Meaning
Simultaneous and identical expansion in both the machine and transverse directions defines the ideal deformation state for producing balanced high barrier films. equal biaxial strain occurs when a square portion of a polymer sheet is stretched at the same rate in both axes. This process aligns the molecular chains uniformly, creating a material with consistent strength in all directions.
Thickness Uniformity
Achieving this balanced state is necessary for preventing the formation of thin spots or weak areas in the final product. If one direction is stretched more than the other, the part may warp or fail prematurely. Precise control of the stretching equipment is required to maintain this balance across the entire width of the web.
Orientation Degree
The amount of stretching determines how much the barrier properties of the resin are improved. As the chains align, they create a more tortuous path for gas molecules to pass through the plastic. This improvement is essential for food packaging applications that require a long shelf life.
Mechanical Balance
Films produced under these conditions show the same tensile strength regardless of the angle of testing. Unbalanced films tend to curl or twist when exposed to heat or tension.
