Viscosity measurement of organic glasses below and above glass transition temperature

Kobayashi, Hiroshi; Takahashi, Hiroki; Hiki, Yoshiyuki

doi:10.1016/s0022-3093(01)00708-6

Cited by 34 publications

(42 citation statements)

References 12 publications

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“…It has been reported that the viscosity of PMMA abruptly changes with temperature near T g . 27 Although the origin of this low peak near T g is unclear, it is believed that the highly temperature dependent viscous behavior of PMMA near T g resulted in slight changes in the DC resistance during cooling toward T g . As temperature goes down below T g , DC resistance gradually decreased, because ATO NPs were compressed further by the rigid matrix polyhedra.…”

Section: B Effects Of Processing Parameters On the Electrical Conducmentioning

confidence: 99%

“…Due to the sensitivity of the electrical measurements, the in-situ electrical measurements can detect the viscosity changes near and below the glass transition temperature (T g ) but that traditional viscosity measurements done in shear deformation will not, although the study of viscosity below T g is of great interest since the true glassy state is realized there. 27 Figure 6 displays the fractured cross sections for PMMA/ATO percolated composites containing 1.06 vol % ATO. The fractured cross section of the composites compression molded at 150 • C (Fig.…”

Section: B Effects Of Processing Parameters On the Electrical Conducmentioning

confidence: 99%

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Fabrication and simulation of semi-transparent and flexible PMMA/ATO conductive nanocomposites obtained by compression molding at different temperatures and pressures

Jin

Gerhardt

2017

AIP Advances

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This paper investigated the effect of temperature and pressure on the microstructure and electrical behavior of compression molded and mechanically blended polymer composites. Poly (methyl methacrylate) (PMMA) and antimony tin oxide (ATO) were used as the matrix and conductive filler respectively and the composition was varied from 0 to 1.75 ATO vol %. Mixtures of the two precursor materials were compression molded at temperatures ranging from 150 to 190 °C and pressures ranging from 12 to 50 MPa. It was found that a segregated network microstructure was formed in all cases but that the distribution of the conductive ATO fillers varied as a function of the compression molding temperature and pressure used. The thickness of the specimens, determined by the amount of precursor materials and pressure used during compression molding, was also found to affect the resulting microstructure and concomitant properties. The electrical conductivity of these polymer matrix composites can be increased by up to 2 orders of magnitude by decreasing the processing temperature, while maintaining the processing pressure and the filler concentration constant. On the other hand, the flexibility of PMCs can be improved by increasing the processing temperature. For the compositions evaluated, the maximum electrical conductivity obtained was 5 x 10-3 S/m (about three orders of magnitude lower than the conductivity of the filler). Finite element simulations were used to model this microstructure-driven phase segregated percolation behavior. COMSOL Multiphysics® was used to calculate the electric potential and current density distribution in a 3D geometry. There was good agreement between the experimental and simulation results.

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Section: B Effects Of Processing Parameters On the Electrical Conducmentioning

confidence: 99%

Section: B Effects Of Processing Parameters On the Electrical Conducmentioning

confidence: 99%

Fabrication and simulation of semi-transparent and flexible PMMA/ATO conductive nanocomposites obtained by compression molding at different temperatures and pressures

Jin

Gerhardt

2017

AIP Advances

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“…It finds use for many applications such as shatterproof glass, [17] additive to control the temperature-dependent viscosity of lubricating oils and hydraulic fluids, [18] as a bone graft material and a femoral window plug in total hip replacement and also in orthopedic surgery to fix prosthetic components, [19] intraocular lenses, [20] cores of communication grade polymer optical fibers, [21] and also as substrate for polymer optoelectronic devices [22] such as materials to fabricate integrated waveguides. [23] It is an intrinsically amorphous material.…”

Section: Full Papermentioning

confidence: 99%

Modifying Thermal Expansion of Polymer Composites by Blending with a Negative Thermal Expansion Material

Chandra

Meyer

Best

et al. 2007

Macro Materials & Eng

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Large positive thermal expansion in polymers is one of the major drawbacks in using polymers in applications where the sample dimensions play an important role. In this paper, we report a method to vary the thermal expansion of PMMA‐based polymer composites by blending with a negative thermal expansion material, PbTiO3. It is shown that the thermal expansion coefficient of the composite can be tailored by suitably adjusting the ratio of polymer and ceramic filler. The coefficient of thermal expansion has been measured using temperature‐dependent step‐height measurements via confocal microscopy. Using SEM, it is shown that the ceramic particles are homogeneously dispersed in the polymer matrix if the composite is obtained by the polymerization of the suspension of PbTiO3 in the monomer MMA. Composite formation is confirmed using XRD and Raman spectroscopy. To estimate the technological viability of such composite films, preliminary results of stress‐strain measurements are also presented.magnified image

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“…2. As mentioned above, once the tip and the measured surface are in contact, the force versus distance measurements are essentially the same as the stress-strain measurements commonly used in material testing [28][29][30]. The main difference is that AFM tips are usually sharp with an end radius less than several tens of nanometers.…”

Section: A Phenomenological Modelmentioning

confidence: 99%

“…If the gradient of the attractive force becomes larger than the force constant of the cantilever, the tip would make a jump to contact with the surface. Once in contact, the measurements of force versus distance are similar to stress-strain measurements commonly used in material testing, in which the tip keeps compressing the sample surface and where the repulsive force from the surface bends the cantilever upward producing the repulsive portion of the force-distance curve [28][29][30]. The slope of this part of the curve contains information about the elastic modulus of the sample.…”

Section: Introductionmentioning

confidence: 99%

Probing the viscoelastic response of glassy polymer films using atomic force microscopy

Yang

Rao

Yin

et al. 2006

Journal of Colloid and Interface Science

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Viscosity measurement of organic glasses below and above glass transition temperature

Cited by 34 publications

References 12 publications

Fabrication and simulation of semi-transparent and flexible PMMA/ATO conductive nanocomposites obtained by compression molding at different temperatures and pressures

Fabrication and simulation of semi-transparent and flexible PMMA/ATO conductive nanocomposites obtained by compression molding at different temperatures and pressures

Modifying Thermal Expansion of Polymer Composites by Blending with a Negative Thermal Expansion Material

Probing the viscoelastic response of glassy polymer films using atomic force microscopy

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