Struktol Company of America201 E. Steels Corners Road • P. O. Box 1649 • Stow, Ohio 44224-0649

Phone: (330) 928-5188Fax: (330) 928-8726

Technical Services: 1-800-327-8649 Internet: www.struktol.com

Producers of Specialty Chemicals

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MOLD RELEASE ADDITIVE EFFECTS ON CHLORINE AND FLUORINE RUBBER COMPOUND

K.-J. Kim1,*, J. Wasko1, M. Hensel2

1 Struktol Co. America 2Schill+Seilacher Aktiengesellschaft

1. Introduction

Group VII atom containing polymers such as chlorine rubber, and fluorine rubber tend to show a high degree polarity due to their high molar attraction constants [1]. Their practical applications include molded parts, cable, hose, o-rings, etc., which require chemical resistance. In molding the final products, there are several problems such as shrinkage, porosity, blisters, poor knitting, backrinding (retractive spew), tearing on molding and bloom. This is due to improper choice of chemical additives, poor mold design, and poor processing conditions.

In order to improve the demolding property of the polymer compounds, the degree of resistance of polymer to additive should be higher. They should not stick on the processing equipment and should easily demold from the equipment at demolding stage i.e. the low degree of cohesion between two materials. The theory that “like dissolves like” says where the square root of the value of the solubility parameter (δ) differences between two materials are less than unity, then they are soluble (miscible) [1]. Fluorinated polymers are good examples of insoluble material for hydrocarbon oil because the polar fluorine is not soluble to non-polar hydrocarbon oil. The solubility of fluorinated plastic/rubber in hydrocarbon oil decreases with increasing fluorine level due to increased dipole moment of fluorine [2]. The typical demolding additives consist of silicon oils, organics, dusting agents, semi-permanent release agents and lubricants [3].

Compounds that are developed for practical use in production can encounter various processing problems. The problems in the processing of rubber are directly related to some of the performance properties that are required for the final products. A substitution of raw materials will not resolve these issues. Perfluorinated sulfonamides are known as very efficient processing additives for specialty polymers (e.g. FKM, ACM or MVQ) that improve the flowabilty, release or demolding.

This research compared the additives based on silicone, fluorinated, non- fluorinated and the availability of an alternative non-fluorinated processing additive based on previous research of Struktol [4-8] and Schill+Seilacher [9]. * e-mail: kkim@struktol.com Paper No. 7 presented at the IRMC 2004 meeting in Cleveland, OH on April 27-28, 2004

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2. Experimental and Results 2.1 Mixing procedure

All the mixings for the CR compounds were in a Banbury internal mixer (BR1600) and mixings for FKM compounds were done on a laboratory open mill with full water-cooling. The mixing cycle for FKM compounds is given on Table 1. 2.2 Compound Formulations and Physical Properties

In the CR compounds, two different systems of CR-compounds have been investigated. First formulation was a general molding compound. Second one was an injection molding formulation. In the CR compounds, the addition of WB16 and WB222 to the CR compound lowered the viscosity of the CR compound by 15% to 45% and improved the flowability as shown in Figure 1. Figure 2 shows the modulus changes at 300% elongation. As the concentration of the WB16 and WB222 is increased the modulus decreased. The WB222 compounds showed higher modulus than the WB16 compounds at each concentration level. At lower levels of WB222 (2phr) the modulus was slightly lower than the Control compound. Figure 3 represents the tensile strength of each compound. As the concentration of the WB16 and WB222 increased the modulus decreased. The WB222 added compound showed no significant decrease in tensile strength versus the Control compound. Overall, the suggested additive loading level of WB222 and WB16 was 2-3phr.

In the FKM-Compounds, three different series of FKM-compounds were investigated. The first series was a red coloured compound based on FKM-copolymer with a bisphenolic cure system and loaded with bariumsulfate/wollastonite. The second series was a non-black compound based on FKM-terpolymer for better low temperature performance and was peroxide cured. The third series was very high molecular weight FKM-copolymer with bisphenolic cure system used and carbon black filled. Table 2 shows CR-formulations and Table 3 shows FKM-formulations of the first series with some typical and often used processing additives compared against a control compound without any processing additive. A typical vegetable wax was used in formulation 2 to improve flowability and release. A well-tried organosilicon-product is Struktol WS280 in compound 3 and an established perfluorinated product, Dynamar PPA 790, which is not available any longer, is added in compound 4. The new Struktol XP 1414 (= HT290) was tested in compound 5. One of the prominent reasons to use processing additives is a desired reduction of the Mooney viscosity of a compound without sacrificing the physical properties. Rheometer data and physical properties of these compounds are given on Table 4.

As shown on Table 4, Struktol HT290 in compound 5 gave the highest reduction in Mooney viscosity. In addition, the lowest minimum torque of ODR-measurement showed the effect of HT290. This compound tended to become a little harder and compression set slightly higher. All deviations of other properties were well within the experimental errors of the respective measurements. Hardness and compression set should be considered and level of HT290 could be reduced. The influence of different levels of HT290 was discussed with the third compound series.

The data of the second compound series, based on the peroxide curable terpolymer Viton GBL 900, showed a significant lower Mooney viscosity for the 2.0phr level of HT290 in compound 4, accompanied by a lower minimum torque as measured by the Rheometer MDR 2000 E (Table 5). The compression set of all compounds was on the same level with slightly advantage for the Control and 1phr level of HT290. The exact formulations of the compounds were given on Table 5. The Mooney viscosity and vulcanisation results were summarized on Table 6. The HT290 2.0phr compound showed the lowest Mooney viscosity and the lowest torque (ML). The details of physical properties of unaged and aged vulcanizates were summarized on Table 7.

Apart from the previously discussed compounds, we evaluated a third series of compounds to see the influence of HT290 level. These carbon black filled compounds were

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based on a very high molecular weight FKM-copolymer with integrated bisphenolic cure system. The exact formulations are given on Table 8.

To obtain the desired effect of improved processing the level of HT290 was in the range of > 1 phr to about 1.5 – 1.75 phr depending on the compound formulation. With a level of 1.5 phr, HT290 exceeds WS280 at 2.0phr regarding reduced Mooney viscosity and extrusion performance. Physical properties were identical within the experimental errors. This was true for aged vulcanizate properties also. With level of 2.0phr compression set was obviously increased by HT290 when the polymer was cured bisphenolic. Details of compound properties are given on Tables 9 and 10. 2.3 Extrusion

The extrusion performance of second and third compound series was measured by extruding the compounds on a cold feed lab extruder through a slit die 2x15mm to produce feeding stripes for injection molding. Extrusion of these FKM compounds was greatly influenced by the use of additives and the type of additive. Significant differences were detected in the extrusion performance (Table 11) and surface quality of the stripes were shown in Figure 4. The new HT290 at 1phr level gave the best extrusion performance regarding extrusion speed, (+15%) extrusion rate (+100%) and surface quality at lower temperature compared to control and perfluorinated additive.

For the black FKM-copolymer compound, the results of extrusion were similar for WS280 at 2.0phr and HT290 at 1.5phr level. Nevertheless, HT290 showed better at lower level with slightly raised extrusion speed and rate. 2.4 Injection molding

The tests on an Arburg Allrounder 220-90-350 injection molding machine for CR and FKM compounds were carried out with a spider mold at constant pressure. With a good processing additive there was a dramatic increase in specimen weight and a greatly improved mold release.

Figure 6 represents the spider mold test for CR compounds. Figure 6 (a) shows the WB16 effects on physical properties. The addition of the WB16 did not change the physical properties such as Mooney scorch, tensile strength, elongation or hardness as shown in Figure 6-1. However, in the injection molding experiments the addition of WB16 lowered the injection time, flow defects and scrap level significantly as shown in Figure 6 (b).

Table 13 and Figure 7 represents the result for spider mold test for FKM compounds for peroxide cured FKM-terpolymer and the same for black FKM-copolymer on Table 14 and Figure 8.

Figure 7 showed the improved flowability of HT290 added compounds without any external mold release agent

The improvement in flowability of the black FKM-copolymer compound was not significant as was shown on the peroxide cured FKM-terpolymer. In comparison of 2phr level of WS280 (+ 47,8%) and 1.5 phr level of HT290 (+41,7%), WS280 exceeded HT290 in injection molding performance. On the other hand, HT290 exhibited better extrusion. With respect to drawback from compression set properties in bisphenolic cured systems, the 2.0phr level of HT290 was not compared. 3. Conclusion

The addition of processing additives including WB16, WB222, PPA790, WS280 and HT290 into chlorine and fluorine rubber compound improved the processability without sacrificing of the physical properties.

With the newly developed Struktol HT290, there is another alternative additive without halogenated hydrocarbons to improve processing properties of FKM-compounds. Depending on the compound formulation and application, HT290 exceeds a perfluorinated

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additive PPA790 clearly. Compared to the well-tried Struktol WS280 it works at a lower level. A careful adjustment to the compound provides a maximum of overall processing properties, while physical properties remain almost unchanged.

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REFERENCES

1. L. H. Sperling, “Polymer multicomponent materials”, John Wiley & Sons, Inc., p. 62-67,

1997 2. M. F. Myntti, Rubber World, 228, 38 (2003) 3. “Rubber Handbook”, Struktol Co. America, 2004 4. L. C. Larsen, W. H. Klingensmith, P. A. Danilowicz, “processing agents to improve

injection molding”, paper presented at a meeting of the Rubber Division, American Chemical Society, Cleveland, OH, Oct., 1981

5. G. Townson, “Injection molding-where is it going”, paper presented at a meeting of the Rubber Division, American Chemical Society, Cleveland, OH, Oct., 1981

6. W. H. Klingensmith, “The effects of processing aids in rubber compounds”, paper presented at a meeting of the Rubber Division, American Chemical Society, Chicage, Il, Oct., 1982

7. W. H. Klingensmith, P. A. Danilowicz, L. C. Larsen, “Effective use of homogenizing agents”, paper presented at a meeting of the Rubber Division, American Chemical Society, Detroit, Mi, Oct., 1980

8. L. C. Larsen, B. C. Howard, J. M. Sherritt, “Injection molding-improved injection molding with processing agents”, paper presented at a meeting of the 54th Canadian Society of Chemistry Division, Ca, 2000

9. R. Galle-Gutbrecht, M. Hensel, and H. Umland, “Processing Additiv to Substitute Perfluorinated Types in Specialty Polymers“, paper presented at the IRC 2002 in Prague

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Tables First stage Open mill, friction 1:1.5, start ca. 25°C 0´ Add polymer, nip adjusted to give a small rolling bank, cut the

sheet to blend 5x, (disperse curatives if not integrated) 2 – 4´ Add the pre-blended ingredients rapidly, sweep the pan and add to

the batch 12 – 23´ Blend the mixed compound by cutting from both sides, at the end

3x cigar rolling and pass endwise, sheet off (end temp. 50 – 73°C) and cool down on metal desk

Remilling after 24h Open mill as before 0´ Add compound, cold rolls set as tight as practical 4´ Cut off after a smooth sheet is obtained, cool down

Table 1 Mixing cycle for FKM compounds Compound 1 2 3 4 5 6

Control WB16/ WB222 2.0phr

WB16/ WB222 3.0phr

WB16/ WB222 4.0phr

WB16/ WB222 5.0phr

WB16/ WB222 6.0phr

Chlorophrene W 100.0 - - - - - Chlorophrene WHV-100 150.0 - - - - - MgO 75.0 - - - - - Stearic Acid 5.0 - - - - - Wingstay 100 1.0 - - - - - N330 1.0 - - - - - Al Silicate 2.0 - - - - - Aromatic oil 2.0 - - - - - Naphthenic Oil 1.0 - - - - - Struktol WB 16/WB 222 2.0 3.0 4.0 5.0 6.0 Curative VC-20 2 2 2 2 2 2 Curative VC-30 4 4 4 4 4 4 (a) General molding-formulation Compound 1 2

Control WB 16 Chlorophrene WHV 34.0 34.0 Chlorophrene WRT 66.0 66.0 Magnesium Oxide 4.0 4.0 Zinc Oxide 5.0 5.0 FEF N550 40.0 40.0 SRF N774 30.0 30.0 Wax 2.2 2.2 Antioxidant 3.0 3.0 Struktol KW400 15.0 15.0 Rape seed Oil 8.0 8.0 ETU 1.0 1.0 TMTD 1.5 1.5 Struktol WB16 - 3.0 (b) Injection molding formulation Table 2 CR-formulations for (a) general molding-formulation and (b) injection molding

formulation

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Compound FKM-co/bisphen./red 1 2 3 4 5

Control Carnauba(1.5phr)

WS280 (1.5phr)

PPA790 (1.5phr)

HT290 (1.5phr)

Viton AL-600 100.0 100.0 100.0 100.0 100.0 Blanc Fix (BaSO4) 20.0 20.0 20.0 20.0 20.0 Tremin 283-800 EST-M (Wollastonit) 20.0 20.0 20.0 20.0 20.0 Maglite DE (MgO high activity) 3.0 3.0 3.0 3.0 3.0 Calciumhydroxid VF 6.0 6.0 6.0 6.0 6.0 Bayferrox 720 ,rot (Fe2O3) 6.0 6.0 6.0 6.0 6.0 Carnauba wax - 1.5 - - - Struktol WS280 - - 1.5 - - Dynamar PPA790 - - - 1.5 - Struktol HT290 - - - - 1.5 Curative VC-20 2.0 2.0 2.0 2.0 2.0 Curative VC-30 4.0 4.0 4.0 4.0 4.0 Table 3 Typical formulations based on FKM-Copolymer, ML 1+10 at 121°C 60, bisphenolic

cure system, with processing additives Compound FKM-co/bisphen./red 1 2 3 4 5 Control Carnauba

(1.5phr) WS280 (1.5phr)

PPA790 (1.5phr)

HT290 (1.5phr)

Mooney ML (1+4) 100 °C (ME) 135 127 128 130 117 Rheometer ODR at 180°C Torque MH (dNm) 53.6 53.8 55.1 53.5 62.9 Torque ML (dNm) 9.5 8.9 10.8 8.8 6.7 tc 10 % (min) 2.0 2.0 2.0 1.9 2.4 tc 90 % (min) 2.8 2.8 2.7 2.6 3.2

Vulc.-time 2 mm (min) 8.0 8.0 8.0 8.0 8.0 Vulc.-time 6 mm (min) 8.0 8.0 8.0 8.0 8.0 at180 °C + post cure 24h / 230 °C

Density (g/ccm) 2.15 2.15 2.13 2.15 2.13 Shore hardness A (SH U) 70 71 71 71 76 Tensile strength (MPa) 13.5 12.5 13.1 13.6 12.1 Modulus 100 % (MPa) 8.6 7.8 8.9 8.4 7.3 Elongation at break (%) 144 143 140 147 170 Rebound (%) 6 7 6 7 6 CS 70 h / 200 °C 25 % (%) 22.2 28.7 26.7 20.9 29.6 Table 4 Rheometer data and physical properties

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Compound FKM-ter/peroxide 1

Control 2

PPA790 (2.0phr)

3 HT290

(1.0phr)

4 HT290

(2.0phr) Viton GBL 900 100.0 100.0 100.0 100.0 ZnO aktiv 3.0 3.0 3.0 3.0 Tremin 283-800 EST-M 35.0 35.0 35.0 35.0 Diak No 8 2.0 2.0 2.0 2.0 Trigonox 101-45B-pd 4.0 4.0 4.0 4.0 Dynamar PPA790 - 2.0 - - Struktol HT290 - - 1.0 2.0 Table 5 Formulations of second compound series, based on peroxide curable FKM-

terpolymer Mooney ML (1+4) 100 °C (ME) 79 76 73 55 Rheometer MDR 2000 E at 180°C Torque ML (dNm) 3.4 3.2 2.6 2.1 Torque MH (dNm) 20.3 20.0 20.1 19.5 Ts 2 (min) 1.3 1.2 1.3 1.3 tc 10 % (min) 1.2 1.1 1.2 1.2 tc 90 % (min) 6.7 6.7 5.9 6.0

Table 6 Rheometer and Mooney data of second compound series Vulc.time (min) at 180°C 15 15 15 15 Post cure 24h/260°C Shore hardness A (SH U) 68 69 70 72

Rebound (%) 5 5 4 5

Density (g/ccm) 2.07 2.07 2.07 2.07

Tensile strength (MPa) 16.9 17.2 17.7 16,5

Elongation at break (%) 156 155 170 171

Modulus 100 % (MPa) 10.4 11.1 9.6 8.8

CS 22 h/200°C/25% (%) 18.9 20.3 19.3 20.8 CS 70 h/200°C/25% (%) 31.7 34.4 30.5 34.4 after ageing, 2 weeks 200°C in air Shore hardness A (SH U) 71 72 73 75 Tensile strength (MPa) 17.9 17.5 17.5 17 Elongation at break (%) 114 156 160 157 Modulus 100 % (MPa) 16.7 11.3 10.5 10.9 Table 7 Physical properties of second compound series

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Compound FKM-co/black 1

Control 2

WS 280 (2.0phr)

3 HT290

(0.5phr)

4 HT290

(1.0phr)

5 HT290

(1.5phr)

6 HT290

(2.0phr) Dyneon FC 2179 100.0 100.0 100.0 100.0 100.0 100.0

Maglite DE 3.0 3.0 3.0 3.0 3.0 3.0

Rhenofit CF 5.1 5.1 5.1 5.1 5.1 5.1

Durex O 20.0 20.0 20.0 20.0 20.0 20.0

Struktol WS280 - 2.0 - - - -

Struktol HT290 - - 0.5 1.0 1.5 2.0

Table 8 Formulations of third compound series, based on FKM-Copolymer, incorp. bisphenolic cure system, black

Compound FKM-co/black 1

Control 2

WS 280 (2.0phr)

3 HT290

(0.5phr)

4 HT290

(1.0phr)

5 HT290

(1.5phr)

6 HT290

(2.0phr) ML (1+4) 100 °C (ME) 110 109 113 110 98 84

Rheometer MDR 2000 at 180°C

tc 10 % (min) 1.3 1.2 1.4 1.5 1.4 1.4

tc 90 % (min) 2.7 2.3 2.6 2.7 2.6 2.6

tc 100 % (min) 7.6 5.1 5.8 6.0 6.9 5.9

Ts 2 (min) 1.2 1.1 1.3 1.4 1.3 1.3

Torque ML (dNm) 4.5 4.3 4.7 4.3 4.1 3.9

Torque MH (dNm) 31.4 33.9 34.9 35.2 34.2 34.5

Table 9 Rheometer data of third compound series, based on FKM-Copolymer, incorp. bisphenolic cure system, black

Compound FKM-co/black 1

Control 2

WS 280 (2.0phr)

3 HT290

(0.5phr)

4 HT290

(1.0phr)

5 HT290

(1.5phr)

6 HT290

(2.0phr) Shore hardness A (SH U) 73 77 77 79 79 81 Rebound (%) 6 6 6 6 6 6

Tensile strength (MPa) 19.2 16.1 17.3 16.2 16.4 16.3

Elongation at break (%) 174 140 143 128 129 122 Modulus 100 % (MPa) 9.1 11.2 11.4 12.2 12.2 12.8

CS 22 h/200°C/25% (%) 7.4 11.0 12.2 12.1 12.8 15.9 CS 70 h/200°C/25% (%) 14.1 18.4 16.4 17.5 20.2 22.9

Table 10 Physical properties of third compound series, based on FKM-Copolymer, incorp. bisphenolic cure system, black

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Compound FKM-ter/peroxide Control PPA790

(2.0phr) HT290

(1.0phr) HT290

(2.0phr) Material temperature (°C) 88 87 84 83 Extrusion speed (m/min) 2.0 1.9 2.3 2.2 Extrusion rate (g/min) 158 166 338 323

Table 11 Material temperature, extrusion speed and rate of second compound series (Troester GS30/K-10D cold feed extruder, 35 1/min, (90,80,90,100°C)

Compound FKM-co/black 1

Control 2

WS 280 (2.0phr)

3 HT290

(0.5phr)

4 HT290

(1.0phr)

5 HT290

(1.5phr)

6 HT290

(2.0phr) Material temperature (°C) 90 86 90 90 86 85 Material pressure (bar) 120 150 127 127 142 155 Extrusion speed (m/min) 1.7 2.9 1.7 2.1 3.1 2.4 Extrusion rate (g/min) 128.5 298.6 130.7 167.7 303.0 345.0 Die swell (g/m) 75.8 102.7 76.7 78.7 101.0 143.0 Table 12 Material temperature and pressure, extrusion speed and rate, die swell of third

compound series (Troester GS30/K-10D cold feed extruder, 35 1/min, (90,80,90,100°C)

Compound FKM-ter/peroxide

Control PPA790 (2.0phr)

HT290 (1.0phr)

HT290 (2.0phr)

Article weigth (g) 17.7* - 27.9** 48.0** Standard dev. +/- 1.4 - 1.4 0.6 Change in weigth (%) - - 58 171 Mold release, rating 1 - 6 2* (6) 6 4 - 5 2 Table 13 Arburg, spider mold test at constant injection pressure, mold temp. 170°C, cylinder

temp. 90°C, die 100°C.* Test for control was carried out with external mold release agent, () rating without mold release.** weight average of 22 specimens

Compound FKM-co/black 1

Control 2

WS 280 (2.0phr)

3 HT290

(0.5phr)

4 HT290

(1.0phr)

5 HT290

(1.5phr)

6 HT290

(2.0phr) Average article weigth* (g) 25.2 37.4 25.8 30.1 35.7 43.5 Standard dev. 1.5 0.9 1.5 2.0 1.0 0.6 Increase of art. weigth (%) - 47.8 2.2 19.4 41.7 72.2 Mold release, rating 1 - 6 3 - 4 2 3 - 4 3 2 - 3 2 - 1 Table 14 Arburg, spider mold test at constant injection pressure, mold temp. 170°C, cylinder

temp. 90°C, die 100°C. No external mold release agent has been used. *average of 30 articles

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Figure captions Figure 1 Additive concentration effects on Mooney viscosity and flow rate of various CR

compound Figure 2 Additive concentration effects on modulus at 300% elongation of various CR

compound Figure 3 Additive concentration effects on tensile strength of various CR compound Figure 4 Surface quality of feeding stripes, FKM-terpolymer compounds Figure 5 Feeding stripes of black FKM- Copolymer show very smooth edges and surface for

2.0phr WS280 and HT290 at 1.5phr and 2.0phr level only. For the control and HT290 at 0,5phr level, rough surfaces are obtained. At 1.0phr level of HT290 surface starts to become smooth.

Figure 6 WB16 effects on Injection molding processing (a) physical properties, and (b) processing properties.

Figure 7 Additive effects on flowability on spider mold test Figure 8 Spider specimens of black FKM-Copolymer compound

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Figure 1 Additive concentration effects on Mooney viscosity and flow rate of various CR

compound

0

20

40

60

80

100

120

140

0 2 3 4 5 6 Additive phr

ML 1+4, 100°C

WB16 Mooney ViscosityWB16 Flow ml/secWB222 Mooney ViscosityWB222 Flow ml/sec

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Figure 2 Additive concentration effects on modulus at 300% elongation of various CR compound

Figure 3 Additive concentration effects on tensile strength of various CR compound

Modulus 300

02

4

68

1012

1416

0 2 3 4 5 6Additive phr

MPa

WB16

WB222

Tensile Strength

1011121314151617181920

0 2 3 4 5 6Additive phr

MPa

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Figure 4 Surface quality of feeding stripes, FKM-terpolymer compounds

Control PPA 790 (2.0phr) HT290 (1.0phr) HT290 (2.0phr)

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Figure 5 Feeding stripes of black FKM- Copolymer show very smooth edges and surface for

2.0phr WS280 and HT290 at 1.5phr and 2.0phr level only. For the control and HT290 at 0.5phr level, rough surfaces are obtained. At 1.0phr level of HT290 surface starts to become smooth.

Control WS 280 (2.0 phr) HT290 (0.5phr) HT290 (1.0phr) HT290 (1.5phr) HT290 (2.0phr)

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(a) WB16 effects on physical properties

(b) WB16 effects on processing properties

Figure 6 WB16 effects on Injection molding processing (a) physical properties, and (b)

processing properties.

0

10

20

30

40

50

60

70

Mooney ScorchT5 (min)

Tensile Strength Elongation (% /10)

Hardness (ShoreA)

Control

Struktol WB16

0

5

10

15

20

25

30

Injection time (min) Flow defect / cycle (%x10)

Scrap level (%)

Control

Struktol WB16

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Control PPA790 (2.0phr) HT290 (1.0phr) HT290 (2.0phr)

Figure 7 Additive effects on flowability on spider mold test

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Control

WS 280 (2.0phr) HT290 (0.5phr)

HT290 (1.0phr) HT290 (1.5phr) HT290 (2.0phr)

Figure 8 Spider articles of black FKM-copolymer comp., same sequence as on Table 14