Can be extruded and shaped into brilliant window designs. Doesn't damage or corrode when scratched. Can be fusion welded to eliminate air and moisture leaks at the joints.
Vinyls are like any other man-made compounds.
There are numerous components in vinyl compounds and there are many vinyl manufacturers that produce numerous types and grades for window manufacturing. Lesser-quality vinyls typically have problems with brittleness or impact resistance, color consistency, and expansion and contraction. The best vinyls are proprietary compounds formulated specifically for manufacturing high-quality windows. The profile design and methods of assembly determine the strength of a window. Just as beams or roof trusses are designed for specific mechanical loads, so are window shapes.