Polymeric materials with intrinsic self-healing ability that can restore from mechanical injury autonomously have attracted great research efforts recently. Disulfi de bonds, which become dynamic upon exposure to heat, UV light, or redox conditions, can be used to introduce healable properties to polymer network. Shape memory effect is a kind of auxiliary recovery force that can accelerate healing process. In this work, a polyurethane material combines disulfi de link and shape memory effect is synthesized. Autonomous healing of a crack takes place upon heating above 80 °C and leads to almost fully recovery of mechanical properties. This healing is achieved by activating shape memory effect and disulfi de exchange reaction simultaneously.

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ABSTRACT:The constant rotational rheological behaviors of PAN/DMSO solutions with two kinds of nonsolvent (water and ethanol) have been investigated, respectively, using a cone-plate rheometer. From viscosity measurements, the flow behavior was described within the shear rate range 0.1-1000 s À1 . The PAN solutions show shear thinning at high shear rates. The viscosities of the solutions decreased with the rising of the temperature at low shear rate. H 2 O content has great influence on the viscosity of the solutions, depending on the hydration of H 2 O and PAN or desolvent effect, according to different H 2 O content. The role of ethanol compared with H 2 O was also researched and higher viscosity was found. Non-Newtonian index, structural viscosity index Dg, and flow activation energy of the PAN/DMSO/H 2 O systems were also studied.