The effect of organoclay addition on the properties of an acrylate based, thermally activated shape memory polymer

Abstract

Shape Memory Polymers (SMPs) exhibit the intriguing ability to change back from an intermediate, deformed shape back to their original, permanent shape. In this contribution a systematic series of t-butylacrylate-copoly(ethyleneglycol) dimethacrylate (tBA-co-PEGDMA) polymers have been synthesised and characterised prior to incorporation of organoclay. Increasing the poly(ethyleneglycol) dimethacrylate (PEGDMA) content in increments of 10% increased the storage modulus from 2005 to 2250 MPa, reduced the glass transition temperature from +41 to − 26°C and reduced the intensity of the associated tan δ peak. The tBA-co-PEGDMA crosslinked networks displayed useful shape memory properties up to PEGDMA contents of 40%. Above this PEGDMA percentage the materials were prone to fracture and too brittle for a realistic assessment of their shape memory capability. The system containing 90% t-butylacrylate (tBA) and 10% PEGDMA was selected as the host matrix to investigate how the incorporation of 1 to 5 mass% of a benzyl tallow dimethylammoniumexchanged bentonite (BTDB) influenced the shape memory properties. X-ray diffraction data confirmed that BTDB formed a microcomposite in the selected matrix and exerted no influence on the storage modulus, rubbery modulus, glass transition temperature, T g , or the shape or intensity of the tan δ peak of the host matrix. Therefore, it was anticipated that the presence of BTDB would have no effect, positive or negative, nor on the shape memory properties of the host matrix. However, it was found that the incorporation of clay, especially at the 1 mass% level, significantly accelerated the speed, compared with the clay-free SMP, at which the microcomposite returned to the original, permanent shape. This accelerated return to the permanent shape was also observed when the microcomposite was coated onto a 100 μm PET film.

Sandwich structures with tunable damping properties: On the use of Shape Memory Polymer as viscoelastic core

“…Indeed, it turns out that efficient Shape Memory effects are associated to fast transitions between stable glassy and rubbery states with large elasticity gap, inducing high loss factor values at glass transition [7,8]. In SMP-related open literature, various experimental results provide loss factors values at glass transition.…”

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

“…It is a shape memory polymer (SMP), and thus presents mechanical properties that are very sensitive to temperature and frequency. Indeed, efficient shape memory effects are associated with fast transitions between stable glassy and rubbery states with a large elasticity gap, inducing high-loss factor values at glass transition [13,14]. This type of material seems to be a good candidate for testing different experimental characterisation methods.…”

Dynamical Mechanical Thermal Analysis of Shape-Memory Polymers

“…As all polymers, Shape Memory Polymers (SMPs) exhibit a strong viscoelastic behavior. 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].…”