The following study evaluates the effects of adding Zonyl® MP1500 fluoroadditive to a standard silicone gum formulation (Dow Corning Silastic® 4-2735). Beneficial improvements in tear strength were observed with as little as 5 phr addition of the fluoroadditive. In order to maximize dispersion of the fluoroadditive within the silicone matrix, a masterbatch was first prepared and subsequently "blended down" to obtain the final compounds. The preparation of a master batch with a high level of Zonyl® MP1500 is a critical part of the compounding operation if the elastomer has a low viscosity. All mixing was performed on a standard two-roll lab mill. Silica filler levels were maintained at the 40 phr level.
|
|
| Silastic® 4-2735 |
100 |
| Zonyl® MP \1500 |
40 |
| Silica (Petrarch SS0216) |
40 |
| Masterbatch Viscosity, ML 1+4 @ 100°C |
27.4 |
|
|
|
|
|
| Silastic® 4-2735 |
100 |
88 |
76 |
52 |
| Silica (Petrarch SS0216) |
40 |
35 |
30 |
20 |
| Masterbatch MB-1 |
-- |
22 |
44 |
88 |
| Di-Cup 40C Peroxide |
4 |
4 |
4 |
4 |
|
|
|
|
|
| Mooney Viscosity |
|
|
|
|
| ML 1+4 @ 100°C |
NA |
9.2 |
9.6 |
14.6 |
| Mooney Scorch @ 121°C |
|
|
|
|
| Minimum |
NA |
4.5 |
4.6 |
7.0 |
| Time to 2 Point Rise, minutes |
NA |
24.8 |
25.5 |
25.8 |
| Time to 5 Point Rise, minutes |
NA |
26.5 |
26.6 |
26.7 |
ODR @ 177°C, 3° Arc,
30-minute Motor |
|
|
|
|
| ML, lbf-in |
NA |
3.2 |
NA |
3.4 |
| Ts2, minutes |
NA |
0.8 |
1.6 |
0.8 |
| Tc90 Minutes |
NA |
2.3 |
4.2 |
2.8 |
| Mc90, lbf-in |
NA |
37.1 |
37.1 |
37.4 |
| MH, lbf-in |
NA |
40.5 |
38.4 |
40.1 |
|
|
|
|
|
| Press Cured: 7 minutes @ 177°C |
|
|
|
|
| Post Cured: 4 hours @ 200°C |
|
|
|
|
| Original Physical Properties @23°C - (Tested Against Grain) |
|
|
|
|
| 50% Modulus, psi |
NA |
80 |
80 |
105 |
| 100% Modulus, psi |
NA |
120 |
115 |
150 |
| Tensile Strength, psi |
NA |
950 |
980 |
695 |
| Elongation @ Break, % |
NA |
418 |
457 |
380 |
| Hardness, Duro A, Pts |
NA |
45 |
47 |
50 |
| Original Physical Properties @23°C - (Tested With Grain) |
|
|
|
|
| 50% Modulus, psi |
NA |
125 |
170 |
200 |
| 100% Modulus, psi |
NA |
155 |
195 |
230 |
| Tensile Strength, psi |
1250 |
1005 |
1060 |
945 |
| Elongation @ Break, % |
NA |
423 |
468 |
446 |
| Hardness, Duro A, Pts |
45 |
43 |
45 |
50 |
| Tear Resistance @ 23°C |
|
|
|
|
Tear Resistance - Tested Against Grain
Die B, pli |
NA |
123 |
117 |
106 |
Tear Resistance - Tested With Grain
Die B, pli |
77 |
111 |
99 |
104 |
|
