

6.3.2.1 Electrical Measurements

6.3.2.2 Transmission Electron Microscopy

6.3.2.3 Atomic Force Microscopy

6.4 Control of Dispersion by Pro­cess ­Para­meters

6.4.1 Mixing Procedures

6.4.2 Temperature, Torque, and Power Consumption

6.4.3 Mixing Time and Rotor Speed

6.4.4 Cooling

6.4.5 Alternative Dispersion Techniques

6.5 Materials Influences on Filler Dispersion

6.5.1 Influence of the Polymer

6.5.1.1 Adsorption from Solution and Melt

6.5.1.2 Influence of the Polymer on Filler Dispersion

6.5.2 Influence of the Filler Morphology and Surface Properties

6.5.2.1 Influence of Surface Specific Area

6.5.2.2 Influence of Structure

6.5.2.3 Influence of Filler Surface Activity

6.5.2.4 Dispersion Kinetics

6.5.2.5 Filler Re-Agglomeration

6.5.3 Influence of Oil on Filler Dispersion

6.6 Effects of Filler Dispersion on ­Material Behavior

6.6.1 Effects on Rheological Properties

6.6.2 Effects on Dynamical-Mechanical Properties

6.6.2.1 Influence of Loading

6.6.2.2 Strain Dependency

6.6.2.3 Effect of Filler Surface Modification

6.6.3 Effect on Ultimate Properties

6.7 Filler Distribution in Polymer Blends

6.7.1 Compatibility of Rubbers

6.7.2 Filler Partition

6.7.3 Evaluation of Filler Distribution

6.7.4 Distribution in Blends with Different Polymer Polarity

6.7.5 Filler Distribution in Blends with Similar Polarity

6.7.6 Filler Transfer

6.7.7 Effects of Filler Distribution

References

Index