Standard Test Method for Tensile Strength and Elongation of Pressure-Sensitive Tapes - PDF

 

ASTM D3759 specifies a standardized method to measure the breaking strength and elongation of pressure-sensitive tapes (PSA tapes).
This test is essential for understanding the mechanical properties of tapes, including their ability to resist stretching and breaking when subjected to force. The results help manufacturers determine how well the tape will perform under stress in various applications, from packaging to automotive and medical use.

Purpose of ASTM D3759

The goals of ASTM D3759 are to:

• Measure the breaking strength (the force required to break the tape).

• Determine the elongation (the amount of stretch before breaking) of pressure-sensitive tapes.

• Evaluate the performance of tapes under tensile stress, providing data on their mechanical durability.

• Compare different tape formulations for product development or quality control.

These properties are critical in determining a tape’s suitability for different applications, including heavy-duty packaging, insulation, bonding, and medical tape usage.

Equipment Required for ASTM D3759 Testing

To perform the ASTM D3759 test, you’ll need the following equipment:

• Universal Testing Machine (UTM):
  A machine capable of applying a continuous tensile load to the specimen. The UTM should be fitted with a load cell appropriate for measuring force in the expected range (often up to 100 pounds-force or more).

• Tensile Grips:
  Specifically designed to hold the ends of the tape securely while the force is applied. The grips should be suitable for tape testing, ensuring they don’t damage the specimen or interfere with the results.

• Tape Samples:
  Cut the tape into strips of uniform width and length. The width should be consistent for each test and typically around 1 inch (25 mm). The length will depend on the setup, often 4 to 6 inches (100 to 150 mm).

• Measuring Equipment:
  To measure elongation, you will need a ruler or micrometer to record the change in length of the tape during testing.

• Environmental Chamber (optional):
  For testing in controlled conditions (e.g., temperature, humidity), an environmental chamber can ensure consistency.

Specimens

• Prepare several specimens of the same tape type to obtain consistent and reliable results.

• Ensure tape samples are free of wrinkles and defects.

• Specimens should be measured and cut precisely to ensure uniformity across tests.

General Test Procedure for ASTM D3759

1. Sample Preparation:

   • Cut tape specimens to the required dimensions, typically 1 inch wide and 4-6 inches long. Ensure edges are straight and consistent.

   • Mount one end of the tape into the grip of the UTM, ensuring that the tape is aligned and taut without any slack.

2. Tensile Testing:

   • Set the UTM to apply a constant force along the tape’s length at a standard rate (often 12 inches/minute or 300 mm/min).

   • Begin the test and allow the machine to pull the tape at the set speed.

   • Record the maximum force (breaking strength) required to break the tape.

   • Monitor the tape for elongation, measuring the amount of stretching the tape undergoes before it breaks.

3. Calculating Results:

   • Breaking Strength: The force (usually measured in pounds or Newtons) that causes the tape to break.

   • Elongation: The percentage increase in the length of the tape before failure.

4. Repeat Testing:

   • Typically, at least three specimens per tape type should be tested to provide an accurate average for breaking strength and elongation.

Results and Reporting

The test report should include:

• Tape identification (brand, type, lot number, manufacturer).

• The average breaking strength and elongation from multiple specimens.

• The test speed and environmental conditions (if applicable).

• Any deviations from the standard procedure.

• Graphical representation of force vs. elongation (stress-strain curve) can also be included for additional insights.

A higher breaking strength and lower elongation typically indicate a stronger, more rigid tape, while lower strength and higher elongation can indicate a more flexible, stretchable tape.

Related ASTM and Similar Standards

Several other ASTM standards are related to the mechanical properties of pressure-sensitive tapes, providing a comprehensive understanding of their performance:

• ASTM D3330 – Standard Test Method for Peel Adhesion of Pressure-Sensitive Tape:
  Measures the adhesion of the tape to a flat surface, an essential property for determining how well the tape will stick.

• ASTM D3750 – Standard Specification for Pressure-Sensitive Tape:
  Provides general specifications for various types of PSA tapes, including dimensional and performance characteristics.

• ASTM D6195 – Standard Test Methods for Loop Tack:
  Measures the initial tack or grab of PSA tapes, important for applications where quick adhesion is required.

• ASTM D3811 – Standard Test Method for Unwind Force of Pressure-Sensitive Tapes:
  Measures the force required to unwind the tape from its roll, impacting packaging and dispensing efficiency.

• PSTC 3 – Pressure Sensitive Tape Council Test Method for Tensile Properties:
  A similar method that also measures tensile strength and elongation but may have variations in procedure.

• ASTM D3654 – Standard Test Method for Shear Adhesion of Pressure-Sensitive Tapes:
  Measures the resistance of tape to sliding forces over time, complementing tensile testing with its focus on shear forces.

Applications of ASTM D3759 Testing

Common industries that utilize ASTM D3759 testing include:

• Packaging and shipping: Ensures tapes can withstand the stress of sealing boxes and packages.

• Automotive: Tapes used for insulation, sealing, and bonding components.

• Medical: Medical adhesive tapes that require flexibility and strength for skin application.

• Electronics: Tapes used in assembly or insulation of sensitive electronic components.

• Construction: Adhesive tapes for mounting, sealing, and protection of building materials.

This test is critical for manufacturers in these industries, as it helps determine tape’s reliability and functionality in real-world applications.

Conclusion

ASTM D3759 provides a standardized method for testing the breaking strength and elongation of pressure-sensitive tapes.
It helps manufacturers and users evaluate tape durability under tensile stress, ensuring the right performance characteristics for their specific application.
ASTM D3759 is typically used alongside other testing methods like ASTM D3330 (peel adhesion) and ASTM D3811 (unwind force) for comprehensive tape performance evaluation.