Effect of strain on the thermomechanical behavior of epoxy based shape memory polymers

• Published in: Journal of polymer research Vol. 20; no. 5; pp. 1 - 10
• Main Authors: Revathi, A., Rao, Sandhya, Rao, Kavitha V., Singh, M. Muralidhar, Murugan, M. Sendil, Srihari, Shylaja, Dayananda, G. N.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-05-2013; Springer Nature B.V
• Subjects: Acrylonitrile butadiene resins; Butadiene; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Cycles; Dispersions; Durability; Failure; Industrial Chemistry/Chemical Engineering; Original Paper; Polymer Sciences; Strain; Tensile tests; Shape frozen; Strain recovery; Thermomechanical cycle; Epoxy-CTBN; Shape memory
• ISSN: 1022-9760; 1572-8935
• DOI: 10.1007/s10965-013-0113-9

The effect of deformation strain on the thermomechanical (TM) behavior of a commercially available bifunctional epoxy resin modified with 5 % carboxyl-terminated butadiene acrylonitrile (CTBN) was studied. The results were compared with those for the unmodified epoxy SMP. The glass transition temperatures (
T
g
) as well as the moduli of these SMPs were determined. Static tensile tests were carried out at both 25 °C and 115 °C to study the effect of CTBN addition on the failure strain. TM cycling tests were conducted for two prescribed strain values: 15 % and 25 %. Further, the effect of the prescribed strain values and TM cycling on the shape-frozen and recovery responses of these SMPs were studied. In addition, microstructure studies were carried out in order to examine the dispersion of the CTBN and the fracture behavior of the CTBN-epoxy SMP. The results show that adding CTBN to the epoxy matrix leads to a slight reduction in storage modulus and
T
g
. Static tensile tests revealed that there was a noticeable improvement in the failure strain of the CTBN-epoxy SMP when it was tested at 115 °C rather than at 25 °C. The cyclic thermomechanical tests performed here prove that the CTBN-epoxy SMP has a better endurance than the unmodified epoxy SMP, as well as enhanced shape-recovery characteristics.