Plastic Deformation of Glassy Polymers: Correlation Between Shear Activation Volume and Entanglement Density

Ho, Janet; Govaert, Leon Le; Utz, Marcel

doi:10.1557/proc-734-b3.3

Cited by 10 publications

(14 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is, therefore, not clear whether there should be a direct correlation between the rubber-elastic response of an entangled or cross-linked network above T g and a neo-Hookean strainhardening response below T g , except possibly at very high entanglement or network densities, such as in the case of poly(carbonate) [34]. However, the chemical cross-link density, as shown in this study, as well as the entanglement density of linear glassy polymers, as shown recently by Ho et al [35], seem to affect the viscous part of the total stress significantly, which can be accounted for by using a strain and crosslink-dependent activation volume. The importance of thermal mobility of polymer chains on strain-hardening was also recognized by van Melick et al [6].…”

Section: Cross-linked Pmmasupporting

confidence: 76%

Non-linear, rate-dependent strain-hardening behavior of polymer glasses

Wendlandt

Tervoort

Suter

2005

Polymer

112

View full text Add to dashboard Cite

Section: Cross-linked Pmmasupporting

confidence: 76%

Non-linear, rate-dependent strain-hardening behavior of polymer glasses

Wendlandt

Tervoort

Suter

2005

Polymer

112

View full text Add to dashboard Cite

“…In metallic glass it is of interest to observe structural relaxation below T g which induces the embrittlement phenomenon [52,53]. The experiments have shown that many polymers present higher activation volume than metallic glasses during the deformation process [54]. Benefiting from the chemical heterogeneity of the side group and the chain backbone in macromolecules, local motion in polymers is easier than in glassy alloys.…”

Section: Stress Relaxation In La-based Metallic Glassmentioning

confidence: 99%

Characteristics of stress relaxation kinetics of La 60 Ni 15 Al 25 bulk metallic glass

et al. 2015

View full text Add to dashboard Cite

a b s t r a c tThe b relaxation typically plays an important role in the plastic deformation of glassy materials. Compared with amorphous polymers, most of the metallic glasses do not show evident b relaxation based on mechanical spectroscopy. However, La 60 Ni 15 Al 25 bulk metallic glass (BMG) exhibits a prominent b relaxation process, which could be an ideal model alloy to investigate the correlation between the b relaxation and mechanical behavior of metallic glasses. In this work, compressive properties and stress relaxation at high temperature (below glass transition temperature T g ) were studied. Stress relaxation of La 60 Ni 15 Al 25 BMG was measured by uniaxial compressive tests and mechanical spectroscopy around both a and b relaxation temperature domain. At higher temperatures and sufficiently low strain rate, the flow behavior of the La 60 Ni 15 Al 25 BMG could be simulated by a master curve, showing that the behavior is independent of temperature, especially on the proximity of the b relaxation process. Because the existence of the b relaxation, a high value of the activation volume for the plastic deformation could be ascribed to the existence of a specific atomic arrangement in the La 60 Ni 15 Al 25 BMG. It is found that compressive stress relaxation kinetics parameter remains temperature independent below T g .

show abstract

“…47 Although the individual material parameters in eq 9, such as size, shear strain, and activation energy of the STZ have been experimentally obtained for different MGs (see Chapter 7 of ref 16 for details), their numerical evaluation for PGs have been limited to some theoretical modeling and simulations, 16,29 and a few experimental studies. 28,30 For the conventional polymeric materials where γ T Ωτ ≫ 2k B Θ at temperatures below their glass transition temperatures, eq 8 can be reduced to…”

Section: Theory Of Homogeneous Flow For Glassymentioning

confidence: 99%

Nanoindentation Study of Yielding and Plasticity of Poly(methyl methacrylate)

2015

View full text Add to dashboard Cite

In this study, an experimental approach is used to characterize the geometrical and micromechanical properties of the shear transformation zones (STZs) in glassy polymers. Nanoindentation experiments have been conducted on both ascast and annealed poly(methyl methacrylate) (PMMA) at different strain rates and temperatures, utilizing continuous stiffness measurement (CSM) technique at room temperature indentations, and conventional loading rate control method for nanoindentations at elevated temperatures. Employing a homogeneous flow theory for analyzing the experimental data, the geometrical properties of the STZs are observed to be almost independent of the thermal history of the samples. While the transformation shear strain of the STZ in PMMA is found to be slightly smaller than that in glassy metals, the size of the STZ in this polymer is shown to be at least 10 times of that in metallic glasses. On the other hand, the activation energy of a single STZ is found to change drastically with annealing. In addition, analysis of the rate sensitivity of the shear flow stress reveals a remarkable transition at a certain strain rate which is believed to pertain to the β-transition. This transition is well-matched with a jump in the STZ activation energy at the same strain rate range; hence, the jump is referred to as the β-transition activation energy, which is found to be about 10% of the STZ nucleation energy for PMMA.

show abstract

Plastic Deformation of Glassy Polymers: Correlation Between Shear Activation Volume and Entanglement Density

Cited by 10 publications

References 39 publications

Non-linear, rate-dependent strain-hardening behavior of polymer glasses

Non-linear, rate-dependent strain-hardening behavior of polymer glasses

Characteristics of stress relaxation kinetics of La 60 Ni 15 Al 25 bulk metallic glass

Nanoindentation Study of Yielding and Plasticity of Poly(methyl methacrylate)

Contact Info

Product

Resources

About