What are Elastomers?
Every day we are dependent upon products and use them as have developed through experimentation and discovery. Having knowledge that evolves regarding the chemical properties, we understand the benefits of developing new products, including products that are made of elastomers.
Countless things like the tires allow the smooth movement of the car over the road. Also, the rubber storage containers in our kitchen and many things with flexible molecular structures are all elastomers. What makes these objects flex and return to original shape? Why are some products rigid compared to others? What holds these structures together? Let us learn more about elastomers.
[Image will be Uploaded Soon]
Elastomers Definition
In chemistry, material made of a long chain of molecules is known as polymer and elastomer. It is known as the polymer having both viscous and elastic properties. A substance which is thick, sticky, and consistent somewhere between the solid and gas stage are known as viscous. How fast or slow a liquid flow is determined by the viscosity of the liquid. When you pour oil from a container, you will see that it pours much slower compared to water, since it is more viscous.
Properties of Elastomers
In chemistry, the bonds that hold several compounds together are very strong compared to size. The flexibility of the object is determined by the bond force and the compound's ability to manipulate into different shapes.
Comparatively, elastomers intermolecular forces are weak. The forces of repulsion and attraction between molecules and other particles are known as intermolecular forces.
As elastomers are not tightly bonded together by attraction to their nucleus, they can stretch apart and have higher failure strain than many other compounds.
The material that will fail at a molecular level when stain is imparted on them, they are known as non-elastic compounds.
The elements used to make elastomers are carbon, silicon, hydrogen, and oxygen, which hold together well in different conditions.
Categories of Elastomers
As a consensus, there are two categories of elastomers:
Thermoset
Thermoplastic
When heated, thermoset elastomers do not melt. When exposed to different types of environmental conditions, they retain their structure. This property of elastomers makes them very useful in different industries where heat and pressure are applied at various levels since they will not break down.
Whereas, thermoplastic elastomers can be melted and reformed into different shapes and configured as per requirement and their use. E.g., you can think of a stick of butter when picturing thermoplastic elastomers. The stick can be cooled and melted many times and molded into different shapes while retaining its original properties.
Elastomers Examples
In manufacturing processes like injection molding, thermoplastic elastomers are used. Thermoplastic polyurethanes are used in many applications, including production of foam seating, seals, gaskets, etc.
All types of saturated and unsaturated rubbers and polysulfide rubbers
Natural Rubber - This is used in the manufacture of gaskets, shoe heels...
Polyurethanes - This material is used in the textile industry for manufacturing elastic clothing such as lycra is also used as foam, wheels, etc.
Polybutadiene - This type of elastomer material is used on wheels or tires of vehicles, giving them extraordinary resistance to wear and tear.
Neoprene - This material is primarily used in manufacturing of wetsuits and is also used as wire insulation, industrial belts, etc.
Silicone - This material is used in a variety of materials and areas since they have excellent chemical and thermal resistance. Silicon is used in manufacture of medical prostheses, pacifiers, lubricants, mold, etc.
Types of Elastomers
Following are the two types of elastomers:
Saturated elastomers
Unsaturated elastomers
Unsaturated Elastomers:
By using sulfur vulcanization unsaturated elastomers can be cured, and non-sulfur vulcanization is desired, for examples:
Synthetic polyisoprene
Butadiene rubber
Neoprene rubber
Nitrile rubber
Butyl rubber
Saturated Elastomers:
This type of elastomers cannot be cured by sulphur vulcanization process, for examples:
Ethylene propylene rubber (EPR)
Ethylene-vinyl acetate (EVA)
Polyacrylic rubber
Silicone rubber
Fluoroelastomers
Polyether block amides.
Chlorosulfonated polyethylene rubber
Do you know?
Elastomers are used to manufacture duckbills and diaphragms of plastic diaphragm check valves; also, O-rings and gasket seals. This is because of its unique physical and chemical properties. Most designing processes can benefit from a better understanding of elastomeric materials.
[Image will be Uploaded Soon]
FAQs on Elastomers
1. What are elastomers and how do their properties differentiate them from other types of polymers?
Elastomers are a category of polymers known for their high elasticity, allowing them to undergo significant deformation and return to their original shape when the stress is removed. Unlike other polymers, elastomers are soft, flexible, and exhibit viscoelastic behavior, which means they combine both viscosity and elasticity.
- They can stretch much more than plastics or hard polymers.
- Most elastomers are either synthetic or derived from natural sources like latex.
- Their structure includes loosely cross-linked polymer chains, giving them flexible, rubber-like properties.
2. How are natural rubber and synthetic elastomers different in terms of origin and use in Physics?
Natural rubber is extracted from the latex of certain trees, whereas synthetic elastomers are produced from petroleum-based substances through chemical processes. In Physics, both are studied for their elasticity and thermal resistance, but their composition and applications vary:
- Natural rubber has unique resilience and flexibility, commonly used where biodegradability is needed.
- Synthetic elastomers, such as neoprene and silicone, offer higher chemical and thermal resistance and are tailored for specific industrial and electrical applications.
3. What are the most important applications of elastomers in daily life and technology as per the current CBSE syllabus?
Elastomers are used in various fields due to their elasticity and durability:
- Consumer goods: Baby products, footwear soles, flexible containers.
- Construction: Sealants, adhesives, insulation materials.
- Industry: Conveyor belts, molds, gaskets, protective coatings.
- Medical: Prosthetics, medical tubing, surgical gloves.
- Electrical: Cable insulation, wire jackets, connectors.
Their ability to deform and recover makes elastomers crucial in applications demanding flexibility and endurance.
4. Why is it important to vulcanize rubber, and how does vulcanization change the properties of elastomers?
Vulcanization is a chemical process that introduces cross-links between polymer chains in rubber. This step is vital because:
- It significantly improves the elasticity, strength, and thermal stability of the elastomer.
- It reduces tackiness and makes the rubber more durable and less sensitive to temperature changes.
- Vulcanized rubber is better suited for tires, shoe soles, and industrial products due to its enhanced properties.
5. What key physical properties allow elastomers to be highly stretchable yet return to their original form, and how is this studied in Physics?
Elastomers have amorphous polymer chains with light cross-linking, allowing the material to be stretched considerably when a force is applied. In Physics, this behavior is examined through:
- Stress-strain curves: Elastomers show high strain for small applied stress and a rapid return to original state.
- Entropy-driven elasticity: The disordered chains become more ordered when stretched, storing energy as entropy, and spontaneously return to disorder when released.
- Studying these allows understanding of material responses in different engineering and technological contexts.
6. What are common misconceptions students have about the differences between elastomers, rubbers, and plastics?
A frequent misconception is that all elastomers are rubber and all flexible materials are elastomers. In reality:
- Not all elastomers are natural rubber; some are synthetic and have different properties.
- Plastic polymers are generally hard and inflexible due to higher cross-linking or crystallinity, whereas elastomers are designed for stretchability.
- Rubber usually refers to elastomers that have been vulcanized or cured, making them more robust and usable in various applications.
7. How does the viscoelastic nature of elastomers impact their performance in engineering applications?
Viscoelasticity means elastomers exhibit both viscous (slow flow) and elastic (spring-like) characteristics. This dual behavior ensures:
- Shock absorption is enhanced in items like automobile tires and sporting goods.
- Flexibility and the ability to return to the original shape protect against permanent deformation.
- Engineering applications benefit from controlled energy dissipation and recovery, which is essential in vibration dampers, seals, and medical devices.
8. In Physics, how does temperature affect the elasticity of elastomers and what practical examples illustrate this effect?
Temperature changes can significantly alter the elasticity of elastomers:
- At low temperatures, elastomers can become stiff and brittle due to reduced molecular motion.
- With increasing temperature, elasticity improves as polymer chains move more freely, up to a point before decomposing.
- A practical example is rubber bands losing elasticity in the cold or car tires performing differently in winter versus summer due to the temperature dependence of their elastomeric compounds.
