How to Make Rubber With Cornstarch & Silicon

Making rubber with cornstarch is a simple and educational experiment that demonstrates the properties of polymers and the process of cross-linking. Here's a step-by-step guide to help you make rubber with cornstarch:

Materials:

1. Cornstarch

2. White vinegar

3. Vegetable oil

4. Mixing bowl

5. Spoon

6. Plastic bag

7. Rolling pin

Instructions:

Step 1: Mixing Cornstarch and Vinegar

- In a mixing bowl, add about 1/2 cup of cornstarch.

- Gradually add 1/4 cup of white vinegar to the cornstarch while stirring continuously.

- Mix the cornstarch and vinegar until you form a smooth paste-like consistency.

Step 2: Adding Vegetable Oil

- Once the mixture is smooth, add about 1 tablespoon of vegetable oil to the bowl.

- Continue mixing until the oil is well-incorporated into the cornstarch-vinegar mixture.

Step 3: Forming the Dough

- Knead the mixture in the bowl with your hands until it forms a soft, pliable dough.

- If the dough is too sticky, add a bit more cornstarch. If it's too crumbly, add a little more vinegar.

Step 4: Rolling and Shaping

- Transfer the dough to a plastic bag.

- Seal the bag and use a rolling pin to flatten the dough into a thin sheet.

- You can also mold the dough into different shapes, such as balls or snakes, using your hands.

Step 5: Cross-Linking

- Once the dough is shaped, place it in the refrigerator for at least 30 minutes.

- This step is crucial for the cross-linking process to occur, transforming the cornstarch mixture into a rubber-like material.

Step 6: Testing the Rubber

- After refrigeration, take the dough out of the refrigerator.

- Test the elasticity of the dough by stretching it or bouncing it.

- You'll notice that the dough has become rubbery and flexible, similar to commercial rubber.

Observations and Explanation:

- The cross-linking process that takes place during refrigeration involves the formation of chemical bonds between the molecules in the cornstarch and the vinegar.

- These cross-links give the material its rubber-like properties, making it stretchy and elastic.

- The vegetable oil acts as a plasticizer, which helps keep the rubber soft and flexible.

This experiment offers a hands-on demonstration of polymer chemistry and cross-linking, which are essential concepts in the production of various synthetic materials.