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Molecular Dynamics Simulation of Interfacial Self-Assembly Structure of the Carbon Fiber Composites

Author: JiaJin
Tutor: HuangYuDong
School: Harbin Institute of Technology
Course: Chemical Engineering and Technology
Keywords: Interface Molecular dynamics simulations Molecular self-assembly Carbon Fiber Au (111) Interfacial interaction energy
CLC: TB332
Type: PhD thesis
Year: 2009
Downloads: 423
Quote: 1
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Abstract


In this paper, molecular self-assembly method of carbon fiber (CF) surface modification, thereby regulating CF composite interface, directed the orderly arrangement of the interface phase. And by molecular dynamics (MD) simulation method, at the molecular level to explore the interface role of law carbon fiber polymer matrix composites, which promote the development of the scientific theory of composite interface and surface treatment technology, has important theoretical and practical significance. Epoxy resin (EP), the choice of a gold surface thiol molecules self-assembled system. Molecular simulation of different chain lengths, thiol molecules of different terminal functional groups of molecular self-assembly and interfacial properties of epoxy film (SAMs) / Au (111), and the simulation results were validated by experiments. In the analog part of the molecule of methyl mercaptan (MT) and 2 - mercaptoethanol (ME) adsorption structures on Au (111) surface using density functional theory (DFT), results showed that the most stable adsorption position for bri -fcc bit. DFT Study based on the establishment of a full coverage of functionalized alkyl thiol molecules S (CH 2 ) n X (X =-OH,-NH < sub> 2 ,-COOH, n = 1 1 7) initial adsorption on Au (111) surface structure and arrangement of the MD simulation method. The simulation results indicate that the the SAMs structure of the terminal functional groups are similar, with the chain length of the change trend and the stability of the three kinds of SAMs strength order: the S (CH 2 ) n COOH gt; S (CH 2 ) n NH 2 gt; S (CH 2 ) n OH. Au (111) surface of the self-assembled S (CH 2 ) n X in the MD simulation results for the initial surface model, established SAMs / Au (111) with ethylene the resin interface model, the simulated annealing method to find the lowest energy of the interface structure. The simulation results show that three different interface system, the interface structure is most stable when the chain length of the self-assembling molecules, respectively, n = 10,11. The three interface system stability order: S (CH 2 ) n NH 2 / EP gt; S (CH 2 ) n COOH / EP gt; S (CH 2 ) n OH / EP. The CF surface metallization using electroless gold plating method, and five kinds of thiol molecules on the surface self-assembly [S (the CH 2 ) n OH (n = 2,6 , 11), S (CH 2 ) 2 NH 2 , S (CH 2 ) 2 Experimental results show that the S (CH 2 ) n OH, the chain length n is 11 composites IFSS ratio n = 2,6 of the composite material IFSS high and with increasing chain length, IFSS decreases and then increases. Different terminal functional groups for the same chain length, thiols, composite IFSS order: S (CH 2 ) 2 NH 2 gt; S (CH 2 ) 2 COOH gt; S (CH 2 ) 2 OH. This result this article MD simulation results are exactly the same. The self-assembly system, the choice of the surface of the hydroxylated / organic silane coupling agent for polyarylacetylene (PAA) resins. Using MD methods focus on the impact of coupling agent chain length of CF / PAA interface performance. The simulation results show that the CF / PAA interface role with the coupling agent molecular chain length increases, decreases and then increases trend; When n = 100, the interfacial energy of the lowest, most stable interface structure. CF / PAA interfacial interaction can occur between the molecular chain of the silane coupling agent and PAA molecule entanglement and the coupling agent is a carbon chain in the coverage of the surface of the carbon fiber. Ozonation on the the CF surface of a silane coupling agent, and the self-assembly of different chain lengths coupling agent (n = 1 1 ) CF / PAA composites interlaminar shear strength (ILSS) and IFSS test. The experimental results show that, with the coupling agent carbon chain length increases, the interfacial strength of the composite material increases gradually. Its interlayer shear fracture is a scanning electron microscope (SEM) analysis also showed that the interfacial bonding properties of the composite material is improved with increasing carbon chain length. Composites of the CF / PAA, the main reason for the increase of its interfacial properties since the entanglement between molecular chains of the assembly on the surface of the carbon fiber coupling agent molecular chain and PAA resin, and this effect on n ≤ 18 enhanced with increasing chain length of coupling agent molecules, this law article obtained by the MD simulation law is consistent.

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CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Composite materials > Non-metallic composite materials
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