scholarly journals Glass Transition and Interfacial Segmental Dynamics in Polymer-Particle Composites

2008 ◽  
Vol 81 (3) ◽  
pp. 506-522 ◽  
Author(s):  
C. G. Robertson ◽  
C. M. Roland
Keyword(s):  
Glass Transition ◽  
Relaxation Times ◽  
Polymer Particle ◽  
Polymer Chains ◽  
Nano Particle ◽  
Segmental Mobility ◽  
Segmental Dynamics ◽  
Reinforcing Fillers ◽  
Segmental Relaxation ◽  
Polymer Interaction

Abstract We review the literature concerned with the effect of proximity to a filler surface on the local segmental mobility of polymer chains. This mobility is commonly assessed from either the glass transition temperature, Tg, or the segmental relaxation times measured by mechanical, dielectric, or NMR spectroscopy. Published studies report increases, decreases, or no change in Tg upon the addition of carbon black, silica, and other reinforcing fillers. Similarly, the segmental relaxation times have been found to increase or be invariant to the presence of nanometer-sized particles. Some of these discrepancies can be ascribed to ambiguous methods of data analysis; others likely reflect the variation in filler-polymer interaction among different systems. There are unequivocal examples of polymers that have segmental dynamics and glass transitions unaffected by nano-particle reinforcement. However, the general principles governing the behavior remain to be clarified, with further work, focusing on the micromechanics at the particle interface, required for resolution of this important aspect of rubber science and technology.

scholarly journals Effect of Temperature and Pressure on Segmental Relaxation in Polymethylphenylsiloxane

2003 ◽  
Vol 76 (5) ◽  
pp. 1106-1115 ◽  
Author(s):  
S. Pawlus ◽  
S. J. Rzoska ◽  
J. Ziolo ◽  
M. Paluch ◽  
C. M. Roland
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Pressure Dependence ◽  
Activation Volume ◽  
Relaxation Times ◽  
Effect Of Temperature ◽  
Loss Peak ◽  
Glass Transition Temperatures ◽  
Segmental Relaxation ◽  
Temperature And Pressure

Abstract Segmental relaxation in a series of polymethylphenylsiloxanes (PMPS) was studied using dielectric spectroscopy. The measurements covered a temperature range of more than 40 deg at pressures from ambient to 115 MPa. The results confirmed that the shape of the loss peak is independent of temperature, pressure and molecular weight. Consequently, the Tg -scaled dependence of the relaxation times was also independent of molecular weight. The pressure dependence of the relaxation times was characterized by means of the activation volume. This quantity changes markedly with pressure at a given temperature. However, the activation volume at the respective glass transition temperatures of the PMPS are essentially invariant to molecular weight. Finally, we measured the dependence of Tg on pressure, with the results well-described by the Andersson equation.

COOPERATIVE FREE VOLUME RATE MODEL APPLIED TO THE PRESSURE-DEPENDENT SEGMENTAL DYNAMICS OF NATURAL RUBBER AND POLYUREA

2019 ◽  
Vol 92 (4) ◽  
pp. 612-624
Author(s):  
Ronald P. White ◽  
Jane E. G. Lipson
Keyword(s):  
Natural Rubber ◽  
Free Volume ◽  
Relaxation Times ◽  
Close Packing ◽  
Rate Model ◽  
Segmental Dynamics ◽  
Glass Forming ◽  
Segmental Relaxation ◽  
The Difference ◽  
New Applications

ABSTRACT We apply the cooperative free volume (CFV) rate model for pressure-dependent dynamics of glass-forming liquids and polymer melts, focusing on two new applications of the model, to natural rubber and to polyurea. In CFV, segmental relaxation times, τ, are analyzed as a function of temperature (T) and free volume (Vfree), where the latter provides an insightful route to expressing dynamics relative to using the system's overall total volume (V). Vfree is defined as the difference between the total volume and the volume at close packing and is predicted independently of the dynamics for any temperature and pressure using the locally correlated lattice equation-of-state analysis of characteristic thermodynamic data. The new results for natural rubber and polyurea are discussed in the context of results on a set of polymeric and small-molecule glass formers that had previously been modeled with CFV. We also discuss the results in the context of recent connections that we have made with the density-scaling approach.

Effects of counterion size and backbone rigidity on the dynamics of ionic polymer melts and glasses

2017 ◽  
Vol 19 (40) ◽  
pp. 27442-27451 ◽  
Author(s):  
Yao Fu ◽  
Vera Bocharova ◽  
Mengze Ma ◽  
Alexei P. Sokolov ◽  
Bobby G. Sumpter ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Relaxation Time ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polymer Melts ◽  
Static Dielectric Constant ◽  
Segmental Dynamics ◽  
Ionic Polymer ◽  
Segmental Relaxation

Backbone rigidity, counterion size and the static dielectric constant affect the glass transition temperature, segmental relaxation time and decoupling between counterion and segmental dynamics in significant manners.

scholarly journals Structural Arrest and Thermodynamic Scaling in Filler-Reinforced Polymers

2009 ◽  
Vol 82 (2) ◽  
pp. 202-213 ◽  
Author(s):  
C. G. Robertson ◽  
R. Bogoslovov ◽  
C. M. Roland
Keyword(s):  
Glass Transition ◽  
Volume Fraction ◽  
Filler Concentration ◽  
Scaling Exponent ◽  
Segmental Dynamics ◽  
Reinforced Polymers ◽  
Filler Volume Fraction ◽  
Segmental Relaxation ◽  
Filler Network

Abstract The role of small silica particles on the stiffness and glass transition dynamics of polyvinylacetate (PVAc) was examined for filler volume fraction (ϕ) from 0 to 0.28. Whereas the influences of bound polymer and a strain-dependent filler network were clearly noted in the shear properties, the only effect of filler on the bulk modulus was the reduction in deformable polymer. The calorimetric glass transition of PVAc and its dependence on cooling rate were unaltered by the presence of the silica, in agreement with previous dielectric relaxation results. In contrast to the temperature dependence of the segmental dynamics, which was independent of ϕ, the effect of volume on segmental relaxation was amplified by the addition of silica. This resulted in larger values for the thermodynamic scaling exponent (γ), which also increased sharply at the filler concentration corresponding to the development of a percolated filler network.

The Influence of Glass-Transition Temperatures of Poly (Ethylene Terephthalate) Films on the Fading Behavior of Fluorescent Brightening Agents

1977 ◽  
Vol 47 (5) ◽  
pp. 361-364 ◽  
Author(s):  
Keiko Suganuma
Keyword(s):  
Glass Transition ◽  
Physical State ◽  
Polymer Chains ◽  
Transition Temperatures ◽  
Segmental Mobility ◽  
Heat Setting ◽  
Glass Transition Temperatures ◽  
The Difference ◽  
Poly Ethylene ◽  
Pet Films

Studies have been made of the dependence of the fading behavior of dispersed-type fluorescent brightening agents in poly (ethylene tetrephthalate) (PET) films on the temperature at which the films have been heat-set and dyed. A measure of the variation in the fading behavior can be given by parameter A, defined as k2 (1st-order)ɛ/ k2' (2nd-order), as in Hida's equation. This constant decreases with increase in the temperatures of heat-setting and dyeing of PET films. And the rate of fading increases with increase in these temperatures. It is found that the physical state of adsorbed dye on PET films varies with these temperatures. The glass-transition temperatures Tg of heat-set PET films were measured. Tg decreases with increase in the heat-setting temperature. The values of parameter A are related to the difference between the dyeing temperature and Tg ( T — Tg), and so the physical state of adsorbed dye on PET films is considered to be governed by the segmental mobility of polymer chains during dyeing. The variation of the rate of fading and parameter A with the dyeing and heat-setting temperatures of PET films might be explained in terms of the additional free volume.

A simulation study on the glass transition behavior and relevant segmental dynamics in free-standing polymer nanocomposite films

Soft Matter ◽  
2019 ◽  
Vol 15 (22) ◽  
pp. 4476-4485 ◽  
Author(s):  
Shu-Jia Li ◽  
Hu-Jun Qian ◽  
Zhong-Yuan Lu
Keyword(s):  
Thin Films ◽  
Glass Transition ◽  
Free Surface ◽  
Simulation Study ◽  
Polymer Nanocomposite ◽  
Polymer Chains ◽  
Nanocomposite Films ◽  
Free Standing ◽  
Segmental Dynamics ◽  
Strong Confinement

In polymer/nanoparticle composite (PNC) thin films, polymer chains experience strong confinement effects not only at the free surface area but also from nanoparticles (NPs).

Effect of Temperature on Ozone Cracking of Rubbers

1966 ◽  
Vol 39 (3) ◽  
pp. 643-650
Author(s):  
A. N. Gent ◽  
J. E. McGrath
Keyword(s):  
Polymer Chains ◽  
Effect Of Temperature ◽  
Ozone Molecule ◽  
Segmental Mobility ◽  
Network Chain ◽  
Styrene Copolymers ◽  
Rates Of Growth ◽  
Rate Controlling Step ◽  
Limiting Value ◽  
Butadiene Styrene

Abstract The rates of growth of single ozone cracks have been measured for vulcanizates of a series of butadiene—styrene copolymers, over a temperature range from − 5° C to 95° C. The rates appear to be determined by two mechanisms. At low temperatures, near the glass transition temperature, they are quantitatively related to the segmental mobility of the polymer. The principal rate-controlling step in this case is concluded to be movement of the polymer chains after scission to yield new surface. At high temperatures the rate approaches a limiting value of 10−3 cm/sec/mg of ozone/1. This is about 1/1000 of the maximum possible value when instantaneous reaction of one incident ozone molecule causes scission of one network chain.

Interlamellar Incorporation of Charged Polymer Nanobeads into Sodium Montmorillonite

2004 ◽  
Vol 847 ◽  
Author(s):  
Svetlana Khvan ◽  
Sang-Soo Lee ◽  
Junkyung Kim
Keyword(s):  
Polymer Matrix ◽  
Surface Characterization ◽  
Particle Surface ◽  
Polymer Particle ◽  
Polymer Chains ◽  
Sem Images ◽  
Tof Sims ◽  
Strong Adhesion ◽  
Density Surface ◽  
Cationic Exchange

ABSTRACTComplete delamination of clay in polymer matrix has been strongly prohibited due to strong adhesion of guest polymer chains between hydrophilic clay as well as degradation and desorption of organic materials in the gallery at high temperature. Incorporation of charged nanosized polystyrene beads directly into the gallery of pristine clay through exfoliation-exchange mechanism has been proposed to overcome the drawbacks.Synthesis of polymer nanobeads via emulsifier-free emulsion polymerization allowed to achieving formation of particles of appropriate particle size and surface charge density. Surface characterization, performed with XPS and ToF SIMS, has provided the results on the existence and the nature of the functional groups on the polymer particle surface, which have been found to be in a good compliance.Morphology of polymer-incorporated clay was observed from TEM, FE-SEM images. Study on mechanism of incorporation via XRD, XPS, ToF-SIMS suggested that adsorption of polymer nanobeads through cationic exchange of intergallery cation of clay for onium ion at the surface of polymer nanobead not only improves compatibility of clay with polymer matrix, but, what is essential, dramatically promotes expansion of clay gallery.

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