Tensile strength testing of plastic packaging bags primarily tests the tensile strength, elongation, and other properties of bags or films to ensure they resist tearing or breaking during use and transportation. Commonly used standards include ASTM D882 and GB/T 1040.
1. Preparation
Equipment:
Electronic universal testing machine (tensile machine) with clamps, measuring tools (vernier caliper, steel ruler), scissors or cutting die, printer/recorder (for recording test curves and data)
Specimen Preparation:
Cut specimens from the plastic packaging bag or film to be tested, avoiding creases, printed ink areas, or edge seals (unless specifically testing edge seal strength).
Cut specimens to standard dimensions, generally 15 mm wide x 200 mm long (or as required by the equipment and clamps).
Number of specimens: ≥5 specimens in each direction (machine direction, transverse direction) are recommended.
Environmental Conditions:
Temperature: 23 ± 2°C
Humidity: 50 ± 5% RH
Specimens should be conditioned in this environment for ≥ 4 hours before testing.
2. Testing Procedure
Set Equipment Parameters:
Gauge Length: Typically 100 mm
Crosshead Speed: Thin films: 50 mm/min, thick films/bags: 100 mm/min mm/min (adjustable according to standard requirements).
Specimen Installation:
Secure one end of the specimen to the upper clamp and the other end to the lower clamp, ensuring the specimen is vertical, free of twist and wrinkles. Be careful not to damage the specimen when clamping.
Test Start:
Start the testing machine and begin tensioning the specimen until it breaks.
The instrument records the **tension (N)-displacement (mm)** curve in real time.
After the test, record the maximum force (Fmax) and elongation at break.
Repeat the Test:
Test the remaining specimens using the same method.
Calculate the mean and standard deviation for each direction.
3. Notes
Test the longitudinal (MD) and transverse (TD) directions separately; performance may vary significantly.
Separate samples from the edge seal area can be taken for a seal strength test.
If the bag is made of composite film, be aware of the risk of delamination.
If the specimen has printed or aluminum-plated surfaces, the test results may be affected and should be recorded.
