Identification of the viscoelastic properties of the tBA/PEGDMA polymer from multi-loading modes conducted over a wide frequency–temperature scale range

Abstract

The viscoelastic properties of tBA/PEGDMA, which is a Shape Memory Polymer (SMP), were characterized over wide bands of frequency and temperature. The continuity of the viscoelastic properties identified according to the frequency, the temperature, the loading mode and the test scale was assessed. Seven experimental methods were used, from quasi-static to high frequencies, in tensile, shear and compression, from the nanoscopic scale to the macroscopic scale. The storage modulus and the loss factor of the SMP were evaluated and compared from one method to the other. The comparison between the various tests was done based on measurements obtained with a Dynamic Mechanical Analysis and extrapolated through the Time-Temperature Superposition principle. All the data gathers on a unique master curve. For the various experimental methods, it appears that all the viscoelastic properties are consistent even if different scales and loading modes are involved. This wide band characterization makes it possible to determine the mechanical viscoelastic properties of the tBA/PEGDMA in order to use it in structural applications. The experimental methods used in this paper combine commercial methods and in-house high-tech methods. It should be emphasized that the set of experiments covers effective measurements from 10 −4 to 10 6 Hz, 0 to 90 C, strain levels from 10 −4 % to 5%, at nano, micro and macro scales on the same material.

Damping control for improvement of acoustic black hole effect

“…The material is a tBA/PEGDMA polymer (named SMP in the following since it is a Shape Memory Polymer) whose behavior can be efficiently described by the model provided in [14]. The model is representative of the set of experiments presented in [28]. This viscoelastic material has strongly dependent mechanical properties, in particular the loss factor can be as high as 2.4 at the glass transition, occurring around 70 • C. Using arbitrary length and thickness, the effect of the temperature control on the reflection coefficient of the ABH equipped with the SMP is illustrated in The next section presents the optimization procedure which has been used to choose the length and thickness of the damping layer.…”

Dynamical Mechanical Thermal Analysis of Shape-Memory Polymers

“…Moreover, optical imaging analyses have not shown any polymer heterogeneity. Finally, it should be emphasised that the tBA/PEGDMA is thermo-rheologically simple, as mentioned in Butaud et al [7]. The mass density of the tBA/PEGDMA is ρ = 1000 kg/m 3 (determined by pycnometer).…”

“…The mass density of the tBA/PEGDMA is ρ = 1000 kg/m 3 (determined by pycnometer). The Poisson's ratio of the tBA/-PEGDMA, determined during quasi-static tests (10 −4 Hz) at room temperature [7], is ν = 0.37 .…”

“…The stable rubbery and glassy states play a major role in the Shape Memory effect, which is associated to a fast transitions between these states with a large elasticity gap, inducing high loss factor values at glass transition [50,2]. The typical values of the loss factor which are reported in SMP-related open literature typicaly vary between 0.5 [4] and more than 2.5 [39,7], most of them being between 1 and 2 [49,53,20,8]. These qualitatively high values of loss factor must be considered for practical applications since they can have strong impact on the efficiency and the behavior of the SMP-based devices.…”

“…The extrapolated properties obtained can then be used to design composite structures. Even if some limitations of this apparatus have been reported, (effect of the instrument compliance [26], of the specimen dimensions [15] or even of the chosen TTS model [8]), and despite of the fact that viscoelastic properties are often obtained only for a specific loading mode, DMA remains a confident way to obtain a description of the behavior which is valid for different loading modes, for different scales, on wide temperature and frequency ranges, even for Shape Memory Polymers [7]. Among others, these materials are very good candidates for temperature-controlled damping devices [6,5].…”