Polydopamine particles as a β-nucleating agent and antioxidant for isotactic polypropylene

Polydopamine particles (PDAPs), a kind of biomimetic synthetic polymer, were found to be a multifunctional filler for isotactic polypropylene (iPP), which is one of the most important commercial resins. PDAPs not only demonstrated a high efficiency in nucleating beta-form crystals but also showed an excellent thermal-oxidative stabilization effect toward iPP. The relative content of beta-form crystals (Phi(beta)) in the nucleated iPP determined by differential scanning calorimetry reached 75.4% when incorporating merely 0.5 wt% PDAPs. The oxidation induction time (OIT) was 285% of that of neat iPP and the initial decomposition temperature (T-i) was increased by 14.5 degrees C when incorporating 1.0 wt% PDAPs. Improved mechanical properties of iPP were also obtained upon adding PDAPs. X-ray diffraction (XRD) results suggested that the nucleating ability of PDAPs toward iPP may be associated with the local order structure of PDAPs and the stabilization ability against degradation should be related with the distinct free radical character which makes PDAPs an effective free radical scavenger.