Model Filled Polymers. 6. Determination of the Crosslink Density of Polymeric Beads by Swelling

1990 ◽  
Author(s):  
Z. Y. Ding ◽  
J. J. Aklonis ◽  
R. Salovey
Keyword(s):  
Crosslink Density ◽  
Filled Polymers ◽  
Polymeric Beads

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.

A Systematic Approach for Designing Multifunctional Thermally Conducting Polymer Structures With Embedded Actuators

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
Wojciech Bejgerowski ◽  
Satyandra K. Gupta ◽  
Hugh A. Bruck
Keyword(s):  
Heat Dissipation ◽  
Systematic Approach ◽  
Assembly Process ◽  
Processing Conditions ◽  
Molding Process ◽  
Filled Polymers ◽  
Thermally Conductive ◽  
Thermally Conducting ◽  
Process Constraints

Thermally conductive filled polymers enable the creation of multifunctional structures that offer both anchoring points for the embedded actuators, as well as heat-dissipation functions, in order to facilitate the miniaturization of devices. However, there are two important challenges in creating these structures: (1) sufficient thermal management to prevent failure of the actuator and (2) the ability of the actuator to survive the manufacturing process. This paper describes a systematic approach for design of multifunctional structures with embedded heat-generating components using an in-mold assembly process to address these challenges. For the first challenge, the development of appropriate thermal models is presented along with incorporation of in-mold assembly process constraints in the optimization process. For the second challenge, a simulation of the molding process is presented and demonstrated to enable the determination of processing conditions ensuring survival of the in-mold assembly process for the embedded actuator. Thus, the design methodology described in this paper was utilized to concurrently optimize the choice of material, size of the structure, and processing conditions in order to demonstrate the feasibility of creating multifunctional structures from thermally conductive polymers by embedding actuators through an in-mold assembly process.

Synthesis of Allyl Pentaerythritol Crosslinker based Polymer Hydrogels and Determination of the Crosslink Density

2021 ◽  
Vol 25 (11) ◽  
pp. 138-142
Author(s):  
Anamica . ◽  
Poorn Prakash Pande
Keyword(s):  
Crosslink Density ◽  
Metal Removal ◽  
Heavy Metal Removal ◽  
Polymer Gels ◽  
Polymer Hydrogels ◽  
Swelling Capacity ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

In this study, we report the synthesis and characterization of polymer hydrogels. The polymer gels have been prepared from acrylic acid (AA) monomer using allyl pentaerythritol as the crosslinker in the presence of potassium persulfate initiator. The synthesized polymer gels have been characterized by Fourier-transform infrared (FT-IR) spectroscopy. The swelling capacity and crosslink density of the synthesized polymer gels have been determined and it was found that some of the polymer samples behave like super-absorbent polymers. These polymeric-gels can be utilized in various applications viz. as a catalyst for dye removal, for anion removal from water and for heavy metal removal etc.

Use of χ As a Function of Volume Fraction of Rubber to Determine Crosslink Density by Swelling

2003 ◽  
Vol 76 (4) ◽  
pp. 832-845 ◽  
Author(s):  
William L. Hergenrother ◽  
Ashley S. Hilton
Keyword(s):  
Carbon Black ◽  
Metal Oxides ◽  
13C Nmr ◽  
Crosslink Density ◽  
Volume Fraction ◽  
Good Measure ◽  
Noticeable Effect ◽  
Wide Range ◽  
The Relationship

Abstract A technique is described allowing a relatively simple determination of χ as a function of vr from swelling in heptane. A good measure of the true νe of the cured elastomer at all values of vr was demonstrated by substituting this relationship for χ in the Flory-Rehner (F-R) equation. The relationship was established over a wide range of vr values by using samples that had the νe of the cured elastomer determined by tensile retraction (TR). Applying this function to samples treated using the thiol probe method of Campbell gave an improved measure of the types of crosslinks present in sulfur-cured stocks. An identical equation describing χ as a function of vr in heptane was obtained with NR, EPDM and SBR containing up to a 0.31 volume fraction of carbon black (CB) and other fillers. The presence of up to 10 % of clay, talc, silica, resins or metal oxides in the CB had no noticeable effect on the relationship measured. However, when the filler contained about 50% silica a distinctly different slope in the relationship was found. The percent S1, S2 and Sx distribution measured was contrasted between measurements made by 13C NMR, swelling with χ = constant or χ as a function of vr.

Determination of the origin of the narrow ESR signal in carbon black filled polymers

1990 ◽  
Vol 138 (2) ◽  
pp. 380-387 ◽  
Author(s):  
John R Harbour ◽  
Mary Jane Walzak ◽  
Richard P Veregin
Keyword(s):  
Carbon Black ◽  
Filled Polymers
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