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Mechanical Properties of Polymers and Composites
14 Dec 1993-
TL;DR: In this article, the authors discuss various mechanical properties of fiber-filled composites, such as elastic moduli, creep and stress relaxation, and other mechanical properties such as stress-strain behavior and strength.
Abstract: Mechanical Tests and Polymer Transitions * Elastic Moduli * Creep and Stress Relaxation * Dynamical Mechanical Properties * Stress-Strain Behaviour and Strength * Other mechanical Properties * Particulate-Filled Polymers * Fiber- Filled Composites and Other Composites.
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TL;DR: In this paper, the influence of interaction between the two polymers on the mechanical and dynamic mechanical properties of the blends is analyzed in detail, and the results are interpreted on the basis of the formation of nylon-ACM graft copolymer at the interfaces.
Abstract: Nylon-6 and acrylate rubber (ACM) were melt blended in a Brabender Plasticorder at 220 °C and 40 rpm rotor speed. The reactive nature of the blend is reflected in the mixing torque behavior of the blends at different compositions. The solubility characteristics of the blends in formic acid solution gives an approximate idea of the amount of nylon-6 grafted onto ACM and vice-versa. A reaction mechanism is proposed based on the well known epoxy—amine and epoxy—acid reactions and is confirmed by infrared spectroscopic studies of the blends. The influence of interaction between the two polymers on the mechanical and the dynamic mechanical properties of the blends is analyzed in detail, and the results are interpreted on the basis of the formation of nylon—ACM graft copolymer at the interfaces. The dynamic mechanical thermal analysis (DMTA) reveals a two phase morphological structure, indicating incompatibility of the blend components. The grafting reaction results in dramatic increase in both the sto...
70 citations
70 citations
01 Jan 2012
TL;DR: In this article, a practical update on results extracted from Voronoi polyhedra analyses of simulated and real physical systems is provided, which is an alternative approach to characterization of amorphous and liquid structures.
Abstract: Materials in the glassy state have become an increasing focus of research and development and are found in a variety of commercial products and applications. While non-crystalline materials are not new, their often unpredictable properties and behavior continue to elude neat systems of classification. For purposes of teaching, there is presently a need for further explication of glasses, especially given their high importance and the wide extent of glassy materials in existence. This work is thus intended to address that need. Voronoi polyhedra have been used to represent amorphous (glassy) structures with considerable success; however, the system and procedure are not well taught and understood as, for example, are Miller Indices for describing crystals. The present article provides a practical update on results extracted from Voronoi polyhedra analyses of simulated and real physical systems. There is an alternative approach to characterization of amorphous and liquid structures, namely the binary radial distribution function, which is explained. Above all this article discusses the nature of the glassy state.
69 citations
01 Oct 2017
TL;DR: Cubuk et al. as mentioned in this paper link structure to plasticity in disordered solids via a microscopic structural quantity, "softness," designed by machine learning to be maximally predictive of rearrangements.
Abstract: Behavioral universality across size scales Glassy materials are characterized by a lack of long-range order, whether at the atomic level or at much larger length scales. But to what extent is their commonality in the behavior retained at these different scales? Cubuk et al. used experiments and simulations to show universality across seven orders of magnitude in length. Particle rearrangements in such systems are mediated by defects that are on the order of a few particle diameters. These rearrangements correlate with the material's softness and yielding behavior. Science, this issue p. 1033 A range of particle-based and glassy systems show universal features of the onset of plasticity and a universal yield strain. When deformed beyond their elastic limits, crystalline solids flow plastically via particle rearrangements localized around structural defects. Disordered solids also flow, but without obvious structural defects. We link structure to plasticity in disordered solids via a microscopic structural quantity, “softness,” designed by machine learning to be maximally predictive of rearrangements. Experimental results and computations enabled us to measure the spatial correlations and strain response of softness, as well as two measures of plasticity: the size of rearrangements and the yield strain. All four quantities maintained remarkable commonality in their values for disordered packings of objects ranging from atoms to grains, spanning seven orders of magnitude in diameter and 13 orders of magnitude in elastic modulus. These commonalities link the spatial correlations and strain response of softness to rearrangement size and yield strain, respectively.
69 citations
TL;DR: The potential of carbon-based nanomaterials to replace conventional conductive materials, such as copper and aluminum, has been highlighted by Endo et al. as discussed by the authors, who presented the forecast on the present, near future, and long term applications of CNTs in various fields.
Abstract: DOI: 10.1002/aelm.201800811 and environmentally friendly conductive cables or wires as a replacement for copper. From this view, carbon-based nanomaterial is a potential candidate. Carbon related nanomaterials including fullerenes, carbon nanotubes (CNTs), and graphene are promising due to their exceptional conductive and electronic transport properties, which may accelerate the practical and potential applications for various kinds of novel engineering areas spanning from electronics, energy storage, and advanced materials to nanotechnology and biotechnology. Among the family of carbon nanomaterials, CNTs have been a particularly attractive material since its discovery in 1991 by Iijima,[1] due to their nanoscale 1D shape, excellent mechanical properties, tunable electrical properties either metallic or semiconducting, high current carrying capacity, and many other exciting properties. These properties have highlighted the potential of CNTs use in a plethora of applications, including electrically conductive fillers in polymer composites, flexible and transparent conductive films, microelectronics (transistors, interconnectors, heat dissipaters), and lightweight conducting wires and cables.[2] Figure 1 points out the forecast presented by Endo et al.[3] on the present, near future, and long term applications of CNTs in various fields. An interesting potential application of CNTs is the long-term electrical conductors, which are able to transmit power from plants to plants or households, as well as be used in electronic devices. Compared to conventional copper cables or wires, CNT based cables have several advantages including 1) a lower density of 1.3 g cm−3 for single-walled carbon nanotubes (SWCNTs)[4] and 2.1 g cm−3 for multiwalled carbon nanotubes (MWCNTs),[5] both of which are much lower than that of copper, 8.96 g cm−3;[6] 2) environmental stability, which can stand with severe conditions including high pressure, large temperature changes, etc.; 3) excellent mechanical performance with a Young’s modulus and strength in the ranges of 1.0 TPa and 50 GPa, respectively;[7] 4) ultrahigh electrical conductivity as high as 108 S m−1 for SWCNTs, which is higher than that of copper (≈107 S m−1)).[8] Furthermore, the limited amount of conventional conductive metal resources in nature and their soaring market price greatly increased the need for a desirable alternative solution that are abundant in nature, low-cost, and The lack of progress to obtain commercially available large-scale production of continuous carbon nanotube (CNT) fibers has provided the motivation for researchers to develop high-performance bulk CNT assemblies that could more effectively transfer the superb mechanical, electrical, and other excellent properties of individual CNTs. These wire-like bulk assemblies of CNTs have demonstrated the potential for being used as electrical conductors to replace conventional conductive materials, such as copper and aluminum. CNT conductors are extremely lightweight, corrosive-resistive, and mechanically strong while being potentially cost-effective when compared to other conventional conductive materials. However, great technical challenges still exist in transferring the superior properties of individual CNTs to highly conductive bulk CNT assemblies, such as continuous wires, cables, and sheets. This paper gives an overview of the state-of-the-art advances in CNT-based conductors in terms of fabrication methods, characterization, conduction mechanisms, and applications. In addition, future research directions and possible attempts to improve performance are analyzed. The opportunities and challenges for related nonmetal competitive conductors are also discussed.
69 citations