Characterization of the vibrational damping loss factor and viscoelastic properties of ethylene-propylene rubbers reinforced with micro-scale fillers
TL;DR: In this article, the influence of microscale fillers on EPR was examined with respect to their vibrational damping capacity and viscoelastic properties, which reinforced the evidence of a direct relation between the vibrational loss factor and its mechanical damping loss factor.
Abstract: The influence of microscale fillers on ethylene–propylene rubbers (EPR) was examined with respect to their vibrational damping capacity and viscoelastic properties. The vibrational damping and dynamic mechanical properties of reinforced EPR were studied in systematic and comparative ways that reinforced the evidence of a direct relation between the vibrational damping loss factor and its mechanical damping loss factor. In this study, the sensitivity of the vibrational damping loss factor of reinforced EPR was quantified with respect to the variation in thickness, filler type, and filler content. Dynamic mechanical relaxation behaviors were also analyzed. The viscoelastic properties in terms of the storage modulus, loss modulus, mechanical damping loss factor, and frequency dependence of molecular relaxation showed interesting results with the filler types and compositions that had good correspondence with the vibrational damping behaviors. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3058–3066, 2001
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TL;DR: Using the strategy spiders deploy to eliminate uncontrolled spinning at the end of dragline silk, ultrafast hybrid carbon nanotube yarn muscles are developed that generated a 9,800 r.p.m. rotation without noticeable oscillation.
Abstract: Artificial muscles composed of carbon nanotube yarns have previously demonstrated fast, large-angle rotations. Here, the authors infiltrate carbon nanotube yarns with a paraffin wax and polystyrene-based copolymer mixture, achieving stable 9,800 r.p.m. rotation without apparent oscillation.
122 citations
TL;DR: In this article, the free volume properties in a system of zinc oxide (ZnO) nanoparticles (20 nm) dispersed in WBPU were measured using positron annihilation lifetime spectroscopy.
Abstract: The free-volume properties in a system of zinc oxide (ZnO) nanoparticles (20 nm) dispersed in waterborne polyurethane (WBPU) were measured using positron annihilation lifetime spectroscopy. Two glass-transition temperatures (Tg), lower Tg ∼ 220 K and higher Tg ∼ 380 K of the ZnO/WBPU nanocomposites, were found and both increase with increasing zinc oxide content from 0% to 5%. These two glass transitions are interpreted from two segmental domains of WBPU; the lower Tg is due to soft aliphatic chains and high Tg is due to polar hard microdomains, respectively. The increase in Tg with the addition of ZnO fillers is mainly attributed to interfacial interactions through hydrogen bonding, van der Walls forces, and electrostatic forces between the polymer matrix and zinc oxide nanoparticles. These results are supported by the data from the dynamic mechanical thermal analysis (DMTA). The relationship between the free volume obtained from nanoscopic positron method and the physical cross-link density from macrosc...
79 citations
TL;DR: In this article, the damping effect of a novel 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10oxide (DOPO)-based oligosiloxane abbreviated as DOPO-PMVS on methyl vinyl silicone rubber elastomers was reported.
Abstract: For the first time, we report the damping effect of a novel 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)-based oligosiloxane abbreviated as DOPO-PMVS on methyl vinyl silicone rubber (VMQ) elastomers. Designed DOPO-PMVS was synthesized by means of hydrophosphination reaction and studied by FT-IR, 1H NMR, 29Si NMR, 31P NMR, and thermogravimetric analysis. The effect of added DOPO-PMVS on damping, mechanical, and thermal properties of VMQ elastomers before and after post-cure was then examined. Interestingly, the dynamic mechanical analysis data showed that the incorporation of 10 wt% DOPO-PMVS significantly improved the damping properties of VMQ elastomers from −20.5 to 200 °C. The effect mechanism was attributed to the hydrogen bonding interactions exerted between DOPO-PMVS and silica. The break and recombination of hydrogen bonding caused by external force resulted in more dissipated energy and enhanced damping properties. Furthermore, the mechanical and thermal properties of VMQ/DOPO-PMVS elastomers were very practical for the application of damping silicon rubber.
36 citations
TL;DR: In this article, the effect of the ZnO nanoparticles on the damping properties were investigated by dynamic mechanical thermal analysis (DMTA), which showed that the nanoparticles affected damping behaviors and significantly increased the values of the tan δ.
Abstract: The polyurethane/ZnO nanoparticle composites were prepared by in situ suspension polymerization. FT-IR results indicated that hydroxy groups on the ZnO nanoparticles reacted with isocyanate groups, which could improve the compatibility between ZnO nanoparticles and polyurethane to give better properties of nanocomposites. The polyurethane/ZnO nanoparticle composites showed the excellent tensile break strength. The effect of the ZnO nanoparticles on the damping properties were investigated by dynamic mechanical thermal analysis (DMTA). The nanoparticles affected the damping behaviors and significantly increased the values of the tan δ. The main reason was the significant formation of “core-shell” structure in the matrix.
31 citations
Cites background from "Characterization of the vibrational..."
...An increase in this temperature corresponds to a decrease in the mobility of the chains([3])....
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...E00 and tan d afford information about transformation change and damping in materials([3])....
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...The ratio E00=E0 is the loss tangent (tan d), which is the ratio of energy loss per cycle to the maximum energy stored per cycle.([3]) The dynamic mechanical properties of the polyurethane= ZnO nanoparticle composites are illustrated in Figs....
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15 Apr 2004-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the properties of magnetite (Fe 3 O 4 ) filled polypropylene (PP) prepared in an extrusion and injection molding process were investigated, and the crystallinity of test samples was estimated.
Abstract: Mechanical properties of magnetite (Fe 3 O 4 ) filled polypropylene (PP) prepared in an extrusion and injection molding process were investigated Various grades of magnetite were used Mechanical spectroscopy was performed in a temperature range from 173 to 428 K with frequencies from 10 −1 to 10 2 Hz, and the crystallinity of test samples was estimated Damping spectra show an α peak of the principal relaxation (∼285 K) at the glass transition temperature, a relaxation β-peak (∼220 K) attributed to local motions in the amorphous phase and an α′-peak (∼365 K) attributed to the relaxation in crystalline parts of the polymer These peaks correspond to drops of the storage modulus The α-peak is decreased by the extrusion process while the α′-peak is increased compared to not extruded PP At high temperatures a drastic increase of the loss factor superposes the α′-peak for higher filler loadings The crystallinity of the polymer matrices varies between 25 and 37% At low temperatures the storage modulus increases with an increase in the magnetite fraction The used particle size distributions show no significant influences on the storage moduli for temperatures from 173 to 285 K, whereas for temperatures above 285 K smaller mean particle sizes lead to higher storage moduli and lower loss factors
26 citations
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01 Jan 1998
TL;DR: In this article, basic materials and composites are discussed, as well as composites and reinforced polymeric matrix systems for general composites, reinforced plastics, and their applications, including environmental effects.
Abstract: Part One: Basic materials. Polymeric matrix systems. Reinforcements and composites. Part Two: Processing methods. General composites and reinforced plastics. Advanced composites. Part Three: Design and analysis. Part Four: Environmental effects. Part Five: Applications.
755 citations
TL;DR: In this paper, the mechanical properties of vapor-grown carbon fiber (VGCF)/nylon and VGCF/polypropylene composites were discussed, and it was shown that fiber injection can significantly improve the tensile strength and modulus of these composites.
Abstract: This article discusses the mechanical properties of vapor-grown carbon fiber (VGCF)/nylon and VGCF/polypropylene composites. Fibers in the as-produced condition yielded composites with marginally improved mechanical properties. Microscopic examination of these composites clearly showed regions of uninfiltrated fibers, which could account for the unsatisfactory mechanical properties. The infiltration of the fibers by both polymers was improved by carefully ball milling the raw fiber so as to reduce the diameter of the fiber clumps to less than 300 μm. Properties of composites made with ball-milled material were improved in every respect. VGCF reinforcement in nylon slightly improved the tensile strength and doubled the modulus, while VGCF in polypropylene doubled the tensile strength and quadrupled the modulus compared to unreinforced material. Moreover, the composites were sufficiently improved that differences in fiber surface preparation became important. For example, air-etched fibers and fibers covered with low concentrations of aromatics produced polypropylene composites with significantly better mechanical properties than did fibers whose surfaces were heavily coated with aromatics. Both the tensile strength and the modulus of the composites fabricated with clean fibers exceeded theoretical values for composites made with fibers randomly oriented in three dimensions, indicating that the injection-molding process oriented the fibers to some extent.
191 citations
TL;DR: In this paper, the electrical properties of short carbon fiber-filled high-density polyethylene (HDPE)/poly(methyl methacrylate)(PMMA) polymer blends have been studied.
Abstract: Morphology and electrical properties of short carbon fiber-filled high-density polyethylene (HDPE)/poly(methyl methacrylate)(PMMA) polymer blends have been studied. The percolation threshold of HDPE50/PMMA50 blends filled with vapor-grown carbon fiber (VGCF), 1.25 phr VGCF content, is much lower than those of the individual polymers. The SEM micrographs verified that the enhancement of conductivity could be attributed to the selective location of VGCF in the HDPE phase. A double percolation is the basic requirement for the conductivity of the composites, i.e., the percolation of carbon fibers in the HDPE phase and the continuity of this phase in the blends, which hereby are defined as the first percolation and the second percolation, respectively. The SEM micrographs also showed that the short carbon fibers could affect the morphology of the blends. With the increase of VGCF content, the HDPE domains are elongated from spherical into strip shape, finally develop to a continuous structure. As a result, the second percolation threshold of the blends filled with 2.5 phr VGCF, 20 wt % HDPE, is lower than that of the blends filled with 1.5 phr VGCF, 30 wt % HDPE. The influence of molding temperature and time on the second percolation threshold has also been investigated. For the composites molded at a lower temperature, the second percolation threshold is shifted to a higher VGCF content, but there is little influence of molding time on the second percolation threshold. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1813–1819, 1998
97 citations
TL;DR: In this article, the Young's modulus (E c ) of plastically strained MMC was reduced with increase in plastic strain (e p ) by in-situ tensile testing in a scanning electron microscope.
Abstract: Fracture of Al 2 O 3 particle in an Al 2 O 3 particle/aluminium alloy metal matrix composite (MMC) under plastic straining was observed by in-situ tensile testing in a scanning electron microscope. The fracture of larger sized particles was found to be preferred to that of smaller sized ones for a given plastic strain. The Young's modulus (E c ) of plastically strained MMC was reduced with increase in plastic strain (e p )
91 citations
TL;DR: In this article, the authors provide an overview of the sources of dislocation generation in metal matrix composites and provide insight into the effects that dislocations have on the damping response of MMCs.
Abstract: The damping response of crystalline metals and alloys is generally associated with the presence of defects in the crystal lattice. The disturbance of these defects, usually in response to an applied cyclic load, dissipates energy, a mechanism known as “internal friction”. The various defects commonly found in crystalline materials include point defects (e.g. vacancies), line defects (e.g. dislocations), surface defects (e.g. grain boundaries) and volume defects (e.g. inclusions). Among these, dislocations are noteworthy because they play a critical role, not only in the damping response of crystalline materials, but also in the overall mechanical behaviour of the materials. Among the various structural materials actively being developed, metal matrix composites (MMCs) have received considerable attention as a result of their potential to combine reinforcement properties of strength and environmental resistance, with matrix properties of ductility and toughness. Of interest is the generally observed phenomenon that MMCs exhibit unusually high concentrations of dislocations, an observation typically attributed to the difference in coefficient of thermal expansion between matrix and reinforcement. The objectives of the present paper are to provide an overview of the sources of dislocation generation in MMCs, and to provide insight into the effects that dislocations have on the damping response of MMCs. The presence of dislocations in MMCs is highlighted on the basis of transmission electron microscopy studies, and the dislocation damping mechanisms are discussed in light of the Granato-Lucke theory.
89 citations