Monofilament entangled materials are a new type of materials with promising mechanical properties. They are made of a single wire randomly packed into a finite volume whose dimensions are much larger than the wire length, thus providing many self-contacts. Their complex internal architecture is investigated using X-ray tomography. The evolution of the number of contacts per unit volume, as well as of the density profiles, is monitored during a compression test in order to link the microstructural evolution of the sample to its mechanical behavior. This material exhibits very interesting properties in terms of vibration damping.