Understanding Charts for the Chemical Resistance of Plastics

One of the most important resources for determining which plastic should be used in a chemical environment is a chemical resistance chart for plastics. These charts show how compatible different plastics are with a variety of chemicals and other fluids that fall on all points of the pH scale, from milk to mineral oil to fruit juice. However, the chart only gives you a snapshot of how a plastic might perform — there are several other environmental factors that need to be understood and considered before you can make a truly informed decision.

Factors Accounted for in Chemical Compatibility Charts

There are three factors, or interactions, that just about all chemical compatibility charts for plastics can tell users about: chemical attack, environmental stress cracking and physical absorption. Knowing what these factors mean in the relationship between plastics and chemicals can go a long way toward informing your choice of plastics for different applications.

Chemical Attack

When a plastic and a chemical are not compatible, the chemical essentially attacks the plastic in a reaction that causes the polymer structure to break down. This occurs at a molecular level and causes the chains that bind the structure together to weaken, become more susceptible to impact and even fail. Part failure can be disastrous for any facility, so be sure to only choose plastics that are up for the job and monitor parts as instructed to ensure they get replaced or repaired when needed.

Environmental Stress Cracking

Chemical attacks are sometimes considered ESC (environmental stress cracking) when related to vulnerabilities in the plastic's structure. ESC occurs in conjunction with internal and external stresses on a plastic. Internal stresses are placed on a plastic part during fabrication and processing, while external stresses occur from the mechanical load on the part. So, when a chemical weakens the plastic's structure, the forces already at work on a plastic cause thin, spiderweb-like cracking that could seriously affect a part's performance.

Physical Absorption

This process is a bit different from a chemical attack since it doesn't affect the molecular structure of the polymers. However, it does seriously affect the physical structure of the plastic part. When chemicals are absorbed into the plastic, it can make the part go soft or brittle, fluctuate in weight and even change in dimension.

Factors Accounted for in Chemical Compatibility Charts

While chemical attack, environmental stress cracking and physical absorption are all serious and important factors covered by a chemical compatibility chart, plastics can be affected by a variety of other factors as well.

Operating Temperature

Temperature plays a massive role in determining how a plastic will interact with a chemical. You should always specify temperature requirements when choosing a plastic because it could influence the type of plastic or additional applications needed to craft a successful system. For example, polyolefins like HDPE and polypropylene function best at low to moderate operating temperatures. However, when temperatures get too high, they tend to go soft and even begin to lose their form. If a holding cabinet, tank or piece of food processing equipment will be placed in an area with extremely high temperatures, HDPE and polypropylene would not be ideal choices.

Exposure Time

It's also important to know how long a part will be exposed to chemicals before choosing your plastic material — even chemical resistant plastics can begin to break down after long exposure. As such, it's important to maintain plastic parts by wiping away any spills and splatters that may occur. If fluids and chemicals will be sitting inside of a plastic tank or another part for extended periods of time, you should always "over-engineer," or choose a plastic that can more than handle your specifications.

Concentration

A chemical in its pure form is very different from one that's been watered down. As such, it's crucial that you choose a plastic that can stand up to a chemical at whatever concentration specification you require. In some chemical compatibility charts, multiple entries will be shown detailing how well a polymer resists chemicals at different concentrations. If this is not the case, it would be best to consult with your parts supplier about what a specific plastic can handle.

Chemical Resistance Chart for Plastics from A&C Plastics

Many of the plastics offered at A&C Plastics are able to resist chemicals all across the pH spectrum. However, as we've explained, certain plastics are better at resisting certain chemicals than others. In the chemical resistance guide for plastics below, you'll see whether a plastic sustains no chemical attack or absorption, moderate attack or severe attack by the various materials listed. Moderate attack means that the plastic can handle exposure but will have a limited lifetime, while severe means the plastic will decompose quickly.

  •  
    No Chemical Attack
  •  
    Moderate Chemical Attack
  •  
    Severe Chemical Attack
  •  
    No Data
MaterialsBSAHDPEPolycarbonatePolypropylenePVC
Acetic acid, concentrated          
Acetone          
Anone          
Benzene          
Benzine          
Bitumen          
Butyl acetate          
Carbon trachloride          
Chlorobenzene          
Chloroform          
Cyclohexane          
Decalin          
Diesel Oil          
Dimethyl formamide          
Diocthyl phthalate          
Edible fats/oils          
Ethyl acetate          
Ethyl ether          
Ethylene chloride          
Freon, Frigen (liquid)          
Fruit juices          
Glycerine          
Glycol          
Heating oil          
Heptane, Hexane          
Hydrogen sulphide (saturated)          
Ink          
Iodine/alcohol solution          
Iso-octane          
Isopropanol          
Linseed oil          
Methanol          
Methylethyl ketone          
Methylene chloride          
Milk          
Nitrobenzene          
Ozone          
Paraffin oil          
Perchlorethylene          
Petroleum          
Phenol (aqueous solution)          
Phosphoric acid (concentrated)          
Propanol          
Pyridine          
Salicylic Acid          
Silicone oils          
Soap solution (aqueous solution)          
Styrene          
Sulphur dioxide          
Tar          
Tartaric acid          
Tetrahydrofurane          
Tetralin          
Toluene          
Transformer oil          
Trichlorethylene          
Triethanolamine          
Urea (aqueous solution)          
Vaseline          
Water (cold)          
Water (warm)          
Wax (molten)          
Wine, Brandy          
Xylene          

Continue Learning About the Chemical Resistance of Plastics

As you may have guessed from our name, A&C Plastics is ready to help you learn about everything plastic. On top of our chemical resistance guide for plastics, we have a treasure trove of other resources on all the chemically resistant plastics we offer and the qualities that make them great for an amazing variety of tasks and applications. If you want to learn more about any of our products, or about who we are as a company, contact A&C Plastics today.

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