I bought some Plasti Dip to use on my wheels and my daughter formed a very good question. How does rubber become a liquid, shoved in a can, stay in there as a liquid, and then dry as a peelable rubber material once applied to a surface? Not just Plasti Dip, but bed liner sprays and other similar products.
I haven’t found a straightforward answer through Google.
In: Chemistry
Two primary methods.
One is the material reacts with something in the air to complete a chemical reaction. The substance in the air can either act as an ingredient for the reaction (it becomes part of the new material compound) or as a catalyst (it greatly speeds up the reaction without becoming part of it).
Edit: In the case of the catalyst, the material is probably setting (becoming solid) inside the container. Its just doing so at an extremely slow rate, so it remains useable for a long time.
Two is drying. The material may be stored with a solvent. The solvent evaporates out of the material and the remaining leftover becomes a solid. Good ol’ Elmer’s glue uses this method. The liquid glue has water. Once the water evaporates the glue material is left as a solid.
Well, Plasti Dip is PVC-based, so it works a lot like PVC solvent cement: there’s a resin component, some plasticizers, and a volatile solvent. In its most solid form, the PVC molecules stick to each other directly, forming a network not unlike a plate of unsauced spaghetti that has been cooked and allowed to sit until the surface has dried: the strands all stick together and form a big, unified mass. Also like spaghetti, adding a lubricant like oil to let the strands slide past each other lets them behave more like a thick liquid. PVC just uses solvents that evaporate in air.
So, when it’s made, it’s plastic. Then they dissolve the plastic in a solvent to let the strands slide apart and make it a liquid. When you expose it to air, the solvent evaporates and the material re-solidifies. The reason it acts like rubber and not plastic has to do, ironically, with the plasticizers: they let the strands move past each other just a little bit, but they aren’t volatile.
If you put powdered sugar/salt in a glass of water, it will dissolve. If you spray this on a surface, it goes on as a liquid. Once it dries, it leaves a white film.
Plasti Dip is basically a 1 part synthetic resin, dissolved in 1-2 parts naptha, and 1 part gasoline. Gasoline and naptha both evaporate quickly, so it dries extra fast.
This is the MSDS, Hexane and Toulene are basically Gasoline; Naptha is camping fuel:
[https://www.tapplastics.com/image/pdf/MSDS%20Plasti%20Dip.pdf](https://www.tapplastics.com/image/pdf/MSDS%20Plasti%20Dip.pdf)
As for bed liners, these are now a bit more complicated. The good ones are a urethane epoxy base. Instead of drying, they cure. They have a chemical mixed in that causes a complex reaction which leads to it hardening over time.
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