Diffusion of permanent liquid dye molecules in human hair investigated by positron lifetime spectroscopy

Chandrashekara, M.; Ranganathaiah, C.

doi:10.1016/j.colsurfb.2008.11.014

Cited by 20 publications

(18 citation statements)

References 22 publications

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“…Hence, the larger the hole size is, the smaller the overlap is; hence, longer the lifetime is. So, the o ‐Ps pickoff lifetime (τ 3 ) and the intensity ( I 3 ) of o ‐Ps are measures of the free‐volume size and the number density, respectively 21, 22. As shown in Figure 7, the o ‐Ps lifetime and free‐volume cell size increased with increasing filler content up to 10 wt %; thereafter, they showed a slight decreasing tendency.…”

Section: Resultsmentioning

confidence: 93%

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Characterization of nanosilica‐filled epoxy composites for electrical and insulation applications

Veena¹,

Renukappa²,

Raj

et al. 2011

J of Applied Polymer Sci

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We report in this article the results of nanosilica (SiO 2 )-filled epoxy composites with different loadings and their electrical, thermal, mechanical, and free-volume properties characterized with different techniques. The morphological features were studied by transmission electron microscopy, and differential scanning calorimetry was used to investigate the glass-transition temperature (T g ) of the nanocomposites. The properties of the nanocomposites showed that the electrical resistivity (q), ultimate tensile strength, and hardness of the composites increased with SiO 2 weight fraction up to 10 wt % and decreased thereafter; this suggested that the beneficial properties occurred up to this weight fraction. The temperature and seawater aging had a negative influence on q; that is, q decreased with increases in the temperature and aging. The free-volume changes (microstructural) in the composite systems correlated with seawater aging but did not correlate so well with the mechanical properties.

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Section: Resultsmentioning

confidence: 93%

“…The operation details, data acquisition, free‐volume parameter calculation, and so on can be found in Refs. 21 and 22.…”

Section: Methodsmentioning

confidence: 99%

Characterization of nanosilica‐filled epoxy composites for electrical and insulation applications

Veena¹,

Renukappa²,

Raj

et al. 2011

J of Applied Polymer Sci

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“…The lifetime of o ‐Ps depends on the overlap of the Ps wave function with the electron wave function of the free‐volume cavity. Therefore, larger the hole size, smaller is the overlap and hence lifetime is longer . Also, it has been well established that the free volume hole size and concentration correlates to several visco‐elastic properties of the polymer under study.…”

Section: Resultsmentioning

confidence: 99%

Free volume as an internal material parameter to probe interfaces in ternary polymer blends: A positron lifetime study

Dinesh

Ranganathaiah

2013

J of Applied Polymer Sci

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A new method to characterize individual interfaces in ternary polymer blends from experimentally measured fractional free volume from Positron Annihilation Lifetime Spectroscopy (PALS) has been developed. By this, we derive the composition dependent miscibility level in ternary polymer blends. This method has its genesis in KRZ (Kirkwood-Risemann-Zimm) theory which introduces hydrodynamic interaction parameter as a measure of excess friction generated at the interface between dissimilar polymer chains resulting in energy dissipation. The method successfully applied for binary blends has been theoretically modified to suit ternary blends in the present work. The efficacy of this method has been tested for two ternary blends namely polycaprolactone/ poly(styrene-co-acrylonitrile)/poly(vinyl chloride) (PCL/SAN/PVC) and polycaprolactone/poly(vinyl chloride)/poly(vinyl acetate) (PCL/PVC/PVAc) in different compositions. We obtained a maximum effective hydrodynamic interaction (a eff ) of 212.60 at composition 80/10/10 of PCL/PVC/PVAc while PCL/SAN/PVC showed 21.60 at 68/16/16 composition. These results suggest that these compositions produce high miscibility level as compared to other compositions. DSC measurements have also been used to supplement positron results.

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“…The positron annihilation lifetime spectra in neat epoxy and MMT loaded nanocomposites were recorded for the pure epoxy and nanocomposites using the positron lifetime spectrometer [17, 18]. The positron lifetime spectrometer consisted of a fast–fast coincidence system with BaF2 scintillators (Scionix, Holland) coupled to photomultiplier tubes (Type XP2020/Q) with quartz windows as detectors.…”

Section: Experimental Measurements and Test Methodsmentioning

confidence: 99%

“…The operation details, data acquisition, analysis of the spectra, and free volume parameters calculation can be found in Refs. 17, 18.…”

Section: Experimental Measurements and Test Methodsmentioning

confidence: 99%

Montmorillonite nanoclay filler effects on electrical conductivity, thermal and mechanical properties of epoxy‐based nanocomposites

Rashmi¹,

Renukappa²,

Ranganathaiah

et al. 2011

Polymer Engineering & Sci

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Epoxy-based nanocomposites with 2, 5, and 7 wt% of montmorillonite (MMT) nanoclay were prepared using high shear melt mixing technique. The microstructural features of the nanocomposites were investigated by transmission electron microscopy (TEM). The thermal and mechanical properties were measured using differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), and dynamic mechanical analyzer (DMA). Further, the effect of voltage, temperature, seawater aging on the electrical conductivity (r DC ) of the nanocomposites was also measured. To understand the free volume behavior upon filler loading, and to observe the connectivity between microstructure and other properties, positron annihilation lifetime spectroscopy was used. The TEM results revealed that MMT nanoparticles were uniformly dispersed in the epoxy matrix. Experimental results showed that the inclusion of 2 wt% MMT nanofiller increased the T g , electrical conductivity, thermal stability, modulus, free volume of the epoxy nanocomposite significantly. This is well explained from the results of T g (DSC and DMA), thermal stability, TGA residue, free volume analysis, and electrical conductivity.

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Diffusion of permanent liquid dye molecules in human hair investigated by positron lifetime spectroscopy

Cited by 20 publications

References 22 publications

Characterization of nanosilica‐filled epoxy composites for electrical and insulation applications

Characterization of nanosilica‐filled epoxy composites for electrical and insulation applications

Free volume as an internal material parameter to probe interfaces in ternary polymer blends: A positron lifetime study

Montmorillonite nanoclay filler effects on electrical conductivity, thermal and mechanical properties of epoxy‐based nanocomposites

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