Abstract: Disclosed herein is a method for producing isotropized “ready-to-use” polymer pellets or granules that contain completely or substantially relaxed matrix molecules and entangled organic nanofibrils with long aspect ratios that will provide superior properties for the products without high cost. These pellets are cost-effectively produced using industrial-scale fiber spinning or melt-blowing/spun-bond equipment followed by an isotropizing pelletizer. These pellets enable one to mass-produce the micro-fibrillar or nanofibrillar composites with superior mechanical properties, because they are readily usable (“ready-to-use”) for industry-scale mass production systems with a very high throughput over 1000 kg/hr. The organic nanofibrils are well dispersed and entangled in the polymer matrix and have a long aspect ratio ranging hundreds to thousands, to tens of thousands.