Comparative Studies on Thermomechanical Behavior of Veriflex®, a Shape Memory Polymer, for a Low Strain (ϵm= 70%): Laser Experiments

An interesting comparative case study on thermomechanical cycles including programming, cooling, unloading and heating to trigger the 1WE was done using Veriflex® at 62°C (T < Tg close to and below 5°C of Tg) and also at 72°C (T > Tg, close to and above 5°C of Tg) for slightly low strains (ϵm = 70%) and the recovery time of 10 min. Accumulation of strain was estimated during the thermomechanical treatments for using both 70% strains at 62°C (T < Tg), as well as at 72°C (T > Tg). Recovery ratios for 70% strains at 62°C (T < Tg), as well as for 72°C (T > Tg) were also estimated. It turns out that programming, cooling, unloading and heating to trigger the 1WE causes an increase of irreversible strain and is associated with a corresponding decrease of the intensity of the 1WE, in particular, during the first thermomechanical cycles. A LSCM (Laser Scanning Confocal Microscopic) study shows very little change in surface structure which evolved during cycling up to 70% strains at 72°C (T > Tg).