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Showing 1 to 20 of 37 for “"amorphous polymers"”.
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Low-energy, localized excitations in amorphous polymers
Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-06-20T20:03:53Z No. of bitstreams: 1 1980_matsumoto.pdf: 4103014 bytes, checksum: 0ca927dd0f785f97fb48332794b75f28 (MD5)
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Mechanics of amorphous polymers and polymer gels
Many applications of amorphous polymers require a thermo-mechanically coupled large-deformation elasto-viscoplasticity theory which models the strain rate and temperature dependent response of amorphous polymeric materials in a temperature range which spans the glass transition temperature of the …
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Cold drawing and crack layer growth in amorphous polymers.
Cold drawing and crack layer growth in amorphous polymers.
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Characterization of the strain hardening response of amorphous polymers
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1992.
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Atomistic simulations of elastic-plastic deformation of amorphous polymers
As the demand for polymers with superior properties increases, an understanding of the fundamental connections between the mechanical behavior and underlying chemical structure becomes imperative. In this work, the thermo-mechanical behavior and the molecular-level origins of plastic deformation of …
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Mechanics of amorphous polymers and polymer nanocomposites during high rate deformation
… mechanical behavior of two exemplary amorphous polymers, PC and PMMA. The experiments included dynamic mechanical thermal analysis (DMTA), as well as uniaxial compression tests over a wide range of strain rates. In both cases, the polymer exhibited a distinct transition in the …
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Low to high strain rate deformation of amorphous polymers : experiments and modeling
… to understand the mechanical behavior of two amorphous polymers--polycarbonate and poly(methvl methacrylate)--at strain rates ranging from 10⁻⁴ to 10⁴ s⁻¹. This spectrum of strain rates was achieved in tension/compression tests using a dynamic mechanical analyzer (DMA), a servo-hydraulic …
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The effects of molecular orientation on the physical aging behavior of oriented glassy amorphous polymers
… has an effect on the rate of physical aging in amorphous glassy polymers. There is already a large body of literature concerning the phenomenon of physical aging, although the vast majority has been directed toward isotropic, unoriented systems. The importance of this study is therefore twofold: …
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A thermo-mechanical finite deformation theory of plasticity for amorphous polymers : application to micro-hot-embossing of poly(methyl methacrylate)
Amorphous thermoplastic polymers are important engineering materials; however, their nonlinear, strongly temperature- and rate-dependent elastic-visco-plastic behavior has, until now, not been very well understood. The behavior has previously been modeled with mixed success by existing constitutive …
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A large-deformation thermo-mechanically coupled elastic-viscoplastic theory for amorphous polymers : modeling of micro-scale forming and the shape memory phenomenon
Amorphous polymers are important engineering materials; however, their nonlinear, strongly temperature- and rate-dependent elastic-viscoplastic behavior is still not very well understood, and is modeled by existing constitutive theories with varying degrees of success. There is no generally agreed …
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Testing theories for thermal transport using high pressure
… materials, such as heat transfer in crystals and amorphous polymers, and across interfaces, using an ultrafast pump-probe method, time-domain thermoreflectance (TDTR), combined with gem anvil cell techniques. I demonstrated that pressure tuning of physical properties of materials is an elegant …
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Modeling viscoelastic cellular materials for the pressing of wood composites
… in the glass transition temperature of the amorphous polymers in wood. 4. To utilize micromechanical models of cellular materials in conjunction with linear viscoelasticity of polymers to develop a nonlinear viscoelasticity model for wood in transverse compression. The approach couples the …
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Volumetric heat capacity enhancement in ultrathin fluorocarbon polymers for capacitive thermal management
… of size dependence in the heat capacity of amorphous polymers as well as highlights their potential for capacitive thermal management.
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Synthesis and characterization of soluble, melt-processible aromatic poly(amide-imides)
… thermal and solid state characterization of the polymers. The synthesis of both high molecular weight as well as controlled molecular weight systems has been attempted. A detailed study of the route employing an acid chloride-anhydride has been conducted, which has particularly emphasized the use …
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Low-temperature thermal expansion of amorphous solids
"For most amorphous materials at temperatures below ~ 1 K, the magnitudes and temperature dependences of specific heat, thermal conductivity and ultrasonic dispersion are qualitatively similar, independent of chemical composition. It has been suggested that thermal expansion also exhibits this …
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Constitutive equations and failure criteria for amorphous polymeric solids
… for the elastic-viscoplastic deformation of amorphous solids. Their theory is motivated by and builds on the work of Parks, Argon, Boyce, Arruda, and their co-workers (e.g. Boyce et al., 1988; Arruda & Boyce, 1993) on modeling the plastic deformation of amorphous polymers. The theory of Anand …
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Applications of thermophysical characterization using the 3-omega technique
… temperature dependent thermal conductivity of polymers, an empirical model is proposed to aid in predicting temperature-dependent thermal conductivity of amorphous polymers. The model depends on only the density, monomer molecular weight, and speed of sound, and its predictions are validated …
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Surface properties of poly(bisphenol-A-carbonate)
… a technique to measure surface free energies of amorphous polymers <br></br>(b) an investigation of chemical polishing and <br></br>c) the problems of injection moulded polycarbonate. <br></br><br></br>Grooves inscribed in an amorphous polymer surface change in dimensions on thermal annealing, …
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Multiscale chemomechanics of polymer deformation under contact : predicting structure-property correlations from the bulk to the interphase
… and response of homogeneous engineering polymers under confined contact loading are characterized as a function of polymer physical and structural properties. The validity of the time-independent metric indentation hardness Hi is evaluated through the combination of nanoindentation and …
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