[Stoian]

i don't know what biaxially oriented refers to.is it about the tacticity of the polymer?
is it isotactic?syndiotactic?or what?

[Biopolmonkey]

http://composite.about.com/library/glossary/b/bldef-b643.htm

It is not giving information about polymer chain tacticity, but their physical orientation within a material. Look up the process of drawing if you would like to find out more.

[typhoon2028]

biaxially oriented is a polymer processing technique used in thin films.  Potato chip bags use biaxially oriented film (Frito Lay).

The proces I am familar with biaxially orients PP and PET.  Polymer is extruded, then it is stretched in the machine direction (made longer, orientation 1).  It is then passed through a large oven that stretches the film in the cross machine direction (makes wider, orientation 2).