On the Filler Flocculation in Silica-Filled Rubbers Part I. Quantifying and Tracking the Filler Flocculation and Polymer-Filler Interactions in the Unvulcanized Rubber Compounds

2002 ◽  
Vol 75 (5) ◽  
pp. 865-890 ◽  
Author(s):  
Chenchy J. Lin ◽  
W. L. Hergenrother ◽  
E. Alexanian ◽  
G. G. A. Böhm
Keyword(s):  
Linear Regression Analysis ◽  
Quantitative Characterization ◽  
Polymer Filler ◽  
Rubber Compounds ◽  
On Line ◽  
Filled Rubbers ◽  
Dynamic Storage ◽  
Vulcanization Process ◽  
Flocculation Process

Abstract Filler flocculation was followed for silica filled compounds containing various alkoxy silanes and non-silane type polar additives. The methodology employed in this paper permitted a quantitative characterization of filler flocculation and polymer-filler interactions after heating the compound under conditions that simulated vulcanization. With the addition of trialkoxy silanes, the reduction of filler flocculation and the degree of polymer-filler interactions were found to depend on the type and the concentration of silane added, and on the mixing drop temperature (Td) used. Greater polymer-filler interactions and flocculation suppression were obtained with a compound containing a tetrasulfane when compared to that containing either a disulfane or a monofunctional-silane. Polar additives such as an amine compound and a sugar alcohol did not reduce the silica flocculation during simulated vulcanization because they were dewetted from the silica surface upon heating. The filler flocculation process was monitored by following the change of dynamic storage moduli using an on-line rheometer. The flocculation process order and process constant were extracted from the non-linear regression analysis of the kinetic data. These kinetic parameters were used to quantify the suppression of filler flocculation by the additives used. Filler flocculation was found not to be affected by the vulcanization process because it occurred prior to the onset of cure.

Mooney Viscosity Stability and Polymer Filler Interactions in Silica Filled Rubbers

2002 ◽  
Vol 75 (2) ◽  
pp. 215-245 ◽  
Author(s):  
Chenchy Lin ◽  
William L. Hergenrother ◽  
Ashley S. Hilton
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Ester ◽  
Hydrolytic Stability ◽  
Unsaturated Rubber ◽  
Polymer Filler ◽  
Rubber Compounds ◽  
Filled Rubbers ◽  
Mooney Viscosity ◽  
Sugar Fatty Acid Ester ◽  
Viscosity Stability

Abstract The change in Mooney viscosity (ML1+4) with aging was followed for silica filled compounds containing various silanes and polar additives. Several mechanisms for the aging stability are postulated and evaluated through experimentation. The type of silane or polar additive used can cause the ML1+4 to increase or even decrease during aging. When bis(triethoxy silanes) are used in silica filled rubbers, the ML1+4 growth during aging is caused by hydrolysis. Silica-silica bridging was found to be responsible for the ML1+4 growth in rubber compounds containing a more thermally stable polysulfide or a sulfur-free bis(triethoxy silane). When the bis(triethoxy silane) is bis(3-triethoxysilylpropyl) tetrasulfide (TESPT), a fraction of TESPT is attached to the unsaturated rubber to give polymer-silica attachments. These attachments further enhance the hydrolytic ML1+4 increase during aging. Chemical coating of the silica with a monofunctional silane or a physical coating with a trialkyl amine compound effectively stops the ML1+4 increase upon aging. The prevention of ML1+4 growth is so efficient that a reduction in the ML1+4 can be realized by absorption of ambient moisture. The extent of ML1+4 reduction caused by moisture depends on the degree of hydrophobation of the coated silicas. Hydrolytic stability was also studied with an amine or a sugar fatty acid ester that formed either strong or weak polar associations to the silica.

Quantitative Characterization of True Leak Rate of Micro to Nanoliter Packages Using a Helium Mass Spectrometer

2007 ◽  
Author(s):  
A. Goswami ◽  
B. Han ◽  
Suk-Jin Ham ◽  
Byung-Gil Jeong
Keyword(s):  
Qualitative Analysis ◽  
Mass Spectrometer ◽  
Linear Regression Analysis ◽  
Quantitative Measure ◽  
Leak Rate ◽  
Accelerated Tests ◽  
Quantitative Characterization ◽  
Rf Filter

The helium mass spectrometer has been used extensively for qualitative analysis of fine leaks. However, qualitative analysis for the small volumes (typically < 10−3 cc) of MEMS packages can produce erroneous results. In addition, the qualitative use of the helium fine leak test does not allow comparison of two different packages. Nor can the results be correlated with data from accelerated tests such as 85°C/85%RH test. These limitations warrant the development of a method to assess hermeticity quantitatively. This paper proposes a procedure to quantitatively measure the true leak rate of micro to nanoliter packages using the helium mass spectrometer. The proposed method is based on the fact that the profile of the measured leak rate signal depends only on the true leak rate and the volume of the package. Prior knowledge of the volume of the package enables determination of the true leak rate by performing a weighted non-linear regression analysis of the data. The method was implemented to measure the true leak rate of a MEMS RF filter package. The package was tested under three different test conditions yielding three different signal profiles. The method yielded a consistent value for the true leak rate, which verified the robustness of the method. The proposed method provides a true leak rate as a quantitative measure of hermeticity. The accurate true leak rates will help evaluate new bonding materials/processes and package designs fast and effectively.

scholarly journals The Milling Process Monitoring Using 3D Envelope Method

2011 ◽  
Vol 423 ◽  
pp. 77-88 ◽  
Author(s):  
Claudiu Bisu ◽  
Alain Gerard ◽  
Miron Zapciu ◽  
Olivier Cahuc
Keyword(s):  
Three Dimensional ◽  
Cutting Parameters ◽  
Milling Process ◽  
Quantitative Characterization ◽  
Envelope Analysis ◽  
Milling Tool ◽  
Envelope Method ◽  
On Line ◽  
Cutting Capacity

This paper proposes a method to vibration analysis in order to on-line monitoring of milling process quality. Adapting envelope analysis to characterize the milling tool materials is an important contribution to the qualitative and quantitative characterization of milling capacity and a step by modeling the three-dimensional cutting process. An experimental protocol was designed and developed for the acquisition, processing and analyzing three-dimensional signal. The vibration envelope analysis is proposed to detect the cutting capacity of the tool with the optimization application of cutting parameters. The research is focused on Hilbert transform optimization to evaluate the dynamic behavior of the machine/ tool/workpiece.

The Hysteresis Temperature and Strain Dependences in Filled Rubbers

2006 ◽  
Vol 79 (1) ◽  
pp. 170-197 ◽  
Author(s):  
Alberto Scurati ◽  
Chenchy J. Lin
Keyword(s):  
Temperature Dependence ◽  
Functional Polymers ◽  
Temperature Hysteresis ◽  
Individual Effect ◽  
Polymer Filler ◽  
Filled Rubbers ◽  
Filler Network ◽  
Dynamic Storage ◽  
Tan Δ ◽  
The Individual

Abstract The strong hysteresis (tan δ) temperature dependence observed in filled compounds containing functional polymers was investigated by studying the individual effect of filler-filler (F-F) and polymer-filler interactions (P-F). Silica filled compounds were prepared by adding n-octyl-triethoxyl or mercatopropyl-trimethoxyl silane. Both silanes are capable of retarding filler flocculation upon heating and give compounds with less developed filler networks either by reducing F-F interactions or by screening filler networks through P-F attachments. The filler network is shown to mediate the low-temperature hysteresis due to the polymer glass transition (Tg) by changing the temperature dependence of the compound dynamic storage modulus (G′). At temperatures far above the Tg, the compound tan δ is governed by mechanisms that control the degree of filler networking. Compounds with less developed networks show weaker strain dependence on G′ and tan δ. Both reduced F-F and increased P-F interactions will give a compound with a less developed network. However, significant reduced tan δ is only found in a system that shows strong P-F interaction due to less energy loss upon deformation by fewer network breakage and increased P-F crosslinks. This is exemplified by comparing the compound loss moduli (G″) of various stocks with corresponding G′ in G-plot (G″ vs. G′).

An Approach to Chemorheology of a Filled SBR Compound

1999 ◽  
Vol 72 (2) ◽  
pp. 361-383 ◽  
Author(s):  
R. Ding ◽  
A. I. Leonov
Keyword(s):  
Kinetic Studies ◽  
Rheological Parameters ◽  
Cross Linking ◽  
Rheological Characterization ◽  
Degree Of Cure ◽  
Unique Possibility ◽  
Rubber Compounds ◽  
Filled Rubbers ◽  
Basic Experiments

Abstract Three steps in complex chemorheological studies are necessary for complete rheological characterization of filled rubbers during cross-linking reaction. They include: (i) kinetic studies of cross-linking reaction, (ii) rheological studies of green rubber compounds, and (iii) correlation between the rheological parameters and the degree of cure. Basic experiments in the steps (i)–(iii) and their modeling are presented in this paper on the example of a filled SBR compound with sulfur accelerated vulcanization. The approach provides a unique possibility to trace therheological properties of rubber compounds from the green to completely cured states.

Quantitative Characterization of Cure. IV. Definition and Measurement of Rate of Cure for Pure-Gum Natural-Rubber Compounds

1952 ◽  
Vol 25 (3) ◽  
pp. 454-467 ◽  
Author(s):  
Geoffrey Gee ◽  
S. H. Morrell
Keyword(s):  
Experimental Studies ◽  
Practical Method ◽  
Mathematical Form ◽  
Quantitative Characterization ◽  
First Order ◽  
Rubber Compounds ◽  
Order Chemical Reaction ◽  
Single Compound ◽  
First Order Chemical Reaction

Abstract The purpose of this paper is to develop a simple practical method of assessing rate of cure, based on sound theoretical principles, and using only measurements which are normally available or easily made. Mathematical and experimental studies of modulus-time curves are presented, and it is shown that several types of gum compound give curves of a simple mathematical form, equivalent to that of a first-order chemical reaction. It is concluded that in such cases rate of cure can be defined and measured by the value of a first-order velocity constant, having dimensions time−1, the reciprocal of which determines the vulcanization period needed to produce a given percentage cure. Application to a substantial number of rubbers has shown that the method is capable of yielding reproducible results for the rate of cure of a single compound, and of distinguishing with high significance between different compounds. A connection is predicted between rate of cure, as thus measured, and scorch; preliminary data are consistent with expectation.

Semiempirical Relationships between Properties and Loading in Filled Elastomers

1989 ◽  
Vol 62 (5) ◽  
pp. 788-799 ◽  
Author(s):  
A. Pouchelon ◽  
P. Vondracek
Keyword(s):  
Filler Loading ◽  
General Validity ◽  
Elongation At Break ◽  
Filled Elastomers ◽  
Polymer Filler ◽  
Adsorbed Polymer ◽  
Percolation Behavior ◽  
Filled Rubbers ◽  
Filler Network ◽  
Dynamic Storage

Abstract The dynamic storage modulus of uncured silica-filled silicone rubber increases sharply when a critical filler loading is reached. A similar behavior has been observed for the conductivity in the same compounds. The experimental data fit a percolation law fairly well, and microscopy confirms the formation of a filler network according to the percolation model. This behavior depends on a polymer-filler interaction level, suggesting a filler network consisting of filler particles bridged together by adsorbed polymer. It has been found that the percolation threshold coincides with the optimum value of elongation at break of the corresponding vulcanizates. The percolation behavior and the relations between properties of filled rubbers described here were observed in various filled rubbers of quite different compositions. This seems to suggest the general validity of the presented relationships in all elastomers reinforced by particulate fillers.

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