Troubleshooting Rubber Problems

Problems can occur during the many steps involved in the manufacture and use of rubber products. There are challenges in selecting and combining materials to form a rubber compound, mixing and processing equipment under varied conditions, or using the finished product in different conditions and environments. From materials to processes to products, this book troubleshoots many of the different rubber-related problems and suggests approaches to solve them. Numerous case studies and references are included.

Many challenges confront the rubber technologist in the development, manufacture, and use of rubber products. These challenges include selecting and combining materials to form rubber compounds suitable for processing, successfully operating a range of manufacturing equipment, and meeting product performance in difficult and diverse environments. Case studies and literature references relate problem solutions to the everyday experience of the rubber technologist. From materials to processes to products, this book identifies many different rubber-related problems and suggests approaches to solve them. Contents: • TSE and TPE Materials, Compounds, Processes, and Products • TSE Materials and Compounds • TSE Processes and Equipment • TSE Products • TPE Materials and Compounds • TPE Processes and Equipment • TPE Products

1 Overview of Rubber Processing p. 1 1.1 Introduction p. 1 1.2 Testing p. 2 1.2.1 Raw Materials Quality Assurance p. 2 1.2.2 Processability Testing of Mixed Compounds p. 2 1.2.3 End Product Testing p. 3 1.3 Conclusion p. 3 References p. 4 2 Raw Materials Acceptance and Specifications p. 5 2.1 Introduction p. 5 2.2 Raw Materials Specifications p. 5 2.2.1 Elastomers p. 6 2.2.2 Fillers p. 7 3 Mixing of Rubber Compounds p. 9 3.1 Introduction p. 9 3.2 Material Flow to the Mixer p. 10 3.2.1 Receipt and Storage of Raw Materials p. 11 3.2.2 Feeding, Weighing, and Charging Raw Materials p. 12 3.2.2.1 Weighing Major Ingredients p. 14 3.2.2.2 Small Component Weighing p. 14 3.3 The Mixing Process p. 15 3.3.1 Incorporation p. 16 3.3.2 Dispersion p. 17 3.3.3 Distribution p. 19 3.3.4 Plasticization p. 20 3.3.5 Natural Rubber Mastication p. 20 3.3.6 Flow Visualization and Modeling of the Mixing Process p. 20 3.3.6.1 Flow Visualization p. 21 3.3.6.2 Modeling p. 21 3.3.7 Flow Behavior on Mills p. 24 3.4 Internal Mixers p. 26 3.4.1 Developments in Internal Mixers p. 29 3.4.1.1 Farrel Mixers p. 29 3.4.1.2 Kobelco Stewart Bolling Mixers p. 30 3.4.1.3 Krupp-Midwest Werner und Pfleiderer Mixers p. 31 3.4.1.4. Pomini Mixers p. 31 3.4.2 Choosing a Mixer p. 32 3.4.3 Inspection and Preventative Maintenance of Mixers p. 32 3.4.4 Internal Mixer Operation p. 33 3.4.4.1 Mixing Procedures p. 33 3.4.4.2 Temperature Control in Internal Mixers p. 37 3.4.4.3 Rotor Speed p. 37 3.4.4.4 Ram Pressure p. 38 3.4.4.5 Batch Size p. 38 3.4.4.6 Dump Criteria p. 40 3.4.5 Control of the Mixing Process p. 41 3.4.6 Scale-Up p. 41 3.5 Take-Off Systems p. 43 3.5.1 Dump Mills p. 43 3.5.2 Packaging p. 44 3.5.3 Single Pass Mixing p. 45 3.6 Other Mixing Equipment p. 45 3.6.1 Mill Mixing p. 45 3.6.2 Continuous Mixing p. 47 3.7 Custom Compounding p. 47 3.8 Troubleshooting the Mixing Process p. 48 3.8.1 Inadequate Dispersion or Distribution p. 49 3.8.2 Scorchy Compound p. 49 3.8.3 Contamination p. 49 3.8.4 Poor Handling on Dump Mill p. 49 3.8.5 Batch-to-Batch Variation p. 49 3.9 Concluding Comments p. 50 References p. 50 4 Flow Behavior of Compounds p. 53 4.1 Introduction p. 53 4.2 Fundamentals of Rheology p. 53 4.3 Effect of Compounding Ingredients on Processing Behavior p. 58 4.3.1 Elastomers p. 58 4.3.2 Fillers p. 59 4.3.2.1 Carbon Blacks p. 59 4.3.3 Plasticizers and Processing Aids p. 60 4.3.3.1 Plasticizers p. 61 4.3.3.2 Processing Aids p. 62 4.3.4 Elasticity p. 63 4.3.5 Conclusion p. 64 References p. 64 5 Testing of Compounds After Mixing p. 65 5.1 Introduction p. 65 5.2 Processability Test Instruments p. 68 5.2.1 The Mooney Viscometer p. 68 5.2.1.1 Delta Mooney p. 69 5.2.1.2 TMS Rheometer p. 70 5.2.2 Capillary Rheometers p. 80 5.2.3 Oscillating Disk Curemeters p. 73 5.2.4 Rotorless Curemeters p. 75 5.2.5 Dynamic Mechanical Rheological Testers p. 75 5.2.6 Stress Relaxation Instruments p. 75 5.2.7 ODR Cure Times Correlation with MDR p. 77 5.3 Comparison of Alpha Technologies Processability Test Instruments p. 78 5.4 Conclusion p. 80 References p. 80 6 The Curing Process p. 83 6.1 Introduction p. 84 6.2 Scorch or Premature Vulcanization p. 84 References p. 85 7 Calendering of Rubber p. 87 7.1 Introduction p. 87 7.2 Equipment p. 87 7.3 Processes p. 88 7.3.1 Feeding p. 88 7.3.2 Sheeting p. 88 7.3.3 Frictioning p. 88 7.3.4 Coating p. 89 7.3.5 Roller Dies p. 89 7.3.6 Downstream Processes p. 90 7.4 Modeling the Calendering Process p. 90 7.5 Troubleshooting Problems in Calendering p. 91 7.5.1 Scorch p. 91 7.5.2 Blistering p. 91 7.5.3 Rough or Holed Sheet p. 91 7.5.4 Tack p. 91 7.5.5 Bloom p. 91 7.6 Conclusions p. 91 References p. 92 8 Extrusion of Rubber p. 93 8.1 Introduction p. 93 8.2 Feeding p. 93 8.2.1 Cold-Feed versus Hot-Feed Extruders p. 94 8.3 Mass Transfer, Conveying, or Pumping p. 96 8.3.1 Flow Mechanism p. 97 8.3.2 Extruder Designs p. 98 8.3.2.1 The Maillefer Screw p. 99 8.3.2.2 The Iddon Screw p. 100 8.3.2.3 The Transfermix p. 101 8.3.2.4 The EVK Screw p. 101 8.3.2.5 The Pin Barrel Extruder p. 101 8.3.2.6 The Cavity Transfer Mixer p. 102 8.3.2.7 Vented Extruders p. 104 8.3.2.8 Dump Extruders p. 104 8.3.2.9 Strainers p. 105 8.3.2.10 Extruder Barrels p. 105 8.4 Extruder Operation and Control p. 105 8.5 Shaping p. 108 8.5.1 Extruder Heads p. 108 8.5.1.1 Coextrusion p. 109 8.5.1.2 Crossheading p. 109 8.5.1.3 Shear Heads p. 109 8.5.2 Dies p. 111 8.5.2.1 Pressure Drop p. 111 8.5.2.2 Die Swell p. 111 8.6 Take-Off and Curing p. 112 8.6.1 Continuous Vulcanization Systems p. 113 8.6.1.1 Pressurized Steam Systems p. 113 8.6.1.2 Hot Air Curing Systems p. 113 8.6.1.3 Hot Air Fluidized Bed Systems p. 114 8.6.1.4 Liquid Salt Bath Systems p. 114 8.6.1.5 Microwave Systems p. 114 8.6.1.6 Shear Head Systems p. 115 8.6.1.7 Electron Beam Systems p. 115 8.6.1.8 Steel Belt Presses p. 116 8.6.1.9 Ultrasonic Vulcanization p. 116 8.7 Troubleshooting the Extrusion Process p. 116 8.7.1 Low Output Rate p. 116 8.7.2 Poor Dimensional Stability of Extrudate p. 117 8.7.3 Excessive Heat Buildup in Compound p. 117 8.7.4 Rough Surface on Extrudate p. 117 8.7.5 Contamination p. 117 8.7.6 Porosity in Extrudate p. 117 8.7.7 Strip Difficult to Feed p. 117 8.7.8 Surging Output p. 118 8.8 Concluding Comments p. 118 References p. 118 9 Molding of Rubber p. 119 9.1 Introduction p. 119 9.2 Compression and Transfer Molding p. 120 9.3 Injection Molding of Rubber p. 122 9.3.1 Injection Molding Equipment p. 125 9.3.1.1 Delivery Systems p. 125 9.3.1.2 Nozzles, Runners, and Gates p. 127 9.3.1.3 Molds p. 128 9.3.1.4 Automatic Ejection p. 129 9.3.1.5 Deflashing p. 129 9.3.2 The Injection Molding Process p. 130 9.3.2.1 Injection Temperature p. 130 9.3.2.2 Screw Speed p. 131 9.3.2.3 Back Pressure p. 131 9.3.2.4 Injection Pressure p. 131 9.3.2.5 Summary p. 131 9.3.3 Monitoring and Modeling the Injection Molding Process p. 131 9.3.4 Control of the Injection Molding Process p. 132 9.3.5 Compounds for Injection Molding p. 133 9.3.6 Problems in Injection Molding of Rubber p. 133 References p. 136 10 Finished Product Testing p. 137 10.1 Introduction p. 137 10.2 Test of Filler Distribution and Dispersion p. 138 10.2.1 Microscopy p. 138 10.2.2 Surface Roughness p. 138 10.3 Tests on Cured Specimens p. 138 10.3.1 Tensile Tests p. 139 10.3.2 Hardness p. 139 10.3.3 Compression Set p. 139 10.3.4 Solvent Resistance p. 140 10.3.5 Aging p. 140 10.3.6 Ozone Cracking p. 140 References p. 140 Index p. 143.

Annotation Injection moulding is one of the most commonly used processing technologies for plastics materials. Proper machine set up, part and mould design, and material selection can lead to high quality production. This review outlines common factors to check when preparing to injection mould components, so that costly mistakes can be avoided. This review examines the different types of surface defects that can be identified in plastics parts and looks at ways of solving these problems. Useful flow charts to illustrate possible ways forward are included. Case studies and a large b257 of figures make this a very useful report.

This section of industry is currently at a crossroads brought about by atmospheric anti-pollution legislation which restricts the choice of solvents, and this problem is addressed in his review with a discussion of new practices such as the use of water-based systems. An additional indexed section containing several hundred abstracts from the Rapra Polymer Library database provides useful references for further reading.

This review has been written as a practical approach to bonding various kinds of elastomers to substrates such as steel and plastics, as used in the manufacture of diverse products such as rubber covered rolls, urethane fork lift wheels, rubber lining for chemical storage or solid rocket motors, engine bushes and mounts, seals for transmissions, electrical power connectors and military tank track pads. Based on the authors' years of experience working closely with end-use customers and it offers a thorough overview of how to successfully bond rubber to a given substrate in the manufacture of quality rubber engineered components. This review is supported by an indexed section containing several hundred key references and abstracts selected from the Rapra Abstracts database.

How to engineer change in your elementary science classroom With the Next Generation Science Standards, your students won’t just be scientists—they’ll be engineers. But you don’t need to reinvent the wheel. Seamlessly weave engineering and technology concepts into your PreK-5 math and science lessons with this collection of time-tested engineering curricula for science classrooms. Features include: A handy table that leads you straight to the chapters you need In-depth commentaries and illustrative examples A vivid picture of each curriculum, its learning goals, and how it addresses the NGSS More information on the integration of engineering and technology into elementary science education

Rubber components are used in many demanding applications, from tyres and seals to gloves and medical devices, and failure can be catastrophic. This review of Rubber Product Failure outlines and illustrates the common causes of failure, while addressing ways of avoiding it. There has been increasing pressure to improve performance so that rubbers can be used at higher temperatures and in harsher environments. For example, the under-the-bonnet temperature has increased in some vehicles and new medical devices require longer lifetimes in potentially degrading biological fluids. The expectations of tyre performance in particular are increasing, and retreads have been in the spotlight for failures. The definition of failure depends on the application. For example, a racing car engine seal that lasts for one race may be acceptable, but in a normal car a life span of 10 years is more reasonable. If appearance is critical as in surface coatings and paints, then discolouration is failure, whilst in seals leakage is not acceptable. Each rubber product must be fit for the use specified by the consumer. Failure analysis is critical to product improvement. the cause of the problem can be much harder to find. It can range from a design fault to poor material selection, to processing problems, to manufacturing errors such as poor dimensional tolerances, to poor installation, product abuse and unexpected service conditions. The rubber technologist must become a detective, gathering evidence, understanding the material type and using deductive reasoning. Testing and analysis of failed materials and components add to the information available for failure analysis. For example, stored aged tyres appeared superficially to be alright for use, but on drum testing small cracks grew more quickly than in new tyres leading to rapid failure in service. Quality control procedures such as product inspection, testing and material quality checks can help to reach 100 percent reliability. In critical applications such as electricians' gloves for high voltage working, gloves are inspected before each use, while engine seals may be routinely replaced before the expected lifetime to avoid problems. in the literature is not high. However, several reviews have been written on specific products and references can be found at the end of this review. Around 400 abstracts from papers in the Polymer Library are included with an index. Subjects covered include tyre wear and failure, seals, engine components, rubber bonding failure, rubber failure due to chloramine in water, tank treads, gloves and condoms, medical devices and EPDM roofing membranes.