Vulcanization and Crosslinking - Additives, Compounding and Formulations - Engineering Sciences Previous Year Questions

1

2008 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2008

The amount of sulphur (S) required for 5% cross linking in 100 kg of Polyisoprene is (atomic masses of H, C, and S are 1, 12, and 32 amu, respectively)

A

23.5 g

B

47 g

C

2.35 kg

D

16 kg

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2

2013 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2013

Vulcanization is related to

A

strengthening of rubber

B

extrusion

C

injection moulding

D

addition polymerisation

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3

2015 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2015

Match the following reagents to their function in natural rubber latex technology

A

P-3; Q-1; R-2; S-4

B

P-3; Q-2; R-4; S-1

C

P-3; Q-1; R-4; S-2

D

P-3; Q-4; R-1; S-2

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4

2016 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2016

In the vulcanization of 50 g of natural rubber, 10 g of sulfur is added. Assuming the mer to S ratio is 1:1, the maximum percentage of cross-linked sites that could be connected is __________ %.
(Given: atomic weight of S is 32 amu and molecular weight of a mer of natural rubber is 68 amu)

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5

2016 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2016

Match the elastomers listed below to the appropriate curing agent:

A

P: Silicone rubber – 1. Zinc oxide + ethylene thiourea; Q: Natural rubber – 2. Diamine; R: Chloroprene rubber – 3. Sulfur; S: Acrylate elastomer – 4. Dicumyl peroxide

B

P: Silicone rubber – 1. Zinc oxide + ethylene thiourea; Q: Natural rubber – 2. Diamine; R: Chloroprene rubber – 3. Sulfur; S: Acrylate elastomer – 4. Dicumyl peroxide

C

P: Silicone rubber – 1. Zinc oxide + ethylene thiourea; Q: Natural rubber – 2. Diamine; R: Chloroprene rubber – 3. Sulfur; S: Acrylate elastomer – 4. Dicumyl peroxide

D

P: Silicone rubber – 1. Zinc oxide + ethylene thiourea; Q: Natural rubber – 2. Diamine; R: Chloroprene rubber – 3. Sulfur; S: Acrylate elastomer – 4. Dicumyl peroxide

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6

2020 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2020

Dicumyl peroxide is a

A

Plasticizer

B

Cross-linking agent

C

Mold release agent

D

Peptizer

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7

2020 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2020

Assume that each cross-link produced by vulcanization of polyisoprene contains an average of two sulphur atoms and that the sulphur is present only in the cross-links. If 40% of the isoprene units are cross-linked, the sulphur content in weight percentage is ____________________ (round off to 2 decimal places).

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8

2021 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2021

A sample of natural rubber (cis-1,4-polyisoprene) is vulcanized such that one of every 240 chain carbon atoms is cross-linked. The formula unit of the isoprene monomer is C₅H₈ (molecular weight = 68 g/mol). The average molecular weight (rounded off to the nearest integer) between cross-links is \_\_\_\_\_\_\_\_ g/mol.

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9

2023 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2023

Among the options given, which agents are used to vulcanize or cure rubbers?

A

Dicumyl peroxide

B

Zinc stearate

C

Carbon black

D

Dinitrobenzene

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10

2025 · Engineering Sciences · Additives, Compounding and Formulations · Vulcanization and Crosslinking

Engineering Sciences (XE) 2025

A rubber contains 70 wt% butadiene (molar mass = 54 g/mol), 20 wt% isoprene (molar mass = 68 g/mol), 5 wt% sulfur and 5 wt% carbon black. Assume that all the sulfur is present in crosslinks.
If each sulfide crosslink contains an average of two sulfur atoms, the percentage of possible crosslinks that are joined by vulcanization is ______%. (Round off to one decimal place)

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