Which of the following polymers involves cross-linkages

Options

A. Rayon
B. Bakelite
C. Melamine
D. Valucanized rubber

Explanation

To determine which of the given polymers involves cross-linkages, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Polymers:**
The options given are:
- Rayon
- Bakelite
- Melamine
- Vulcanized rubber

2. **Analyze Rayon:**
- Rayon is a regenerated cellulose fiber. Its structure is linear and consists of beta-1,4-glucose linkages.
- **Conclusion:** Rayon does not involve cross-linkages; it is a linear polymer.

3. **Analyze Bakelite:**
- Bakelite is a type of thermosetting plastic made from phenol and formaldehyde. It is known for its cross-linked structure.
- **Conclusion:** Bakelite involves cross-linkages.

4. **Analyze Melamine:**
- Melamine is a type of thermosetting polymer made from melamine and formaldehyde. It also forms a cross-linked network structure.
- **Conclusion:** Melamine involves cross-linkages.

5. **Analyze Vulcanized Rubber:**
- Vulcanized rubber is rubber that has been treated with sulfur to create cross-links between the polymer chains, enhancing its strength and elasticity.
- **Conclusion:** Vulcanized rubber involves cross-linkages.

6. **Final Conclusion:**
- Among the options, Bakelite, Melamine, and Vulcanized Rubber are cross-linked polymers. Rayon is not a cross-linked polymer.

### Answer:
The polymers that involve cross-linkages are Bakelite, Melamine, and Vulcanized Rubber.

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