Influence of Crosslinking Processes on Properties of EPDM/PP Blends

The growing demand for high-performance insulation materials in the wind power industry underscores the need for advanced materials capable of withstanding harsh conditions, particularly for high-voltage cable insulation. Modifying ethylene-propylene diene monomer (EPDM) by blending with polypropylene (PP) is crucial for improving its mechanical, electrical, and thermal properties. This study systematically investigates the effects of crosslinking temperature and thermal history on the structure and performance of EPDM/PP blends, aiming to optimize crosslinking conditions for superior insulation performance. The impact of crosslinking temperature (160°C.,180°C, 200°C) and thermal history (Cooling process after crosslinking) on the properties of EPDM blended with 5 wt.% isotactic polypropylene is examined. The findings reveal that high crosslinking temperatures increase crosslinking density, enhancing the bond between the amorphous PP region and EPDM molecular chains while suppressing the growth of PP crystalline regions and reducing crystallinity. Upon elevating the temperature from 160° C to 200° C, EPDM exhibits a notable enhancement of 50 % in tensile strength, coupled with a 21 % improvement in elongation at break. Furthermore, both resistivity and breakdown strength experience significant increases. Conversely, there is a deterioration in elasticity, dielectric temperature stability, and dielectric loss performance. Slow cooling rates allow for more time for PP molecular chains to crystallize, improving crystallinity and enhancing the electrical resistivity, breakdown strength, and mechanical properties at elevated temperatures. This study deepens the understanding of factors influencing the performance of EPDM blends and provides key theoretical and practical guidance for further optimization, which is significant for advancing the application in high-voltage insulation materials.