How Does Plastic React when it’s Exposed to Chemicals?
When storing liquids, particularly acids and chemicals, it’s crucial to realize that they can be extremely corrosive. For this reason, when manufacturing a basin or container, it’s important to choose a material that’s customized for the substance it is destined to hold. In other words, we need to consider the type of chemical involved, its concentration and storage temperature. The goal is to choose a basin material that won’t be attacked by the chemical it’s meant to store. If you use the wrong kind of plastic, it will deteriorate as soon as it comes into contact with the chemicals. The structure of the basin will be compromised and could even become damaged as a result of this exposure, ultimately weakening and losing its shape. When plastic deteriorates, it’s no longer as effective. We also need to consider that fine plastic particles may detach and make their way into the basin’s liquid. Ideally, we need to choose a plastic that reacts well to chemicals and other corrosive agents.
Unlike metal, which rusts when it comes into contact with corrosive products, plastic doesn’t “rust” in response to corrosion. Instead, it deteriorates. Some plastics even dissolve when they come into contact with certain solvents. That’s why it’s important to consider the types of chemicals that a basin or a tank was designed to contain.
What’s the Chemical Resistance of Plastic?
The term chemical resistance refers to a material’s capacity to withstand exposure to corrosive agents over a certain period of time while maintaining its properties. Following exposure to a corrosive substance, how a plastic reacts depends on a number of factors:
- The type of chemical involved
- The concentration of the chemical
- The storage temperature of the chemical
- The rate at which the chemical will be absorbed by the plastic
In other words, a plastic’s chemical resistance is its ability to withstand exposure to corrosive products without reacting. The more a plastic reacts to corrosive agents, the weaker its chemical resistance will be. Conversely, a plastic that’s said to have a high chemical resistance is a plastic that will be practically inert (without movement or reaction) when exposed to corrosive chemicals. A plastic that barely reacts to chemicals will be able to withstand exposure to corrosive agents safely without the risk of deterioration. The basin will therefore remain intact.
What Plastics Have the Highest Chemical Resistance?
Plastics with a Low Reactivity to Corrosive Chemicals:
HDPE Polyethylene
- Compliant with FDA standards
- Often used to make basins and tanks
- Excellent rigidity
- Easy to weld
Polypropylene
- Compliant with FDA standards
- Very low coefficient of friction
- Excellent thermal stability
- Often used to protect cables
- Highly resistant to abrasion
- Does not react to chemicals
PVDF (polyvinylidene fluoride)
- Extremely resistant, even to chemicals that are highly corrosive
- Highly specialized, high performance material (higher cost)
- Can withstand ongoing exposure to temperatures as high as 140 °C
