Compounding Ingredients and Formulation Construction
Introduction
Similarly, a rubber block can be compressed, and as soon as the load is released, the block will assume its original shape and dimensions. Rubber is relatively inert to the degrading effects of the atmosphere and of many chemicals.
Elastomers: Properties, Uses, and Vulcanization
- Elastomer Nomenclature (ASTM D-1418)
- Elastomer Properties
- Natural Rubber (NR)
- Styrene-Butadiene Rubber (SBR)
- Polybutadiene Rubber (BR)
- Ethylene Propylene Rubber (EPDM/EPM)
- Nitrile Rubber (NBR)
- Hydrogenated Nitrile Butadiene Rubber (HNBR)
- Chloroprene Rubber (CR)
- Ethylene Vinyl Acetate Rubber (EVA)
- Butyl Rubber (IIR)
- Polyurethane (PU)
- Silicone Rubber (VMQ/MVQ/HTV)
- Acrylic Rubber (ACM)
- Fluorocarbon Rubber (FKM)
Q—Rubbers with silicon and oxygen in the polymer chain—silicone rubber (MQ) and fluorosilicone rubber (FVMQ). Due to the absence of unsaturation in the polymer backbone, silicone rubber is not attacked by ozone.
Fillers
- Function of Filler
- ASTM Designation of Rubber-Grade Carbon Blacks
- Compounding with Carbon Black
- Effect of Increased Surface Area
- Equal Hardness Approach
- Non-Black Fillers
- Silica Fillers
- Other Filler Systems
Carbon black is produced by the incomplete combustion process of the carbon black feedstock (CBFS). The composition of the carbon black mainly depends on the process conditions of the carbon black production process.
Protective Agents
- Oxygen Aging at Lower or Higher Temperature (Aging in the
- Accelerated Oxidation in the Presence of Heavy Metal
- Fatigue
- Crazing
- Frosting
- Heat Aging in the Absence of Oxygen
- Ozone Crack Formation
- Auto-Oxidation
- Mechanism of Oxygen Attack
- How an Antioxidant Performs Its Function
- How an Anti-Ozonant Performs Its Action
- Antidegradants
- Classification of Antidegradants
- Application of Different Antidegradants
Presence of unsaturation in the polymer backbone - The saturated polymers are less affected by oxygen than unsaturated polymers. In the presence of vinyl side chains (eg in CR, SBR, NBR), crosslinks form during aging.
Vulcanizing Chemicals
- Changes Achieved in a Product Due to Vulcanization
- Vulcanizate Structure and Property Relation
- Vulcanization Chemicals
- Parameters of Vulcanization
- Crosslinking Agents
- Sulfur Vulcanization
- Sulfur Donor Vulcanization
- Peroxide Vulcanization
- Vulcanization with Resins
- Metal Oxide Vulcanization
- Radiation Curing
- Conventional, Semi-Efficient, and Efficient Vulcanization
- Accelerator
- Classification of Accelerators
- Accelerated Sulfur Vulcanization for General-Purpose
- Primary Accelerators
- Secondary Accelerator or the Boosters
- Activators
- Retarders
- Effect of Other Compounding Ingredients on Vulcanization
- Antidegradants
- Fillers
For soft rubber goods, 0 to 5 phr of sulfur is used, depending on the amount of accelerator used and the properties of the vulcanizate required. This form of sulfur is insoluble in most solvents and gums, hence the name insoluble.
Processing Aids
The limitation of the above retarders is that they reduce the effectiveness of the accelerators and thus prolong vulcanization time. The choice of oils for a particular rubber formulation depends on the oil compatibility criteria.
Formula Construction
- Cost of Compounds
1 Specific gravity • The ratio of the weight of unit volume of a material to the weight of the same volume of water at a given temperature. The pyrolysis system involves the thermal decomposition of the sample - the breakdown products enter the gas chromatograph where they are separated and identified.
Principal Chemical and Analytical Methods Used in Reverse Engineering
Chemical Methods
- Introduction
- Chemical Analysis
The analysis of elastomeric materials should be based on a comparison of the material with an appropriately selected control material. During analysis, sample preparation is important to obtain a representative sample from the sample. This section discusses two main types of testing: chemical analysis and physical analysis.
Chemical analysis is generally carried out for a representative sample taken from the bulk; therefore, the sample preparation technique plays an important role. Tables 2.1 and 2.2 provide a brief overview of the variety of chemical tests needed to characterize different raw materials, their definitions, meaning and methods used, various critical control parameters, basic necessary tools for analysis, and widely used instrumental techniques.
Infrared Spectroscopy
- Introduction
- Estimation of Vinyl Acetate Content in Polyethylene Vinyl Acetate
- Determination of Microstructure of Polybutadiene (BR) Rubber
- Measurement of Mole% of Epoxidation in Epoxidized Natural
- Determination of Ethylene Content in Ethylene Propylene
- Test Method A (for Mass% Ethylene in EPM and EPDM
- Test Method C (for All EPM and EPDM Polymers
- Test Method D (for All EPM and EPDM Polymers
- Determination of Acrylonitrile Content (ACN) of Acrylonitrile
- Quantitative Determination of the Microstructure of the
- Determination of Residual Unsaturation in Hydrogenated
- Carbon Type Analysis (C A , C P , and C N ) of the Rubber Process Oil
- Miscellaneous Quantitative Applications of FTIR
Melting point is an important tool to identify materials and to check the purity of materials. Pellet strength is related to the bulk strength and friction characteristics of the carbon black. The titer value indicates the purity of the materials and also the processing characteristics of the stearic acid.
The percentage of soap is calculated from the weight of the original sample and the titrations. The ethylene content of the unknown sample was measured using the calibration curve.
Thermal Analysis
- Introduction
- Polymers
- Some Important Technical Terms Related to Thermal Analysis
- Principle of Differential Scanning Calorimetry (DSC) Operation
- Application of DSC
- Glass Transition Temperature, T g
- Melting and Crystallization
- Curing or Vulcanization
- Oxidation and Degradation
- Specific Heat or Heat Capacity
- Principle of Thermogravimetric Application
- Interference
- Application of Thermogravimetric Analysis in Polymer
- Decomposition
- Stability and Kinetics
- Composition
- Differential Thermal Analysis (DTA)
- Thermomechanical Analysis (TMA) and Thermodilatometry (TD)
- Dynamic Mechanical Analysis (DMA)
- Evolved Gas Detection (EGD) and Evolved Gas Analysis (EGA)
Finally, depending on the nature of the polymer, ash may be produced due to degradation. In a conventional heat flux DSC design, the magnitude of the thermal constant in the system varies with temperature. DSC can also be used to determine the degree of crystallization and crystallization kinetics.
The purity of the polymer additives can also be judged from Tm and the degree of crystallinity. The nature of TG curve depends on the surrounding atmosphere of the sample being tested.
Chromatography
- Introduction
- Retention Behavior
- Partition Ratio
- Resolution
- Speed of Analysis
- Thin-Layer Chromatography (TLC)
- Gas Chromatography (GC)
- Carrier Gas
- Sample Injection
- The Column
- Detectors
- Carrier Gas Flow
- Injector System
- Sample Handling Techniques
- High-Performance Liquid Chromatography (HPLC)
- Mobile Phase
- Pumps
- Sample Introduction
- The Column
- Detectors
- HPLC Separation
- Gel Permeation Chromatography (GPC)
In general, the temperature of the sample port is around the boiling point of the least volatile component. Depending on the sample characteristics, sample handling plays an important role in gas chromatography. The sample must be dissolved in a portion of the mobile phase to eliminate the unnecessary solvent peak.
Only molecules that absorb in the UV region near the wavelength of the detector can be monitored. The sensitivity of UV detectors strongly depends on the molar absorption coefficients of the sample components.
Atomic Absorption Spectroscopy (AAS)
- Introduction
- Analysis Principle of Atomic Absorption Spectrometric
- Atomic Absorption Spectrophotometer (AAS)
- Atomic Emission Spectroscopy
- Atomic Fluorescence Spectroscopy
- Various Applications of Atomic Absorption Spectrometric
- Analysis of Natural Rubber, Synthetic Rubbers, and
- Steel Wire Characterization
- Analysis of Rubber Compounding Ingredients
- Reverse Engineering/Benchmarking
In the case of direct current plasma (DCP), the sample is drawn through a nebulizer into a premix spray chamber using argon as the carrier gas. The top of the torch is centered in a radio frequency induction coil which is an energy source in the system. The typical analysis data of two steel wire samples used in the tire industry are given in Table 2.21.
The function of bead wires is to hold the tire with the rims of the car. The AAS-FIAS analysis condition used in the above study and characterization data for pearl wire samples are shown in Tables 2.22 and 2.23, respectively.
Microscopy and Image Analysis
- Introduction
- Identification of Carbon Black Type
- Carbon Black Identification by Transmission Electron
- Elastomer Blend Morphology by TEM
- Microtomy, Staining, and TEM Analysis
- TEM Image Analysis—Examples
- TEM Observations
One compound contained 50 phr of N-110 carbon black and the other compound contained 50 phr of N-330 carbon black. Two compounds (Compounds A and B listed in Table 2.29) were mixed in Banbury with 40 phr of N-650 carbon black and suitable curing agents. In our examples, we used two cured elastomeric compounds, each containing 40 phr of N-650 carbon black and appropriate curing agents.
The carbon black tends to enter the polymer phases (i.e. polybutadiene rubber, natural rubber, and EPDM rubber) in the same order, unless it is mixed in such a way that it is forced into the different polymer phases before mixing. Their together. In the compound B (NR/polybutadiene) sample shown in Figures 2.31 through 2.36, the carbon black would tend to enter the polybutadiene phase rather than the natural phase.
Mass Spectrometry
- Introduction
- Method
- Interpretation of Mass Spectrum Data
- The Molecular Ion
- Isotopes
- Accurate mass measurements
- The General Appearance of the Spectrum
Young's modulus is the ratio between tensile (or compressive) stress and tensile (or compressive) strain, i.e. The accuracy of the final test result largely depends on the accuracy with which the test subject was prepared. The test method can then be reduced to measuring the volume loss of the test tire.
The ingredients play different roles during the mixing, processing and final use of the rubber product. The homogenization step in the case of the reverse engineering process of rubber products helps distribute the chemical ingredients evenly in the sample.
Principal Physical Test Methods
Introduction
The stress/strain curve for vulcanized rubber is "S" shaped and this shape can be modified by test temperature, test speed, specimen dimensions, and its previous history. Heat evolution uses a portion of the energy input and the stress/strain draw curve does not follow the same course as the stretch curve. One of the main differences between rubber and other engineering materials is in the large elastic stresses to which the former can be subjected without rupture.
The first three of the above can be more or less avoided by using a suitable type of synthetic rubber. Moreover, the deformation of rubber does not involve any deformation of the inter-atomic bonds, and thus the force required is lower than that of a metal.
Visco-Elastic Behavior
Long-range deformation and recovery from it, however, operate with a delay (i.e., time-dependent), so that the deformation is more or less out of phase with the stress, causing hysteresis and heat build-up. This type of elasticity can be connected to a system consisting of a coil spring and an oil pan in parallel. Creep, cold flow, and stress relaxation, which are also set, are at least partially related to such rheological behavior, which can be related to that of a pot (motion in such is irreversible without a spring).
Long-range (low-modulus or high) elasticity of a very distinct kind occurs especially in unfilled rubbers that have been lightly vulcanized (cross-linked) to prevent inelastic flow. Below the glass transition temperature, however, such materials stiffen (i.e. lose their long-range elasticity).
Elastic Modulus
- Effect of Mixing and Molding
- Effect of Cutting/Die Cut from Sheet
- Test Pieces from Finished Products
Young's modulus can be derived from measurements of extension under load or bending of a bar or beam or deformation under compressive load. A related quantity is the internal friction, equal to the out-of-phase modulus divided by the angular frequency of the deformation cycles. Bulk modulus is the ratio of external pressure change to column change for reversible conditions and indicates the resistance of a substance to volume compression.
It is not a modulus in the strict sense of the word and is more appropriately called "Strain at X% Strain" or simply "X% Strain Value". It is essential that the cutters are sharp and free of nicks or bumps in the cutting edge, as this can cause defects in the test piece, leading to premature failure.
Some Special Features of General Physical Tests
- Tensile Stress-Strain
- Test Procedure
- Interpretation
- Design Calculations
- Heat Aging
- Interpretation
- Set
- Permanent Set
- Tension Set
- Compression Set
- Interpretation
- Hardness
- Hardness Tests
- Hardness Test Apparatus
- Compression of Hardness Measurements
- Interpretation
- Abrasion
- The ISO Abrader
One goal in the extrusion of rubber compounds is to obtain a smooth extrusion that accurately reproduces the contours of the extrusion die. Some of these chemicals change composition during one of the processing stages, called vulcanization. In addition to the representative sample, the condition of the rubber product on which the reverse engineering is to be carried out is also important.
All these phenomena cause aging of the rubber product, which results in changes in physical properties as well as loss of various chemical components from the product. This can be easily verified by the date of manufacture, which is available on the surface of the rubber product.
Reverse Engineering Concepts
General Concepts and Examples
- Solvent Extraction
- Ash Content Determination
- Chemical Digestion
- Different Instrumentation Techniques
In this chapter we discuss the general concept of reverse engineering a rubber product and the typical testing methods used to obtain information about the material composition of the rubber compound. Some of these organic chemicals are present in the rubber product as it is, and some change its chemical structure during the final curing of the rubber product. Some of these inorganic materials are essential for specific rubbers, and some fillers are generally used to expand the rubber product to reduce the cost of the compound.
Chemical digestion is one of the best analytical techniques to characterize the content of chopped matter in rubber products. Material reverse engineering typically works as shown in the flow diagram presented in Scheme 4.2, which details the analytical steps involved.
Formula Reconstruction—Specific Example
- Sample Preparation
- Brief Description and Use of Analytical Techniques
- Formula Reconstruction
- Comparison of Reconstructed Formulation with Actual Recipe
Numerical Problem on Reverse Engineering
Formulation Reconstruction: Case Studies
Tire Tread Cap
- Objective
- Experimental Methods
- Sample Preparation
- Extraction
- Composition Analysis
- Results and Discussion
Tire Sidewall
- Objective
- Experimental Methods
- Sample Preparation
- Reverse Engineering Analysis
- Micro Analysis
- Ash Analysis
- Elemental Analysis
- Results
Tire Inner Liner
- Objective
- Experiment
- Sample Preparation
- Pyrolysis
- GC-MS Analysis
- Ash Analysis
- Elemental Analysis
- Results
Heat Resistance Conveyor Belt Cover Compound
- Objective
- Experiment
- Sample Preparation
- Extraction
- Composition Analysis
- Results and Discussion
Fuel Hose Cover
- Objective
- Experiment
- Sample Preparation
- Extraction
- Composition Analysis
- Results and Discussion
Rubber Seal
- Objective
- The Experiment
- Sample Preparation
- Analysis
- Results
V-Belt Compound
- Objective
- Experiment
- Sample Preparation
- Elemental Analysis
- Thermogravimetric Analysis
- Differential Scanning Calorimetric Analysis
- Infrared Spectroscopy
- Compositional Analysis
- Observations
- Top Rubber
- Base Rubber
- Conclusions
Rubber Covered Rolls
- Objective
- Experiment
- Sample Preparation
- Analysis
- Results
Rubber Part in Rubber-Metal Bonded Ring
- Objective
- Experiment
- Analysis
- Results
Non-Black Elastic Tape
- Objective
- Experiment
- Sample Preparation
- Extraction
- Composition Analysis
- Results and Discussion
Rubber Diaphragm of Audio Speaker
- Objective
- Experiment
- Sample Preparation
- Extraction
- Composition Analysis
- Results and Discussion
Rubber Sealant
- Objective
- Experiment
- Analysis
- Results
