The Preparation of Rigid Tough Balanced Polypropylene Based on the Synergistic Nucleation of Aluminum Organophosphate and Sodium Stearate

ABSTRACT Bis [2,2′‐methylene‐bis(4,6‐di‐tert‐butylphenoxy) phosphoric acid] hydroxyl aluminum (OPAl) is a promising α‐nucleating agent for improving the crystallization and mechanical properties of impact polypropylene copolymer (IPC). However, its poor dispersion due to agglomeration limits its effectiveness. To address this, sodium stearate (NaSt) was introduced to form a composite nucleating system (OPAl‐NaSt). In situ variable‐temperature FTIR revealed a red shift and broadening of the carboxylate (COO − ) peak, confirming hydrogen bond formation between OPAl and NaSt. This interaction enhanced OPAl dispersion in the nonpolar IPC matrix. SEM and molecular dynamics simulations further supported the improved dispersion and molecular compatibility. DSC analysis showed a 16.1°C increase in crystallization peak temperature, indicating faster crystallization, while POM revealed refined spherulite structures. The reduced crystallization activation energy confirmed enhanced crystallization kinetics. As a result, the mechanical properties of IPC improved significantly: tensile strength increased by 12.8%, flexural modulus by 37.9%, and impact strength by 16.7%. The OPAl‐NaSt system outperformed the commercial nucleating agent NA‐21. This study offers a cost‐effective strategy to achieve balanced rigidity and toughness in IPC through synergistic nucleation and dispersion control.