Damping, Thermal, and Mechanical Properties of Polycaprolactone-Based PU/EP Graft IPNs: Effects of Composition and Isocyanate Index

Abstract

A series of polycaprolactone (PCL)-based polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer networks (IPNs) were prepared and their damping propertiesand thermal stability, as well as mechanical properties, were systematically studied in terms of composition and the values of the PU isocyanate index (R). The morphologies of the PU/EP IPNs were observed by scanning electron microscope (SEM) and atomic force microscope (AFM) characterization and the relationship between the morphologies and the properties is also discussed. The damping properties and thermal stability measurements revealed that the formation of PU/EP IPNs could significantly improve not only the damping properties but also the thermal stability. Meanwhile, the mechanical tests showed that the tensile strengths of the IPNs decreased, while their impact strengths increased with increasing PU content. The value of the PU isocyanate index also had significant impacts on the properties of the IPNs when the PU to EP ratio was fixed, which could be an effective means for manipulating the fabrication of PU/EP IPNs. From the results obtained, the PCL-based PU/EP IPNs hold promise for use in structural damping materials.

Keywords:

• damping properties
• interpenetrating polymer networks (IPNs)
• isocyanate index
• polycaprolactone-based polyurethane
• PU/EP

Acknowledgments

The financial support from the National Science Foundation for Distinguished Young Scholars of China (grant no. 51025517), the Innovative Group Foundation of NSFC (grant no. 50721062), and the 973 Project of China (2007CB607606) are acknowledged. The authors are grateful to Xin Shao from Liaocheng University for DMA support.