Printer Friendly

Low volatility plasticizers for AEM compounds.

AEM polymers were introduced to the elastomers market almost 40 years ago. Most of the AEM polymers are terpolymers of ethylene, methyl acrylate and an acidic cure site monomer which allows for curing with a diamine. Some of the AEM polymers are copolymers of ethylene and methyl acrylate, and these are cured with peroxides. Parts made from AEM compounds are used in a variety of automotive applications, and there has been a steady growth in the use of AEM polymers (ref. 1).

Some of the attractive properties of AEM compounds include heat and fluid resistance rating according to ASTM D2000 of EE, EF, EG and EH (175[degrees]C heat rating, volume increase in IRM 903 from 30 to 80%); can meet low temperature requirements of -40[degrees]C; good compression set at 150[degrees]C; and good CSR properties in engine oil and transmission fluid for 2,000 hours at 150[degrees]C.

End uses for AEM compounds include turbocharger hoses; transmission oil cooler (TOC) hoses; PCV (positive crankcase ventilation hoses) and EGR (exhaust gas recovery) hoses; seals and gaskets for automatic transmissions; seals and gaskets for engines; and many other applications.

Influence of market trends on AEM compounds

There have been many changes in the automotive marketplace over the years that favored the growth of AEM polymers, including higher engine temperatures, longer warranty times/ higher mileage warranties, more aggressive automotive fluids and government changes in allowable emission levels from cars.

The higher temperatures and longer warranty times have led to AEM compounds replacing some elastomers that could not hold up to the higher temperatures and longer times. In some cases, the temperature requirements are getting more stringent and they are pushing the limits of AEM compounds.

Low volatility plasticizers

An AEM compound is typically made up of seven to ten ingredients, and most compounds use a plasticizer at a level of anywhere from 3 to 20 phr. All of the ingredients in the AEM compound have to be able to perform at the high and low temperature requirements before and after heat aging. In some cases, the traditional plasticizers used with AEM compounds are insufficient for heat aging as the test conditions become more severe.

This article will review the performance of AEM compounds made with low volatility plasticizers (ref. 2). These low volatility plasticizers help AEM compounds provide several features, including better heat aging properties; better low temperature properties after heat aging; better (lower) compression set; and less weight loss in the post cure ovens.

There are many definitions for plasticizers, and three important properties are that the plasticizer is compatible with the elastomer; lowers the Tg of the compound; and lowers the viscosity of the compound

This study looked at five different plasticizers that were evaluated in AEM compounds. All of the plasticizers met the three criteria listed above. Some of the plasticizer properties are shown in table 1.

The first plasticizer shown in the table is DOS (dioctyl sebacate). and it is a good plasticizer for many elastomer applications where the heat aging requirements are relatively mild. However, it is not a good plasticizer for AEM compounds because it is too volatile at the high temperatures seen in the end use applications.

A laboratory test was designed to look at the volatility of the plasticizers. A small sample was placed in a TGA (thermogravimetric analyzer) at room temperature, and then it was heated up quickly (20[degrees]C/min.) to 175[degrees]C and then held there for 12 hours. The total weight loss was measured and the results are shown in table 2. This table also includes the molecular weight of the different plasticizers. The higher MW plasticizers have significantly lower weight loss.

Typical heat aging tests for AEM compounds are for one and six weeks at 150[degrees]C, and also for one week at 175[degrees]C. The weight loss of a plasticizer in a cured compound will not be as high as for the neat plasticizer in the TGA test, but the expectation is that not much of the DOS plasticizer will remain in the compound after a week at 175[degrees]C.

A potential concern for the higher MW plasticizers is that the low temperature properties will not be as good as for a lower MW plasticizer. These concerns were addressed by studying the low temperature properties of compounds (not neat plasticizers) both before and after heat aging of the compounds.

Structures of the plasticizers are shown in figure 1. These diagrams came from literature searches done using the CAS numbers.

Compound evaluation

The plasticizers were evaluated in standard AEM formulations and the compound properties were measured before and after heat aging. As a way to follow what happened to the plasticizers during heat aging, the weight loss of the compounds was measured after the post-cure step and after each of the heat aging steps.

[FIGURE 1 OMITTED]

The formulations are shown in table 3. The first compound is a control compound with no plasticizer and 50 phr N550 black. All of the plasticized compounds had 15 phr plasticizer, and the carbon black level was increased to 65 phr N550 black to match the hardness of the control compound. The last compound was a second control compound that had no plasticizer and 65 phr N550 black, and as expected, it had the highest hardness.

The rheology properties for the compounds are shown in table 4. The compounds with 15 phr of plasticizer had significantly lower viscosity than the control with no plasticizer and 50 phr black. All of the plasticized compounds were relatively close in viscosity. Most of the plasticized compounds had similar values for delta torque of the MDR curve, but the standard ether ester compound had a slightly lower delta torque compared with the other plasticized compounds.

The samples were press-cured for ten minutes at 180[degrees]C and then post-cured for four hours at 175[degrees]C. The initial physical properties are shown in table 5. All of the plasticized compounds had slightly higher modulus and hardness values compared to the control with no plasticizer. If the black level were lowered 5 phr black to about 60 phr, then the hardness and modulus values for the plasticized compounds would have been closer to the control.

The table also includes the total weight loss that occurred during the post-cure step, which was four hours at 175[degrees]C. The two control compounds without plasticizer lost about 2 weight percent. This is due to volatiles from the cure system and the volatiles from the release package. The compound with the DOS plasticizer lost about 4% of its weight, which is double what the control compound lost. Based on some assumptions, this translates into a loss of about 34% of the plasticizer, or about 5 phr of plasticizer. This probably accounts for the relatively high hardness (76 durometer A) for the DOS-based compound. The standard ether ester compound lost about 15% of its plasticizer (about 2 phr) during the post-cure step.

The compounds with the TOTM, 810TM and the low volatility ether ester plasticizer had similar weight loss compared to the control, which means that the plasticizer weight loss in the post-cure step was minimal. Compounds made with these three plasticizers will have less weight loss in the post-cure step, and this could be an attractive feature for large scale commercial post-cure ovens. The DOS compounds will have the highest weight loss, and the standard ether ester compounds will have a weight loss between the DOS compound and the other three plasticizers.

Heat aging in air for one week at 150[degrees]C and for one week at 175[degrees]C

The compounds were aged in air for one week at 150[degrees]C and for one week at 175[degrees]C. The physical properties after aging for one week at 150[degrees]C are shown in table 6. The table also includes the total weight loss from the combination of the postcure oven and the heat aging. After one week at 150[degrees]C (and the post-cure step), over 90% of the DOS has been lost from the compound.

The DOS-based compound has significantly higher absolute values for hardness and modulus compared to the other plasticized compounds. In fact, the hardness and modulus values are similar to the control compound, with 65 phr black and no plasticizer.

Table 7 shows the properties and weight loss after aging in air for one week at 175[degrees]C. After aging at this condition, almost all of the plasticizer is gone from the compounds with the standard ether ester plasticizer, as well as the compound with TOTM. The hardness and modulus values are relatively high and they are close to the control compound with 65 phr black and no plasticizer. Only about 20% of the plasticizer is gone from the 810TM and the low volatility ether ester compounds, and their hardness and modulus values are closer to the control with 50 phr black.

The heat aging requirements for most compounds typically allow for less than 50% loss in tensile and elongation, and less than a 15 point change in hardness. The compounds that lost most of their plasticizer (DOS--1 week/150[degrees]C, TOTM and standard ether ester for 1 week/175[degrees]C) still met the standard heat aging requirements. Compared with the less volatile plasticizers, they had a much higher change in hardness and in M50.

Figure 2 shows the stress/strain curves for the above compounds after they have aged in air for one week at 175[degrees]C. The plot only goes out to 100% elongation, which is probably higher than most parts will see in their end use. The data are split into two groups. The first three plasticized compounds have lost almost all of their plasticizer and they have a stress strain curve similar to the control with 65 phr black. The last two plasticized compounds retained most of their plasticizer and they have stress strain curves similar to the 50 phr black control.

[FIGURE 2 OMITTED]

Compression set

The compounds were tested for compression set using the ASTM plied method (D 395B), as well as the molded ISO pellets (815-1). They were tested at a relatively mild condition of 70 hours at 150[degrees]C and a more severe condition of one week at 175[degrees]C. Results are shown in table 8.

The compounds with the DOS and the standard ether ester plasticizer were the highest in compression set after 70 hours at 150[degrees]C. They were also significantly higher in compression set when measured for one week at 175[degrees]C.

The TOTM compound had low compression set values at both test conditions. It was as good as the 810TM in compression set, and it was slightly better than the low volatility ether ester plasticizer.

Many older AEM compounds used DOTG as the accelerator, but it is being replaced due to regulatory issues (ref. 3). The DOTG was a good accelerator for the cure step and it had an added benefit of low compression set. A concern when replacing the DOTG has been meeting the compression set targets. If a DOTG based compound has been using the standard ether ester plasticizer, then one way to improve compression set when moving away from DOTG is to switch to the TOTM, the 810TM or the low volatility ether ester plasticizer. DOTG was not used in this study.

Low temperature performance

The low volatility plasticizers improved the heat aging properties and the compression set properties of the AEM compounds, as expected. A key issue is how these plasticizers perform in low temperature tests before and after heat aging. The two low temperature tests used in this study were Tg by DSC and TRIO. The initial values are shown in table 9. The two ether ester based plasticizers have the best low temperature properties, while the two trimellitate plasticizers are not quite as good. (The trimellitate plasticizers were better in compression set.)

Table 10 shows the low temperature properties after heat aging. The DOS compound has no improved low temperature properties after aging in hot air for one week at 150[degrees]C compared to the control with no plasticizer. After aging for a week in air at 175[degrees]C, the compound with the standard ether ester plasticizer does not have any better low temperature properties compared to the control with no plasticizer. The same is true for the TOTM compound.

The two compounds with the low volatility plasticizers still have low temperature properties that are better than the compounds without plasticizer. After a week at 175[degrees]C, the compound with the low volatility ether ester plasticizer has the lowest Tg value. The two low volatility compounds have similar TRIO values after heat aging for a week at 175[degrees]C.

Fluid aging in Dexron VI automatic transmission fluid

The compounds were fluid aged for one week at 150[degrees]C in Dexron VI. The results are shown in table 11. All of the plasticized compounds had significantly lower volume increase compared to the compounds with no plasticizer, and they also had less change in hardness.

The compounds with TOTM and 810TM had the lowest volume increase in the Dexron VI. Follow-up studies were done with several other engine oils and automatic transmission fluids, and the compounds with the trimellitate plasticizers had the lowest volume increase. The one exception was IRM 903; the trimellitate plasticizers were similar to the ether ester plasticizers in volume increase in IRM 903.

As part of the fluid aging study, the Tg by DSC was measured on the compounds after aging in Dexron VI, and the results are shown in table 12. It was interesting to note that all of the compounds, including the compounds with no plasticizer, had similar Tg after fluid aging. The compounds with no plasticizer had a significant drop in Tg after aging in the fluid.

Improved hose compound

Several follow-up studies have been done with AEM polymers and the low volatility plasticizers. One example is a study for improving the properties of hose compounds. Ideally, a hose compound should have both good dynamic properties and low compression set. However, it is difficult to optimize both of these properties because an improvement in one property typically hurts the other property.

Compounds based on the AEM GXF polymer have been used for many years in turbocharger hoses because they are easy to process and they have good dynamic properties. Most AEM GXF compounds use the standard ether ester plasticizer. An improved polymer, AEM HT, was introduced recently as an upgrade over AEM GXF for hose applications because it maintains the good dynamic properties and it has lower compression set values (ref. 4). A study was done comparing AEM GXF compounds with the standard ether ester plasticizer versus AEM HT compounds using the low volatility plasticizers.

The heat aging conditions for turbocharger components are becoming more stringent for a variety of reasons, including more crowded engine compartments, higher operating pressures, etc. To simulate the more severe conditions, the study compared the compounds after aging at relatively severe conditions. The two key tests included measuring compression set after aging for one week at 175[degrees]C, rather than for 70 hours at 150[degrees]C; and measuring dynamic properties by running a DeMattia flex test on samples aged in hot air for one week at 175[degrees]C rather than running on the original samples.

The formulations used in this study are shown in table 13, along with some of the cured properties. The goal was to make 70 durometer A compounds with different states of cure so as to compare the trade-off between compression set and dynamic properties (as measured by DeMattia Flex). The curative levels (HMDC) were varied, as well as the black levels. All of the compounds had hardness values near 70 durometer A.

The AEM HT compounds had 15 phr of the 810TM plasticizer, while the AEM GXF compounds only had 10 phr of the standard ether ester plasticizer. These levels were set so that the two sets of compounds would have similar initial low temperature properties (the ether ester plasticizer has slightly better low temperature compared to the trimellitates). All of the compounds did have similar initial low temperature properties, but the 810TM compounds had significantly better low temperature properties after heat aging for one week in air at 175[degrees]C. The 810TM compounds also had lower volume swell in IRM 903.

Table 14 shows the two key properties for this study, including compression set after a week at 175[degrees]C, and the DeMattia test results (pierced samples) run on samples aged in air for a week at 175[degrees]C.

The results are shown graphically in figure 3 with the DeMattia results plotted on a logarithmic scale. The compounds with the AEM HT and the low volatility plasticizer perform significantly better than the AEM GXF compounds with the standard plasticizer at these relatively severe aging conditions.

If the average compression set is held constant at 52%, the AEM GXF compound will go through 1,500 cycles before the crack growth reaches 8.5 mm. It takes the AEM HT compound 40,000 cycles before the crack growth reaches 8.5 mm.

If the cycles to reach a crack growth of 8.5 mm are held constant at 5,000 cycles, then the AEM GXF/standard ether ester compound will have an average compression set of 65%. The AEM HT/810TM compound will have a compression set of 38%.

Conclusions

AEM compounds that use a low volatility plasticizer have several advantages over the "standard" ether ester plasticizer, including less weight loss in the post-cure oven; better heat aging properties, especially as the test time and temperature are increased; better compression set properties, especially as the test time and temperature are increased; better compression set properties if DOTG has to be removed from an AEM compound; better low temperature properties after heat aging; the low volatility trimellitate plasticizer provides lower volume swell in engine oils and transmission fluids; the low volatility trimellitate plasticizer has the best compression set properties of the plasticized compounds; and the low volatility ether ester plasticizer has the best low temperature properties after heat aging

[FIGURE 3 OMITTED]

The combination of an improved plasticizer as well as an improved AEM polymer provides compounds with a step change improvement over compounds made with standard AEM polymers and the standard ether ester plasticizer. An example is for hose compounds where the trade-off between compression set and dynamic properties (DeMattia) can be optimized.

Laboratory methods

The ASTM and ISO methods used for this work are shown in table 15.

This article is based on a paper presented at the 186th Technical Meeting of the Rubber Division, ACS, October 2014.

References

(1.) http://www.dupont.com/Vamac--background information on AEM polymers.

(2.) "New high and low temperature esters for acrylic elastomers, " S. O 'Rourke, Rubber Division, ACS Technical Meeting, October 2009, paper 62.

(3.) "Formulation suggestions for replacing DOTG in AEM compounds," E. McBride, K. Kammerer and L. Lefebvre, Rubber Division, ACS Technical Meeting, October 2010, paper 32.

(4.) "HT-AEM solution for high performance turbocharger hoses," E. McBride and C.S. Grant, Hose Manufacturers Conference 2011, Cleveland, OH.

by Edward McBride, DuPont Performance Polymers
Table 1--general information on five plasticizers used in study

                        Name          Chemical name
                        used in
                        article

High volatility         DOS           Dioctyl sebacate
  plasticizer (poor
  heat aging)
Standard plasticizers   Standard      Bis[2-[2-(2-
  (good heat aging)     ether ester   butoxyethoxy)ethoxy]ethyl]
                                      adipate
                        TOTM          Tris(2-ethylhexyl)trimellitate
Low volatility          810TM         Tri(N-octyl-N-decyl) trimellitate
  plasticizers (very    LV ether      Polyethylene glycol ester of 2-
  good heat aging)      ester         ethylhexanoic acid

                        CAS           Commercial or
                        number        industry names

High volatility         122-62-3      DOS
  plasticizer (poor
  heat aging)
Standard plasticizers                 TP 759
  (good heat aging)     65520-46-9    W759
                                      Nycoflex ADB 30
                        3319-31-1     TOTM
Low volatility          67989-23-5    810TM
  plasticizers (very    9004-93-7     Tegmer812
  good heat aging)                    Alcanplast PO 80
                                      ADK Cizer RS 735

Table 2--weight loss results for plasticizers
in TGA test

Name used              Molecular                                  MW
in article             formula

DOS                    [C.sub.26][O.sub.4][H.sub.50]             427
Standard ether ester   [C.sub.26][O.sub.10][H.sub.50]            523
TOTM                   [C.sub.33][O.sub.6][H.sub.54]             547
810TM                  [C.sub.39][O.sub.6][H.sub.66]      590 to 630
LV ether ester         [C.sub.32][O.sub.16][H.sub.64]     650 to 750
                                                         (estimated)

Name used               % weight loss
in article                in TGA test
                         -12 hours at
                        175[degrees]C

DOS                                67
Standard ether ester               26
TOTM                               15
810TM                             1.2
LV ether ester                    5.4

Table 3--formulations used in study

                             Control,       15 DOS    15 standard
                             no plast     65 black    ether ester
                             50 black                    65 black

AEM G                             100          100            100
FEF, N550                          50           65             65
DOS                                             15
Standard ether ester                                           15
TOTM
810TM
LV ether ester
Hindered amine AO                 2.0          2.0            2.0
Stearic acid                      1.5          1.5            1.5
Alkyl phosphate release           1.0          1.0            1.0
Octadecyl amine (scorch)          0.5          0.5            0.5
HMDC curative                     1.5          1.5            1.5
DBU based accelerator             2.0          2.0            2.0
70% active
phr                             158.5        188.5          188.5

                              15 TOTM     15 810TM
                             65 black     65 black

AEM G                             100          100
FEF, N550                          65           65
DOS
Standard ether ester
TOTM                               15
810TM                                           15
LV ether ester
Hindered amine AO                 2.0          2.0
Stearic acid                      1.5          1.5
Alkyl phosphate release           1.0          1.0
Octadecyl amine (scorch)          0.5          0.5
HMDC curative                     1.5          1.5
DBU based accelerator             2.0          2.0
70% active
phr                             188.5        188.5

                             15LV ether    Control, no
                               ester 65    plasticizer
                                  black       65 black

AEM G                               100            100
FEF, N550                            65             65
DOS
Standard ether ester
TOTM
810TM
LV ether ester                       15
Hindered amine AO                   2.0            2.0
Stearic acid                        1.5            1.5
Alkyl phosphate release             1.0            1.0
Octadecyl amine (scorch)            0.5            0.5
HMDC curative                       1.5            1.5
DBU based accelerator               2.0            2.0
70% active
phr                               188.5          173.5

Table 4--compound rheology properties

                               Control, no      15 DOS    15 standard
                               plasticizer    65 black    ether ester
                                  50 black                   65 black

Mooney viscosity
ML (1+4)@100[degrees]C                  53          37             37
Mooney scorch, 121[degrees]C
Min. viscosity--MU                    20.0        12.2           12.6
t5--minutes                            7.0         8.2            8.6
t10--minutes                           9.5        11.3           11.9
t15--minutes                          11.8        15.7           16.5
MDR at 180, 0.5[degrees]
  arc, 15 minutes
ML, dNm                               0.61        0.54           0.56
MH, dNm                               16.2        15.3           13.9
Delta torque, dNm                     15.6        14.7           13.3
tS2, minutes                          0.74        0.78           0.82
t50, minutes                           2.0         2.1            2.1
t90, minutes                           7.0         7.3            7.4

                                15 TOTM    15 810TM
                               65 black    65 black

Mooney viscosity
ML (1+4)@100[degrees]C               42          41
Mooney scorch, 121[degrees]C
Min. viscosity--MU                 13.7        13.4
t5--minutes                         8.2         8.4
t10--minutes                       11.4        11.5
t15--minutes                       15.1        15.3
MDR at 180, 0.5[degrees]
  arc, 15 minutes
ML, dNm                            0.57        0.57
MH, dNm                            15.8        16.0
Delta torque, dNm                  15.2        15.5
tS2, minutes                       0.75        0.76
t50, minutes                        2.1         2.1
t90, minutes                        7.3         7.2

                                     15 LV    Control, no
                               ether ester    plasticizer
                                  65 black       65 black

Mooney viscosity
ML (1+4)@100[degrees]C                  39             79
Mooney scorch, 121[degrees]C
Min. viscosity--MU                    13.2           28.9
t5--minutes                            8.5            6.7
t10--minutes                          11.9            8.8
t15--minutes                          16.3           10.8
MDR at 180, 0.5[degrees]
  arc, 15 minutes
ML, dNm                                0.57          1.11
MH, dNm                               15.9           22.3
Delta torque, dNm                     15.3           21.2
tS2, minutes                          0.79           0.62
t50, minutes                           2.2            2.0
t90, minutes                           7.6            7.2

Table 5--initial properties of cured compounds and weight loss in the
post-cure oven

                       Control, no     15 DOS   15 standard   15 TOTM
                       plasticizer   65 black   ether ester   65 black
                          50 black                 65 black

Hardness, durometer A           67         76            72        72
M50, MPa                       2.2        3.5           3.1       3.0
M100, MPa                      5.8        7.7           6.9       7.3
M200, MPa                     15.8       15.9          14.6      16.1
Tensile strength, MPa         17.1       16.7          16.6      17.3
% elongation                   215        219           228       226
Total weight loss in          1.9%       4.60%         3.0%      2.1%
  PC step
% plasticizer lost                         34%          15%      3.4%
phr plasticizer lost                      5.2           2.2       0.5

                        15810TM          15LV   Control, no
                       65 black   ether ester   plasticizer
                                     65 black      65 black

Hardness, durometer A        72            73            81
M50, MPa                    3.2           3.2           5.0
M100, MPa                   7.5           8.0          11.5
M200, MPa                  15.7          16.5
Tensile strength, MPa      17.1          17.6          19.1
% elongation                222           209           175
Total weight loss in       1.9%          1.9%          2.0%
  PC step
% plasticizer lost         1.5%          1.6%
phr plasticizer lost        0.2           0.2

Table 6--properties and weight loss after heat aging for one week at
150[degrees]C

One week in air at             Control, no      15 DOS    15 standard
150[degrees]C                  plasticizer    65 black    ether ester
                                  50 black                   65 black

Hardness, durometer A                   71          84             77
M50, MPa                               2.8         4.8            3.3
M100, MPa                              6.7         9.6            6.6
Tensile strength, MPa                 19.4        17.6           15.5
% elongation                           274         219            251
Change in hardness, points               4           8              5
% change M50                           25%         38%             7%
% change in M100                       14%         26%            -4%
% change in TS                         13%          5%            -7%
% change in elongation                 28%          0%            10%
Weight loss from heat aging                       5.7%           2.9%
Total weight loss PC +                           10.0%           5.8%
  heat age
% plasticizer lost                                 93%            39%
phr plasticizer lost                              13.9            5.9

One week in air at              15 TOTM     15810TM
150[degrees]C                  65 black    65 black

Hardness, durometer A                74          74
M50, MPa                            3.2         3.1
M100, MPa                           7.0         7.1
Tensile strength, MPa              16.0        16.2
% elongation                        234         239
Change in hardness, points            2           2
% change M50                         6%         -4%
% change in M100                    -4%         -5%
% change in TS                      -7%         -6%
% change in elongation               4%          7%
Weight loss from heat aging        3.0%        1.2%
Total weight loss PC +             5.0%        3.1%
  heat age
% plasticizer lost                  30%          5%
phr plasticizer lost                4.5         0.8

One week in air at                   15 LV    Control, no
150[degrees]C                  ether ester    plasticizer
                                  65 black       65 black

Hardness, durometer A                   75             84
M50, MPa                               3.2            5.1
M100, MPa                              7.4           11.5
Tensile strength, MPa                 16.1           20.5
% elongation                           225            205
Change in hardness, points               2              3
% change M50                           -2%             3%
% change in M100                       -7%             1%
% change in TS                         -8%             7%
% change in elongation                  8%            17%
Weight loss from heat aging           1.2%           0.9%
Total weight loss PC +                3.1%           2.9%
  heat age
% plasticizer lost                      6%
phr plasticizer lost                   0.8

Table 7--properties and weight loss after heat aging for one week at
175[degrees]C

After one week in air at       Control, no     15 DOS    15 standard
175[degrees]C                  plasticizer    65 black   ether ester
                                  50 black                  65 black

Hardness, durometer A                   74         87             85
M50, MPa                               2.7        5.1            4.6
M100, MPa                              6.3        9.2            8.3
Tensile strength, MPa                 17.0       15.1           14.5
% elongation                           244        197            218
Change in hardness, points               7         11             13
% change M50                           22%        47%            47%
% change in M100                        8%        20%            20%
% change in TS                         -1%        -9%           -13%
% change in elongation                 14%       -10%            -4%
Weight loss from heat aging                      6.6%           7.2%
Total weight loss PC +                3.8%      10.9%          10.0%
  heat age
% plasticizer lost                                96%            85%
phr plasticizer lost                             14.4           12.8

After one week in air at       15 TOTM    15810TM
175[degrees]C                  65 black   65 black

Hardness, durometer A               85         77
M50, MPa                           4.3        3.4
M100, MPa                          8.3        6.8
Tensile strength, MPa             15.1       13.6
% elongation                       202        212
Change in hardness, points          13          5
% change M50                       43%         4%
% change in M100                   14%       -10%
% change in TS                    -13%       -21%
% change in elongation            -11%        -4%
Weight loss from heat aging       8.6%       3.4%
Total weight loss PC +           10.5%       5.2%
  heat age
% plasticizer lost                 91%        25%
phr plasticizer lost              13.7        3.8

After one week in air at              15LV    Control, no
175[degrees]C                  ether ester    plasticizer
                                  65 black       65 black

Hardness, durometer A                   75             84
M50, MPa                               3.1            5.3
M100, MPa                              6.5           11.5
Tensile strength, MPa                 13.6           17.7
% elongation                           206            167
Change in hardness, points               2              3
% change M50                           -3%             7%
% change in M100                      -18%             0%
% change in TS                        -23%            -8%
% change in elongation                 -2%            -5%
Weight loss from heat aging           2.8%           1.5%
Total weight loss PC +                4.7%           3.5%
  heat age
% plasticizer lost                     19%
phr plasticizer lost                   2.8

Table 8--compression set after 70 hours at 150[degrees]C and after one
week at 175[degrees]C

                                Control, no     15 DOS    15 standard
                                plasticizer    65 black   ether ester
                                   50 black                  65 black

70 hours at 150[degrees]C
ASTM plied                               18         26             26
ISO molded                               20         29             29
Average for 70 hours at                  19         27             28
  150[degrees]C
168 hours at 175[degrees]C
ASTM plied                               33         49             47
ISO molded                               38         56             53
Average for 168 hours at                 35         53             50
  175[degrees]C

                                15 TOTM    15810TM
                                65 black   65 black

70 hours at 150[degrees]C
ASTM plied                           20         18
ISO molded                           22         22
Average for 70 hours at              21         20
  150[degrees]C
168 hours at 175[degrees]C
ASTM plied                           35         35
ISO molded                           41         41
Average for 168 hours at             38         38
  175[degrees]C

                                      15 LV    Control, no
                                ether ester    plasticizer
                                   65 black       65 black

70 hours at 150[degrees]C
ASTM plied                               22             20
ISO molded                               25             20
Average for 70 hours at                  24             20
  150[degrees]C
168 hours at 175[degrees]C
ASTM plied                               40             36
ISO molded                               43             39
Average for 168 hours at                 41             37
  175[degrees]C

Table 9--initial low temperature properties

Initial values          Control, no    15 DOS   15 standard   15 TOTM
                        plasticizer   65 black  ether ester   65 black
                           50 black                65 black

Tg by DSC, [degrees]C         -29.5     -37.2         -40.2     -36.3
TR10, [degrees]C, 50%         -27.8     -32.3         -35.3     -30.2
  elongation

Initial values          15810TM          15LV   Control, no
                        65 black  ether ester   plasticizer
                                     65 black      65 black

Tg by DSC, [degrees]C     -36.3         -39.8         -29.3
TR10, [degrees]C, 50%     -30.3         -33.7         -26.3
  elongation

Table 10--low temperature properties after heat aging

                               Control, no     15 DOS    15 standard
                               plasticizer    65 black   ether ester
                                  50 black                  65 black

Tg by DSC, [degrees]C
Initial                              -29.5      -37.2          -40.2
One week in air at                   -29.1      -29.3          -35.8
  150[degrees]C
One week at 175[degrees]C            -28.5      -28.9          -29.9
TR10, [degrees]C, 50%
  elongation
Initial                              -27.8      -32.3          -35.3
One week in air at                   -25.3      -23.8          -29.6
  150[degrees]C
One week at 175[degrees]C            -24.1      -23.4          -24.1

                               15 TOTM    15810TM
                               65 black   65 black

Tg by DSC, [degrees]C
Initial                          -36.3      -36.3
One week in air at               -33.4      -35.9
  150[degrees]C
One week at 175[degrees]C        -29.5      -33.7
TR10, [degrees]C, 50%
  elongation
Initial                          -30.2      -30.3
One week in air at               -28.0      -29.4
  150[degrees]C
One week at 175[degrees]C        -24.6      -29.2

                                      15LV    Control, no
                               ether ester    plasticizer
                                  65 black       65 black

Tg by DSC, [degrees]C
Initial                              -39.8          -29.3
One week in air at                   -39.0          -29.3
  150[degrees]C
One week at 175[degrees]C            -37.0           -28.8
TR10, [degrees]C, 50%
  elongation
Initial                              -33.7          -26.3
One week in air at                   -31.6          -27.5
  150[degrees]C
One week at 175[degrees]C            -29.3           -24.8

Table 11--fluid aging in Dexron VI for one week at 150[degrees]C

After one week in Dexron VI   Control, no     15 DOS    15 standard
at 150[degrees]C              plasticizer    65 black   ether ester
                                 50 black                  65 black

Hardness, durometer A                  59         72             69
M50, MPa                              2.8        4.0            3.7
M100, MPa                             8.4        9.7            9.2
Tensile strength, MPa                10.6       16.4           16.6
% elongation                          120        161            174
Volume increase                         21        14             14
Change in hardness, points             -8         -4             -3
% change in M50                       25%        15%            20%
% change in M100                      44%        26%            33%
% change in TS                       -38%        -2%             0%
% change in elongation               -44%       -26%           -23%

After one week in Dexron VI   15 TOTM    15810TM
at 150[degrees]C              65 black   65 black

Hardness, durometer A              70         71
M50, MPa                          4.0        4.0
M100, MPa                        10.3        9.8
Tensile strength, MPa            17.0       17.2
% elongation                      158        171
Volume increase                    10         10
Change in hardness, points         -2         -1
% change in M50                   32%        23%
% change in M100                  40%        31%
% change in TS                    -2%         0%
% change in elongation           -30%       -23%

After one week in Dexron VI         15 LV    Control, no
at 150[degrees]C              ether ester    plasticizer
                                 65 black       65 black

Hardness, durometer A                  70             71
M50, MPa                              3.9            5.0
M100, MPa                             9.9           13.6
Tensile strength, MPa                14.3           17.5
% elongation                          138            124
Volume increase                        13             20
Change in hardness, points             -3            -10
% change in M50                       21%             0%
% change in M100                      25%            19%
% change in TS                       -19%            -9%
% change in elongation               -34%           -29%

Table 12--Tg by DSC after aging in Dexron VI for one week at
150[degrees]C

After one week in Dexron VI    Control, no     15 DOS    15 standard
  at 150[degrees]C             plasticizer    65 black   ether ester
                                  50 black                  65 black
Tg by DSC, [degrees]C
Initial                                -30        -37            -40
After fluid aging                      -35        -35            -37

After one week in Dexron VI    15 TOTM    15 810TM
  at 150[degrees]C             65 black   65 black

Tg by DSC, [degrees]C
Initial                            -36        -36
After fluid aging                  -35        -35

After one week in Dexron VI           15LV    Control, no
  at 150[degrees]C             ether ester    plasticizer
                                  65 black       65 black
Tg by DSC, [degrees]C
Initial                                -40            -29
After fluid aging                      -37            -34

Table 13--formulations for comparing AEM GXF and AEM HT

                                      AEM GXF     AEM GXF     AEM GXF
                                     0.9 HMDC    1.2 HMDC    1.5 HMDC

AEM GXF                                   100         100         100
AEM HT                                     --          --          --
N550                                       64          60          56
Standard ether ester                       10          10          10
810TM                                      --          --          --
Hindered amine AO                           2           2           2
Stearic acid                                1           1           1
Alkyl phosphate release                     1           1           1
HMDC curative                             0.9         1.2         1.5
DBU based accelerator                       1           1           1
Total phr                               179.9       176.2       172.5
Post-cure properties
Hardness, durometer A                      70          70          72
Tg by DSC, [degrees]C
Initial                                 -37.9       -37.4       -37.0
After one week at 175[degrees]C         -31.5       -30.5       -30.7
After one week in IRM 903
  150[degrees]C
Volume increase                            71          63          60

                                       AEM HT      AEM HT      AEM HT
                                     0.8 HMDC    1.0 HMDC    1.2 HMDC

AEM GXF                                    --          --          --
aem ht                                    100         100         100
N550                                       69          66          64
Standard ether ester                       --          --          --
810TM                                      15          15          15
Hindered amine AO                           2           2           2
Stearic acid                                1           1           1
Alkyl phosphate release                     1           1           1
HMDC curative                              0.8        1.0         1.2
DBU based accelerator                       1           1           1
Total phr                               189.8         187       185.2
Post-cure properties
Hardness, durometer A                      71          70          70
Tg by DSC, [degrees]C
Initial                                 -37.0       -37.4       -36.6
After one week at 175[degrees]C         -34.9       -35.9       -35.3
After one week in IRM 903
  150[degrees]C
Volume increase                            63          58          55

Table 14--compression set after one week at 175[degrees]C and DeMattia
results after heat aging in air

                                      AEM GXF     AEM GXF     AEM GXF
                                     0.9 HMDC    1.2 HMDC    1.5 HMDC

168 hours at 175[degrees]C
ISO molded pellet                          66          54          48
ASTM plied pellet                          74          61          56
Average 168 hours at 175[degrees]C         70          57          52
DeMattia cut growth RT-D 813
Aged one week at 175[degrees]C
Cycles to 8.5 mm                        8,000       2,600       1,500

                                       AEM HT      AEM HT      AEM HT
                                     0.8 HMDC    1.0 HMDC    1.2 HMDC

168 hours at 175[degrees]C
ISO molded pellet                          49          37          34
ASTM plied pellet                          54          46          43
Average 168 hours at 175[degrees]C         52          42          38
DeMattia cut growth RT-D 813
Aged one week at 175[degrees]C
Cycles to 8.5 mm                       40,000      12,000       4,500

Table 15--laboratory test methods

Rheology                           ASTM       ISO

Mooney viscosity                 D 1646     289-1
Mooney scorch                    D 1646     289-2
MDR                              D 5289      6502
Physicals
Hardness                         D 2240    7619-1
Tesnile, elongation, modulus      D 412        37
Volume increase                   D 471      1817
Air aging                         D 573       188
TR10                             D 1329      2921
Tg by DSC                        D 3418     22768
Compression set                   D 395     815-1
DeMattia, pierced (nicked)        D 813       133
DeMattia, not pierced             D 430       132
COPYRIGHT 2015 Lippincott & Peto, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2015 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:McBride, Edward
Publication:Rubber World
Date:Apr 1, 2015
Words:6242
Previous Article:Smart science drives fluorosilicone rubber innovation.
Next Article:Recent advances in EPDM and dynamically vulcanized thermoplastic elastomers.
Topics:

Terms of use | Privacy policy | Copyright © 2018 Farlex, Inc. | Feedback | For webmasters