Physical parameters of polyethylene packaging film

In terms of tensile strength, the longitudinal tensile strength of low-density polyethylene packaging film is generally about 10-20MPa, and the transverse tensile strength is 2-5 MPa; The longitudinal tensile strength of high-density polyethylene packaging film can reach 25-50MPa, and the transverse tensile strength is 5-15MPa. The tensile strength reflects the maximum stress that the film can withstand during the stretching process. The elongation at break of polyethylene packaging film can reach 500% -800% for low-density polyethylene packaging film and around 100% -500% for high-density polyethylene packaging film. The elongation at break reflects the ability of the film to stretch until it breaks. The heat sealing performance is one of the important physical parameters of polyethylene packaging film, and its heat sealing temperature range is generally between 120-160 ℃. Good heat sealing performance can ensure the sealing and firmness of the packaging. The transparency of polyethylene packaging film varies greatly among different types. The transmittance of ordinary low-density polyethylene packaging film is about 80% -90%, while the transmittance of specially treated high transparency polyethylene packaging film can reach over 90%. Transparency affects the display effect of products.
Its haze, the haze of low-density polyethylene packaging film is usually between 5% and 15%, which reflects the optical uniformity of the film. The lower the haze, the clearer and more transparent the film. The hardness of polyethylene packaging film, Shore hardness, is generally between 40-70 degrees. Different hardness results in different tactile and scratch resistance properties of the film. In terms of friction coefficient, the dynamic friction coefficient is usually between 0.2-0.5, and the static friction coefficient is around 0.3-0.6. A suitable friction coefficient is convenient for packaging operations and stacking stability. The breathability of polyethylene packaging film is generally around 200 5000cm ³/(m ² · 24h · 0.1MPa) for oxygen and 250g/(m ² · 24h) for water vapor. The breathability affects the storage environment of the product.

The tear resistance of polyethylene packaging film is generally between 30-200g in the dart impact test. The tear resistance is related to the ability of the packaging film to resist tearing during use.