Thermo-Responsive Shape-Memory Effect and Surface Features in Polycarbonate (PC)

Abstract

The influence of programming strain and temperature on the shape memory effect and surface morphology in programmed polycarbonate (PC) samples via uni-axial stretching is investigated. It is found that the samples programmed at around the glass transition start temperature not only have micro-cracks on their surface, but also show a necking phenomenon. Furthermore, the surface of the necked area is concave, but the surface of the non-necked area is convex. On the other hand, despite the samples programmed at high temperatures being able to deform in a uniform manner at macroscopic scale, their surfaces are still uneven, either concave or convex. While the samples programmed at low temperatures are able to achieve full shape recovery, stretching at higher temperatures over the glass transition range to a higher strain may result in non-recoverable deformation.

Influence of Long-Term Storage on Shape Memory Performance and Mechanical Behavior of Pre-stretched Commercial Poly(methyl methacrylate) (PMMA)

“…After a predetermined period of storage time (up to one year), the samples were taken out and then heated to their previous programming temperature for shape recovery. We did not heat the programmed samples in a step-by-step manner as in our previous works to characterize other engineering polymers [13][14][15][16], since the shape recovery of this PMMA upon heating to 130 • C is always about 100% [46,47,56]. Each test was repeated four times.…”

“…[1][2][3][4][5]. In addition to a lot of purposely developed ones [6][7][8][9][10][11], many conventional engineering polymers have been confirmed to have excellent SME, in particular heat-induced (heating-responsive) SME [12][13][14][15][16][17][18][19][20]. The phenomenon of the SME provides an additional dimension to reshape product design in many ways [6,21,22].…”

A Brief Review of the Shape Memory Phenomena in Polymers and Their Typical Sensor Applications

“…The SME, in particular the heating-responsive SME, of many commercial polymers has been characterized (e.g., in [24,25,26,27,28,29,30] for polycarbonate (PC), poly(ether ether ketone) (PEEK), ethylene-vinyl acetate (EVA), polytetrafluoroethylene (PTFE), poly-ε-caprolactone (PCL) and poly(methyl methacrylate) (PMMA)).…”

“…As shown in the shape memory anti-counterfeit label in Figure 5, embossing and debossing are associated with out-of-plane programming of SMPs. If we use commercially available engineering polymers, such as polycarbonate (PC) and PMMA sheets, as the substrate, after embossing at room temperature using a Vickers indenter (for PC, refer to Reference [24]) or hot compressed using a special mold (for PMMA, refer to Reference [28]), concave or convex impression is produced. After heating to over their respective T g (≈142 °C for PC [24] and ≈115 °C for PMMA [30]), their surfaces become flat.…”

“…If we use commercially available engineering polymers, such as polycarbonate (PC) and PMMA sheets, as the substrate, after embossing at room temperature using a Vickers indenter (for PC, refer to Reference [24]) or hot compressed using a special mold (for PMMA, refer to Reference [28]), concave or convex impression is produced. After heating to over their respective T g (≈142 °C for PC [24] and ≈115 °C for PMMA [30]), their surfaces become flat. In addition to heating to flatten, heating to appear provides not only vision, but also tactile sensation, which differs from many currently used anti-counterfeit technologies.…”