Which of the following characteristics of thermosetting polymers?

Options

A. Heavily branched cross linked polymer s
B. Linear slightly branched long chain molecules
C. Become infusible on moulding so cannot be reused
D. Soften on heating and harden on cooling can be reused

Explanation

To determine the characteristics of thermosetting polymers, we need to analyze the provided options one by one:

### Step 1: Understand the Definition of Thermosetting Polymers
Thermosetting polymers are a class of polymers that, once set into a given shape, cannot be remolded or reheated to change their form. They undergo a chemical change when heated, resulting in a rigid structure.

### Step 2: Analyze Each Option
1. **Option 1: Heavily branched cross-linked polymers**
- Thermosetting polymers are indeed heavily branched and cross-linked. This structure contributes to their rigidity and inability to be reshaped after curing.

2. **Option 2: Linear slightly branched long chain molecules**
- This description fits thermoplastics rather than thermosetting polymers. Thermoplastics can be reshaped upon heating, which is contrary to the behavior of thermosetting polymers.

3. **Option 3: Becomes infusible on molding, so cannot be reused**
- This is a characteristic of thermosetting polymers. Once they are molded and cured, they cannot be melted down or reshaped.

4. **Option 4: Soften on heating, harden on cooling, so can be reused**
- This characteristic describes thermoplastics, not thermosetting polymers. Thermosetting polymers do not soften upon reheating.

### Step 3: Conclusion
Based on the analysis:
- The correct characteristics of thermosetting polymers are:
- **Option 1**: Heavily branched cross-linked polymers
- **Option 3**: Becomes infusible on molding, so cannot be reused

### Final Answer
The characteristics of thermosetting polymers are:
- Option 1: Heavily branched cross-linked polymers
- Option 3: Becomes infusible on molding, so cannot be reused

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