or textiles the capsule size is preferably about 1 to 15 and preferably 2 to 10 microns for use in heat transfer fluids the capsule size may range from about 1 to 100 microns and preferably 2 to 40 microns the microencapsulated pcm 39 s of the present invention can be used in a variety of applications for example they may be used as the thermal transfer medium in a heat transfer fluid for use in lasers supercomputers and other applications requiring high thermal transfer efficiencies they also may be coated on fibers or incorporated into fibers to prepare insulative fabrics they may be added to plastics or resins such as polypropylene and acrylics and spun into fibers or extruded into filaments beads or pellets useful in thermal transfer applications such as insulative apparel such as clothes shoes boots etc building insulation for use in walls floors etc the microcapsules are generally obtained as a slurry in water they may be used as a slurry or the slurry may be dried and the microcapsule used as a dry powder the microcapsules may also be incorporated into a binder to provide coatings useful in many of the applications in which unencapsulated pc 39 s are not satisfactory the addition of the flame retardant.