Reducing the Surface Stickiness of Multiphase Polypropylene Particles: An Environmentally Friendly and Scalable Method

Multiphase polypropylene is an important engineering plastic. Stickiness concerns in multiphase polypropylene particles with a high rubber content are well known, and they are not favorable to industrial production stability. However, there has been a scarcity of green and effective surface stickiness reduction techniques. In this work, a Damp mode was employed to construct multiple concentration zones at the particle scale, allowing the synthesis of polypropylene with a high rubber content, reduced particle surface stickiness, and dramatically increased copolymerization activity. The rubber content limit of the conventional gas-phase technique (designated as the Dry mode) was found to be approximately 30 wt % before the particles became sticky, whereas the rubber content limit of the Damp mode was found to be 45 wt %. More notably, early in the procedure, the gas-phase copolymerization activity was boosted by 86.7%. Furthermore, given the same rubber content, the impact strength and flexural modulus of the polymers synthesized in both modes and commercial resins were found to be essentially the same. Lastly, the polymer particles synthesized in Damp mode had a multizone structure with an EPR-rich core and an EPR-poor shell. This work establishes a new method for reducing the surface stickiness of multiphase polypropylene particles, paving the way for the manufacturing of high-performance polypropylene resins using ordinary polypropylene plants.