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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: It is pointed out here that larger microscopic hierarchical metal-oxide particles with high surface porosity also impart good insulation properties, and suggested mechanisms for improved insulation using nanoparticles, such as increased charge trap density, adsorption of impurities/ions, and induced particle dipole moments are considered.
Abstract: Recent progress in the development of polyethylene/metal-oxide nanocomposites for extruded high-voltage direct-current (HVDC) cables with ultrahigh electric insulation properties is presented. This is a promising technology with the potential of raising the upper voltage limit in today's underground/submarine cables, based on pristine polyethylene, to levels where the loss of energy during electric power transmission becomes low enough to ensure intercontinental electric power transmission. The development of HVDC insulating materials together with the impact of the interface between the particles and the polymer on the nanocomposites electric properties are shown. Important parameters from the atomic to the microlevel, such as interfacial chemistry, interfacial area, and degree of particle dispersion/aggregation, are discussed. This work is placed in perspective with important work by others, and suggested mechanisms for improved insulation using nanoparticles, such as increased charge trap density, adsorption of impurities/ions, and induced particle dipole moments are considered. The effects of the nanoparticles and of their interfacial structures on the mechanical properties and the implications of cavitation on the electric properties are also discussed. Although the main interest in improving the properties of insulating polymers has been on the use of nanoparticles, leading to nanodielectrics, it is pointed out here that larger microscopic hierarchical metal-oxide particles with high surface porosity also impart good insulation properties. The impact of the type of particle and its inherent properties (purity and conductivity) on the nanocomposite dielectric and insulating properties are also discussed based on data obtained by a newly developed technique to directly observe the charge distribution on a nanometer scale in the nanocomposite.
148 citations
Cites background from "Mechanical Properties of Polymers a..."
...[15] The interfacial regions are heterogeneous in terms of both physical and chemical structures, resulting in a particle “interaction zone” with electrical properties that are different from those of both the bulk polymer matrix and the particles.[16] The volume (size) of the interaction zone depends not only on the intrinsic characteristics of the polymer and the nanoparticle, but also on the extrinsic mechanical, rheological, and electrical conditions....
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01 Jan 1986
TL;DR: In this article, a review of the properties of polymeric hollow micro-and macrospheres is presented, and the main applications and trends of syntactic foams are outlined.
Abstract: The review deals with a special kind of gas-filled polymeric materials: the syntactic polymer foams, or spheroplastics, consisting of a polymer matrix and a hollow spherical filler. The survey covers the following aspects: preparation and properties of polymeric hollow micro- and macrospheres; physical principles of syntactic foam formation: rheology, regulation of apparent density, space factor and packing of syntactic compositions; chemical and technological principles of formation; preparation of syntactic foams based on epoxy, polyester, phenol, polyimide, and other resins, as well as the newest types of foams — prepregs, poly-phase structures, elastomeric and reinforced foams. The specificity of physical properties and methods of calculation of strength parameters are discussed. Attempts are made to evaluate the effect and contribution of size and packing of spheres on the principal physical properties. The main applications and trends of syntactic foams are outlined.
147 citations
TL;DR: In this article, cellulose diacetate-graft-poly(lactic acid)s (CDA-g-PLAs) were synthesized successfully over a wide range of composition in combination of different ways of graft polymerization: a copolycondensation of lactic acid; a ring-opening copolymerization of l -lactide in dimethyl sulfoxide; and a copolemerization similar to the second, but in bulk, each initiated at residual hydroxyl positions on CDA.
147 citations
TL;DR: In this article, the development of polymer heat exchangers in the last decade, including cutting edge materials characteristics, heat transfer enhancement methods of polymer materials and a wide range of polymeric heat exchanger applications are reviewed and compared with literature.
Abstract: Due to their low cost, light weight and corrosive resistant features, polymer heat exchangers have been intensively studied by researchers with the aim to replace metallic heat exchangers in a wide range of applications. This paper reviews the development of polymer heat exchangers in the last decade, including cutting edge materials characteristics, heat transfer enhancement methods of polymer materials and a wide range of polymer heat exchanger applications. Theoretical modelling and experimental testing results have been reviewed and compared with literature. A recent development, the polymer micro-hollow fibre heat exchanger, is introduced and described. It is shown that polymer materials do hold promise for use in the construction of heat exchangers in many applications, but that a considerable amount of research is still required into material properties, thermal performance and life-time behaviour.
147 citations
TL;DR: In this article, the multwalled carbon nanotube (MWNT) reinforced thermoplastic polyurethane (TPU) nanocomposites were prepared through melt compounding method followed by compression molding.
Abstract: The multi-walled carbon nanotube (MWNT) reinforced thermoplastic polyurethane (TPU) nanocomposites were prepared through melt compounding method followed by compression molding. The spectroscopic study indicated that a strong interfacial interaction was developed between carbon nanotube (CNT) and the TPU matrix in the nanocomposites. The microscopic observation showed that the CNTs were homogeneously dispersed throughout the TPU matrix well apart from a few clusters. The results from thermal analysis indicated that the glass transition temperature (Tg) and storage modulus (E′) of the nanocomposites were increased with increase in CNTs content and their thermal stability were also improved in comparison with pure TPU matrix. The rheological analysis showed the low frequency plateau of shear modulus and the shear thinning behavior of the nanocomposites. The electrical behaviors of the nanocomposites are increased with increase in weight percent (wt%) of CNT loading. The mechanical properties of nanocomposites were substantially improved by the incorporation of CNTs into the TPU matrix.
147 citations