| Summary: | 碩士 === 國立宜蘭大學 === 化學工程與材料工程學系碩士班 === 102 === Olefin block copolymer (OBC) and polycaprolactone (PCL) were melt-blended to form green shape memory blends. The shape memory behaviors of OBC/PCL blends were investigated at 60/40 proportions. Due to the lack of good compatibility between OBC and PCL, OBC-g-GMA (Glycidyl Methacrylate, GMA) and dicumyl peroxide (DCP) were added to improve the compatibility. In addition, ZnO with different aspect ratios were added to investigate their shape memory effect.
The SEM technique confirmed the improved compatibility between OBC and PCL after modification. The crystallization temperatures of OBC/PCL blends with modification slightly increased, but the melting temperatures were not varied much. Viscosity of OBC/PCL-D (peroxide modified) and OBC/OBC-g-GMA/PCL-D blends was higher than that of OBC/PCL and OBC/OBC-g-GMA/PCL blends. XRD (X-Ray Diffractometer) confirmed the crystal structure of hexagonal wurtzite ZnO. TGA showed that thermal stability of OBC/PCL blends increased 35.4 oC with the addition of ZnO. From UV (UV-visible absorption spectra) measurement, ZnO-filled OBC/PCL blends exhibited high UV absorption capability.
For the shape memory test, OBC/OBC-g-GMA/PCL-D blends exhibited better shape memory effect in comparison with the unmodified blends at the predeformation temperature of 65 oC. Its’ shape fixing ratio (Rf) and the shape recovery ratio (Rr) were up to 96.7 % and 95.7 %, respectively. In recovery stress, the recovery stress peak temperature basically corresponded to the predeformation temperature, suggesting a unique “memory” effect. Through the stress relaxation process for holding 10 minutes before cooling the samples, Rf of OBC/PCL blends without DCP modification was improved, up to 96.9 %. With new pre-cycle training processes at different temperatures, Rr of OBC/PCL blends with or without modification reached 100 % even after three shape memory cycles. Finally, Rf of OBC/PCL blends with the addition of ZnO was higher than OBC/PCL blends without ZnO.
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