Which product should i use to straighten coarse hair for a partial sew in? perm, relaxer, or texturizer?

im an african american male who is about to get his first partial sew in weave but everytime i straighten or flat iron my hair, its not blending in with the weave hair. what product should i use? A Perm, A Relaxer, or A Texturizer and what name brand product works best for coarse african american short hair