Materials including support layers and fiber-free compositions are disclosed, as well as related articles and methods for making the materials. The fiber-free compositions are formed from a precursor composition that includes a nitrile butadiene rubber, a nanoclay and a cure package including a sulfur-based curing agent. The fiber-free compositions may have a substantially reduced weight and compressive modulus in comparison to conventional rubber. Thus, the fiber-free compositions may provide improved ballistic properties in addition to reduced density and thickness. Precursor compositions for forming the insulative composition may have good flow characteristics. The fiber-free compositions may be used in a variety of applications, such as personnel body armor, ground vehicle armor and aircraft armor systems.