How to measure burst strength/resistance

Burst strength (or burst resistance) refers to a material’s ability to withstand internal pressure before rupturing. It is a critical measure of a material’s tensile strength and extensibility, particularly in the packaging industry where materials must maintain integrity to protect contents during shipping. Films, paper, membranes and plastic sheets are prone to bursting when strained, which compromises product safety.

Bursting is also an undesirable trait in products like balloons and condoms, where the elastic limit of the material must not be exceeded during use.

Burst strength testing is essential in several industries, including packaging, textiles, and material production. Using a Texture Analyser, various materials can be subjected to controlled internal pressure to assess their ability to resist bursting. Here are some specific applications:

• Packaging material testing: Measuring the burst strength of materials such as paper, cardboard, plastic films, and laminates to ensure they can withstand the internal pressure of the packaged contents. For example, evaluating the burst resistance of corrugated cardboard to ensure it’s suitable for shipping fragile items.
• Burst testing of flexible containers: Assessing the resistance of pouches, bags, and blister packs commonly used in the food, pharmaceutical, and cosmetic industries to prevent leakage. For example, measuring the burst strength of a pouch containing liquid detergent to ensure it withstands transport and storage.
• Textile fabric testing: Determining the burst resistance of textiles and fabrics to ensure durability and resistance to tearing, particularly in high-stress applications like automotive airbags. For example, measuring the burst strength of airbag fabrics to confirm they can withstand the force generated during inflation.
• Seal integrity testing: Ensuring the seals in packaging - such as heat-sealed bags or blister packs - maintain integrity and prevent contamination/leakage by measuring the burst strength of the sealed areas.
• Paper and board testing: Assessing the burst resistance of paper and board used in bookbinding, printing, and paper bags to ensure product durability. For example, testing paper shopping bags to ensure they can carry heavy items without tearing.
• Inflatable product testing: Testing the burst resistance of products like balloons, inflatable toys, and air mattresses to ensure they can withstand internal pressure during use without bursting prematurely.
• Pharmaceutical packaging testing: Ensuring the integrity of blister packs used for pharmaceuticals by measuring their burst resistance to prevent contamination and to ensure it protects medication from moisture.

In these examples, a Texture Analyser applies controlled distance/pressure to materials or containers until they burst. The maximum force or pressure measured during these tests provides essential data on the material’s burst strength, ensuring product safety and quality across various industries.

In a typical burst strength/resistance test, a sample is clamped securely around its edges exposing a circular region, and a spherical probe is pushed centrally downwards into the exposed sample until rupture occurs. The Texture Analyser records the force and distance throughout the biaxial extension test.

Imitative test using the Film Support Rig.

Imitative test using the Tortilla/Pastry Burst Rig. 

A full explanation of this curve and its analysis can be accessed within Exponent Connect software. Existing Exponent users can upgrade to Exponent Connect specification.

Below is a video example of how we can help you understand curve analysis for an example property. 

• Temperature: Temperature can significantly affect the mechanical properties of materials, influencing their elasticity, plasticity, and overall strength, which in turn impacts the measured burst strength.
• Humidity: Humidity levels can alter the moisture content of samples, potentially changing their physical properties and affecting their resistance to bursting.
• Test speed: The rate at which force is applied during the burst strength test can influence the measured results, as materials may respond differently to varying speeds of deformation. The chosen speed should remain constant for comparison purposes.
• Sample positioning: Proper centring, clamping and alignment of the sample in the testing attachment ensures uniform force distribution and accurate burst strength measurements.
• Absence of defects or obvious weak points: Pre-existing defects or weak points in the sample can lead to premature failure and inaccurate burst strength measurements, so samples should be carefully inspected before testing.
• Sample thickness: The thickness of the material being tested directly affects its burst strength, with thicker samples generally requiring more force to burst.
• Sample homogeneity: Uniform composition and structure throughout the sample ensure consistent burst strength measurements, while inhomogeneities can lead to variations in results.

The Stable Micro Systems Texture Analyser excels in optimising burst strength/resistance measurements through its combination of specialised fixtures designed specifically for burst strength testing of materials from packaging films to food products.

Comprehensive Exponent Connect software captures detailed force-distance-time profiles, allowing for in-depth analysis of burst characteristics. With customisable parameters and simultaneous multi-parameter measurement, the system can simulate real-world conditions and provide a complete picture of the bursting process.

Backed by Stable Micro Systems' expertise in method development and data interpretation, this Texture Analyser is the optimal choice for researchers and manufacturers seeking to accurately measure and optimise burst strength across various industries.