Thermodynamic Properties and Polymer Solvent Interaction Parameters for Silicone Rubber Networks

1968 ◽  
Vol 41 (3) ◽  
pp. 608-620 ◽  
Author(s):  
R. D. Seeley
Keyword(s):  
Thermodynamic Properties ◽  
Network Structure ◽  
Silicone Rubber ◽  
Volume Fraction ◽  
Swelling Behavior ◽  
Effective Number ◽  
Solvent Interaction ◽  
Molecular Weights ◽  
Linear Relationships ◽  
Equilibrium Swelling

Abstract The relationships of the volume fraction of rubber (silica reinforced silicone rubber vulcanizates) at equilibrium swelling to a corresponding solvent-rubber interaction parameter have been found to agree quite well with theory throughout the entire range of volume fractions investigated. Composite sigmoidal curves were constructed from the ϕrs versus μ data for the different vulcanizates. Temperature and solvent effects were found to merely shift the plotting points along the curves for the respective vulcanizates. Contrary to other work linear relationships between ϕrs and μ were found in this investigation only in the range of moderate dilations. Such relationships could lead to serious misinterpretations if the investigations involved ϕrs versus μ data near an inflection point. Thus, the value of μ relative to a corresponding ϕrs not only depend upon solvent (s) and temperature, but also upon the level of vulcanization at moderate to high dilations. The entropy, enthalpy, and free energy changes associated with the configurational changes occurring in the network structure of the rubber were calculated. The thermodynamic properties were found to be consistent and uniform throughout the dilation range. Limiting osmotic pressures were determined to obtain effective number average molecular weights of the crosslinked chains. The molecular weight values were found to average slightly less than three times those obtainable from ve/Vr data. Finally, this investigation has shown that reinforced silicone rubber vulcanizates at equilibrium swelling in a variety of solvents exhibit the swelling behavior predicted by theory. However, swelling behavior at moderate to high swelling was found to be unrelated to the rubber in general, but related more specifically to the network structure of the vulcanizate. At low dilations, the characteristics of the silicone rubber species control the swelling behavior.

scholarly journals Experimental demonstration of negative refraction with 3D locally resonant acoustic metafluids

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Benoit Tallon ◽  
Artem Kovalenko ◽  
Olivier Poncelet ◽  
Christophe Aristégui ◽  
Olivier Mondain-Monval ◽  
...  
Keyword(s):  
Experimental Data ◽  
Yield Stress ◽  
Multiple Scattering ◽  
Silicone Rubber ◽  
Acoustic Waves ◽  
Scattering Theory ◽  
Negative Refraction ◽  
Volume Fraction ◽  
Experimental Demonstration ◽  
Acoustic Beam

AbstractNegative refraction of acoustic waves is demonstrated through underwater experiments conducted at ultrasonic frequencies on a 3D locally resonant acoustic metafluid made of soft porous silicone-rubber micro-beads suspended in a yield-stress fluid. By measuring the refracted angle of the acoustic beam transmitted through this metafluid shaped as a prism, we determine the acoustic index to water according to Snell’s law. These experimental data are then compared with an excellent agreement to calculations performed in the framework of Multiple Scattering Theory showing that the emergence of negative refraction depends on the volume fraction $$\Phi$$ Φ of the resonant micro-beads. For diluted metafluid ($$\Phi =3\%$$ Φ = 3 % ), only positive refraction occurs whereas negative refraction is demonstrated over a broad frequency band with concentrated metafluid ($$\Phi =17\%$$ Φ = 17 % ).

Effect and Detection of Loose Chain Ends in Crosslinked Polyurethane Elastomers

1971 ◽  
Vol 44 (1) ◽  
pp. 152-165 ◽  
Author(s):  
A. E. Oberth
Keyword(s):  
Crosslink Density ◽  
Volume Fraction ◽  
Present Theory ◽  
Swelling Ratio ◽  
Polyurethane Elastomers ◽  
Equilibrium Volume ◽  
Equilibrium Swelling ◽  
Volume Swelling

Abstract The effect of loose chain ends on tensile properties and equilibrium swelling of crosslinked polyurethane rubbers is studied. As in plasticized elastomers, tensile strength and elastic modulus are reduced approximately by a factor (1−νE,P)2, where νE,P is the volume fraction of loose chain ends, plasticizer, or both. This effect is much larger than predicted by present theory. Also the equilibrium volume swelling ratio, V0/V, of rubbers having terminal chains or an equal volume of plasticizer is the same, provided they do not differ in crosslink density. However, the volume fraction of “network rubber” in the equilibrium swollen specimen, ν2, differs owing to the non-extractability of terminal chains. On this basis a method is proposed which allows experimental determination of the volume fraction of loose ends. Elastomers abounding in loose chain ends show markedly less long term stress relaxation. This effect is not clearly understood but is useful to detect the presence of non load-bearing network.

Equilibrium swelling behavior of thermally responsive metal affinity hydrogels, Part I: Compositional effects

Polymer ◽  
2008 ◽  
Vol 49 (17) ◽  
pp. 3737-3743 ◽  
Author(s):  
Ganesh Iyer ◽  
L.M. Viranga Tillekeratne ◽  
Maria R. Coleman ◽  
Arunan Nadarajah
Keyword(s):  
Swelling Behavior ◽  
Metal Affinity ◽  
Thermally Responsive ◽  
Equilibrium Swelling ◽  
Compositional Effects

scholarly journals Thermal Decomposition and Ceramifying Process of Ceramifiable Silicone Rubber Composite with Hydrated Zinc Borate

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1591
Author(s):  
Jiuqiang Song ◽  
Zhixiong Huang ◽  
Yan Qin ◽  
Xinyi Li
Keyword(s):  
Thermal Decomposition ◽  
Compressive Strength ◽  
Network Structure ◽  
Silicone Rubber ◽  
Bending Strength ◽  
Linear Shrinkage ◽  
Decomposition Temperature ◽  
Zinc Borate ◽  
Air Atmosphere ◽  
Rubber Composite

The ceramifiable silicone rubber composite was prepared using hydrated zinc borate and kaolin as ceramifiable fillers. Effects of the hydrated zinc borate content and the combustion temperature on the properties of the ceramifiable silicone rubber composite were investigated. Thermal decomposition and ceramifying processes of the composite in a muffle furnace under air were also studied. The results showed that the density and the hardness of the composites increased as the content of the hydrated zinc borate increased from 0 to 30 phr. The tensile strength and elongation at break decreased. In addition, hydrated zinc borate decreased the decomposition temperature of the composite, whereas the residue weight under air atmosphere was increased. In the process of decomposition and oxidation of the ceramifiable silicone rubber composite in air, B2O3 was generated by the decomposition of zinc borate and participated in the formation of the residue network structure, which decreased the temperature of the ceramifying transition. The new phases, zinc aluminate (ZnO·Al2O3) and aluminum-rich mullite (9Al2O3·2SiO2), appeared after high-temperature thermochemical reactions. Microscopy images revealed that different structures were formed at different temperatures. The network structure of the ceramic residue became increasingly compact, and the compressive strength increased from 0.31 to 1.82 MPa with the increase of temperature from 800 to 1400 °C, which had a better protective effect on heat transfer and mass loss. The weight loss and the linear shrinkage of the ceramic residue was 37.6% and 21.9%, respectively, with the 30 phr content of hydrated zinc borate. The bending strength was improved from 0.11 to 11.58 MPa, and the compressive strength also increased from 0.03 to 1.14 MPa.

Thermodynamic Properties and Swelling Behavior of Glycolipid Monolayers at Interfaces

2001 ◽  
Vol 105 (22) ◽  
pp. 5178-5185 ◽  
Author(s):  
Matthias F. Schneider ◽  
Gerald Mathe ◽  
Motomu Tanaka ◽  
Richard R. Schmidt
Keyword(s):  
Thermodynamic Properties ◽  
Swelling Behavior

Simulation of Compressive Strength of SiC Foam

2010 ◽  
Vol 97-101 ◽  
pp. 3028-3032
Author(s):  
Long Zhi Zhao ◽  
Na Li ◽  
Ming Juan Zhao ◽  
Jian Zhang ◽  
Hong Yan
Keyword(s):  
Finite Element ◽  
Compressive Strength ◽  
Network Structure ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Three Dimension ◽  
Reduction Degree ◽  
Ansys Software ◽  
Element Simulation ◽  
Dimensional Network

A three-dimension finite element simulation for the model of three-dimensional network structure foam was made by ANSYS software in this paper. Influence of magnitude of load, loading position and volume fraction on the compressive strength of SiC foam three-dimensional network structure was investigated. The results show that with the increase of magnitude of load and the decrease of volume fraction, the compressive strength of foam decreases gradually. Non-deformability decreases with the increase of load; moreover, the reduction degree becomes bigger gradually. Compressive strength of SiC foam and volume fraction are nonlinearly dependable.

scholarly journals Radiopaque Chitosan Ducts Fabricated by Extrusion-Based 3D Printing to Promote Healing After Pancreaticoenterostomy

2021 ◽  
Vol 9 ◽  
Author(s):  
Maoen Pan ◽  
Chaoqian Zhao ◽  
Zeya Xu ◽  
Yuanyuan Yang ◽  
Tianhong Teng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Pancreatic Duct ◽  
Silicone Rubber ◽  
The Body ◽  
Molecular Weights ◽  
Pancreatic Duct Stent ◽  
3D Printed

Long-term placement of non-degradable silicone rubber pancreatic duct stents in the body is likely to cause inflammation and injury. Therefore, it is necessary to develop degradable and biocompatible stents to replace silicone rubber tubes as pancreatic duct stents. The purpose of our research was to verify the feasibility and biological safety of extrusion-based 3D printed radiopaque chitosan (CS) ducts for pancreaticojejunostomy. Chitosan-barium sulfate (CS-Ba) ducts with different molecular weights (low-, medium-, and high-molecular weight CS-Ba: LCS-Ba, MCS-Ba, and HCS-Ba, respectively) were soaked in vitro in simulated pancreatic juice (SPJ) (pH 8.0) with or without pancreatin for 16 weeks. Changes in their weight, water absorption rate and mechanical properties were tested regularly. The biocompatibility, degradation and radiopaque performance were verified by in vivo and in vitro experiments. The results showed that CS-Ba ducts prepared by this method had regular compact structures and good molding effects. In addition, the lower the molecular weight of the CS-Ba ducts was, the faster the degradation rate was. Extrusion-based 3D-printed CS-Ba ducts have mechanical properties that match those of soft tissue, good biocompatibility and radioopacity. In vitro studies have also shown that CS-Ba ducts can promote the growth of fibroblasts. These stents have great potential for use in pancreatic duct stent applications in the future.

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