Chemical Cracking: Causes and Solutions

Key Takeaways

• Chemical cracking occurs when incompatible chemicals penetrate stressed plastics, causing cracks and premature failure.

• Amorphous plastics such as acrylic, polycarbonate, ABS, and PVC are especially susceptible to chemical cracking.

• Preventing chemical cracking requires selecting compatible materials and verifying chemical resistance for the intended environment.

What is Chemical Cracking?

Chemical cracking occurs when plastics react with certain chemicals, causing cracks or other damage. Chemicals that contact stressed areas can penetrate the material, weaken it, and eventually cause fractures.

Causes

Chemical cracking often results from adhesives or lubricants that are incompatible with the plastic. Cracks may appear immediately, or they may take months or even years to develop. Over time, the strength of the part or product can decrease significantly, potentially leading to sudden failures that may cause injury or accidents.

Because plastics are more chemically reactive than metals, it’s essential to select materials tested against all chemicals the part may encounter. For instance, although acrylic is often used for partition panels, PET is a safer choice when exposed to alcohol-based disinfectants.

Most Susceptible Materials

Amorphous plastics (including acrylic, polycarbonate, PVC, and ABS) are particularly vulnerable to chemical cracking.

Crystalline plastics, in contrast, are generally more resistant because chemicals have difficulty penetrating their structured regions.

Chemical Triggers

Chemicals that commonly cause chemical cracking include acetone and benzene. The effect varies by material, with polycarbonate, ABS, and acrylic being particularly susceptible.

Detergents can also trigger chemical cracking, so it’s important to know the material before using them for cleaning. Other substances, such as industrial silicones, oils, and certain household products, may also contain components that can induce cracking.

Always verify chemical compatibility for the specific material before use.

Preventative Measures

The most effective way to prevent chemical cracking is to follow proper chemical handling procedures and confirm material compatibility.

Cracks can also result from internal stress or environmental loads. If problems occur, review both the material and the operating conditions to identify the root cause.

Step Up Your Project with Yumoto Electric

Yumoto Electric delivers high-quality components fast, worldwide. We provide precision machining for a wide range of metals and engineering plastics. We have experience with over 200 materials including metals such as aluminum alloys, stainless steel, molybdenum, and titanium, and engineering plastics including PEEK, PPS, MC Nylon, and POM.

If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.