Struktol Company of America

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1 Producers of Specialty Chemicals Struktol Company of America 21 E. Steels Corners Road P. O. Box 1649 Stow, Ohio STP229 HALOGEN ATOM CONTAINING ELASTOMER COMPOUND PROCESSING WITH PROCESSING ADDITIVES K.-J. Kim 1, *, J. VanderKooi 1, J. Wasko 1, M. Hensel 2 1 Struktol Co. America 2 Schill+Seilacher Aktiengesellschaft 1. Introduction Halogen group 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 heat and chemical stability. Recently fluoroelastomers target aerospace sealing uses [2]. Problems such as shrinkage, porosity, blisters, poor knitting, backrinding (retractive spew), tearing on molding and bloom are often found in the final products the in molding. This is due to improper choice of chemical additives, poor mold design, and poor processing conditions, etc. The degree of resistance of polymer to environmental conditions should be higher to improve the demolding property of the final compounds. Final products 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 solubility parameter (δ) differences between two materials are small, 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 polymer in hydrocarbon oil decreases with increasing fluorine level due to increased dipole moment of fluorine [3]. The typical demolding additives consist of silicon oils, organics, dusting agents, semi-permanent release agents and lubricants [4]. 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 such as halogenated polymer that improve the flowabilty, release or demolding. Soap, ester, silicone, fluorinated, and non-fluorinated type processing additives based on previous research of Struktol [5-9] and Schill+Seilacher [1] were compared. * kkim@struktol.com Paper presented at the Automotive Elastomers Conference 24 meeting in Dearborn, MI on June 18-19, 24 (Paper No.19) Phone: (33) Fax: (33) Technical Services: Internet:

2 2. Experimental 2.1 Materials The polychloroprene elastomers (CR) used were Neoprene W (ML 4-49), Neoprene WHV-1 (ML 9-11), Neoprene WHV (ML ), and Neoprene WRT (ML 41-51) supplied by DuPont Dow. The fluorocarbon elastomers (FKM) used were Viton AL-6 (ML 6) ter-polymer, Viton GBL-9 (ML 9) ter-polymer,and Dyneon FC 2179 (ML 8) copolymer supplied by DuPont Dow. Various fillers, barium sulfate, wollastonite, MgO, CaOH, Fe1O3, ZnO, etc were added into compounds. The additives tested were WB16 (mixture of calcium soap and saturated fatty acid amids), WB222 (aliphatic fatty acid esters), WS28 (organo silicon compound), and (fatty acids mixed with waxes) supplied by Struktol Co. America and PPA79 (perfluorinated compound) was from Dynamar, which is not available any longer. 2.2 Mixing All the mixings for the polychloroprene elastomer (CR) compounds were in a Banbury internal mixer (BR16) and mixings for fluorohydrocarbon elastomer (FKM) compounds were done on a laboratory open mill with full water-cooling. The mixing cycle for FKM compounds is given in Table Mixing Formulations In the CR compounds, two different systems of CR-compounds have been investigated. First formulation CR-I (compound 1) was a general molding compound. Second one CR-II (compound 2) was an injection molding formulation compound. Table 2 shows CR-formulations of typical and often used processing additives compared against a control compound without any processing additive. In the FKM-Compounds, three different series of FKM-compounds were investigated. The first series, FKM-I (compound 3), was a red coloured compound based on Viton AL-6, FKM-terpolymer, with a bisphenolic cure system and loaded with bariumsulfate/wollastonite. Table 3 shows FKM-I formulation with some typical and often used processing additives such as carnauba (vegetable wax), WS28 (organosilicon additive), PPA79 (perfluorinated additive), and (without perfluorinated) at 1.5phr were compared against a control compound (without any processing additive) to improve flowability and release. The second series, FKM-II (compound 4), was a non-black compound based on Viton GBL 9, FKMterpolymer, which was peroxide cured. The new Struktol (=XP 1414) was tested. The PPA 79 and the HT 79 (1. and 2.phr) effects were compared. The exact formulations of the compounds are summarized in Table 4. The third series, FKM-III (compound 5), was very high molecular weight, Dyneon FC 2179, FKM-copolymer with bisphenolic cure system used and carbon black filled. The at various range (.5, 1., 1.5 and 2.phr) were compared with the WS28 at 2.phr. The exact formulations are summarized in Table Results 3.1 Processability and Cure Properties 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. In FKM-I compound, Struktol gave the highest reduction in Mooney viscosity nd ODR torque as shown in Figure 2. 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 STP229 2

3 be considered and level of could be reduced. The influence of different levels of was discussed with the third compound series. Rheometer data properties of these compounds are summarized in Table 6. In FKM-II compound (compound 4), terpolymer Viton GBL 9 compound showed a significant lower Mooney viscosity at 2.phr level of, and a higher extrusion rate as shown in Figure 3. The at 1.phr level showed higher extrusion rate than the PPA79 at 2.phr, which implied that the was better processing additive than the PPA79. The compression set of all compounds was on the same level with slightly advantage for the Control and 1phr level of. The 2.phr compound showed the lowest Mooney viscosity and the lowest torque (M L ). The Mooney viscosity and vulcanisation results were summarized in Table 7. In FKM-III compound (compound 5), copolymer Dyneon FC 2179 filled with carbon black showed improved processability by the addition of WS28 and as shown in Figure 4. As the concentration of the increased, the processability improved significantly. While the Mooney viscosity of WS28 and (.5 and 1.phr) are close to each other the extrusion rate of the WS28 significantly higher than the (.5 and 1.phr). This represented the low concentration level of (.5 and 1.phr) was not effective for processability improvement in the FKM-II compound. However, at the same concentration level at 2.phr, the exceeds the WS28 compound regarding reduced Mooney viscosity and extrusion performance. The Mooney viscosity and vulcanisation results were summarized in Table Elongation Modulus Figure 5 shows the modulus changes of CR-I compound at 1% 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 the modulus was slightly lower than the Control compound. Figure 6 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 up to 4.phr. Overall, the suggested additive loading level of WB222 and WB16 was 2-3phr. Figure 7 shows the modulus changes of the FKM-I compound at 1.5phr level each. The addition of the carnauba, PPA79 and slightly reduced the modulus; however, the WS28 showed no significant reduction of the modulus at 1% elongation. The details of physical properties of each compound were summarized in Table 9. Figure 8 shows the modulus changes of the FKM-II compound of PPA79 and (1. and 2.phr). The addition of teh (1. and 2.phr) slightly reduced the modulus; however, the PPA79 showed no reduction of the modulus at 1% elongation. The details of physical properties of unaged and aged vulcanizates were summarized in Table 1. Figure 9 shows the modulus changes of the FKM-III compound of WS28 and (.5, 1., 1.5 and 2.phr). The addition of WS28 and improved the tensile modulus. As the concentration of the HT increased, the modulus increased proportionally. The physical properties were identical within the experimental errors. This was true for aged vulcanizate properties also. With level of 2.phr compression set was obviously increased by when the polymer was cured bisphenolic. Details of compound properties are summarized in Table Screw 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-II compounds was greatly influenced by the use of additives and the type of additive. Significant differences were detected in the extrusion performance as shown in Table 12 and surface qualities of the STP229 3

4 stripes were shown in Figure 1. The new at 1phr level gave the best extrusion performance regarding extrusion speed, (+15%) extrusion rate (+1%) and surface quality at lower temperature compared to control and perfluorinated additive. Details of compound processability are summarized in Table 12. Figure 11 shows extrudates of the black FKM-III compound. The appearances of the smoothness of the extrudates were similar for WS28 at 2.phr and at 1.5phr level. Nevertheless, showed better at lower level with slightly raised extrusion speed and rate. Details of compound processability are summarized in Table Injection Molding The tests on 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 12 shows the spider mold test for CR-II compounds. Figure 12 (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 12 (a). However, in the injection molding experiments the addition of WB16 lowered the injection time, flow defects and scrap level significantly as shown in Figure 12 (b). Figure 13 shows the photographs took from the spider mold for FKM-II compounds. The photograph showed the improvement of the flowability by the addition of at 2.phr and mold release rate (MRR) improved by the addition of the and it was proportionally improved as the concentration increased. Details of compound properties are summarized in Table 14. Figure 14 shows the photographs took from the spider mold for FKM-III compounds. The photograph showed the improvement of the flowability by the addition of WS28 and (.5, 1., 1.5 and 2.phr) and MRR of each compound improved. In compounds, the MRR was proportionally improved as the concentration increased. Details of compound properties are summarized in Table Conclusion Various types of additives, soap, ester, silicone, perfluorinated, and fatty acid compounds, were compounded into chlorine (soap, ester, and silicone) and fluorine (silicone, perfluorinated, and fatty acid compounds) elastomer compound. The addition of processing additives into chlorine and fluorine elastomer improves the processability without sacrificing of the physical properties. Depending on the compound formulation and application, some non-perfluorinated additives (carnauba, WB16, WB222, and WS28) shows improved processability in the chlorine and fluorine elastomer compound. In CR compound, the WB16 and WB222 exceed vegetable wax (carnauba) clearly. Comparing perfluorinated and non-perfluorinated additives in FKM compounds, the and WS28 exceeds or equal to a perfluorinated additive (PPA79), respectively. A careful adjustment to the compound provides a maximum of overall processing properties, while physical properties remain almost unchanged. STP229 4

5 REFERENCES 1. L. H. Sperling, Polymer multicomponent materials, John Wiley & Sons, Inc., p , E. Thomas, Fluoroelastomers target aerospace sealing uses, Rubber & Plast. News, May 17, 24, p M. F. Myntti, Rubber World, 228, 38 (23) 4. Rubber Handbook, Struktol Co. America, 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., G. Townson, Injection molding-where is it going, paper presented at a meeting of the Rubber Division, American Chemical Society, Cleveland, OH, Oct., 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., 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., 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, 2 1. R. Galle-Gutbrecht, M. Hensel, and H. Umland, Processing Additiv to Substitute Perfluorinated Types in Specialty Polymers, paper presented at the IRC 22 in Prague STP229 5

6 Tables First stage Open mill, friction 1:1.5, start ca. 25 C 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 Blend the mixed compound by cutting from both sides, at the end 3x cigar rolling and pass endwise, sheet off (end temp C) and cool down on metal desk Remilling after 24h Open mill as before 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 CR-I (Compound 1) Control WB16/ WB222 2.phr WB16/ WB222 3.phr WB16/ WB222 4.phr WB16/ WB222 5.phr WB16/ WB222 6.phr Chlorophrene W (ML 4-49) Chlorophrene WHV (ML 9-1) MgO Stearic Acid Wingstay N Al Silicate Aromatic oil Naphthenic Oil Struktol WB 16/WB Curative VC Curative VC (a) General molding-formulation CR-I CR-II (Compound 2) Control WB 16 Chlorophrene WHV (ML ) Chlorophrene WRT (ML 41-51) Magnesium Oxide Zinc Oxide FEF N SRF N Wax Antioxidant Struktol KW Rape seed Oil ETU TMTD Struktol WB16-3. (b) Injection molding formulation CR-II Table 2 CR-formulations for (a) general molding-formulation CR-I and (b) injection molding formulation CR-II STP229 6

7 FKM-I-ter/bisphen./red (Compound 3) Control Carnauba WS28 PPA79 Viton AL-6 (ML 6) Blanc Fix (BaSO 4 ) Tremin EST-M (Wollastonit) Maglite DE (MgO high activity) Calciumhydroxid VF Bayferrox 72,rot (Fe 2 O 3 ) Carnauba wax Struktol WS Dynamar PPA Struktol Curative VC Curative VC Table 3 Typical formulations based on FKM-I compound with processing additives FKM-II-ter/peroxide (Compound 4) Control PPA79 Viton GBL 9 (ML 9) ZnO aktiv Tremin EST-M Diak No Trigonox 11-45B-pd Dynamar PPA Struktol Table 4 Formulations of FKM-II compound FKM-III-co/black (Compound 5) Control WS 28 (.5phr) Dyneon FC 2179 (ML 8) Maglite DE Rhenofit CF Durex O Struktol WS Struktol Table 5 Formulations of FKM-III compound based on FKM-Copolymer, incorp. bisphenolic cure system, black STP229 7

8 FKM-I-ter/bisphen./red (Compound 3) Control Carnauba WS28 PPA79 Mooney ML (1+4) 1 C (ME) Rheometer ODR at 18 C Torque MH (dnm) Torque ML (dnm) tc 1 % (min) tc 9 % (min) Vulc.-time 2 mm (min) Vulc.-time 6 mm (min) at18 C + post cure 24h / 23 C Table 6 Rheometer data of FKM-I compound FKM-II-ter/peroxide (Compound 4) Control PPA79 Mooney ML (1+4) 1 C (ME) Rheometer MDR 2 E at 18 C Torque ML (dnm) Torque MH (dnm) Ts 2 (min) tc 1 % (min) tc 9 % (min) Table 7 Rheometer and Mooney data of FKM-II compound FKM-III-co/black (Compound 5) Control WS 28 (.5phr) ML (1+4) 1 C (ME) Rheometer MDR 2 at 18 C tc 1 % (min) tc 9 % (min) tc 1 % (min) Ts 2 (min) Torque ML (dnm) Torque MH (dnm) Table 8 Rheometer data of FKM-III compound based on FKM-Copolymer, incorp. bisphenolic cure system, black STP229 8

9 FKM-I-ter/bisphen./red (Compound 3) Control Carnauba WS28 PPA79 Density (g/ccm) Shore hardness A (SH U) Tensile strength (MPa) Modulus 1 % (MPa) Elongation at break (%) Rebound (%) CS 7 h / 2 C 25 % (%) Table 9 Physical properties of FKM-I compound FKM-II-ter/peroxide (Compound 4) Control PPA79 Vulc.time (min) at 18 C Post cure 24h/26 C Shore hardness A (SH U) Rebound (%) Density (g/ccm) Tensile strength (MPa) ,5 Elongation at break (%) Modulus 1 % (MPa) CS 22 h/2 C/25% (%) CS 7 h/2 C/25% (%) after ageing, 2 weeks 2 C in air Shore hardness A (SH U) Tensile strength (MPa) Elongation at break (%) Modulus 1 % (MPa) Table 1 Physical properties of FKM-II compound FKM-III-co/black (Compound 5) Control WS 28 (.5phr) Shore hardness A (SH U) Rebound (%) Tensile strength (MPa) Elongation at break (%) Modulus 1 % (MPa) CS 22 h/2 C/25% (%) CS 7 h/2 C/25% (%) Table 11 Physical properties of FKM-III compound based on FKM-Copolymer, incorp. bisphenolic cure system, black STP229 9

10 FKM-II ter/peroxide (Compound 4) Control PPA79 Material temperature ( C) Extrusion speed (m/min) Extrusion rate (g/min) Table 12 Material temperature, extrusion speed and rate of FKM-II compound (Troester GS3/K-1D cold feed extruder, 35 1/min, (9,8,9,1 C) FKM-III co/black (Compound 5) Control WS 28 (.5phr) Material temperature ( C) Material pressure (bar) Extrusion speed (m/min) Extrusion rate (g/min) Die swell (g/m) Table 13 Material temperature and pressure, extrusion speed and rate, die swell of FKM-III compound (Troester GS3/K-1D cold feed extruder, 35 1/min, (9,8,9,1 C) FKM-II ter/peroxide (Compound 4) Control PPA79 Article weigth (g) 17.7* ** 48.** Standard dev. +/ Change in weigth (%) Mold release, rating 1-6 2* (6) Table 14 Arburg, spider mold test at constant injection pressure, mold temp. FKM-II compound. FKM-III co/black (Compound 5) Control WS 28 (.5phr) Average article weigth* (g) Standard dev Increase of art. weigth (%) Mold release, rating Table 15 Arburg, spider mold test at constant injection pressure, mold temp. FKM-III compound. STP229 1

11 Table Titles Table 1 Mixing cycle for FKM compounds Table 2 CR-formulations for (a) general molding-formulation CR-I and (b) injection molding formulation CR-II Table 3 Typical formulations based on FKM-I compound with processing additives Table 4 Formulations of FKM-II compound Table 5 Formulations of FKM-III compound based on FKM-Copolymer, incorp. bisphenolic cure system, black Table 6 Rheometer data of FKM-I compound Table 7 Rheometer and Mooney data of FKM-II compound Table 8 Rheometer data of FKM-III compound based on FKM-Copolymer, incorp. bisphenolic cure system, black Table 9 Physical properties of FKM-I compound Table 1 Physical properties of FKM-II compound Table 11 Physical properties of FKM-III compound based on FKM-Copolymer, incorp. bisphenolic cure system, black Table 12 Material temperature, extrusion speed and rate of FKM-II compound (Troester GS3/K-1D cold feed extruder, 35 1/min, (9,8,9,1 C Table 13 Material temperature and pressure, extrusion speed and rate, die swell of FKM-III compound (Troester GS3/K-1D cold feed extruder, 35 1/min, (9,8,9,1 C) Table 14 Arburg, spider mold test at constant injection pressure, mold temp. FKM-II compound. Table 15 Arburg, spider mold test at constant injection pressure, mold temp. FKM-III compound. Figure captions Figure 1 WB16 and WB222 concentration effects on Mooney viscosity and flow rate of various CR-I compound Figure 2 Various additive, carnauba, WS28, PPA79, and at 1.5phr, effects on processability in FKM-I compound Figure 3 Perfluorinated (PPA79) and non-perfluorinated (HT79 additive effects on processability in FKM-II compound Figure 4 Silicone (WS28) and non-perfluorinated (HT79 additive effects on processability in FKM-III compound Figure 5 Additive concentration effects on modulus at 3% elongation of various CR-I compound Figure 6 Additive concentration effects on tensile strength of various CR-I compound Figure 7 Various additive, carnauba, WS28, PPA79, and at 1.5phr, effects on modulus at 1% elongation in FKM-I compound Figure 8 Perfluorinated (PPA79) and non-perfluorinated (HT79 additive effects on modulus at 1% elongation in FKM-II compound Figure 9 Silicone (WS28) and non-perfluorinated (HT79 additive effects on modulus at 1% elongation in FKM-III compound Figure 1 Extrudate smoothness of FKM-II compounds Figure 11 Extrudates of FKM-III compounds Figure 12 WB16 effects on Injection molding processing CR-II (a) physical properties, and (b) processing properties. Figure 13 Perfluorinated (PPA79) and non- perfluorinated () additive effects on flowability on spider mold test FKM-II Figure 14 Silicon (WS28) and perfluorinated (PPA79) additive effects on flowability on Spider mold test of FKM-III compounds STP229 11

12 Mooney Torque ML(1+4) at 1 o C (MU) 1 5 WB16 WB222 CR-I Processability Control Flow Rate (ml/sec) Additives Figure 1 WB16 and WB222 concentration effects on Mooney viscosity and flow rate of various CR-I compound Mooney Torque ML(1+4) at 1 o C (MU) FKM-I Torque Control Carnauba WS28 PPA ODR Torque (dnm) at 18 o C Additives Figure 2 Various additive, carnauba, WS28, PPA79, and at 1.5phr, effects on processability in FKM-I compound STP229 12

13 Mooney ML(1+4) at 1 o C (MU) FKM-II Processability Extrusion Rate (g/min) Control PPA(2.) HT(1.) HT(2.) 1 Additives Figure 3 Perfluorinated (PPA79) and non-perfluorinated (HT79 additive effects on processability in FKM-II compound Mooney ML(1+4) at 1 o C (MU) FKM-III Processability Extrusion Rate (g/min) Control WS(2.) HT(.5) HT(1.) HT(1.5) HT(2.) 1 Additives Figure 4 Silicone (WS28) and non-perfluorinated (HT79 additive effects on processability in FKM-III compound STP229 13

14 2 15 CR-I Modulus at 3% Elongation Modulus (MPa) 1 5 WB222 WB16 Control Additive (phr) Figure 5 Additive concentration effects on modulus at 3% elongation of various CR-I compound Tensile Strength (MPa) CR-I Tensile Strength WB222 WB16 1 Control Additive (phr) Figure 6 Additive concentration effects on tensile strength of various CR-I compound STP229 14

15 Modulus (MPa) FKM-I Modulus at 1% Elongation Control Carnauba WS28 PPA79 Additives Figure 7 Various additive, carnauba, WS28, PPA79, and at 1.5phr, effects on modulus at 1% elongation in FKM-I compound Modulus (MPa) FKM-II Modulus at 1% Elongation Control PPA(2.) HT(1.) HT(2.) Additives Figure 8 Perfluorinated (PPA79) and non-perfluorinated (HT79 additive effects on modulus at 1% elongation in FKM-II compound STP229 15

16 Modulus (MPa) FKM-III Modulus at 1% Elongation Control WS(2.) HT(.5) HT(1.) HT(1.5) HT(2.) Additives Figure 9 Silicone (WS28) and non-perfluorinated (HT79 additive effects on modulus at 1% elongation in FKM-III compound STP229 16

17 Control PPA 79 Figure 1 Extrudate smoothness of FKM-II compounds Control WS 28 (2. phr) (.5phr) Figure 11 Extrudates of black FKM-III compound show very smooth edges and surface for 2.phr WS28 and at 1.5phr and 2.phr level only. For the control and at.5phr level, rough surfaces are obtained. At 1.phr level of surface starts to become smooth. STP229 17

18 Control Struktol WB Mooney Scorch T5 (min) Tensile Strength Elongation (% / 1) Hardness (Shore A) (a) WB16 effects on physical properties Control Struktol WB Injection time (min) Flow defect / cycle (% x1) Scrap level (%) (b) WB16 effects on processing properties Figure 12 WB16 effects on Injection molding processing CR-II (a) physical properties, and (b) processing properties. STP229 18

19 Control PPA79 MRR: 2 (6*) MRR: 6 MRR: mold release rate (1 easy-6 hard) *without mold release application MRR: 4-5 MRR: 2 Figure 13 Perfluorinated (PPA79) and non- perfluorinated () additive effects on flowability on spider mold test FKM-II Control MRR: 3-4 WS 28 MRR: 2 (.5phr) MRR: 3-4 MRR: 3-4 MRR: 2-3 MRR: mold release rate (1 easy-6 hard) MRR: 2-1 Figure 14 Silicon (WS28) and perfluorinated (PPA79) additive effects on flowability on Spider mold test of FKM-III compounds STP229 19