High-temperature Shape Memory Behavior of Semi-crystalline Polyamide Thermosets.
ACS applied materials & interfaces(2018)
摘要
We have explored semi-crystalline poly(decamethylene terephthalamide) (PA 10T) based thermosets as single-component high-temperature (> 200 °C) shape memory polymers (SMPs). The PA 10T thermosets were prepared from reactive thermoplastic precursors. Reactive phenylethynyl (PE) functionalities were either attached at the chain termini or placed as side-groups along the polymer main-chain. The shape fixation and recovery performance of the thermoset films were investigated using a rheometer in torsion mode. By controlling the Mn of the reactive oligomers, or the PE concentration of the PE side-group functionalized copolyamides, we were able to design dual-shape memory PA 10T thermosets with a broad recovery temperature range of 227-285 °C. The thermosets based on the 1000 g·mol-1 reactive PE precursor and the copolyamide with 15 mol% PE side-groups show the highest fixation rate (99%) and recovery rate (≥90%). High temperature triple-shape memory behavior can be achieved as well when we use the melt transition (Tm ≥ 200 °C) and the glass transition (Tg = ~125 °C) as the two switches. The recovery rate of the two recovery steps are highly dependent on the crystallinity of the thermosets and vary within a wide range of 74%-139% and 40-82% for the two steps, respectively. Reversible shape-memory events could also be demonstrated when we perform a forward and backward deformation in a triple shape-memory cycle. We also studied the angular recovery velocity as a function of temperature, which provides a thermokinematic picture of the shape recovery process and helps to program for desired shape memory behavior.
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关键词
semiaromatic polyamides,semicrystalline thermosets,high-temperature shape memory,dual-shape memory,triple-shape memory,recovery velocity
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