there is disclosed a process and apparatus for the continuous production of a thermoplastic product having biaxially oriented components . preferably the thermoplastic compound includes filler . the process may be used to manufacture hollow profiles or sheets . the product is made by a continuous extrusion process which biaxially orients the components by forcing a molten thermoplastic compound through a contoured die with a contoured mandrel therein and then cooling the compound to preserve the imparted orientation . with respect to the sheets a biaxially oriented hollow profile is formed , then cut along the axial direction and then flattened into a sheet .