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Vulcanisation of Elastomers

Vulcanization is a process that transforms raw rubber into a usable material through the formation of crosslinks between polymer chains. This process involves the use of sulfur as a crosslinking agent that forms bridges between the chains, altering the physical properties from a soft material to a resilient elastic rubber. The degree of crosslinking and resulting material properties are influenced by factors like the sulfur content, accelerators, activators, retardants, temperature, and cure time used in the vulcanization process.

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222 views1 page

Vulcanisation of Elastomers

Vulcanization is a process that transforms raw rubber into a usable material through the formation of crosslinks between polymer chains. This process involves the use of sulfur as a crosslinking agent that forms bridges between the chains, altering the physical properties from a soft material to a resilient elastic rubber. The degree of crosslinking and resulting material properties are influenced by factors like the sulfur content, accelerators, activators, retardants, temperature, and cure time used in the vulcanization process.

Uploaded by

darshan baskar
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Vulcanization is a crucial process in rubber production, transforming raw elastomers into usable

materials with enhanced properties. It involves the formation of crosslinks between the
elastomer chains, resulting in a three-dimensional network structure that imparts desirable
characteristics such as elasticity, resilience, and tensile strength.

The process of vulcanization typically involves the use of sulfur as the crosslinking agent. Sulfur
reacts with the double bonds present in the elastomer chains, forming intermolecular bridges
that connect the individual chains together. This crosslinking process alters the physical
properties of the elastomer, transforming it from a soft, gummy material into a resilient, elastic
rubber.

Factors influencing the vulcanization process include:

1. Sulfur Content: The amount of sulfur used affects the degree of crosslinking and the
resulting properties of the vulcanized rubber. Increasing sulfur content generally leads to
increased crosslinking, resulting in stiffer and harder rubber.
2. Accelerators: Accelerators are additives that enhance the rate of sulfur reaction with the
elastomer chains, speeding up the vulcanization process. They act as catalysts, reducing
the activation energy required for the sulfur-elastomer reaction.
3. Activators: Activators are additives that promote the formation of active sulfur species,
which are more readily reactive with the elastomer chains. They ensure that the sulfur is in
a form that can effectively participate in the crosslinking process.
4. Retardants: Retardants are additives that slow down the vulcanization process, allowing
for better control over the reaction and preventing premature curing. They are often used
in thick rubber articles to ensure uniform curing throughout the material.
5. Temperature: Temperature plays a significant role in the vulcanization process. Higher
temperatures generally accelerate the reaction, while lower temperatures slow it down.
The optimal temperature depends on the specific elastomer and the desired properties of
the vulcanized rubber.
6. Time: The duration of vulcanization, also known as the cure time, is crucial for achieving
the desired crosslinking density. Inadequate cure time results in undercured rubber with
poor properties, while excessive cure time leads to overcured rubber with reduced
elasticity.

Vulcanization is an essential step in rubber production, transforming raw elastomers into


versatile materials with a wide range of applications. By controlling the vulcanization process,
manufacturers can tailor the properties of rubber to suit specific needs, from soft, flexible rubber
bands to strong, durable tires.

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