N-vinylcaprolactam (NVC) is a transparent pale yellow solid at room temperature. When heated to 60 degrees, it is slowly melted like edible gelatin. It is a thermoplastic polymer.
Olefinamides generally have no liquid form at normal temperature, and there are no high and low molecular weights such as PEG and PPG which are classified as liquid. The appearance of n-vinylcaprolactam looks a lot like high quality first grade rosin with a slight odor (for reference).
The color of n-vinylcaprolactam (NVC) is slightly yellower than CPL.