which of the following are highly crossed linked polymers

Options

A. Alkyd resin
B. Melamac
C. LDPE
D. PAN

Explanation

To determine which of the given options are highly cross-linked polymers, we need to understand what cross-linked polymers are and identify the characteristics of each option provided.

### Step-by-Step Solution:

1. **Understanding Cross-Linked Polymers**:
- Cross-linked polymers are those in which the polymer chains are interconnected by covalent bonds. This structure enhances the strength and stability of the material.
- Common examples of highly cross-linked polymers include thermosetting plastics, which cannot be remolded after they have set.

2. **Analyzing the Options**:
- **Option A: Alkyl Resin**:
- Alkyl resins are known to be thermosetting polymers. They have a network structure due to cross-linking, making them rigid and heat-resistant. Thus, they are considered highly cross-linked.
- **Option B: Melamine**:
- Melamine is also a thermosetting polymer that forms a highly cross-linked network upon curing. It is used in various applications, including laminates and adhesives, due to its durability and heat resistance.
- **Option C: LDPE (Low-Density Polyethylene)**:
- LDPE is a thermoplastic polymer characterized by a branched structure. It does not have significant cross-linking and can be remolded upon heating, making it a non-cross-linked polymer.
- **Option D: PAN (Polyacrylonitrile)**:
- PAN is primarily a linear polymer and does not exhibit significant cross-linking. It is used in applications like fibers and does not fit the definition of a highly cross-linked polymer.

3. **Conclusion**:
- Based on the analysis, the highly cross-linked polymers from the given options are **Alkyl Resin** and **Melamine**.

### Final Answer:
The highly cross-linked polymers among the options provided are **Alkyl Resin and Melamine**.

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