A pvc pond liner is very well suited for small to large ponds.
It is made from polyvinyl chloride and is very similar to a pool liner. But please don't use pool liners because they contain a algaecides that are harmful to your plant life.
When buying a plastic pond liner check first that it is labeled fish and plant safe.
With UV protection built in to increase its life span it is still a vinyl material.
Vinyl when exposed to sun light will turn brittle and crack given enough time. So to overcome this all edges above the water line should be covered to protect the edge from sun light. This will help increase the life span of your liner.
A pvc liner is highly flexible and has some stretch or give to conform easily to your design and may be refered to as a flexible pond liner. It will also conform to small stones or roots under the liner.
Available in several thicknesses from 20 mil to 45 mil and is usually embossed, which will increase the surface area for beneficial bacteria to grow.
This product can provide years of service in garden ponds if installed properly and maintained.