| 학회 | 한국화학공학회 |
| 학술대회 | 2002년 봄 (04/26 ~ 04/27, 강원대학교) |
| 권호 | 8권 1호, p.1889 |
| 발표분야 | 고분자 |
| 제목 | Marrucci 모델의 대변형 진동 전단 유동 특성 |
| 초록 | The zero-shear-rate viscosity increases much faster than linearly with concentration, indicating strong polymer-polymer interactions at larger concentration. There are two approaches in the large concentrations system. There is the approach in modeling the interactions of the polymer molecules which builds on the classical network theories of rubber elasticity to analyze the melt and concentrated system. In the network theories of macromolecular solids, chemical crosslinks are described as points, or junctions, at which connecting portions of molecules are forced to move together for all times. In adapting this theory to liquids we assume the junctions are not permanent, but are continually being created and destroyed. The melt and concentrated system need to analyze the nonlinear area because the systems involve large, rapid deformations which cannot be modeled using the theory of linear viscoelasticity, which predicts a superimposable, linear dependence of the amplitude of the stress response on the amplitude of the imposed strain. Among the nonlinear experiments, step shear rate test (measurement of shear viscosity as a function of shear rate) is often conducted. As it provide the information how readily the material can be processed or shaped into a useful product, it can be helpful in polymer processing as in injection molding. However, as deformation is too fast at high shear rate, the material doesn't have enough time to respond to the environment and hardly provides the information on its microstructure. Another nonlinear experiment is large amplitude oscillatory shear (LAOS). It is normally generated by strain sweep test, which is used to check the linear viscoelastic regime before the frequency sweep test. As storage modulus G' and loss modulus G'' are defined only in the linear viscoelastic regime, the moduli at large strain lose mathematical background, and have normally been neglected. However, provided that enough care is taken, LAOS test can provide plentiful amount of additional information. In addition, it allows both strain amplitude and time scale to be varied independently, and it is easy to generate because it does not involve any sudden jump in speed or position. We calculated the LAOS test by network model of Marrucci paper. |
| 저자 | 김승하, 심훈구, 안경현, 이승종 |
| 소속 | 서울대 |
| 키워드 | LAOS; FFT; Strain sweep |
| 원문파일 | 초록 보기 |
