Improving rheology of EP(D)M based compounds through continuous mixing.

EP(D)M elastomers are widely used in many fields in formulations based on reinforcing filler, mostly carbon black. The carbon black is typically a reinforcing filler, and on the basis of its structure, it is possible to tailor its reinforcing effect.

The types of carbon blacks characterized by elementary particles of smaller dimensions have greater reinforcing effect; they, in fact, give aggregates having higher superficial area and porosity. The structure of the carbon black is so characterized not only by the nature of elementary particles, but mainly by the structure of their aggregates. Several aggregates further give weak giant assemblies called agglomerate.

It is reported that the optimal dispersion of the carbon black in a polymer matrix coincides with the breaking of the carbon black agglomerate to form aggregates (refs. 1-5). During the discontinuous phase of mixing (internal mixer), after an initial phase of incorporation that is not always detectable, the compound viscosity and the power absorbed from the rotors are quickly reduced as the carbon black disperses. Once a good dispersion is reached, a very slight reduction of the mixing torque is observed due to the compound self-heating and small degradation of the polymer.

The types of carbon blacks with higher reinforcing effect are characterized by a higher specific energy and longer dispersion time, while less reinforcing carbon blacks require lower specific energy and shorter dispersion time.

In the present study, original Polimeri Europa know-how on EP(D)M post-modification technology is used to obtain a master in which the product, beyond having improved rheology and adapted to the final application, contains a limited amount of pre-dispersed reinforcing filler. The strong reinforcing effect of the filler in the master (refs. 6-8) allows, without changing the final compound characteristics, to obtain applicative compounds using low reinforcing carbon black with strongly reduced dispersion energies, such to allow to prepare them using a continuous mixing technology generally not usable in the elastomer fields.

The preparation of elastomeric compounds based on carbon black using continuous mixing technology (e.g., twin-screw or co-kneter extruders) would constitute a large economic and ecological advantage. However, the economization of the process would only become obvious if at the end of the extruder the compound also contained the curing system. The high specific energy of dispersion leads, however, to make it impossible to keep the compounds under the scorch temperature in a screw zone where it is possible to feed the curing system. The only possibility to apply this mixing technology would be the strong reduction of the output (productivity) of the extruder, with loss of competitiveness of the process.

Experimental

All the polymers used are derived from the process of traditional slurry polymerization: They are commercial EPM and EPDM Polimeri Europa products.

* EPDM 1: ethylene/propylene/5-ethylidene-2-norbornene (ENB) amorphous (55% wt. ethylene, 4.5% wt. ENB) having ML (1+4) at 125[degrees]C = 75.

* EPDM 2: ethylene/propylene/ENB semi-crystalline terpolymer (69% wt. ethylene, 4.4% wt. ENB) having ML (1+4) at 125[degrees]C = 60.

* EPM OE 1: ethylene/propylene amorphous oil-extended copolymer (56% wt. ethylene, 50% wt. oil) having ML (1+4) at 125[degrees]C = 31.

EPDM OE 3 ethylene/propylene/ENB semi-crystalline oil-extended ter-polymer (67% wt. ethylene, 5.3% wt. ENB, 40% wt. oil) having ML (1+4) at 125[degrees]C = 43.

* EPDM 4: ethylene/propylene/ENB amorphous ter-polymer (55% wt. ethylene, 4.5% wt. ENB) having ML (1+4) at 125[degrees]C = 55.

According to the references 6 and 7, the post-modification processes have been carried out by a 35 mm intermeshing twin screw extruder (Maris TM35V) at high temperature with an output of 6-8 kg/h.

The compounds were prepared according to well-known methodologies, through an internal mixer (1,600 [cm.sup.3]). Some compounds were also prepared using a free volume 390 [cm.sup.3] Brabender Plasti-Corder mixing chamber with internal mixer-type rotors and a free volume 99 [cm.sup.3] Haake Rheocord mixing chamber with cam type rotors. The Haake Rheocord mixing chamber free volume became 69 [cm.sup.3] with the roller type rotors (higher shear rate condition).

The Mooney compound viscosity test and Mooney stress relaxation test (parameters are calculated on the range 1.6 to 5 sec.) have been carried out according to ISO 289 (ASTM D 1646) norms. The dynamic mechanical tests have been carried out with the RPA 2000 instrument (Alpha Technologies) at 100[degrees]C, frequency sweep with 14% strains and strain sweep with a frequency of 1.2 and 0.6 rad/sec.

The rheology tests under extrusion conditions have been conducted with the Extrusiometer instrument of Goettfert at a screw temperature of 100[degrees]C and die temperature of 110[degrees]C. It has four pressure transducers along the screw, one on the extruder head and two along the rheometer slit die. Corresponding to each pressure transducer, there is a melt temperature sensor. The screw torque and the screw back pressure (axial force, normal stress) are also measured.

Under stable conditions, the extrusion output can be measured, and from this the apparent shear rate is calculated.

The difference between the pressures measured along the slit die allows the shear stress to be calculated. With the shear stress and the shear rate corrected according to Rabinowitsch/ Weissenberg, the true viscosity is calculated.

Result and discussion

Two compounds for a building profile application were prepared, using the following polymer bases:

1. EPDM 1 (amorphous) and EPDM 2 (semi-crystalline) in a 70/30 ratio.

2. Master 1080; a post-modified master containing 140 parts of EPM OE 1 (70 parts of polymer matrix + 70 of oil), 30 parts of EPDM2 and 25 parts of silica Ultrasil VN3 (Degussa) as reinforcing filler.

The compounds were prepared in the 1,600 [cm.sup.3] internal mixer using the traditional upside down methodology, with a rotor speed of 60 RPM and a mixing time of five minutes. The formulations are reported in table 1.

The Mooney viscosity, the parameters of the Mooney relaxation [slope, area (MLRA) and MLRA/ML] and the uncured compound tensile tests are collected in table 2. Despite having a similar Mooney viscosity, the 1080/FP/02 compound has elasticity far higher than the reference one. This is an effect of the theological post-modification process that led to a more favorable balancing between fluidity and shape stability (refs. 6-8).

In comparison to the reference, the uncured compound tensile tests show that the 1080/FP/02 fillers reinforce at least as much, even though the latter compound contains the lower reinforcing carbon black SRF N772.

A peroxide based curing system was added in two different amounts for each compound. In table 3, the cured compound tensile tests are reported. It is confirmed that the compound prepared from post-modified master, although it has been obtained using a less reinforcing carbon black, was not worse for tensile property.

The dynamic mechanical tests have been performed on the uncured compounds with the RPA 2000 instrument (ref. 9) using a frequency sweep at 100[degrees]C and 14% of strain. The results are reported in figure t. As it is known, the complex viscosity vs. frequency (rad/s) plot may give a similar behavior to the apparent viscosity vs. shear rate plot (ref.10).

The Mooney stress relaxation results were well confirmed by the RPA 2000 test. The 1080/FP/02 compound has similar viscosity and elasticity to the reference one at the frequencies related to the extrusion process (10-100 rad/s); while at low frequencies, related to the shape stability, it has much higher viscosity. It was indeed reported that the Mooney relaxation slope and MLRA/ML are related to the tan [delta] measured at about 0.1 rad/s (low tan [delta] = low slope = higher MLRA/ML) (refs. 11-14).

In order to verify the degree of reinforcement induced by the fillers, the RPA 2000 strain sweep tests were carried out at the frequency of 1.2 rad/s on the uncured compounds (refs. 5 and 15-16). At low strain, the high storage modulus (G') is due to the establishment of a filler aggregate-aggregate network, which leads to the reinforcing effect. This structure is altered with rising strain. The storage modulus (and viscosity) fall from low to high strain is therefore related to the reinforcing effect of fillers. The storage modulus (G') and complex viscosity vs. strain plots are reported in figure 2.

[FIGURE 1 OMITTED]

An evident reduction of the reinforcing effect is not observed if 1080/FP/01 reference compound (with carbon black type N550) is compared to 1080/FP/02 (with a less reinforcing carbon black type N772). Furthermore, if you consider the plots of complex viscosity vs. strain, 1080/FP/02 seems to have a better reinforcing effect.

In order to maximize the performance of the new compounds, it is generally preferred to improve the viscosity/fluidity rather than the compound shape stability, which was already optimized for the application. However, having prepared compounds with similar viscosity should make the mixing processes evaluation easier (incorporation and dispersion specific energy). Despite knowing that the dispersion of less reinforcing carbon black usually requires shorter times and less specific energy, this effect may be difficult to estimate.

For each evaluated compound, the mixing process simulations were carried out using the Haake Rheocord 99 [cm.sup.3] mixing chamber with cam-type rotors. The mixing chamber external temperature was kept at 70[degrees]C and the rotor speed was 45 rpm. The mixing process simulations were performed using a well-known upside down method. For each compound, the torque vs. mixing time plots are reported in figure 3 (top).

The optimum dispersion times (t' point) were obtained by the log torque vs. log time plot, as reported in figure 3 (bottom), assuming that after dispersion the log torque decay is linear with the log time (ref. 17).

[FIGURE 2 OMITTED]

It is possible that the graphical method to evaluate the time of optimal dispersion is too qualitative; in any case, since the curves of torque (figure 3 top) quite overlapped after dispersion, an implicit but obvious confirmation of the elaboration is given.

The times and the specific energies necessary to the compound dispersion are reported in table 4. The table 4 data analysis is clear: The difference of specific energy necessary to prepare 1080/FP/02 compared with 1080/FP/01 is such to suggest that they can really be prepared with different mixing processes.

If it had to be applied to a continuous mixing process (and admitting to be able to prepare the 1080/FP/02 compound with an output of Q it would be easy to calculate that), having to remove the same amount of heat in order to avoid the scorch of its curing system, 1080/FP/01 (which requires a higher specific energy to be prepared) would be obtainable at a productivity about four times less.

[FIGURE 3 OMITTED]

As formerly pointed out, it is advisable to prepare a post-modified master, which allows obtaining a compound with lower viscosity. The original post-modification Polimeri Europa process is able to easily control the polymer molecular weight and, as a consequence, the final compound viscosity.

Three EPDM based compounds were prepared using the following polymer bases:

* EPDM 1 and EPDM OE 3;

* Master 1123, a post-modified master containing 79 parts of EPDM 1, 35 parts of EPDM OE 3 (21 parts of dry polymer + 14 of oil) and 32 parts of silica Ultrasil VN3 (Degussa) as reinforcing filler.

The compound formulations are reported in table 5. Each compound has an identical polymer base.

The compounds were prepared in the 1,600 [cm.sup.3] internal mixer using the traditional upside down methodology, with a rotor speed of 60 rpm and a mixing time of five minutes.

The uncured compound Mooney viscosity data [ML (1+4) at 100[degrees]C] were: l123/FB/01 = 88 (reference compound); 1123/FB/02 = 63; and 1123/FB/03 = 43.

Because of the small formulation modification between l123/FB/01 and 1080/FP/01, the difference of 20 Mooney viscosity units does not seem reasonable. It is possible that, probably caused by the high EPDM OE 3 molecular weight, the 1123/FB/01 compound was not properly dispersed (this despite the 1123/FB/01 mixing specific energy of about 0.28 kWh/kg compared to about 0.24 kWh/kg for 1123/FB/03).

All three compounds were given additional mixing in an open mill mixer for five minutes; after that, the Mooney viscosities were measured another time. The data are reported in table 6. Actually, the fillers in the 1123/FB/01 compound were not effectively dispersed, while they were very well dispersed in the 1123/FB/03 compound.

The dynamic mechanical tests were performed on these compounds using the RPA 2000 instrument (frequency sweep at 100[degrees]C and 14% strain). The results are reported in figure 4.

The two compounds that were prepared starting from the post-modified master (1123/FB/02 and 1123/FB/03) have a better fluidity at medium-high frequencies without worsening the dimensional stability. This is true also when the carbon black type of the reference formulation (N550) is replaced by a less reinforcing carbon black (N772).

The RPA 2000 strain sweep tests of uncured compounds were carded out at 100[degrees]C and at 0.6 rad/s of frequency. As previously discussed, this test allows evaluation of the filler reinforcing effect by the G' fall in strain. The G' and tan [delta] vs. strain plots are reported in figure 5.

[FIGURE 4 OMITTED]

As expected, the 1123/FB/02, which has the same carbon black type as the reference compound, has the best filler reinforcing effect. Regarding the 1123/FB/03 compound, it seems that the filler reinforcing effect is at least the same as the reference one: unfortunately, the comparison is not easy because the G' vs. strain curves neither cross nor overlap at any point. However, the tan [delta] vs. strain plots seem to confirm a better filler reinforcing effect in 1123/FB/03 than in the reference compound. 1123/ FB/03 is, in fact, more elastic at low strain and less elastic at high strain.

In order to better estimate the filler reinforcing effect in the post-modified compounds, the RPA 2000 strain sweep tests were carried out on two other compounds:

1. 1124/FB/3B, similar to 1123/FB/03 but characterized by a slight reduction of the total paraffinic oil amount (from 70 to 65 phr): ML (1+4) at 100[degrees]C = 46.

2. 1128/FB/1B, similar to 1123/FB/01 in which replacing a portion of EPDM 1 with EPDM 4 gave a reference compound having a lower (but nearer to the application target) Mooney viscosity: ML (1+4) at 100[degrees]C = 69.

On the top of figure 6, the G' modulus vs. strain plots ['or 1124/FB/3B and 1123/FB/01 are reported. On the bottom of the same figure analogous plots are reported for 1123/FB/03 and 1128/FB/01B.

[FIGURE 5 OMITTED]

In both diagrams, the G' modulus curves overlap at low strain. So it becomes evident that, with increasing strain, the compounds prepared from a post-modified master have a higher modulus tall. This fall between low and high strain G' modulus is related to the filler-filler structure loss. As a consequence, from a theological evaluation point of view, the 1123/ FB/03 and I124/FB/3B (which contain N772 carbon black type) filler reinforcing effects are at least the same as the reference compounds (which contain N550 carbon black type).

It is necessary, however, to evaluate the filler type substitution effect on the cured compounds. Therefore, some applicative characterizations were carried out on the cured reference compounds and on the ones obtained from a post-modified master. The tensile and compression set test results are reported in table 7.

[FIGURE 6 OMITTED]

From the application point of view, the products obtained from a post-modified master have similar properties to the traditional ones. They are therefore suitable for the applications for which they were developed.

Although the difference of Mooney viscosity is such to cancel any doubt on the better fluidity of 1123/FB/03 compared to 1123/FB/01, compound processability and theology tests were carried out in extrusion conditions with the G/3ettfert Extrusiometer instrument. This better fluidity, in terms of productivity improvement, has to be quantified. Moreover, it should be verified if the different Mooney viscosity can counterbalance the well known tendency of the product with a higher shear thinning to have a higher extrudate swelling. The tests were carried out at 100[degrees]C, with a screw speed of 8, 16 and 30 rpm. Only with the screw speed of 30 rpm was the typical industrial extrusion process shear rate reached.

The extrusion output vs. head pressure plots are reported in figure 7 (top). At the same head pressure, the post-modified 1123/FB/03 compound shows a much higher productivity (2.9 kg/h vs. 1.2 kg/h) than the reference. In addition, according to the bottom of figure 7, the torque of 1123/FB/03 is lower than the reference in each tested condition. So, all the process parameters show that the post-modified 1123/FB/03 compound allows reaching a much better productivity than the reference.

[FIGURE 7 OMITTED]

The process parameters are in any case influenced by the extruder geometry, particularly by the die geometry. It is possible that the viscoelastic behavior of a compound (e.g., pressure loss in die entrance) would interfere with the correct test evaluation. In order to clarify any doubts, the instrument is able to calculate the correct theological parameters from:

* The direct measure of pressure gradient inside the die (true shear stress); and

* the Rabinowitsch/Weigenberg correction (true shear rate).

In the top of figure 8, the extrusion output vs. the true shear stress plots are reported. The result of the output vs. the head pressure plots (top of figure 7) is mostly confirmed.

The compound viscosity vs. shear rate plots are reported in the bottom of figure 8.

In order to investigate if the particular rheology (high shear thinning) of the 1123/FB/03 compound would lead to an excessive swelling, the normal stress ([sigma]) was evaluated during the extrusion tests. The ratio between the normal and shear stresses is linked to the extrudate swelling according to the following equations (ref. 14):

Sr = [sigma] / (2 x [tau])

Sr = [B.sup.2] - (1/[B.sup.4)], where B = D/[D.sub.0]

Plots of the calculated swelling vs. the extrusion test parameters (shear rate and output) are shown in figure 9. Probably due to the difference in Mooney viscosity, the 1123/FB/03 compound does not show higher swelling than the reference during the extrusion.

[FIGURE 8 OMITTED]

To verify if the 1123/FB/03 compound can be prepared with low mixing specific energy, a new compound (1128/C/03A) was prepared using a 390 [cm.sup.3] Brabender Plasti-Corder mixing chamber with Banbury type rotors. The mixing was carried out for 1.5 minutes with 60 rpm rotor speed (corresponding to a specific energy of 0.07kWh/kg).

The following compounds were also produced with a longer mixing time of five minutes:

* 1128/C/01 having the same formulation as l123/FB/01 reference compound; and

* 1128/C/03 having the same formulation as 1123/FB/03 (and 1128/C/03A) compound.

The Mooney viscosity, specific energy and mixing time data are reported in table 8. After only 90 seconds of mixing the compound prepared from the post-modified master reached a complete filler dispersion.

A simulation of 1123/FB/03 compound preparation in a twin screw extruder was carried out with a 69 [cm.sup.3] Haake Rheocord mixing chamber, kept at 70[degrees]C (external temperature).

In order to best reproduce the extrusion mixing condition (high shear rate), the roller type rotor was used at 200 rpm. In figure 10 and in table 9, the measured melt temperatures are reported as a function of the specific energy. The compound that was produced with a specific energy of 0.07 kWh/kg did not reach the scorch temperature of the curing systems; while if it were processed at a specific energy of 0.27, the compound would reach a temperature higher than the scorch temperature.

[FIGURE 9 OMITTED]

According to what was discussed above, the continuous mixing process can be described by the picture in figure 11, where:

* In the phase A, carbon black and solid master are stirred together to begin the imbibition and incorporation of filler on the crumbed master surface.

* In the phase B, during the product conveying to the extruder, the imbibition and superficial incorporation continue.

* In the phase C, distribution and dispersion of carbon black are prevalent. In this section, the majority of the specific energy previously calculated is applied to the material. As a result, in this phase there is the most heat evolution of the process. Because of the inefficient heat exchange of the extrusion, the melt temperature of the compound should not raise much above the scorch temperature of the curing system.

* During the phase D, an additional amount of oil can be fed. This is optional but opportune to improve the efficiency of filler dispersion in phase C. In the phase D, a limited cooling from the barrel wall takes place, and additional cooling will occur if the temperature of the fed oil is lower than the melt.

* In the phase E, the curing system is fed. The curing system has to be mixed into the melt compound without reaching the scorch temperature. Taking into account the heat generation caused by head pressure, at the end of this phase the melt temperature should be kept 10-15[degrees]C below the scorch temperature.

[FIGURE 10 OMITTED]

[FIGURE 11 OMITTED]

It is hence clear that, to efficiently prepare the compound in a continuous mixing plant, it is necessary to drastically reduce the dispersion specific energy. If the specific energy is still high, the output should be greatly reduced to avoid scorch.

Conclusion

It has been previously shown that it is possible to post-modify EP(D)M elastomers to tailor the compound theology to a specific application. It has also been shown that it is possible to post-modify a master (containing inorganic reinforcing fillers) to reduce the mixing cost and improve the polymer-filler interaction (refs. 6-8).

In this work, the post-modified master was used in standard compounds for a building profile filled with carbon black. The post-modified master allows the reinforcing carbon black of the standard formulation to be replaced with a less reinforcing type of carbon black. All the characterization tests performed show that the compounds prepared from the masters and less reinforcing carbon black were globally not less reinforced than the reference compounds.

According to the data obtained from the mixing process evaluations, it is possible to estimate that the dispersion specific energy to prepare compounds from the post-modified master is about four times lower than the standard. The high reduction of dispersion specific energy leads to the assumption that a continuous mixing process is applicable; with good output and the addition of the curing system in the same apparatus without scorch problems.

The reduction of dispersion specific energy can also lead to a good improvement in the discontinuous traditional internal mixing process. That is true if the low discharge temperatures allow obtaining the final compound in a single pass mixing procedure.

As was well shown, the post-modification process allows one to obtain compounds having better fluidity without affecting shape stability. In fact, all the compounds produced from the post-modified material, while being characterized by the same shape stability as the reference compounds, showed lower Mooney viscosity and higher shear thinning.

As a consequence, the extrusion tests carried out with the Goettfert Extrusiometer confirmed that the compound produced according to the Polimeri Europa post-modification process has at least a doubled extrusion output than the reference one, without any worsening of the extrusion swelling.

References

(1.) L. White and N. Tokita, J. Appl. Polymer Sci., 12 (1968), p. 1,589.

(2.) N. Nakajima and E.R. Harrell, Rubber Chemistry and Technology, 57(1984), p. 153.

(3.) H. Palmgreen, Rubber Chemistry and Technology, 48 (1975), p. 462.

(4.) A.Y. Coran and J.-B. Donnet, Rubber Chemistry and Technology, 65 (1992), p. 998.

(5.) J.L Leblanc, Prog. Polym. Sci., 27 (2002), p. 627.

(6.) T. Tanaglia (to Polimeri Europa S.p.A.), Eur. Patent 1 604 999, Dec. 14, 2005.

(7.) T. Tanaglia (to Polimeri Europa S.p.A.), Eur. Patent 1 661 920, May 31, 2006.

(8.) T. Tanaglia, Rubber World, vol. 235, No. 4, January 2007, p. 22.

(9.) H. Pawlowski and J. Dick, Rubber World, vol. 206, No.3, June 1992, p. 35.

(10.) W.P. Cox and E.H. Merz J. Polym. Sci., 28 (1958), p. 619.

(11.) N. Vennemann and S. Lupfert, Kautschuk Gummi Kunststoffe, 44 (1991), p. 270.

(12.) H. C. Booij, Kautschuk Gummi Kunststoffe, 44 (1991), p. 128.

(13.) P.A.M. Steeman and Jo H.M. Palmen, J. Appl. Polym. Sci., 74 (1999), p. 1,220.

(14.) J.L. Leblanc, Rheologie Des Elastomeres, Edition Artel (1996).

(15.) J. Dick and H. Pawlowski, Rubber World, vol. 211, No. 4, January 1995, p. 20.

(16.) J. Dick, H. Pawlowski and J. Moore, Rubber World, vol. 221, No. 4, January 2000, p. 23.

(17.) E. Diani, L Gargani and E. Lauretti, Kautschuk Gummi Kunststoffe, 38 (1985), p. 912.

by Tiziano Tanaglia, Polimeri Europa

([e-mail])

Table 1--building profile formulation

                                 1080/FP/01   1080/FP/02

EPDM 1 (phr)                             70
EPDM 2 (phr)                             30
Master 1080 (phr)                                    195
Zinc oxide (phr)                          5            5
Carbon black N550 (phr)                 110
Carbon black N772 (phr)                               85
Calcium carbonate (phr)                  25           25
Paraffinic oil (phr)                     70
Stearic acid (phr)                        1            1

Table 2--uncured compound Mooney and
tensile tests
                                 1080/FP/01   1080/FP/02
Mooney (1+4) at 100[degrees]C
Viscosity                                68           71
Mooney relaxation
  Slope                               0.631        0.445
  MLRA                                  308          695
  MLRA/ML                              4.50         9.80
Uncured compound tensile              test
M100% (MPa)                            0.40         0.43
M200% (MPa)                            0.31         0.39
Hardness, durometer A                    29           28

Table 3--cured compound tensile tests

Cured compound                 1080/FP/01      1080/FP/02

Tensile (MPa)                 10.8    11.6    13.0    13.5
Elongation at break (%)        200     280     230     300
M100% (MPa)                    4.1     2.4     3.8     2.1
M200% (MPa)                   10.8     7.1    10.8     7.0
Hardness, durometer A              61               59

Table 4--time and specific energy of filler dispersion

                                 1080/FP/01   1080/FP/02

t' point (seconds)                   619          162
Specific energy (kWh/kg)            0.27         0.07
Specific energy (MJ/[m.sup.3])       810          210
Temperature at t' ([degrees]C)       101           91

Table 5--building profile formulation

                              1123/FB/01   1123/FB/02   1123/FB/03

EPDM 1 (phr)                        79
EPDM 3 (phr)                        35
Master 1123 (phr)                               146          146
Zinc oxide (phr)                     5            5            5
Carbon black FEF N550 (phr)        110           82
Carbon black SRF N772 (phr)                                   82
Calcium carbonate (phr)             25           25           25
Paraffinic oil (phr)                56           56           56
Stearic acid (phr)                   1            1            1

Table 6--uncured compound Mooney tests

                            1123/FB/01   1123/FB/02   1123/FB/03

ML (1+4) at 100[degrees]C         88           63           43
After 5 min. of open mill homogenization
ML (1+4) at 100[degrees]C         78           57           41
[delta]ML                         10            5            2
Mooney relaxation
  Slope                        0.623        0.481        0.515
  MLRA/ML                        4.5          6.5          5.3

Table 7--cured compound tensile and compression set
tests

                         1080/   1123/   1123/   1124/
                         FP/01   FB/01   FB/03   FB/3B

ML (1+4) at
  100[degrees]C             68      78      41      46
Tensile (MPa)             11.6    12.6    11.1    12.0
Elong. at break (%)        280     280     330     270
M 100% (MPa)               2.4     2.9     2.0     2.8
M 200% (MPa)               7.1     8.1     5.6     8.2
C. set - 23[degrees]C/
  24 hr.                             5       5
C. set - 70[degrees]C/
  24 hr.                                             5
C. set - 100[degrees]C/
  24 hr.                             9      10      10

Table 8--390 [cm.sup.3] mixing chamber compounding test

                             1128/C/03A   1128/C/01   1128/C/03

ML (1+4) at 100[degrees]C          41          74          42
Mixing time (seconds)              90         300         300
Specific energy (kWh/kg)         0.07        0.29        0.27

Table 9--extrusion mixing process simulation carried out in
a 90 [cm.sup.3] mixing chamber with a roller type rotor
at 200 rpm

Specific energy (kWh/kg)              0.07   0.27
Melting temperature ([degrees]C)       114    159
Melting T--starting T ([degrees]C)      44     89
Mixing time (seconds)                   64     87