Vulcanisation — Summer 2019

Differentiate vulcanized rubber and unvulcanized rubber.

List out the different allotropic forms of sulphur. Write on any two.

Discuss in detail about the vulcanization of thick rubber articles.

Write a brief note on ‘Dynamic Vulcanization’.

With labeled diagram, explain the construction of Moving Die Rheometer(MDR).

Explain the reaction chemistry of sulphur vulcanization.

Define the term ‘crosslinks density’. Explain effect of crosslink density on the given properties of vulcanizate with graph:(i) Modulus and Strength (ii)Hysteresis (iii) Resilience

Write in brief on xanthate accelerator.

Explain the term ‘crosslinking efficiency’ with respect to peroxide cure. How it can be improved?

Write a short note on thiourea accelerators.

Give any two examples of peroxides with carbonyl group with it’s structure.

Explain the vulcanization by metal oxides with suitable example.

Write a short note on sulphur donors.

Explain the physical method to assess the state of cure.

Give comparison between various continuous vulcanization techniques.

Discuss in detail about the limitations of vulcanization temperatures.

Which different phases are observed during free heating?

How vulcanization is carried out in autoclave?

Discuss the following features with respect to liquid curing method:(i)Influence of accelerator and vulcanizing agents(ii)Advantages and Disadvantages

Explain the working principle of fluidized bed vulcanization technique.

How vulcanization is carried out under water?

Discuss in detail about electron beam vulcanization technique.

Give the limitations of hot air vulcanization technique.

Write a short note on cold cure.

Discuss in detail about the microwave vulcanization technique.