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Mosoabisane MFT, Luyt AS, van Sittert CGCE. Comparative experimental and modelling study of the thermal and thermo-mechanical properties of LLDPE/wax blends. JOURNAL OF POLYMER RESEARCH 2022. [DOI: 10.1007/s10965-022-03136-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
AbstractThe interactions and morphology of molecules in a polymer blend influence the physical properties of the blend. However, little is known about the influence of molecular interaction and morphology on the thermal and mechanical properties of LLDPE/wax blends. Although cooling rate can be used to investigate blends' thermal and mechanical properties, it is inadequate to determine interactions between the molecules in the LLDPE/wax blends. However, since the morphology is related to the thermal and mechanical properties of polymer blends and could be related to the cooling rate, LLDPE/wax samples prepared by melt mixing were cooled at different rates. The thermal and mechanical properties of the LLDPE/wax blends were modelled through molecular dynamic simulations. The modelled transitions were compared to experimentally determined mechanical relaxations of LLDPE/wax blends to investigate the effect of wax addition on the blend crystallinity. The crystallization behaviour of the blends was studied by differential scanning calorimetry, dynamic mechanical behaviour by dynamic mechanical analysis, and differences in crystallinity by X-ray diffraction. There were no significant differences between the results for the slow- and quench-cooled samples, confirming the rapid crystallization of both the LLDPE and the wax. Experiments and molecular dynamics simulations confirmed the cocrystallization of wax with LLDPE.
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Song J, Li J, Li Z. Molecular dynamics simulations of uniaxial deformation of bimodal polyethylene melts. POLYMER 2021. [DOI: 10.1016/j.polymer.2020.123210] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hosoya R, Morita H, Nakajima K. Analysis of Nanomechanical Properties of Polyethylene Using Molecular Dynamics Simulation. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ryohei Hosoya
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku Tokyo 152-8552, Japan
| | - Hiroshi Morita
- National Institute of Advanced Industrial Science and Technology (AIST), Central 2-1, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Ken Nakajima
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku Tokyo 152-8552, Japan
- Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Hall KW, Percec S, Shinoda W, Klein ML. Property Decoupling across the Embryonic Nucleus-Melt Interface during Polymer Crystal Nucleation. J Phys Chem B 2020; 124:4793-4804. [PMID: 32413263 DOI: 10.1021/acs.jpcb.0c01972] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spatial distributions are presented that quantitatively capture how polymer properties (e.g., segment alignment, density, and potential energy) vary with distance from nascent polymer crystals (nuclei) in prototypical polyethylene melts. It is revealed that the spatial extent of nuclei and their interfaces is metric-dependent as is the extent to which nucleus interiors are solid-like. As distance from a nucleus increases, some properties, such as density, decay to melt-like behavior more rapidly than polymer segment alignment, indicating that a polymer nucleus resides in a nematic-like droplet. This nematic-like droplet region coincides with enhanced formation of ordered polymer segments that are not part of the nucleus. It is more favorable to find nonconstituent ordered polymer segments near a nucleus than in the surrounding metastable melt, pointing to the possibility of one nucleus inducing the formation of other nuclei. In this vein, there is also a second region of enhanced ordering that lies along the nematic director of a nucleus, but beyond its nematic droplet and fold regions. These results indicate that crystal stacking, a key characteristic of lamellae in semicrystalline polymeric materials, begins to emerge during the earliest stages of polymer crystallization (i.e., crystal nucleation). More generally, the findings of this study provide a conceptual bridge between polymer crystal nucleation under nonflow and flow conditions and are used to rationalize previous results.
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Affiliation(s)
- Kyle Wm Hall
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States.,Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Simona Percec
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Wataru Shinoda
- Department of Materials Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Michael L Klein
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States.,Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
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Hall KW, Percec S, Klein ML. Polymer nucleation under high-driving force, long-chain conditions: Heat release and the separation of time scales. J Chem Phys 2019; 150:114901. [PMID: 30902014 DOI: 10.1063/1.5084773] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
This study reveals important features of polymer crystal formation at high-driving forces in entangled polymer melts based on simulations of polyethylene. First and in contrast to small-molecule crystallization, the heat released during polymer crystallization does not appreciably influence structural details of early-stage, crystalline clusters (crystal nuclei). Second, early-stage polymer crystallization (crystal nucleation) can occur without substantial chain-level relaxation and conformational changes. This study's results indicate that local structures and environments guide crystal nucleation in entangled polymer melts under high-driving force conditions. Given that such conditions are often used to process polyethylene, local structures and the separation of time scales associated with crystallization and chain-level processes are anticipated to be of substantial importance to processing strategies. This study highlights new research directions for understanding polymer crystallization.
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Affiliation(s)
- Kyle Wm Hall
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Simona Percec
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Michael L Klein
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
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Wei Q, Wang Y, Wang S, Zhang Y, Chen X. Investigating the properties and interaction mechanism of nano-silica in polyvinyl alcohol/polyacrylamide blends at an atomic level. J Mech Behav Biomed Mater 2017; 75:529-537. [DOI: 10.1016/j.jmbbm.2017.08.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 08/18/2017] [Accepted: 08/22/2017] [Indexed: 01/27/2023]
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Li Z, Lai S, Gao W, Chen L. Molecular dynamics simulation of self-diffusion coefficients for several alkanols. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2017. [DOI: 10.1134/s0036024417070317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Strength of Alkane–Fluid Attraction Determines the Interfacial Orientation of Liquid Alkanes and Their Crystallization through Heterogeneous or Homogeneous Mechanisms. CRYSTALS 2017. [DOI: 10.3390/cryst7030086] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Wei Q, Wang Y, Che Y, Yang M, Li X, Zhang Y. Molecular mechanisms in compatibility and mechanical properties of Polyacrylamide/Polyvinyl alcohol blends. J Mech Behav Biomed Mater 2017; 65:565-573. [DOI: 10.1016/j.jmbbm.2016.09.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 09/06/2016] [Accepted: 09/07/2016] [Indexed: 11/16/2022]
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Gao R, He X, Zhang H, Shao Y, Liu Z, Liu B. Molecular dynamics study of the isothermal crystallization mechanism of polyethylene chain: the combined effects of chain length and temperature. J Mol Model 2016; 22:67. [PMID: 26932477 DOI: 10.1007/s00894-016-2931-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 02/04/2016] [Indexed: 10/22/2022]
Abstract
A molecular level understanding of the polyethylene (PE) crystallization process was elucidated by molecular dynamics simulation of three states, with varying chain length and temperature. The process can be classified into the following three states: (1) nucleation controlled state, (2) competitive state of crystal growth process and new nuclei formation, and (3) crystal growth controlled state, which could be quantified by the evolution of nuclei number. With increasing chain length, two phenomena occur: the single crystallization mechanism changes from state (1) to (3), and the crystal size increases while the b/a axial ratio in the lateral surface decreases. These changes can be explained from a thermodynamic point of view, in that the van der Waals (vdW) interaction per CH2 unit is strengthened and more nucleation sites are generated for longer chain. Size effect (meaning different surface fractions when the chain collapses into a globule) was an important factor determining vdW energy per unit and the crystallization states of a single PE chain. On the other hand, the crystallization states were independent of chain length for short chains systems with the same size effect. In both conditions, a long chain generates multi-crystal domains, and a short chain prefers a single crystal domain. Our results not only provide molecular level evidence for crystallization states but also clarify the influence of chain length on the crystallization process.
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Affiliation(s)
- Rui Gao
- State Key Laboratory of Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
| | - Xuelian He
- State Key Laboratory of Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
| | - Haiyang Zhang
- State Key Laboratory of Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
| | - Yunqi Shao
- State Key Laboratory of Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
| | - Zhen Liu
- State Key Laboratory of Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
| | - Boping Liu
- State Key Laboratory of Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
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