Quasi-static and dynamic characterization of polyurea microspheres reinforced polyurea matrix composite
Sophia Do, Sophia Stepp, George Youssef
Abstract
Polymer matrix composites currently have a wide range of applications in the aerospace, automotive, and biomedical industries. The specific strength and stiffness of this class of materials can easily be engineered; however, the enhanced strength and stiffness are highly dependent on the quality of the interfacial bonding between the reinforcement and matrix. It is thus the aim of this research to synthesize and characterize a polyurea matrix composite that is reinforced by polyurea microspheres to reduce the mechanical mismatch and improve bonding. For this composite, a hyper-viscoelastic polyurea formed from Versalink® P1000 and Isonate® 143 L, was chosen for its superior moisture resistance, and excellent thermal and impact mitigation properties. From the micro-scale mechanical characterization, the composite displayed a 23 % increase in elastic modulus compared to the bulk counterpart. As a result of the quasi-static mechanical characterization, it was found that the elastic moduli were comparable between the composite and the neat polyurea, but showed an increase in yield stress and decrease in the area under the stress-strain curve as well as the loss of strain at failure. Dynamic mechanical testing indicated the comparable time-dependent response of the composite and neat samples above glass transition (Tg), while displaying a difference below Tg.