Nitrile gloves are a form of synthetic rubber made from acrylonitrile butadiene rubber (NBR), serving as a widely used alternative to natural rubber latex. They are popular across many industries, from medical to automotive, due to their strength and puncture resistance. While nitrile gloves offer a barrier against many substances, determining if they are acid resistant is complex. The protection level depends entirely on the specific acid type, its concentration, and the physical properties of the glove.
Understanding Nitrile’s Chemical Structure
Nitrile gloves are manufactured using a synthetic polymer derived from acrylonitrile and butadiene monomers. This chemical composition gives the material its inherent resistance to oils, greases, and many solvents. The dense molecular structure of the resulting synthetic rubber creates a more compact barrier compared to the looser structure of natural rubber latex. This tight barrier is especially effective against the penetration of non-polar compounds, such as petroleum products. The presence of acrylonitrile enhances the glove’s overall chemical stability, which explains why nitrile gloves are generally preferred over latex for handling a wide range of chemicals encountered in industrial settings.
Resistance to Acids and Caustics
Nitrile gloves do provide protection against many common acids and caustics, provided they are in diluted forms. For instance, nitrile is often effective for short-term handling of weak acids, such as acetic acid at a 10% concentration, commonly found in vinegar solutions. They also demonstrate resistance to moderately concentrated mineral acids, including sulfuric acid up to 47% and nitric acid up to 10% concentration. The material’s structure helps it resist both low and high pH extremes, making it suitable for many weak caustic solutions like sodium hydroxide at 40% concentration. The protection provided is based on the material’s ability to slow the rate at which the chemical permeates through the glove.
Factors Determining Glove Protection Level
The effectiveness of a nitrile glove as a chemical barrier is significantly influenced by several practical factors beyond the chemical itself. One major factor is the glove’s thickness, typically measured in mils, where one mil equals one-thousandth of an inch. Thicker gloves, usually industrial grades ranging from 6 to 8 mils, offer a more robust barrier and a longer breakthrough time before a chemical can permeate the material. The concentration of the acid is another critical variable, as resistance decreases dramatically when concentration increases, even for the same chemical. Higher temperatures also accelerate molecular movement, which can significantly hasten the rate of chemical permeation through the glove material. Therefore, manufacturers’ chemical resistance charts, which specify breakthrough times, must be consulted, as a simple blanket statement of “acid-resistant” is insufficient for safety planning.
When Nitrile Gloves Are Not Safe
Despite their broad resistance profile, nitrile gloves are not universally protective and should never be used with certain aggressive chemicals. They offer poor protection against highly concentrated, strong oxidizing acids, such as concentrated nitric acid or chromic acid. These powerful oxidizing agents can rapidly degrade the nitrile material, leading to barrier failure. Nitrile also has poor resistance to specific organic solvents, which can quickly cause the material to swell, crack, or dissolve. Key examples include ketones, such as acetone and methyl ethyl ketone (MEK), as well as aromatic solvents like toluene and benzene. For handling these high-risk chemicals, specialized materials like Butyl or Viton gloves are often necessary to ensure adequate safety.