RESEARCH ON RESIN-IMPREGNATED, COLLIMATED BORON FILAMENTS AND IMPROVED HIGH-MODULUS, HIGH-STRENGTH FILAMENTS AND COMPOSITES.
Annual summary rept. 1 Oct 64-30 Sep 65,
WHITTAKER CORP SAN DIEGO CA NARMCO RESEARCH AND DEVELOPMENT DIV
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Efforts were made to maximize the portion of the basic strength in boron filaments which could be utilized in composite tape, NOL-rings, laminate panels, and test specimens therefrom. The objective was approached by comparative studies of the effectiveness of various etchants, finishes, resin systems, and processing variables. The latter processing variables were those involved in the conversion of reeled boron filaments supplied as Government-furnished property into collimated, preimpregnated multifilament tape and then into press laminate panels and NOL-rings from which test specimens were cut and evaluated. Tensile strength utilization of boron fibers in NOL-ring composites was increased 50 by an as-received fiber treatment consisting of nitric acid etching for 20 seconds at 248 F followed by 2-second exposure to a nitrogen atmosphere at 1500 F. Boron fiber reinforced bidirectional panel specimens using Epon 8281031 MNABMDA resin system had average composite strengths of 54 ksi tensile, 86.7 ksi flexural, and 149.2 compressive. The average moduli were 20,500,000 psi tensile, 20,600,000 psi flexural, and 20,600,000 psi compressive. In general, only tensile strength results are inferior to those of S-glass composites. It is recommended that higher shear strength, high-modulus resins, better finishes, and further improved fibers and processes be developed to correct this deficiency. Author
- Laminates and Composite Materials
- Metallurgy and Metallography