Molecular Simulation Studies on the Mechanical Responses of Polymers: Strain-Induced Crystallization of Thermoplastic Elastomer And Creep Analysis with Ree-Eyring Theory : Strain-Induced Crystallization of Thermoplastic Elastomer and Creep Analysis With Ree-Eyring Theory
- 주제(키워드) 열가소성 탄성중합체 , 기계적 물성 , 리-아이링 이론 , 크립 물성 , Thermoplastic elastomer , mechanical property , Ree-Eyring theory , Creep behavior
- 발행기관 서강대학교 일반대학원
- 지도교수 성봉준
- 발행년도 2026
- 학위수여년월 2026. 2
- 학위명 석사
- 학과 및 전공 일반대학원 화학과
- 실제URI http://www.dcollection.net/handler/sogang/000000082758
- UCI I804:11029-000000082758
- 본문언어 영어
- 저작권 논문은 저작권에 의해 보호받습니다.
초록(요약문)
In the modern era, the utilization of polymeric materials has been progressively in- creasing. Polymers are now employed in a wide range of applications, such as household items, automobiles and electronic devices. Accordingly, recent polymer research has been focused on two primary areas: first, the design of polymer materials possessing proper- ties optimized for specific applications; and second, the exploration of polymer materials that offer high processability and recycling potential. During my master’s program, I con- ducted research on polymer materials that align with the two previously mentioned areas using Molecular Dynamics (MD) simulations. First, this paper introduces research on the phenomenon of Strain-Induced Crystal- lization occurring during the extension of Thermoplastic Elastomers (TPEs). TPEs are materials of interest because, unlike conventional elastomers, they melt into a liquid state under high temperature conditions while show elastomeric properties at room temperature. Due to these characteristics, TPEs possess high processability and recyclability. Strain- Induced Crystallization (SIC) refers to the formation of new crystalline domains when an elastomer is under an excessive deformation. Induced crystalline domains influence the material’s transparency and mechanical properties. Notably, irreversible SIC occurs in TPEs; the induced crystalline domains do not degrade when the applied stress is removed, while conventional elastomers exhibit a reversible SIC. However, a molecular-level under- standing of this irreversible phenomenon remains insufficient. This paper, utilizing MD simulations, presents a molecular level mechanism for the irreversible SIC in TPEs, and investigates the relationship between composition of TPEs and SIC tendency. Based on these results, a design guideline for synthesizing TPEs with desired mechanical properties is proposed. Second, this paper introduces a creep MD simulation methodology for investigating the mechanical properties of polymer materials. Creep experiment is a well-known method- ology to investigate the mechanical properties by analyzing the time-dependent response of a material under a constant stress. Because Creep behavior is known to be influenced by the material’s Young’s modulus and viscosity, mechanical properties can be determined by analyzing the creep experiment results. Investigating mechanical properties by using MD simulation offers advantages: mechanical properties of materials with desired compo- sitions can be explored without material loss, and molecular-level analysis is also possible. However, this approach has significant limitations. The timescale probed by MD simula- tion (nanoseconds to microseconds) is extremely short compared to the timescale probed by real experiment (seconds to hours), which leads to an exceedingly high deformation rate. Due to this gap, predicting experimental results from MD simulation data remains a chal- lenge. This paper proposes a methodology to implement creep simulation by using MD simulation and predict mechanical properties by applying the theoretical Burgers model. Furthermore, to overcome the limitations of MD simulation, this paper presents a method- ology that combines the Ree-Eyring theory, which describes the strain-rate dependency of viscosity in non-Newtonian fluids, to extrapolate and predict mechanical properties at real experimental timescales.
more목차
Abstract i
1 Mechanism and Effect of Strain Induced Crystallization of Thermoplastic Elas-
tomer on Mechanical and Structural Irreversibility 1
1.1 Introduction 1
1.2 Model and Methods 3
1.2.1 Model 3
1.2.2 Simulation detail 4
1.2.3 Calculated properties 7
1.3 Result and discussion 8
1.3.1 Rearrangement of the hard segment occurs during the deformation . 8
1.3.2 Effect of rearrangement of the hard segment on irreversibility 11
1.3.3 The trend of recrystallization of the hard segment within various
compositions 14
1.4 Summary and Conclusions 15
1.5 References 15
2 Prediction of Low Strain Rate Creep Behavior Using Molecular Dynamics
Simulation with Ree-Eyring Theory 18
2.1 Introduction 18
2.2 Model and Methods 20
2.2.1 Model 20
2.2.2 Simulation detail 21
2.2.3 Data analysis 22
2.3 Data and Results 24
2.3.1 Creep simulation reproduced via servo control algorithm 24
2.3.2 Burgers model analysis 25
2.3.3 Predicting low strain rate viscosity using Ree-Eyring theory 26
2.4 Summary and Conclusions 27
2.5 References 28
3 Prediction of Storage/Loss Modulus of Polyethylene with Equilibrium and Non-
Equilibrium Molecular Dynamics Simulation 30
3.1 Introduction 30
3.2 Model and Methods 32
3.2.1 Model 32
3.2.2 Simulation detail 33
3.3 Data and Results 35
3.3.1 Calculation of storage and loss modulus by Green-Kubo method 35
3.3.2 Calculation of storage and loss modulus via non-equilibrium MD
simulation 36
3.4 Summary and Conclusions 38
3.5 References 39
