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aem polymer for seals and gaskets with low oil swell and improved processing.

by:DMS Seals     2020-06-06
AEM polymers (
Vinyl acrylic rubber)
It has more than 30 years of commercial value.
Cured compounds made of polymers have a good performance balance, including the following properties (refs. 1-3)
* Heat resistant up to 175 [degrees]
C. The peak is as high as 200 [degrees]C;
* Low to-good low temperature performance40[degrees]C;
* Good fluid resistance in transmission fluid and oil;
* Excellent ability to fight
Condensation through gas and waste gas;
* Excellent dynamic performance;
* Good damping performance;
* Low compression setting value;
* Excellent relaxation performance of pressure stress (CSR)testing.
Curing parts made of AEM polymer are used in many automotive applications such as: * turbo charger hoses for gasoline and diesel engines;
* Fuel hose cover;
* Transmission oil cooler hose;
* Hose for oil cooler;
* Turning the exhaust hose and vacuum tube;
* Seals and washers in the transmission system;
* Seals and washers in the engine system;
Most of the AEM grades are ternary polymers made of ethylene, methyl acetate, and acidic curing site monomer.
Cure with diammonium in two stages.
There is an initial stress treatment, usually after an hour of treatment step at 175 [degrees]C.
The AEM double polymer is made of the Asian nail blue and the methyl ester.
The dipolymer compound is cured with peroxide, which is usually not cured after curing. [
Figure 1 slightly]
In 1975, the latest development of AEM polymer has been commercialized and several polymers have been added over the years.
For the past five years, people have been working on the development of AEM polymers to give the compounds better processing properties and/or better physical properties (refs. 4 and 5).
Four new polymers have been or are being developed, and some of the features of these grades include higher viscosity and improved polymer structure.
Historically, the viscosity of the AEM polymer is relatively low compared to most rubber.
The typical Mooney viscosity of the \"standard\" AEM polymer is in ML (1+4)@100[degrees]C.
The four levels recently developed usually measure about 30 mu under the same conditions.
When replacing the \"standard\" polymer with a high viscosity AEM polymer, the composite viscosity usually increases by 50 to 60%.
For the processing of low hardness compounds, the higher viscosity is a significant advantage.
Recently developed polymer structures have been optimized to provide a combination of low compression permanent deformation, improved high temperature physical properties and/or better thermal aging properties.
It also helps to minimize coke burning problems that may come from higher composite viscosity.
The combination of higher viscosity and less coke burning, as well as the improved polymer structure, has resulted in significant improvements in both injection and compression molding processes.
The first polymer aem ip of this family was designed for the injection molding market.
Its composition is similar to that of AEM Gpolymer, so there is a good balance between fluid resistance and low temperature performance.
Compounds made of this polymer are much easier to handle in injection and compression molding machines.
The second polymer aem ht of the series is designed for the hose market, and it has excellent dynamic performance and low coke burning.
It also has components similar to the aem g polymer.
This article will review the third polymer aem3110 in this family.
It is designed for the molding market and its location is similar to that of the aem gls polymer.
Compared with aem g series compounds, it has significantly improved fluid resistance, trade-
Tg is a little higher.
Compared to the aem gls compound, the compound made of this polymer is easier to inject and compress the mold.
The hose market is developing a fourth polymer that combines the fluid resistance of the aem gls family with excellent dynamic performance and low Coke sintering.
In general, the AEM compound has good fluid resistance to the automatic transmission fluid (ATF)
And oil.
Volume expansion of \"standard\" AEM compounds (
G polymer based on AEM)
In oil and ATFs, in 150 [after a week [degrees]
C varies from 10 to 25%.
The expansion in synthetic-based fluids is lower, and the expansion in mineral-based fluids is higher.
The trend for OEMs is to move from mineral-based fluids to synthetic-based fluids, which leads to a decrease in the expansion value of AEM compounds.
Rm 903 is a test fluid with a relatively high aromatic content and is used in the ASTM fluid resistance class.
The compound of \"standard\" AEM will have a burst of 40 60% IRM903 150 a week after aging 【degrees]C.
Compared with the expansion in commercial transport fluids and oil, the expansion of aemcompods in rm 903 is much higher.
Aem gls is one of the most polar of AEM polymers, and compounds made of aem gls have lower expansion values.
In conveying fluid and oil, the typical expansion range is between 3 and 15%, while in rms 903, the expansion range is between 25 and 35%.
There\'s a trade-
Improve the fluid resistance of the AEMGLS compound.
The low temperature performance is not very good, and the Tg of the polymer is about 6 [degrees]C higher.
The Mooney viscosity of the aem gls polymer is 18. 5 MU (measured at100[degrees]C)
This relatively low viscosity means that the composite viscosity of some compounds is lower.
The biggest problem is that compounds with low hardness or compounds with high plasticizer content.
Some low viscosity aem gls compounds have problems during injection molding, including sticky mold, sticky mold and bad hottear.
Similar treatment problems were also observed for low viscosity sityaem G compounds, and the introduction of aem ip significantly reduced these treatment problems (ref. 4).
Injection molding studies at DuPont laboratories in Switzerland demonstrate the benefits of the ofAEM IP compound.
The compound formula and molding conditions were selected in order to encounter processing difficulties during the test.
These include: * low hardness/low viscosity compounds with minimum black and no plasticizer;
* The standard release package used in the formula, but did not spray the external mold release onto the mold during the test;
* Inject the mold into o-
Renewal of 35 cycles;
* At the end of each cycle, o-
The ring was automatically removed. The o-
Rings that cannot be automatically removed are manually removed;
And * Number of o-removed manually
Statistics at the end of each cycle;
Lower numbers mean it\'s easier to composite. [
Figure 3 slightly]
Table 2 shows that the low hardness compounds of aem g and aem ip are similar at first;
About 25% o-
You must remove the wine manually.
Percentage manually removed after 35 cycles-
The MSDS of aem g compound increased to about 50%, but the MSDS of aem ip compound decreased to less than 25%.
One possible explanation is that the low hardness of the aem g compound contaminated the mold and the processing process deteriorated gradually.
Improved fluid resistance and improved properties of the processed aem ip polymer have resulted in improved processing being used to design a polymer with very good fluid resistance and good processing performance.
Some features of the polymer AEM 3110 include: * higher viscosity, about 30 mu;
* Similar to the level of methyl propylene in aem gls, providing similar fluidity;
* Improved design of polymer structure;
* Reduce the problem of dirt;
* Reduce burning;
* Provide better tears;
And * can use less efficacy and still meet the goals set by compression.
Based on aem gls and AEM 3110, repeated injection molding studies with low hardness compounds.
The AEM 3110 compound was significantly better in the molding test.
Compared with the aem gls compound using the same formula, the AEM 3110 compound without DOTG has a good compressed set compound, and the compressed set value made from AEM 3110 is lower.
This benefit is important for compounds that cannot use DOTG as an accelerator.
Compounds using alternating accelerators and AEM 3110 combinations can satisfy the compression set properties of compounds based on aem gls and DOTG.
Table 3 shows an aem gls compound that DOTG acts as a catalyst compared to the aem gls and AEM 3110 compounds based on DBU accelerators.
The first two data columns in the table show that when DBU replaces DOTG in aem gls compound, the compression set increases significantly, which is undesirable.
The last column of data shows the results of the AEM 3110/DBU compound, and the compressed set value is actually lower than that of the aem gls/dotg compound.
More information on replacing DOTG in AEM compounds can be found in reference 6.
Thermal aging improvement in air is a function of many factors, including time, temperature and test criteria.
The test criteria can be based on the absolute value of properties such as hardness change, percentage change in elongation, or elongation.
Compared with compounds based on aem gls, compounds made of fromAEM 3110 have better thermal aging properties in the air.
Table 4 shows some formulations and initial properties of compounds based on aem gls, AEM 3110 and HT-ACM.
These compounds are heated for 6,000 hours in air [150]degrees]C.
This type of test takes a long time, but it is more representative of what may be seen separately, rather than using accelerated aging in a shorter period of time at higher temperatures.
Compounds based on AEM 3110 have the best thermal aging of the three compounds studied.
Figures 4, 5 and 6 show that its hardness changes very little and is the only compound of the three compounds that has an elongation value greater than 50% after 6,000 hoursdegrees]C.
Some specifications limit the hardness to 15 points.
According to these criteria, aem gls and HT-
ACM failed in just over 3 000 hours while AEM 3110 compound failed in just over 4,000 hours.
Since the commercial of AEM compounds, thermal aging plasticizer has been used with AEM compounds to improve the low temperature performance.
AEM\'s \"standard\" plasticizer is an ether/Ester plasticizer with good low temperature performance and good heat-resistant balance.
The benefits of plasticizer in AEM compounds include: * Improved low temperature performance;
* Lower expansion in fluid, Lower VI;
* Low viscosity, important for compounds with higher hardness;
Lower cost compounds. [
Figure 4 slightly][
Figure 5 Slightly]
One problem with the \"standard\" plasticizer is that it cannot be maintained and the thermal aging conditions become more serious
The temperature is high and the time is long.
As OEMs seek better performance, higher temperatures and longer periods of time are used more often.
With the increase of thermal aging conditions, the plasticizer will have significant weight loss after aging in the air furnace. Through DSC, the low temperature performance of the plasticizer (such as Tg) will also rise accordingly.
For AEM compounds that retain the \"standard\" plasticizer\'s low temperature performance but significantly improve the thermal aging performance, less volatile plasticizer is available (ref. 7).
In the formulation based on aem gls and AEM 3110, these plasticizer were studied with the goal of obtaining the following combination: * good low temperature performance before and after thermal aging;
* The AEM compound has very good fluid resistance;
* Feasible viscosity for injection molding applications.
Table 5 shows the formulation, flow properties and initial physical properties of the compounds using these two plasticizer.
The compound does not contain plasticizer or 20 parts of plasticizer.
The black level was adjusted to maintain a constant hardness;
The hardness values range from 72 to 76.
The concern is that aem gls compounds with 20 copies of either type of plasticizer have a low viscosity of the compound and may be difficult to process.
AEM 3110 compound containing 20 parts of plasticizer has a significantly higher viscosity and should be easier to process.
All compounds containing 20 plasticizer have an initial Tg value40[degrees]C.
The compound also contains 2.
0 blocked amine antioxidants, 0.
5phrocecyl Amine, 1.
0 phosphate released, 1.
5 parts of citric acid, 2 parts.
0 accelerators based on DBU and 1.
5 HMDC treatments.
The initial Tg in the table refers to the DSC Tg before the aging of the air or fluid.
The actual Tg value in the table comes from the inflection point of the curve-
Not the initial start of the DSC curve. [
Figure 6 slightly]
These compounds age in the air for a week to reach 175 [degrees]
C, the results are shown in Table 6.
The table includes the results of thermal aging and weight loss after compression, Tg (at 150[degrees]C).
One week after the Air Age, 175 [degrees]
C, the weight loss of the two compounds with the \"standard\" plasticizer exceeded 8%, and Tg increased significantly.
They also have relatively high compression set values when tested at 150 [degrees]C.
The weight loss of these two compounds with \"low volatile\" plasticizer is much lower, the increase in Tg is much less, and their compression setting values are also better.
AEM 3110 compounds with 20 \"low volatile\" plasticizer have a compression setting value for aem gls compounds that are close to plasticizer-free.
Table 7 shows the results of fluid aging after a week [at150]degrees]
C in SF 105 or rm 903.
Compounds with 20 phrplasticizer have a relatively low expansion value.
The expansion values of these compounds in SF 7% are below.
The Tg value of different compounds after fluid aging has only a small benefit to the high plasticizer level.
One possible explanation is that compounds that do not have plasticizer absorb some liquid, while some plasticizer may be extracted from compounds that contain 20 servings of plasticizer.
The AEM 3110 compound with 20 \"low volatile\" plasticizer has a good performance combination, including: * working viscosity;
* Good preliminary medical examination;
* After a week of air aging, a good medical examination was conducted at 175 [degrees]C;
* Good compression settings;
* Good low temperature performance before and after thermal aging;
Low Expansion of SF 105 and rm 903.
After aging liquid
In physical studies at high temperatures, previous sections included information on the low temperature properties of AEMcompounds before and after thermal aging and fluid aging.
Another area of concern for AEM parts is the high temperature performance of the parts after aging in the fluid.
End users want AEM parts to have good high temperature physical properties before and after fluid aging.
Aging of standard fluid (
ASTM D471, ISO 1817)
Only physical phenomena are observed at room temperature.
In fact, after the fluid age, the part must work at high temperature.
Extensive testing has been carried out in this field and several different aemcompods have been added to several different fluids.
This section will show the results of the studies carried out in the fluid Dexron VI of the automatic transmission.
The same is true of the trend in which this fluid is applied to other fluids.
Table 8 shows the three compound formulations, as well as their initial physical properties, including high temperature physical properties tested by DSC and low temperature properties of Tg.
Figure 7 and Figure 8 show the tensile strength and elongation after fluid aging.
These results are measured at room temperature, which is typical for fluid aging data.
Results of aem g compounds were used as controls and the results of aem ip and AEM 3110 compounds were compared with them.
When measured at room temperature, aem ip and AEM 3110 compounds have better physical properties after fluid aging. [
Figure 7 Slightly]
Figures 9 and 10 show the tensile strength and elongation measured after fluid aging, and the result of this measurement is [degrees]C.
Compared with aem g control, compounds based on aem ip and AEM 3110 have better physical properties at high temperatures.
Another problem is what happens to low temperature performance after fluid aging.
The previous section showed that after fluid aging, the Tgs of AEM 3110 and AEM gls compounds without plasticizer were lower, while Tg of compounds containing 20 plasticizer increased.
In this series of experiments, the compound contains 10 plasticizer parts.
Tgs before and after fluid aging are shown in Figure 11.
Tgof reduced by about-5[degrees]
C of these compounds in this ATF.
Seals and washers made from \"standard\" AEM compounds have been successfully used in sealing applications for engines and transmissions for many years.
They are finally used in high temperature and low temperature extremes.
Compounds made from aem ip and AEM 3110 will also meet the upper and lower temperature requirements for sealing sand washers used in the engine and transmission. [
Figure 8:[
Figure 9 omitted
Conclusion The compounds made from AEM 3110 have attractive performance combinations, including: * feasible viscosity; * low scorch;
* Good processing in injection molding and compression molding applications, especially for low hardness compounds;
* Very good fluid resistance;
* No good compression setting value for DOTG;
* Good thermal aging properties;
* Good low temperature performance before and after thermal aging using appropriate plasticizer;
* Good performance at high temperature
Before and after fluid aging. [
Figure 10 slightly][
Figure 11 omitted]References (1. )
AEMpolymers data. (2. )
Manual of special elastomer, edited by robert Klingender, published by CRC Press, 2007-
Chapter of AEM and FKM. (3. )Kirk-
Encyclopedia of Chemical Technology
Chapter \"vinyl acrylic rubber-
Wu and Mike bride, 2003, published by John Willie and his son. (4. )\"Vamac Ultra-
New high viscosity AEM polymer with extended application possibilities, \"K.
Kammerer, nearly 2009. (5. )\"Vamac Ultra-
The new AEM polymer and development meet the needs of modern engine technology.
Kammerer, IRC, 2012. (6. )
\"The recipe proposal to replace DOTG in aemcompods,\" E. McBride, K. Kammerer, L.
Lefebv re, ACS RubberShow, October 2010, paper 32. (7. )
\"New high and low temperature ester of acrylic rubber,\" S.
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