Abstract
A series of segmented multiblock copolymers containing aramid hard segments and extended polycaprolactone soft segments (with an Mn of 4,200 or 8,200 g mol–1) was prepared and tested for their shape-memory properties. Chain extenders were essential to raise the hard segment concentration so that an extended rubbery plateau could be observed. Dynamic mechanical thermal analysis provided a useful guide in identifying (i) the presence of a rubbery plateau, (ii) the flow temperature, and (iii) the temperature when samples started to deform irreversibly.
Highlights
When an elastic material is deformed, elastic energy is stored within the material but is immediately recovered once the applied stress is released [1,2]
We have reported a synthetic route to segmented multiblock copolymers with aramid hard segments and polytetrahydrofuran or polycarbonate soft segments [11,12], including polymers with polycaprolactone soft segments of intermediate molecular weight (3,000 g mol–1) which showed promising shape-memory properties [13]
Dynamic mechanical thermal analysis served as a useful technique to establish which polymers were suitable or unsuitable for shape-memory applications
Summary
When an elastic material is deformed, elastic energy is stored within the material but is immediately recovered once the applied stress is released [1,2]. Polymers 2010, 2 flexible spectacle frames to stents and actuated devices Despite their wide-spread use, shape-memory alloys are comparatively expensive and have limited maximum strain (≤8%). A key design feature of SMPs requires that the soft segment gives rise to a thermal transition slightly above the working temperature. This means that the soft segment must possess either a melting or a glass transition just above room or body temperature. We have reported a synthetic route to segmented multiblock copolymers with aramid hard segments and polytetrahydrofuran or polycarbonate soft segments [11,12], including polymers with polycaprolactone soft segments of intermediate molecular weight (3,000 g mol–1) which showed promising shape-memory properties [13]. Dynamic mechanical thermal analysis (DMTA) served as a useful tool to identify polymers with promising shape-memory properties
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