PVT of amorphous and crystalline polymers and their nanocomposites

Utracki, L. A.

doi:10.1016/j.polymdegradstab.2009.07.020

Cited by 15 publications

(5 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The flexibility ratio 3c/s -where 3c represents external volume dependent degrees of freedom and s is the number of segments in the polymer chain [36][37][38] -is generally assigned the value 1. 36 and 37) are the reduced PVT variables and y is the fraction of occupied volume, related to the free volume fraction through: f v = 1 − y. P * , V * , and T * are the characteristic scaling parameters in MPa, cm 3 /g, and K, respectively, that are determined from PVT equilibrium melt data and contain the molecular characteristics of the system.…”

Section: Free Volume Diffusion Modelmentioning

confidence: 99%

Free volume holes diffusion to describe physical aging in poly(mehtyl methacrylate)/silica nanocomposites

Cangialosi

Boucher

Alegría

et al. 2011

The Journal of Chemical Physics

View full text Add to dashboard Cite

The spontaneous thermodynamically driven densification, the so-called physical aging, of glassy poly(mehtyl methacrylate) (PMMA) and its nanocomposites with silica has been described by means of the free volume holes diffusion model. This mechanism is able to account for the partial decoupling between physical aging and segmental dynamics of PMMA in nancomposites. The former has been found to be accelerated in PMMA/silica nanocomposites in comparison to "bulk" PMMA, whereas no difference between the segmental dynamics of bulk PMMA and that of the same polymer in nanocomposites has been observed. Thus, the rate of physical aging also depends on the amount of interface polymer/nanoparticles, where free volume holes disappear after diffusing through the polymer matrix. The free volume holes diffusion model is able to nicely capture the phenomenology of the physical aging process with a structure dependent diffusion coefficient.

show abstract

Section: Free Volume Diffusion Modelmentioning

confidence: 99%

Free volume holes diffusion to describe physical aging in poly(mehtyl methacrylate)/silica nanocomposites

Cangialosi

Boucher

Alegría

et al. 2011

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…35 In the same system, we can observe both the increase and decrease depending on the nonmaterial load-ing. 36 The decrease of the free volume will reduce the available space for molecules to move in, which in turn will limit the molecular mobility of the PP chains. 37 Moreover, nanoclay particles acted as obstacles which hindered the molecular mobility of the nanocomposites as compared to the neat resin.…”

Section: Viscoelastic Analysis: Experimentalmentioning

confidence: 99%

Viscoelastic properties of polypropylene/organo‐clay nano‐composites prepared using miniature lab mixing extruder from masterbatch

Ali

Elleithy

2011

J of Applied Polymer Sci

View full text Add to dashboard Cite

Polypropylene (PP) was melt blended with nano organo-clay masterbatch at different ratios; namely 5, 10, and 15 wt % of nano-clay. The effect of organo-clay content on the viscoelastic properties of the nano-composite was studied. A miniature laboratory mixing extruder, LME, was used to blend the nano organo-clay masterbatch with PP at 260 C and 250 rpm. The blend was pelletized first, and then a thin ribbon was extruded. Two viscoelastic tests were performed; frequency sweep at constant temperature of 80 C, and temperature sweep at constant frequency of 1.0 rad/s. As the loading of nano-clay increased, the storage modulus, G', and the thermal resist-ance increased as well. Different viscoelastic models were tried and 3-elements Maxwell model was found to describe well the viscoelastic properties of the nano-composites. The ratio of the complex modulus to the corresponding matrix modulus at different frequencies was found to vary proportional to the nanoclay loading. This dependency was described reasonably well by modified Guth model using particle aspect ratio of 12.1.

show abstract

“…Certainly, the eventual effect of nanoparticles on hole fraction or on free volume is a subject of interests, but very few paper refer to PVT measurements of nanocomposites. The efforts of Utracki [ 52 , 53 , 54 , 55 , 56 , 57 , 58 ] have been mostly directed to adapt and apply the PVT equations of state to nanocomposites obtained from dispersions of organoclays, in amorphous and semicrystalline polymer matrixes. The existence of a percolation threshold for the constitution of a nanoparticle/polymer chain network is not treated in these works, probably because PVT measurements are not able to detect this physical fact.…”

Section: Resultsmentioning

confidence: 99%

Liquid-State and Solid-State Properties of Nanotube/Polypropylene Nanocomposites Elaborated via a Simple Procedure

et al. 2013

View full text Add to dashboard Cite

Non-modified Multiwalled Carbon Nanotubes (MWCNT) and polypropylene (PP) in absence of compatibilizer have been chosen to elaborate MWCNT/PP nanocomposites using a simple melt-mixing dispersing method. Calorimetry results indicate little effect of MWCNTs on crystallinity of PP, revealing not much interaction between nanotubes and PP chains, which is compatible with the employed manufacturing procedure. In any case, a hindering of polymer chains motion by MWCNTs is observed in the molten state, using oscillatory flow experiments, and a rheological percolation threshold is determined. The percolation limit is not noticed by Pressure-Volume-Temperature (PVT) measurements in the melt, because this technique rather detects local motions. Keeping the nanocomposites in the molten state provokes an electrical conductivity increase of several orders of magnitude, but on ulterior crystallization, the conductivity decreases, probably due to a reduction of the ionic conductivity. For a concentration of 2% MWCNTs, in the limit of percolation, the conductivity decreases considerably more, because percolation network constituted in the molten state is unstable and is destroyed during crystallization.

show abstract

PVT of amorphous and crystalline polymers and their nanocomposites

Cited by 15 publications

References 61 publications

Free volume holes diffusion to describe physical aging in poly(mehtyl methacrylate)/silica nanocomposites

Free volume holes diffusion to describe physical aging in poly(mehtyl methacrylate)/silica nanocomposites

Viscoelastic properties of polypropylene/organo‐clay nano‐composites prepared using miniature lab mixing extruder from masterbatch

Liquid-State and Solid-State Properties of Nanotube/Polypropylene Nanocomposites Elaborated via a Simple Procedure

Contact Info

Product

Resources

About