AEM with good heat resistance, low temperature and dynamic properties.AEM AEM Applied and Environmental Microbiology (journal) AEM Association of Equipment Manufacturers AEM Academic Emergency Medicine (journal) AEM Agnico-Eagle Mines Limited AEM Advanced Engine Management background AEM polymers (Vamac) have been commercially available for over thirty years. Cured compounds made from AEM polymers have a good balance of properties, including some of the following features (refs. 1 and 2): * Heat resistance up to 175[degrees]C; * good low temperature properties down to -40[degrees]C; * good fluid resistance in transmission fluid and engine oils; * good damping damping In physics, the restraint of vibratory motion, such as mechanical oscillations, noise, and alternating electric currents, by dissipating energy. Unless a child keeps pumping a swing, the back-and-forth motion decreases; damping by the air's friction opposes the properties; * low compression compression, external stress applied to an object or substance, tending to cause a decrease in volume (see pressure). Gases can be compressed easily, solids and liquids to a very small degree if at all. set values in air (70 hours at 150[degrees]C); and * excellent performance in CSR (1) (Customer Service Representative) A person who handles a customer's request regarding a bill, account changes or service or merchandise ordered. Agents in call centers are known as CSRs. See call center. testing in engine oils (six weeks at 150[degrees]C). Cured parts made from AEM polymers are used in automotive applications such as: * Turbo charger CHARGER, Scotch law. He in whose favor a decree suspended is pronounced; vet a decree may be suspended before a charge is given on it. Ersk. Pr. L. Scot. 4, 3, 7. hoses; * fuel hose covers; * transmission oil cooler hoses; * seals and gaskets in transmission systems; * seals and gaskets in engine systems; and * torsional vibration Torsional vibration is angular vibration of an object--commonly a shaft along its axis of rotation. Torsional vibration is often a concern in power transmission systems using rotating shafts or couplings where it can cause failures if not controlled. dampers. Most AEM grades are terpolymers made from ethylene ethylene (ĕth`əlēn') or ethene (ĕth`ēn), H2C=CH2, a gaseous unsaturated hydrocarbon. It is the simplest alkene. , methyl acrylate Methyl acrylate is a volatile alpha beta unsubstituted methyl ester used in the preparation of Polyamidoamine (PAMAM) dendrimers typically by michael addition with a primary amine. Methyl acrylate is a contact allergen present in nail lacquer. and an acidic acidic /acid·ic/ (ah-sid´ik) of or pertaining to an acid; acid-forming. acidic, adj having the properties of an acid; acid-forming properties. cure site monomer monomer (mŏn`əmər): see polymer. monomer Molecule of any of a class of mostly organic compounds that can react with other molecules of the same or other compounds to form very large molecules (polymers). . They are cured with diamines and they are cured in two stages. There is an initial press cure that is followed by a relatively long post cure step. There are some AEM polymers that are dipolymers made from ethylene and methyl acrylate. The dipolymer compounds are typically cured with peroxide peroxide (pərŏk`sīd), chemical compound containing two oxygen atoms, each of which is bonded to the other and to a radical or some element other than oxygen; e.g. and normally do not need to be post cured. [FIGURE 1 OMITTED] Low temperature property improvements--plasticizer AEM compounds can be formulated for·mu·late tr.v. for·mu·lat·ed, for·mu·lat·ing, for·mu·lates 1. a. To state as or reduce to a formula. b. To express in systematic terms or concepts. c. to meet low temperature requirements by using the AEM G polymer polymer (pŏl`əmər), chemical compound with high molecular weight consisting of a number of structural units linked together by covalent bonds (see chemical bond). and the appropriate type and appropriate level of a plasticizer plas·ti·ciz·er n. Any of various substances added to plastics or other materials to make or keep them soft or pliable. plasticizer or -ciser Noun . A series of compounds was made with 0, 10 and 20 phr of a polyether/ ester plasticizer. The carbon black level was modified mod·i·fy v. mod·i·fied, mod·i·fy·ing, mod·i·fies v.tr. 1. To change in form or character; alter. 2. to keep a constant hardness. A graph graph, figure that shows relationships between quantities. The graph of a function y=f (x) is the set of points with coordinates [x, f (x)] in the xy-plane, when x and y are numbers. of the Tg (measured by DSC (1) (Digital Signal Controller) A microcontroller and DSP combined on the same chip. It adds the interrupt-driven capabilities normally associated with a microcontroller to a DSP, which typically functions as a continuous process. See microcontroller and DSP. ) versus plasticizer level is shown in figure 1. A "standard" AEM compound with no plasticizer has a Tg (by DSC) of -27[degrees]C. With 10 phr of a polyether/ester plasticizer, the Tg drops to -35[degrees]C, and with 20 phr of plasticizer, the Tg drops to -41[degrees]C. The increased plasticizer/black level changes the compound in different ways, with some benefits and some drawbacks. The results are shown in table 1. Increasing the plasticizer level and then increasing the carbon black level will have the net effect of lowering the viscosity, and the lower viscosity may help or hurt processability. The higher plasticizer/black levels will raise the compression set values, and at some point this may become a concern. The volume increase in typical fluids, such as Service Fluid 105, will actually drop, and this can be beneficial. Heat aging with plasticized compounds Change in Tg with heat aging AEM compounds are usually used where there is a requirement for exposure to high temperature for an extended period of time. As the compounds age at elevated temperatures, there is a loss in the amount of plasticizer. This can be seen by a change in the measured low temperature properties, and also by the loss in weight of the aged sample. Figure 2 shows the Tg vs. plasticizer level after aging for one week at 175[degrees]C. A similar trend can be seen after heat aging for six weeks at 150[degrees]C. After one week at 175[degrees]C, the compound with 20 phr plasticizer has a Tg that is only about 4[degrees]C lower than the compound without any plasticizer. Before heat aging, the compound with 20 phr plasticizer was about 14[degrees]C lower than the compound without any plasticizer. Change in weight of compound with heat aging In a related study, two 70 hardness compounds were prepared from an AEM G polymer. One had no plasticizer and the other had 10 phr of plasticizer. The compounds were aged for one week at 175[degrees]C. The compound without plasticizer lost about 3% of its weight and this was probably from the combination of process aids and the accelerator accelerator: see particle accelerator. (1) A key combination such as Alt-G or Ctrl-Shift H that is used to activate a task. (2) An incubator that expects to develop the company considerably faster than normal. See incubator. (figure 3). The compound with 10 phr plasticizer lost about 7% of its weight, and the weight loss was probably from the combination of process aids, accelerator and plasticizer. Most of the weight loss appears to be from the plasticizer. It was estimated that after heat aging for one week at 175[degrees]C, less than 3 phr of the plasticizer, out of the original 10 phr, remains in the compound. It is very difficult to choose a plasticizer that provides the following desirable combination of properties: * Lowers the Tg of an AEM compound initially; and * maintains the low Tg after heat aging --survives post cure condition of 4 hours at 175[degrees]C; --low volatility Volatility 1. A statistical measure of the tendency of a market or security to rise or fall sharply within a period of time. 2. A variable in option pricing formulas that denotes the extent to which the return of the underlying asset will fluctuate between now and the at 175[degrees]C for one week; and --low volatility for six weeks at 150[degrees]C [FIGURE 2 OMITTED] There are no known plasticizers plasticizers mostly triaryl phosphates, such as tricresyl, triphenyl phosphates, which are poisonous. See also triorthocresyl phosphate. that can be used in an AEM compound that will maintain good low temperature properties after long-term Long-term Three or more years. In the context of accounting, more than 1 year. long-term 1. Of or relating to a gain or loss in the value of a security that has been held over a specific length of time. Compare short-term. heat aging. New polymer Another approach to improve the low temperature properties of an AEM compound is to modify the polymer to have a lower initial Tg. The compound still needs to maintain the following properties: * Good heat resistance at high temperature; * good fluid resistance; * good compression set; and * good dynamic properties. A new polymer, AEM-LTX, was developed to improve the low temperature properties (ref. 3). The goal was to make a compound that had a Tg of -40[degrees]C after six weeks heat aging in air at 150[degrees]C (or 1 week at 175[degrees]C) while maintaining the other good features of an AEM compound. Some of the features of the new polymer are: * Same cure site monomer as AEM G polymer --need two step cure, initial press cure followed by a post cure; and --good compression set and good CSR properties; * no unsaturation un·sat·u·rat·ed adj. 1. Of or relating to an organic compound, especially a fatty acid, containing one or more double or triple bonds between the carbon atoms. 2. Capable of dissolving more of a solute at a given temperature. in polymer --good heat resistance after exposure to high temperatures; and * polymer backbone backbone: see spinal column. The part of a network that handles the major traffic. It employs the highest-speed transmission paths in the network and may also run the longest distances. designed to have good flex properties --good dynamic properties at low temperature and elevated temperature. [FIGURE 3 OMITTED] Performance of compounds made from AEM-LTX vs. AEM G A series of compounds were made comparing AEM-LTX to AEM G. The compounds were formulated with 0, 10 and 20 phr of plasticizer. The compounds were formulated to have a nominal Trifling, token, or slight; not real or substantial; in name only. Nominal capital, for example, refers to extremely small or negligible funds, the use of which in a particular business is incidental. NOMINAL. Relating to a name. hardness of about 62 durometer Du`rom´e`ter n. 1. An instrument for measuring the degree of hardness; especially, an instrument for testing the relative hardness of steel rails and the like. A, and this was achieved by varying the black level. The range in hardness was from 60 to 64. The compound formulations are shown in table 2. Rheology The rheology results are shown in table 3. The compounds with the high plasticizer and high black levels are relatively low in viscosity. The compounds made from the AEM--LTX have similar viscosity, scorch and cure rates as compared to the same compound made with the AEM G polymer. Figure 4 shows a graph of the viscosity versus plasticizer levels. Cured properties The samples were press cured for five minutes at 175[degrees]C and then post cured for four hours at 175[degrees]C. The physical properties are shown in table 4. The cured physical properties are all relatively close. Low temperature properties There are many different test methods for measuring the low temperature properties of compounds. Several of these methods were used to measure the low temperature properties of the compounds including Tg by DSC, TR10, Tg by DMA--by loss modulus See modulo. and by tan delta, and static oring Oring may refer to:
There is not a perfect low temperature test. Each application will have an end use test, and those results may correspond to one of the low temperature tests. For example, the static o-ring O-ring, n a doughnut-shaped flexible gasket made of synthetic material. Used as an overdenture attachment. test was developed to predict the temperature at which an o-ring will leak (programming) leak - With a qualifier, one of a class of resource-management bugs that occur when resources are not freed properly after operations on them are finished, so they effectively disappear (leak out). This leads to eventual exhaustion as new allocation requests come in. . The low temperature results are shown in table 5 and figure 5. The AEM-LTX compound with no plasticizer has a range of low temperature values that include -55[degrees]C (static o-ring) up to -32[degrees]C (DMA- tan delta). This is very similar to the AEM G compound with 20 phr of plasticizer. As a general statement, the AEM G compound with 20 phr of plasticizer has cured properties that are comparable to the AEM-LTX compound with no plasticizer. There is a difference in viscosity because the AEM-LTX compound with no plasticizer is about 50% higher in viscosity than the AEM G compound with 20 phr of plasticizer. The AEM-LTX compound with 20 phr plasticizer has the best low temperature properties and these range from -41[degrees]C (DMA (1) (Digital Media Adapter) See digital media hub. (2) (Document Management Alliance) A specification that provides a common interface for accessing and searching document databases. Tg by tan delta) to -63[degrees]C (static o-ring). [FIGURE 4 OMITTED] Tg after heat aging The compounds were aged in air at the following two conditions: * six weeks at 150[degrees]C; and * one week at 175[degrees]C. After the heat aging, the low temperature properties were measured by DSC. The Tg results after heat aging for one week at 175[degrees]C are shown in table 6 (the results for six weeks at 150[degrees]C were similar). The compounds with no plasticizer had a Tg increase of about 1[degrees]C. The compounds with 10 phr of plasticizer had an average increase of about 6[degrees]C, and the compounds with 20 phr of plasticizer had an increase of about 10[degrees]C. [FIGURE 5 OMITTED] The AEM-LTX compound with no plasticizer had a Tg of -41[degrees]C after heat aging for one week at 175[degrees]C (or six weeks at 150[degrees]C). The AEM G compound with 20 phr plasticizer had a good initial low temperature value, but it increased by 12[degrees]C after heat aging for one week at 175[degrees]C. Results are shown in figure 6 for Tg by DSC. Tg after fluid exposure The compounds were aged for one week at 150[degrees]C in several different fluids. At the end of the aging, the Tg of the compounds was measured using DSC. The results are shown in table 7. After one week in ASTM ASTM abbr. American Society for Testing and Materials #1 all three of the AEM LTX LTX Liver Transplant LTX Lane Training Exercise LTX Laptop Expansion (Slot) compounds had similar Tgs even though they had different levels of plasticizers. The same trend can be seen in the AEM LTX compounds aged in SF 105. The Tg of AEM G compounds after fluid aging were also much closer after the fluid aging. The results for SF 105 are shown in figure 7. Dynamic properties The new polymer AEM-LTX has good high temperature heat resistance (175[degrees]C) and good low temperature properties after heat aging (less than--40[degrees]C). For some potential applications such as CVJ CVJ Constant Velocity Joint CVJ Crevalle Jack (FAO fish species code) boots boot 1 n. 1. Protective footgear, as of leather or rubber, covering the foot and part or all of the leg. 2. there is also a requirement for good dynamic properties. It is not always an easy task to predict dynamic performance of a molded mold 1 n. 1. A hollow form or matrix for shaping a fluid or plastic substance. 2. A frame or model around or on which something is formed or shaped. 3. Something that is made in or shaped on a mold. part from a test run on a slab of cured compound. The DeMattia Flex test (ASTM D 430 and D 813) is used by the industry to predict dynamic properties. [FIGURE 6 OMITTED] The first attempt made at producing a low Tg AEM polymer met the high temperature and the low temperature requirements. However some of the molded parts made from that polymer failed in the bench tests due to poor dynamic performance. Improvements were made to the polymer that kept the good high and low temperature properties, but that improved the dynamic properties. The AEM--LTX is slightly better than AEM G in dynamic properties. The DeMattia results from three compounds are shown in table 8. The polymers used were AEM G, the first generation attempt, and AEM-LTX. All three compounds had the same formulation formulation /for·mu·la·tion/ (for?mu-la´shun) the act or product of formulating. American Law Institute Formulation , and this means that the AEM G compound has a slightly higher hardness. The Tg for the compounds was relatively low because the plasticizer level was 17.5 phr. The compounds were press cured for 10 minutes at 180[degrees]C and then post cured for four hours at 175[degrees]C. [FIGURE 7 OMITTED] The key dynamic test to run is a bench test. The DeMattia test is only a predictor of dynamic properties. In some cases the DeMattia is a good predictor of bench performance, but it is not always a good predictor. Conclusion AEM-LTX is a new polymer that has a good combination of: * High temperature resistance; * good low temperature properties initially and after heat aging; * good compression set values; * good CSR properties; and * good dynamic properties. After heat aging for six weeks at 150[degrees]C, the useful temperature range of a compound based on AEM--LTX ranges from -40[degrees]C up to 175[degrees]C. This article is based on a paper presented at a meeting of the Rubber Division, ACS (Asynchronous Communications Server) See network access server. (www.rubber.org See .org. (networking) org - The top-level domain for organisations or individuals that don't fit any other top-level domain (national, com, edu, or gov). Though many have .org domains, it was never intended to be limited to non-profit organisations. RFC 1591. ). References (1.) www.dupont Dupont, DuPont, Du Pont, or du Pont may refer to: Companies
(2.) "New Vamac polymer with high temperature flex resistance," E. McBride, Y.T. Wu, D.D. King and K. Kammerer, Rubber Division, Fall 2003. (3.) "From the voice of the customer to new products: Development of a new AEM polymer with improved low temperature properties," K. Kammerer, Y.T. Wu and L. Lefebvre Lefebvre is a common French surname. It is also spelled Lefèvre, LeFebvre, LeFèvre, and is used in the related forms Lefeuvre, Favre, Faure, Favret, Favrette or Dufaure. , to be published shortly in KGK KGK Kesintisiz Güç Kaynaklari . by E. McBride, Y.T. Wu, M.A. Stewart Stewart, river, Canada Stewart, river, 331 mi (533 km) long, rising in the Mackenzie Mts., central Yukon Territory, Canada, and flowing generally W to the Yukon River S of Dawson. , L. Lefebvre and K. Kammerer, DuPont (http://www2.dupont.com/Vamac/en_US/index.html)
Table 1 - properties of AEM G compounds with different plasticizer
levels
AEM G Compound No 10 phr 20 phr
plasticizer plasticizer plasticizer
Tg by DSC, [degrees]C -27 -35 -41
Hardness, durometer A 64 63 64
Carbon black, phr 42 50 60
Mooney viscosity, MU
ML (1+4) @ 100[degrees]C 42 30 24
Compression set, %
70 hours at 150[degrees]C 18 22 25
Vol. incr. in SF 105, % 28 21 16
(The formulation used was 100 phr AEM-G, 1.5 phr stea-
ric acid, 1.0 phr alkylated phosphate, 0.5 phr octadecyl
amine, 2.0 phr hindered amine antioxidant, 1.25 phr
HMDC, 2.0 phr DOTG, ans 2.0 phr DPG. The plasticizer
used was a polyether/ester type and the black was N550.
The compounds were press cured for five minutes at
175[degrees]C and then post cured for four hours at 175[degrees]C.)
Table 2 - compound formulations for AEM - LTX and AEM G with different
plasticizer levels and a constant hardness
AEM-LTX AEM G AEM-LTX
and no and no and 10
plast. plast. phr plast.
Hardness 60 64 61
AEM - LTX 100 0 100
AEM - G 0 100 0
Black, N550 48 42 56
TP-759 0 0 10
Diak #1 1.25 1.25 1.25
DPG 2 2 2
DOTG 2 2 2
AEM G AEM-LTX AEM G
and 10 and 20 and 20
phr plast. phr plast. phr plast.
Hardness 63 63 64
AEM - LTX 0 100 0
AEM - G 100 0 100
Black, N550 50 66 60
TP-759 10 20 20
Diak #1 1.25 1.25 1.25
DPG 2 2 2
DOTG 2 2 2
Table 3 - rheology results for AEM - LTX and AEM G, compounds
AEM-LTX AEM G AEM-LTX
and no and no and 10
plast. plast. phr plast,
Mooney viscosity
ML (1 +4) @ 100[degrees]C 36.8 41.9 25.8
Mooney scorch 121[degrees]C
Min. viscosity, MU 12.1 14 8.4
t10, minutes 14.8 13.1 17
MDR 177[degrees]C,
0.5[degrees]arc
20 minutes
ML, dNm 0.41 0.40 0.33
MH, dNm 9.63 9.41 8.42
tS2, minutes 1.21 1.17 1.34
t50, minutes 2.13 1.98 2.15
t90, minutes 9.41 9.76 8.89
AEM G AEM-LTX AEM G
and 10 and 20 and 20
phr plast. phr plast. phr plast.
Mooney viscosity
ML (1 +4) @ 100[degrees]C 29.9 23 24.3
Mooney scorch 121[degrees]C
Min. viscosity, MU 9.7 7.9 8.2
t10, minutes 14.1 17.4 15.1
MDR 177[degrees]C,
0.5[degrees]arc
20 minutes
ML, dNm 0.31 0.37 0.31
MH, dNm 8.02 7.83 7.35
tS2, minutes 1.29 1.37 1.39
t50, minutes 1.98 2.08 2.03
t90, minutes 9.67 8.92 10.1
Table 4 - cured physical properties of AEM - LTX and AEM G compounds
AEM-LTX AEM G AEM-LTX
and no and no and 10
plast. plast. phr plast.
Hardness, duro. A 59.6 64.1 60.9
Mod. at 100% elong, Mpa 3.1 3.2 3.1
Tensile strength, MPa 14.3 17.5 12.7
%elongation 360 443 372
Die C tear, N/mm 28.2 31.9 27.5
%compression set
70 hours at 150[degrees]C 21.9 17.8 22.5
AEM G AEM-LTX AEM G
and 10 and 20 and 20
phr plast. phr plast. phr plast.
Hardness, duro. A 62.9 63.4 63.6
Mod. at 100% elong, Mpa 3.1 3.1 3.2
Tensile strength, MPa 15.3 11.0 13.3
%elongation 441 355 411
Die C tear, N/mm 32.7 27.7 31.5
%compression set
70 hours at 150[degrees]C 21.6 25.2 24.9
Table 5 - low temperature properties of AEM - LTX and AEM G compounds
AEM-LTX AEM G AEM-LTX
and no and no and 10
plast. plast. phr Plast.
Tg by DSC, [degrees]C -42 -27 -49
TR10 results, [degrees]C -39 -26 -45
DMA results (1 Hz freq)
Tg, loss mod., [degrees]C -37 -26 -41
Tg, tan delta, [degrees]C -32 -20 -35
Static o-ring test, [degrees]C -55 -41 -59
AEM G AEM-LTX AEM G
and 10 and 20 and 20
phr Plast. phr Plast. phr Plast.
Tg by DSC, [degrees]C -35 -54 -41
TR10 results, [degrees]C -30 -45 -36
DMA results
Tg, loss mod., [degrees]C -33 -45 -35
Tg, tan delta, [degrees]C -27 -41 -31
Static o-ring test, [degrees]C -48 -63 -54
Table 6 - low temperature properties of AEM - LTX
and AEM G compounds after heat aging in air for
one week at 175[degrees]C
AEM-LTX AEM G AEM-LTX
and no and no and 10
plast. plast. phr plast.
Tg by DSC, [degrees]C -42 -27 -49
Tg after heat aging,
1 week at 175[degrees]C -41.3 -26.1 -42.4
Delta Tg, [degrees]C 0.6 1.3 6.1
AEM G AEM-LTX AEM G
and 10 and 20 and 20
phr plast. phr plast. phr plast.
Tg by DSC, [degrees]C -35 -54 -41
Tg after heat aging,
1 week at 175[degrees]C -28.1 -43.4 -29.7
Delta Tg, [degrees]C 7.0 10.2 11.6
Table 7 - low temperature properties of AEM - LTX
and AEM G compounds after fluid aging in ASTM #1
and SF 105
AEM-LTX AEM G AEM-LTX
and no and no and 10
plast plast. phr plast
Tg by DSC, [degrees]C -42 -27 -49
Tg after 1 week at 150[degrees]C
in ASTM #1 -43.8 -28.5 -44.6
Delta Tg, [degrees]C 2 1 -4
Tg after 1 week at 150[degrees]C
in SF 105 -50.6 -33.4 -51.2
Defta Tg, [degrees]C -9 -6 -3
AEM G AEM-LTX AEM G
and 10 and 20 and 20
phr plast. phr plast. phr plast
Tg by DSC, [degrees]C -35 -54 -41
Tg after 1 week at 150[degrees]C
in ASTM #1 -30.3 -45.8 -32.1
Delta Tg, [degrees]C -5 -8 -9
Tg after 1 week at 150[degrees]C
in SF 105 -34.3 -51.9 -35.1
Defta Tg, [degrees]C 1 2 6
Table 8 - DeMattia flex properties of AEM - LTX and AEM G compounds
Polymer AEM G First attempt AEM-LTX
at low temp.
Hardness, durometer A 68 62 64
M50% (MPa) 1.6 1.4 1.4
M100% (MPa) 3.4 3.4 3.0
Tensile strength (MPa) 13.0 9.8 10.7
Elongation, % 365 264 335
Crescent tear die C,
ISO 34, Fmax (Nmm) 28.3 19.5 23.0
Tg by DSC, [degrees]C -40 -51 -53
DeMattia at 150[degrees]C, D 430
Cycles to failure 495 45 655
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