Studies on Thermo-Mechanical Behaviour of Toughened Shape Memory Epoxy Resins
摘要
Epoxy resins are extensively used for high-performance structural applications worldwide. Apart from exhibiting desirable mechanical behaviour suited for aerospace and allied applications, epoxy resins are also found to be suitable for smart shape memory (SM) applications. Epoxy-based shape memory polymers (SMEPs) are very useful for deployable components, morphing wings, etc. This is possible due to tailored epoxy formulations that demonstrate excellent strain capability without compromising on structural strength. In the present work, four different epoxy formulations are evaluated for their cyclic thermo-mechanical behaviour. One of them is an inherently tough high-temperature epoxy while the other three have been toughened using three different pre-dispersed elastomeric phase. The four SMEPs are coded as SMEP-01, 02, 03, and 04, respectively. Neat resin castings were prepared using stainless steel mould plates. The Tgs of the SMEPs were measured using Differential Mechanical Analyzer (DMA). SMEP-01 has a Tg of 160 °C while the other three had a Tg of 125 ± 3 °C. The thermo-mechanical tests were conducted using a custom-designed set-up in three point bending (Flexure) mode. The deformation temperature was set at Tg + 20 °C, and five TM cycles were carried out for each of the formulations. SMEP-01 exhibited the best cyclic SM behaviour in terms of its shape fixity and shape recovery, compared to the other three. The order of SM behaviour varied as SMEP-01 > SMEP-02 > SMEP-03 > SMEP-04. However, all the four SMEP formulations sustained the five SM cycles demonstrating cyclic shape memory performance that would suit various applications.