Abstract: A powder blend of rigid polyvinyl chloride resin having higher packing densities than previously known is disclosed. The higher packing densities provide improved physical properties and production rates. There is also disclosed a process for the manufacture of a powder blend of suitable thermoplastic polymer resins having high packing densities for processing into articles. The process includes mixing and thermokinetically heating a batch of powder blend in a high intensity mixer having a plurality of blades attached to arms rotating about an axis with a blade tip speed of at least about 25 meters/second to a predetermined temperature below commencement of agglomeration, and cooling the batch in a high intensity mixer having a plurality of blades attached to arms rotating about an axis with a blade tip speed less than about 16 meters/second but sufficient to attain high packing densities, to a temperature at which the batch can be stored without agglomeration occuring.