The polycarbonate polyols(PCD) obtained by ring-opening polymerization of a general cyclic monomer is mostly a linear flexible structure. which is used as a raw material to synthesize polyurethanes. and it is difficult to simultaneously ensure good thermal-mechanical properties and weather resistance due to insufficient rigidity of the main chain. However. https://www.foldlyers.shop/product-category/usb-external-hdd-enclosures/