TY  - JOUR
A1  - Yan, Wan
A1  - Fang, Liang
A1  - Nöchel, Ulrich
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Influence of programming strain rates on the shape-memory performance of semicrystalline multiblock copolymers
T2  - Journal of polymer science : B, Polymer physics
N2  - Multiblock copolymers named PCL-PIBMD consisting of crystallizable poly(epsilon-caprolactone) segments and crystallizable poly[oligo(3S-iso-butylmorpholine-2,5-dione)] segments coupled by trimethyl hexamethylene diisocyanate provide a versatile molecular architecture for achieving shape-memory effects (SMEs) in polymers. The mechanical properties as well as the SME performance of PCL-PIBMD can be tailored by the variation of physical parameters during programming such as deformation strain or applied temperature protocols. In this study, we explored the influence of applying different strain rates during programming on the resulting nanostructure of PCL-PIBMD. Programming was conducted at 50 degrees C by elongation to epsilon(m)=50% with strain rates of 1 or 10 or 50 mmmin(-1). The nanostructural changes were visualized by atomic force microscopy (AFM) measurements and investigated by in situ wide and small angle X-ray scattering experiments. With increasing the strain rate, a higher degree of orientation was observed in the amorphous domains. Simultaneously the strain-induced formation of new PIBMD crystals as well as the fragmentation of existing large PIBMD crystals occurred. The observed differences in shape fixity ratio and recovery stress of samples deformed with various strain rates can be attributed to their different nanostructures. The achieved findings can be relevant parameters for programming the shape-memory polymers with designed recovery forces. (c) 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1935-1943
KW  - atomic force microscopy (AFM)
KW  - crystal structures
KW  - crystallization
KW  - multiblock copolymer
KW  - stimuli-sensitive polymers
KW  - SAXS
KW  - shape-memory effect
KW  - WAXS
KW  - X-ray scattering
Y1  - 2016
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/44930
SN  - 0887-6266
SN  - 1099-0488
VL  - 54
SP  - 1935
EP  - 1943
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -