Article
Polymer Science
Niklas Neumann, Sascha Thinius, Gideon Abels, Andreas Hartwig, Katharina Koschek, Laura Boskamp
Summary: A synthesis approach was investigated for crosslinkable hyperbranched prepolymers with adjustable degrees of methylation and methacrylation, achieving full conversion of hydroxyl groups. The substitution degrees of methacrylate could be adjusted by catalyzed esterification using predefined partially methylated polyglycerol-based precursors. The combination of methacrylic anhydride, triethylamine, and 4-dimethylaminopyridine was proven effective for complete conversion of primary and secondary hydroxyl groups. NMR, IR, and Raman spectroscopy confirmed the insertion of methacrylic crosslinking groups in the polymeric backbone. The photopolymerization of obtained prepolymers resulted in higher crosslink density, stiffness, and glass transition temperature with increasing methacrylate content.
Article
Polymer Science
Mattanun Sangkhawasi, Tawun Remsungnen, Alisa S. Vangnai, Rungtiva P. Poo-arporn, Thanyada Rungrotmongkol
Summary: This study compared the structural dynamics and physical properties of bio-based material polyethylene vanillic (PEV) and commonly used polymer polyethylene terephthalate (PET) using computational methods. The results showed that PEV had higher flexibility and glass transition temperature than PET, consistent with experimental evidence.
Article
Materials Science, Multidisciplinary
Z. Mollaei, F. Kermani, F. Moosavi, M. Kahani, S. Mollazadeh, J. Vahdati Khaki
Summary: Entropy has an interesting relationship with glass properties in glass science and engineering. The relationship between entropy and glass characteristics such as glass transition temperature, bond length, and concentration of non-bridging oxygens was successfully validated through molecular dynamics simulation.
MATERIALS TODAY COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Lujia Wang, Dingyu Bao, Dongwei Wang, Haitao Yang, Jiawei Liu, Jianwen Zhang
Summary: This article investigates the effect of branching degree on SiO2/EP modified by hyperbranched polyester through simulation and experimental verification. The results show that as the branching degree increases, the thermal conductivity, mechanical properties, and dielectric constant increase, while the glass transition temperature decreases.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2023)
Article
Chemistry, Physical
Hasan Zerze
Summary: Polymer crystallization is an important topic in both fundamental physics and manufacturing. Molecular dynamics simulations were used to study polyethylene crystal nucleation and growth, revealing that the nucleation rate decreases with increasing droplet size and nuclei primarily emerge from the surface.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Polymer Science
Na Teng, Jinyue Dai, Shuaipeng Wang, Xiaoling Liu, Jingyuan Hu, Xiaosu Yi, Xiaoqing Liu
Summary: A novel epoxy resin modifier, EHBFR, was designed and synthesized in this study, which effectively improved the fire safety and low-temperature impact strength of modified DGEBA without decreasing its T-g. The addition of EHBFR offers a promising strategy for constructing high-performance epoxy thermosets with excellent flame retardancy and enhanced properties.
EUROPEAN POLYMER JOURNAL
(2021)
Article
Polymer Science
Jiachen Wang, Zhanqiang Li, Majid Basharat, Shaojun Wu, Shuangkun Zhang, Xinfang Zhang, Hanlin Ma, Wei Liu, Dezhen Wu, Zhanpeng Wu
Summary: This study focuses on adjusting the Tg of polyphosphazenes by introducing ethoxy substituents to improve overall performance. Molecular dynamics simulations show that the Tg of the polymers gradually decreases with an increase in ethoxy content, in good agreement with experimental values.
Article
Materials Science, Multidisciplinary
Chunyu Chen, Cong Zhong, Ao Li, Sanxi Huang, Yan Zhang, Huidan Zeng, Qun Zu
Summary: This study used molecular dynamic simulations to investigate the effect of Li2O introduction on the structure and properties of MgO-Al2O3-SiO2 glasses. The results showed that Li ions can enhance the network structure of the glass at low Li2O content, while excessive Li2O content can lead to the disruption of the network structure. The glass transition temperature and hardness of the glass reach a maximum at a Li2O addition of 3 mol%.
MATERIALS TODAY COMMUNICATIONS
(2022)
Article
Engineering, Environmental
Na Teng, Jinyue Dai, Shuaipeng Wang, Jingyuan Hu, Xiaoqing Liu
Summary: This study presents a successful approach to improve the flame retardancy, toughness, T-g, and strength of epoxy resins by incorporating a hyperbranched flame retardant. The modified epoxy resin shows excellent properties, indicating its potential for commercial applications.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Nanoscience & Nanotechnology
Qi An, William L. Johnson, Konrad Samwer, Sydney L. Corona, William A. Goddard
Summary: The formation of the G-phase is primarily driven by the reduction of local distortion energy in the liquid phase. In the case of pure metal, deviatoric strain energy is the dominant driving force for the L-G and L-X transitions.
SCRIPTA MATERIALIA
(2021)
Article
Polymer Science
Mattanun Sangkhawasi, Tawun Remsungnen, Alisa S. Vangnai, Phornphimon Maitarad, Thanyada Rungrotmongkol
Summary: This study investigated the structural and dynamical properties as well as estimated glass transition temperature of PET/PEV blended polymers using molecular dynamics simulations. The results indicate that the 3/2 blending ratio showed the highest number of contacting atoms and potential hydrogen bonds, making it the most suitable ratio model for further experimental studies.
Article
Polymer Science
Lida Yu, Yang Yu, Jiahao Shi, Xiaorui Zhang, Feng Gao, Chenhao Li, Zhou Yang, Jingui Zhao
Summary: Bismaleimide (BMI) resin has great potential in aerospace, electronic, and machinery fields due to its extraordinary thermal stability. In this study, BMI resin modified by hyperbranched polyimide (HBPI) was obtained. The modified resin showed improved mechanical strength and enhanced dielectric properties.
Article
Engineering, Mechanical
Haiming Lu, Yao Tang, Xunuo Cao, Panpan Zhu, Weifeng Zou, Tiefeng Li, Rui Xiao, Haofei Zhou
Summary: This study investigates the change in glass transition temperature (Tg) under different stress states in amorphous materials using molecular dynamics simulations. A theoretical model based on the free volume theory and Eyring model is proposed to quantify the stress dependence of Tg. The potential applications of tuning Tg through external stress and the sensitivity of Tg to hydrostatic and shear stresses are discussed.
EXTREME MECHANICS LETTERS
(2023)
Article
Polymer Science
Carlos Fernandez-de-Alba, Andrew M. Jimenez, Mozhdeh Abbasi, Sanat K. Kumar, Kay Saalwaechter, Guilhem P. Baeza
Summary: This study investigates the slowing down of polymer dynamics in nanocomposites, using low-field NMR relaxometry to quantify the fraction of immobilized polymer on filler surfaces. Two different modeling approaches are used to explain the slowing down phenomenon, with NMR results indicating that the segmental relaxation of the immobilized layer is approximately 1 decade slower than in bulk polymer.
Article
Polymer Science
Xiangrui Zheng, Yafang Guo, Jack F. Douglas, Wenjie Xia
Summary: To understand the structure-property relationships of cross-linked thermosetting polymers, this study investigates the effect of cohesive energy and cross-link density on their segmental dynamics and mechanical properties. Increasing cross-link density leads to higher glass transition temperature and fragility of glass formation, while increasing cohesive energy decreases fragility. Additionally, the macroscopic mechanical properties are strongly correlated with the local molecular stiffness. These findings provide insights for the molecular design of cross-linked thermosets.
