A company develops composite materials using core-shell particles: ceramic, metal, or polymer elements coated with a ceramic oxide shield. The particles are mixed into thermoplastic resins, including polyethylene. During the melt processing, the high shear in the mixing damages or removes the particle shell and exposes the core particle surface. Due to the aggressive action of mixing core-shell particles with the polymer, the particles become deformed, and the coating scrapes off or cracks. The coating on core-shell particles needs to be preserved during thermoplastic mix processing; the matrix must remain a thermoplastic resin.