Which of the following is not a step growth polymer ?

Options

A. Polybutadiene
B. Nylon-6,6
C. Glyptal
D. Terylene

Answer

To determine which of the following is not a step growth polymer, we need to analyze the polymerization processes of the given options.

### Step-by-Step Solution:

1. **Understanding Polymerization Types**:
- **Step Growth Polymerization**: This involves the reaction between monomers that can react with each other in multiple ways, leading to the formation of larger molecules and the release of byproducts (like water or alcohol).
- **Chain Growth Polymerization**: This involves the addition of monomers with unsaturated bonds, where the polymer grows by the addition of one monomer at a time without the release of byproducts.

2. **Analyzing the Options**:
- **Option 1: Polybutadiene**:
- Polybutadiene is formed through chain growth polymerization. There are no byproducts released during this process. Therefore, this is not a step growth polymer.
- **Option 2: Nylon 6,6**:
- Nylon 6,6 is formed from hexamethylene diamine and adipic acid. During the polymerization, water is released as a byproduct. This indicates that it is a step growth polymer.
- **Option 3: Glyptal**:
- Glyptal is formed from the reaction of phthalic acid and ethylene glycol. This reaction also releases water as a byproduct, indicating that it is a step growth polymer.

3. **Conclusion**:
- Based on the analysis, polybutadiene is the only option that does not involve step growth polymerization since it is formed through chain growth polymerization.

### Final Answer:
**Polybutadiene is not a step growth polymer.**