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Rubber Chemical Resistance

13 May 2024 Posted by: makeyourmark New Technologies

Rubber, renowned for its elasticity and durability, finds widespread use in various industries, from automotive to pharmaceuticals. One critical aspect of rubber’s utility is its resistance to chemicals, making it indispensable in environments where exposure to corrosive substances is a concern. Rubber’s unique chemical resistance stems from its molecular structure, which consists of long polymer chains that are inherently resistant to degradation by many chemicals. However, the chemical resistance of rubber can vary depending on the type of rubber and the specific chemicals it encounters. Factors such as temperature, concentration, and duration of exposure also play a significant role in determining the extent of rubber’s resistance to chemicals. Understanding these factors is paramount for ensuring the longevity and effectiveness of rubber-based products in environments where chemical exposure is a constant challenge.

Chemical Compatibility of Rubber

Chemical compatibility is a critical consideration when selecting rubber materials for specific applications. Different types of rubber exhibit varying degrees of resistance to different chemicals, and using the wrong type of rubber can lead to premature degradation or failure of the product.

Natural rubber, for example, is highly resistant to water and weak acids but is not suitable for use with oils, greases, or strong acids. On the other hand, neoprene rubber offers excellent resistance to oils, greases, and ozone, making it ideal for use in automotive applications. However, it may not be suitable for applications requiring resistance to strong acids or aromatic hydrocarbons.

When determining the chemical compatibility of rubber, it is important to consider not only the type of rubber but also the specific chemicals it will be exposed to. Different chemicals can have varying effects on rubber, with some causing swelling, softening, or hardening, while others may cause cracking or degradation of the material.

Temperature, concentration, and duration of exposure are also crucial factors that influence chemical compatibility. Higher temperatures and concentrations of chemicals can accelerate the degradation process, leading to faster deterioration of the rubber material.

To ensure the chemical compatibility of rubber, it is essential to consult chemical compatibility charts and tables provided by rubber manufacturers. These resources provide valuable information about the compatibility of different types of rubber with a wide range of chemicals, helping users select the most suitable rubber material for their specific application.

ILT’s Table for Septa Material and Combinations

Septa should be determined by the type of sample for analysis. There are 6 common types of liner manufactured in conjunction with vials that can be inserted into crimp caps, screw caps, and/or snap caps.

The hardness, or durometer, of rubber can have an influence on sealing. Another term for durometer is Shore hardness. Shore A Durometer hardness measures the resistance of a material to indentation. The hardness gives an indication of the type of properties to expect from a material, but is not always the indicator of performance. The typical hardness for chromatography septa is Shore A 45, +/- 5, but can also be Shore A 35 +/- 5, or Shore A 50 +/- 5. 

Septa used in chromatography almost always has a Fluoro-polymer material facing the sample. A commonly-used Fluoro-polymer is PTFE.

**Table Legend:

Poor = Post injection, this septum will exhibit sample loss and deterioration.

Fair = Post injection, this septum will maintain integrity for a limited period of time with some deterioration.

Good = Post injection, this septum will maintain integrity for an extended period of time minor deterioration.

Excellent = Post injection, this septum will maintain integrity for a high percentage of analytical sample analysis with absolute minimal deterioration.

Read more about the chemical packaging industry on our blog page or learn more about ILT, the world leader in manufacturing seals and septa here.