What is the difference between upvc and pvcu?

We often hear upvc and pvcu, so are upvc and pvcu the same?

Both are the same. UPVC pipe, also known as PVC-U pipe, is a plastic pipe made of polyvinyl chloride (PVC) resin as raw material and does not contain plasticizers. Amorphous thermoplastic resin made from the polymerization reaction of vinyl chloride monomer, with certain additives (such as stabilizers, lubricants, fillers, etc.) added to catalytically degrade and oxidatively decompose the resin.

In the PVC production process, in order to increase the plasticizing performance of PVC and improve production efficiency, plasticizers (such as DOP, DBP, DINP, etc.) are added. PVC products with plasticizers will be softer. Generally, PVC products that do not contain plasticiers are collectively called UPVC, and can also be written as PVC-U.