Polymer-based positive temperature coefficient (PTC) composites are of special interest because they have great potential in temperature-sensitive devices. To obtain a reproducible PTC composite with acceptable PTC intensity, effect of conductive filler content, processing conditions and filler treatment with nitric acid, and titanate coupling agents on room temperature resistivity and PTC intensity of carbon-black-filled low-density polyethylene composites have been described and discussed herein. The results showed that filler arrangement is a key factor influencing the ultimate material performance, which can be tailored in various ways.