| 摘要 |
A heat recoverable article comprising a conductive polymeric material with particular electrical properties. Preferably, when expanded from X% to Y% to render it recoverable the resistivity of the composition decreases on expansion in at least part of the X -Y expansion range. Preferably the composition exhibits a pseudo PTC ratio (peak resistivity/resistivity at 25 DEG C) in the range 11/2 - 10. Preferably the composition has a resistivity which increases on recovery as measured in the direction of current flow, throughout the temperature range 20 DEG C to Te (extrapolated end temperature). The article is preferably tubular, and the electrical behaviour allows it to be conveniently electroded with elongate electrodes, while avoiding overheating during recovery. |
