This study reports the development and performance of a pilot-scale barrel atmospheric plasma reactor for the atmospheric plasma activation treatment of polymer particles. The polymer particles treated included acrylonitrile butadiene styrene (ABS) and polypropylene (PP). These particles had diameters in the range of 3–5mm. The initial studies were carried out using a laboratory-scale barrel reactor designed to treat polymer particle batch sizes of 20 g. A pilot-scale reactor that could treat 500 g particle batch sizes was then developed to facilitate pre-industrial-scale treatments. The effect of operating pulse density modulation (PDM) in the range 10％–100％ and plasma treatment time on the level of activation of the treated polymers were then investigated. ABS revealed a larger decrease inwater contact angle compared with PP after plasma treatment under the same conditions.The optimal treatment time of ABS (400 g of polymer particles) in the pilot-scale reactorwas 15 min. The plasma-activated polymer particles were used to fabricate dog-bone polymer parts through injection molding.Mechanical testing of the resulting dog-bone polymer parts revealed a 10.5％ increase in tensile strength compared with those fabricated using non-activated polymer particles.