A process for manufacturing extrudable/melt spinnable concentrate pellets which contain phase change materials (PCMs), whether the PCMs are micro-encapsulated absorbed into carrier polymers, or non-micro-encapsulated within the concentrate pellets. The polymer matrix within the concentrate pellets can be any thermoplastic polymer or combination of thermoplastic polymers, and the concentrate pellets can then be blended into similar thermoplastic polymers to form mono-filament melt spun fibers, extruded films, injection molded products, etc., or the concentrate pellets can be blended with other thermoplastic polymers to form bi-component or multi-component melt spun fibers, extruded films, injection molded products, etc.