Abstract: The present invention is directed to a thermally actuated immobilizing structure useful as a splint, as a cast and for immobilizing, positioning, grasping or manipulating inanimate objects. The structure includes a flexible container containing a thermoplastic material and a matrix material embedded in the thermoplastic material. The matrix material preferably comprises elongate, generally parallel strands. The thermoplastic material and the strands are adapted to permit relatively unhindered relative movement among the strands when the thermoplastic material is flowable so the structure can be formed into the desired shape. The thermoplastic material and the strands are adapted to substantially inhibit or prevent relative movement among the strands to lock the strands in place, thus forming a rigid structure, when the thermoplastic material is solid. The strands preferably have roughened surfaces so adjacent strands are mechanically interlocked to inhibit relative longitudinal movement among the strands.

Abstract: A fluid pressure actuated immobilizing structure finds particular utility as a reusable, temporary emergency cast. The structure includes a flexible, nonexpandable outer container, a flexible, non-porous inner container and a pressure-sensitive matrix material. The matrix material and the inner container are both housed within the outer container. The matrix material is adapted to permit relatively unhindered relative movement among the matrix elements under normal conditions; the matrix material locks into a substantially rigid mass when squeezed together to freeze the immobilizing structure into the shape existing immediately before pressurization. Since the outer container does not expand, pressurizing the structure causes the structure to turn rigid without squeezing the patient.