What is activator in rubber?

Typical rubber vulcanization systems consist of rubber, sulfur accelerator, metal oxide and fatty acid, where the last two ingredients represent the activator. The most common activator is zinc fatty acid ester which is often formed in-situ by reaction of fatty acid with zinc oxide. …

Which of the following ingredient is used as a activator in rubber closure?

Two other ingredients that play an important role in vulcanization chemistry are known as “activators,” commonly zinc oxide and stearic acid.

What is cross linking agent used in vulcanization?

Vulcanization is a chemical process that converts natural rubber and other polydiene elastomers into cross-linked polymers. The most common vulcanization agent is sulfur. It forms bridges between individual polymer molecules when heated with rubber. The cross-linked elastomers have much improved mechanical properties.

Who is activator?

A transcriptional activator is a protein (transcription factor) that increases transcription of a gene or set of genes. Most activators are DNA-binding proteins that bind to enhancers or promoter-proximal elements. The DNA site bound by the activator is referred to as an “activator-binding site”.

How does a tire curing press work?

The green tire is inserted into a tire press where an internal tire bladder is inflated causing the green tire to press up against the mold. The action of pressing up against the mold combined with intense heat causes the rubber to conform to the mold, creating the tread and sidewall lettering in the process.

What ingredient is in rubber?

The main chemical constituents of rubber are elastomers, or “elastic polymers,” large chainlike molecules that can be stretched to great lengths and yet recover their original shape. The first common elastomer was polyisoprene, from which natural rubber is made.

What is rubber accelerator?

Rubber accelerators are chemicals used to speed up the manufacturing process of rubber (vulcanisation). This process makes untreated natural rubber latex suitable for use in the manufacture of many rubber products.

Why does rubber have to be cross linked to be useful?

These crosslinks tie all the polymer molecules together. Because they are tied together, when the rubber gets hot, they can’t flow past each other, nor around each other. This is why the Charles Goodyear’s vulcanized rubber doesn’t get brittle in when it gets cold.

How do the cross-links change the properties of rubber?

The cross-links prevent flow and provide the rubber products with a high degree of elasticity and toughness even far above their glass-transition temperature.