- Author
-
Zukas, W.
- Title
- Fire Resistant Organic Composite Material. December 21, 1998-July 20, 1999.
- Coporate
- Foster-Miller, Inc., Waltham, MA
- Sponsor
- Naval Surface Warfare Center, West Bethesda, MD
- Report
-
NAV-0028-FM-99112-1285
August 1999
160 p.
- Distribution
- AVAILABLE FROM National Technical Information Service (NTIS), Technology Administration, U.S. Department of Commerce, Springfield, VA 22161. Telephone: 1-800-553-6847 or 703-605-6000; Fax: 703-605-6900. Website: http://www.ntis.gov
- Keywords
-
composite materials
|
fire resistant materials
|
vinyl esters
|
additives
- Identifiers
- Vacuum Assisted Resin transfer Molding (VARTM)
- Abstract
- The technical feasibility of fabricating fire resistant composite structures through vacuum assisted resin transfer molding (VARTM) fabrication technology was shown in this Phase I program. Fire resistance was achieved in a single fabrication step through the use of additives to vinyl ester resins and through the use of phenolic resins. A number of different additives were explored during the course of the Phase I program. The most promising results were obtained with the use of a low melting inorganic barrier layer incorporated into the reinforcement preform in combination with intumescent additives. As the composite incorporating this barrier material was tested for fire resistance with cone calorimetry, the thermal load served to first remove (burn) the surface resin then heat and melt the additive glass. This melting phenomena effectively sealed the composite surface and reduced the heat release late and mass loss of the composite. The combination with an intumescent material further reduced the heat release rate and mass loss of the composite through the formation of a thick insulating layer. Cure cycle modification of phenolic resins also held promise as a route to utilize these inherently fire resistant organic resins in composite structures. Low temperature cures were used to minimize void formation through the reduced vapor pressure of dissolved volatiles and increased resin viscosity. Once significant cure is achieved, higher cure cycle temperatures completed the cure reactions for optimum physical performance. Phenolic composite flexural properties similar to product literature values for both phenolic and vinyl ester composites were achieved through cure steps at low temperature. Improvements in short beam shear values for the phenolic composites were observed for variations in cure cycle and with the addition of siloxane and layered silicate clay additives. However, these values were not as high as those measured for a vinyl ester control. Although shown by others to lead to improved fire resistance in thermoplastics, the formation of nanocomposite materials through the incorporation of silicate clays into the vinyl ester resins showed little improvement in fire resistance as measured with cone calorimetry at loading levels thought feasible for VARTM processing. Neither untreated or treated clays, leading to different levels of dispersion in the resin, showed improvements in fire resistance at 5 weight percent levels. Higher levels may lead to improvements, however, these same higher levels would also increase resin viscosity making preform infiltration difficult at best.