A New Look at Measurements of Network Density

1986 ◽  
Vol 59 (1) ◽  
pp. 138-141 ◽  
Author(s):  
Robert A. Hayes
Keyword(s):  
Hysteresis Loop ◽  
Interaction Parameters ◽  
Network Density ◽  
Stress Strain ◽  
Solvent Interaction ◽  
Solvent Method ◽  
Strain Data ◽  
Good Agreement ◽  
Polymer Solvent ◽  
New Look

Abstract A two-solvent method for determining the polymer-solvent interaction parameters independently of stress-strain data is described. The values obtained are much lower than those reported previously. Network densities calculated from swelling data and these interaction parameters are in good agreement with those calculated from the return portion of a hysteresis loop at high elongations.

Collagen; ultrastructure and its relation to mechanical properties as a function of ageing

1972 ◽  
Vol 180 (1060) ◽  
pp. 293-315 ◽  
Keyword(s):  
Deformation Behaviour ◽  
Life Time ◽  
Periodic Pattern ◽  
Albino Rats ◽  
Structure And Properties ◽  
Stress Strain ◽  
Good Correspondence ◽  
Bearing Unit ◽  
Strain Data ◽  
Good Agreement

Tail tendons from Fischer and Sprague-Dawly albino rats of ages from 2 weeks to 3 years were investigated under the polarizing microscope as regards structure and deformation behaviour. Periodically extinguishing bands were observed along the otherwise featureless tendons. By analysing the behaviour of this extinction pattern under appropriate rotations of the tendon, it could be deduced that the orientation of the basic birefringent units varies periodically along the tendon and that this periodic pattern corresponds to a planar arrangement of the anisotropic entities. All the relevant parameters of this periodic structure could be determined in a representative manner from polarizing optics alone. Subdivision of the tendons revealed regularly undulating or rather crimped subunits in good correspondence to what has been deduced from the extinction bands in the intact tendons. The crimp angle was found to decrease while the periodicity increased - in approximate proportion to the length of the tail - with the age of the rat implying constancy of crimp number during the life time of the animal. On elongation the periodicity was gradually removed. The calculated fibre elongation necessary to eliminate the crimp was in good agreement with observation for mature rats but was larger for young rats implying the simultaneous stretching of the fibre itself. Stress-strain properties of tendons were measured and models for crimp straightening were tested. It was found that a model containing inflexible hinges, corresponding to the ‘elastica’ problem in mechanics gave reasonable fit with experiment. Analysis of stress-strain data on this basis leads to a basic load bearing unit, the diameter of which increases from 100 to 500 nm with the age of the animal. Implications of these findings for the structure and properties of the tendons, also in relation to ageing are pointed out.

Polymer–solvent interaction parameters in polymer solutions at high polymer concentrations

2002 ◽  
Vol 969 (1-2) ◽  
pp. 245-254 ◽  
Author(s):  
C. Etxabarren ◽  
M. Iriarte ◽  
C. Uriarte ◽  
A. Etxeberrı́a ◽  
J.J. Iruin
Keyword(s):  
Polymer Solutions ◽  
Interaction Parameters ◽  
High Polymer ◽  
Solvent Interaction ◽  
Polymer Solvent

PHENOMENOLOGICAL MODEL FOR COUPLED ALCOHOL AND TEMPERATURE SENSITIVE HYDROGELS

2011 ◽  
Vol 03 (02) ◽  
pp. 279-298 ◽  
Author(s):  
JUNDIKA CANDRA KURNIA ◽  
ERIK BIRGERSSON ◽  
ARUN S. MUJUMDAR ◽  
SOCK PENG TAY ◽  
YONG KIN YEW ◽  
...  
Keyword(s):  
Interaction Parameter ◽  
Temperature Sensitive ◽  
Solvent Interaction ◽  
Model Predictions ◽  
Relevant Field ◽  
Transient Models ◽  
Stimuli Sensitive ◽  
Good Agreement ◽  
Water Alcohol ◽  
Polymer Solvent

A mathematical model for stimuli-sensitive hydrogels in a water-alcohol solution is presented and analyzed, in which a new polymer-solvent interaction parameter is proposed to capture the deformation of the hydrogel due to changes in the external alcohol content and temperature. The nature of this parameter is determined in the limit of pure dilatation for poly(N-isopropylacrylamide) hydrogels immersed in tempered water-methanol and -ethanol solutions. Overall, good agreement between the resulting model predictions and experiments is achieved; the transition temperatures and "re-entrant phenomenon" are also captured reasonably well. The herein derived expression for the polymer-solvent interaction parameter can be introduced into more generic transient models that also account for fluxes of the relevant field variables.

Micromechanical Modeling of Two-Phase Steels

2000 ◽  
Vol 653 ◽  
Author(s):  
Mikael Nygårds ◽  
Dilip Chandrasekaran ◽  
Peter Gudmundson
Keyword(s):  
Micromechanical Model ◽  
Tensile Tests ◽  
Micromechanical Modeling ◽  
Uniaxial Tensile ◽  
The Finite Element Method ◽  
Stress Strain ◽  
Two Phase ◽  
Representative Cell ◽  
Strain Data ◽  
Good Agreement

AbstractA two-dimensional micromechanical model based on the finite element method is presented to model two-phase ferritic/pearlitic steels, by aid of generalised plane strain elements. A periodic representative cell containing 100 ferrite grains, and the desired fraction pearlite is used. By applying periodic boundary conditions, loading by an average stress or strain state is possible.Uniaxial tensile tests were performed on specimens containing the ferrite and pearlite microstructures, and on two-phase materials containing 25% and 58% pearlite respectively. The stress-strain data of the pearlite material is used to fit a laminar dependent Taylor relation to represent the pearlite workhardening. Thereafter, laminar spacings in the two-phase materials are measured, and the total stress-strain response of the materials is modelled. Comparisons between generated data and experiments show good agreement up to a strain of 2%.

Sign in / Sign up

Export Citation Format

Share Document