형상기억 거동의 동적기계적 해석

김병규; 이상엽; 이정삼; 백상현; 최영진; 이장우; Xu M

Korean Journal of Rheology, Vol.9, No.1, 33-39, March, 1997

Export Citation

형상기억 거동의 동적기계적 해석

Dynamic Mechanical Interpretations of Shape Memory Behavior

김병규, 이상엽, 이정삼, 백상현, 최영진, 이장우, Xu M

초록

PCL, MDI, BD 및 DMPA를 이용, 폴리우레탄(PU)을 ionomer 및 nonionomer형태로 제조하였으며, 이때 연질성분의 함량(SSC) 및 길이가 PU의 기계적, 동적기계적 특성은 물론 형상기억특성에 미치는 영향을 연구하였다. Ionomer는 nonionomer에 비하여 경도, 탄성율 및 강도가 모두 우수하였으며 그 효과는 실온에서, 경질성분의 함량(HSC)이 높은 PU일수록 보다 뚜렷하였는데 이는 HSC가 증가할수록 ion중심의 농도가 증가하며 ion중심간의 Coulomb력이 고온보다 실온에서 보다 큰데 기인하는 것으로 해석하였다. 반복인장하중실험에서 ionomer는 nonionomer에 비해 회복변형이 크고 산류변형이 작았는데 이는 ionomer의 고무탄성율이 보다 큰데 기인한 것으로 해석하였다. 나아가 재료의 형상기억거동은 기본적으로 탄성율의 온도의존성에 크게 의존함을 알 수 있었다.

Polyurethane (PU) ionomers and nonionomers with various soft segment contents (SSC) and lengths have been synthesized from polycaprolactone diols (PCL), 4, 4'-diphenylmethane diisocyanate (MDI), 1, 4-butane diol (BD), and dimethylol propionic acid (DMPA), and tested for shape memory behavior as well as for mechanical and dynamic mechanical properties. It was found that ionomers gave higher hardness, modulus and strength as compared with nonionomers, and the effects were more pronounced with increasing hard segment contents (HSC) and at room temperature since the increased HSC makes use of more Coulombic forces which are stronger at room temperature than at high temperature. Regarding the tensile cyclic behavior, ionomers gave higher recovery strain and lower residual strain, and these were interpreted in terms of dynamic mechanical properties, i.e., the higher the rubbery modulus, the higher the recovery strain results. It was found that the shape memory behavior is basically governed by the temperature dependent modulus of the materials.

Keywords:Shape memory polyurethane ionomer;cyclic loading;shape fixability;recoverability.

[References]

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[1] Ishii M, Plastic Science, June, pp. 158-163 (in Japanese) (1989)

[2] Hayashi S, Plastic Science, June, pp. 169-172 (in Japanese) (1989)

[3] Masao M, Hirata A, Plastic Science, June, pp. 173-178 (in Japanese) (1989)

[4] Tobushi H, Hayashi S, Kojima S, Jpn. Soc. Mech. Engrs. Intl. J., 35(3), 296 (1992)

[5] Kim BK, Lee SY, Xu M, Polymer, 37(26), 5781 (1996)

[6] David DJ, Staley HB, Analytical Chemistry of Polyurethanes, Wiley-Interscience, New York (1969)

[7] Mark JE, Eisenberg A, Grassley WW, Mandelkern L, Koenig JL, Physical Properties of Polymers, Amer. Chem. Soc., Washington, D.C. (1984)

[8] Lee JC, Kim BK, J. Polym. Sci. A: Polym. Chem., 32(10), 1983 (1994)

[9] Lee YM, Lee JC, Kim BK, Polymer, 35(5), 1095 (1994)

[10] Kim BK, Lee JC, Polymer, 37(3), 469 (1996)