Pressure Distribution Pad Using Mosites #10320
The manufacturing of composite aerospace articles quite often involves the co-vulcanization of flat or contoured panels with various shapes of strengtheners (J-stringers; I-Beam stiffeners; C-channels; etc). In order to assure proper consolidation of the composite pre-preg at these bond joints and to prevent movement of the reinforcing members during autoclave cycles, rubber cauls are employed. These rubber cauls are shaped to the configuration of the tool cavity and are intended to be reusable. A high temperature resistant elastomer that has good dimensional stability upon extended cure cycling is necessary.
Some aircraft manufacturers use castable RTV silicone for these rubber parts; others specify a non silicone containing elastomer for the application (butyl; chlorobutyl; etc). The above mentioned elastomers have advantages and disadvantages, but the need remains for a more durable elastomer product.
Mosites Rubber Company has developed a fluorocarbon elastomer that appears ideally suited for this application. It exhibits low shrinkage upon vulcanization; withstands extended head age cycling with minimal further shrinkage and can be co-cured with epoxy prepreg reinforcement if a more rigid, less flexible rubber part is desired. Because it is a fluorocarbon polymer, exposure to temperatures up to 450°F will have no adverse effect on the cured rubber part.
The material is supplied in uncured or “B” stage calendered sheet form, 1/16 inch thick x 54 inches wide. Other thicknesses widths may be available as special order request.
Physical properties shown below were obtained on 0.080 inch thick ASTM samples. They are typical of Mosites #10320 but should not be used to set Quality Control Specification minimum values.
|Mosites #10320- Original Properties|
|Hardness (Shore A)||78|
|Tensile Strength (psi)||2980|
|Elongation at Break (%)||158|
|Tear Strength- Die C (ppi)||143|