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Carbon fiber / fluorinated polymer composites research

Author: YaoLiNa
Tutor: LiuZhaoTie
School: Shaanxi Normal University
Course: Polymer Chemistry and Physics
Keywords: Carbon fiber / polyethylene trifluoroethyl methacrylate composite materials Blending method Situ polymerization Percolation threshold Conductive and dielectric properties
CLC: TB332
Type: Master's thesis
Year: 2010
Downloads: 166
Quote: 0
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Abstract


Carbon fiber (Carbon Fibers, referred CFs) is a new reinforcing material can be used for the composite material modification. Usually Carbons which not only has the inherent characteristics, but also has high conductivity, a large aspect ratio, low density, high specific strength, high resistance to corrosion, high temperature and resistance to oxidation and many other advantages. Take advantage of the the CFs unique physical and chemical properties, and high temperature fluoropolymer, excellent surface properties, the CFs fluoropolymer composite with excellent performance can be obtained CFs / fluoropolymer matrix composites. Therefore, the study of CFs / fluoropolymer matrix composites and performance has important theoretical and practical significance. The two types of carbon fibers (mark of CFs-1 and of CFs in-2) heat treatment or restore, blending and in situ polymerization of a composite carbon fiber / poly trifluoroethyl methacrylate (PTFEMA), and thermal and electrical properties. 1 the CFs-1 and CFs-2 structure and performance. Analysis known: CFS-1 and CFS-2 having a characteristic diffraction peak of graphite (002), and the carbon, oxygen element is the main component thereof, the fibers having different diameters. The nitric oxide CFS (Mark CFs-11, CFs-22), the diameters are thicker, and the surface roughness is increased, the surface oxygen content is increased, the surface carbon content is reduced. Description oxidized CFs containing groups on the surface, and effectively improve the the CFs with PTFEMA between the combination. 2, in the medium of supercritical carbon dioxide (scCO2) using the in situ polymerization CFs-1/PTFEMA composite using 1H NMR and FT-IR characterization of the composite structure, and test the composite PTFEMA molecular weight and molecular weight distribution . Compared with the homopolymerization of the monomer TFEMA after a CFs-1 was added under the same conditions, the monomer conversion and polymer molecular weight is reduced. TFEMA conversion of from 80% reduced to 60%, the polymer molecular weight dropped from 19000 to 13000, which may be caused due to the small amount of oxygen in the epoxy coating its surface adsorption of air after heat treatment CFs surface. The oxygen consumption of polymerization inhibitor as a radical polymerization initiator so that the monomer-initiator is not sufficient, the conversion decreased, and the epoxy coating may act as a chain transfer agent or terminating agent so that the polymer molecular weight decreases. Therefore, follow-up studies have CFs surface modification. 3 to the Blend Method CFs-1/PTFEMA composite reference to discuss scCO2 as the reaction medium, heat treatment CFs as a reinforcing material in situ polymerization CFs-1/PTFEMA conductive properties of the composite. For CFs-1/PTFEMA composite materials, the in situ polymerization of CFs dispersibility superior to the blend prepared CFS dispersibility; the two prepared CFs-1/PTFEMA composites have good conductivity; Sui CFs high three orders of magnitude increase in the content of 1 mass resistivity (ρv) radiate a magnitude decreasing, and in situ polymerization of ρv Blend Method. In situ polymerization the CFs-1 content of 12% (CFs-1: PTFEMA) composites, for example, The analysis temperature changes affect the resistivity of the composite material. The results show that: with increasing temperature, the material is first demonstrated strong PTC effect, material NTC effect when the temperature rose to 80-85 ℃ range. The NTC effect reduces the conductive properties of the material should therefore be effective in reducing the material NTC effect. Blend Method CFs-1/PTFEMA, and CFs-11/PTFEMA composite materials for reference, research scCO2 for medium, hydrogen reduction the CFs-2 and CFs-22, as a reinforcing material, in situ polymerization the composite dielectric CFs-2/PTFEMA and CFs-22/PTFEMA performance. The results showed that: the room temperature and a frequency of 1 × 103 Hz, the permittivity of CFs-11/PTFEMA composites Seepage the threshold below CFs-1/PTFEMA composite materials, which is due to the blending method, the oxidation of the part of the fiber breakage, so that the original reduced, longer fibers in the matrix difficult lap caused by the conductive network; CFs-22/PTFEMA percolation threshold of the dielectric constant of the composite material is higher than CFs-2/PTFEMA composite material, this is because the in situ polymerization of CFs surface oxidation, increases the surface roughness, also increases the interface polarization effects, resulting in the increase in the dielectric. Room temperature and frequency 2 × 105Hz, Sui the CFs-11 content increases, CFs-11/PTFEMA composite material dielectric loss first slowly increased, close to the percolation threshold (5%), the dielectric loss surge, and low dielectric loss of the composite material in CFs-1/PTFEMA composites, because the after oxidation, the surface base body PTFEMA in CFS-11 adhesion, compatibility is better, so that the gap between the filler and the matrix is ??reduced, and reduce the loss caused by interfacial polarization. With increasing frequency, the composite dielectric constant change is a slow reduction process, there is no sudden increase or sudden reduction phenomenon; frequency (0.01-3) × 105 Hz range, CFs-11/PTFEMA and CFs-22/PTFEMA composite The dielectric loss is maintained at less than 0.15, showing a slightly decreasing tendency. Show that two composites has certain dielectric properties, and to expand the range of applications of the carbon fiber composite material.

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