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An approach to high-density, high-modulus binders for explosives is to blend low-density, high-modulus polymers with high-density, low-modulus polymers. Improved properties, which these pairs theoretically should have, are discussed. Two attempts to achieve miscibility between a high-density fluoropolymer (Kel-F 800) and high-modulus thermoplastics (Lucite 130 and Phenoxy PKHJ) were unsuccessful. These blends are immiscible and their physical properties are additive or only slightly enhanced. Anelastic properties of the blends indicate phase separation by the presence of two glass transitions, one associated with each phase.

Raychem Stylan aromatic polymer and P h i l l i p s Ryton R-4 polyphenylene s u l f i d e are essentially unchanged a f t e r 100 hours. Ryton appears t o be satisfactory a t 25OoC, although i t flowed badly a t 30OoC. A t 25OoC .-. r v Elork Planned Exposure tests are continuing a t both test temperatures.

As part of our long-range goal to improve the properties of weapon cushions, we evaluated the usefulness of the Yerzley mechanical oscillograph in detecting differences among Y3333 cellular silicones. Our interest centered on the Yer~ley test method~ not the Y3333 cushion material. We measured four properties of Y3333: density, thickness, resilience, and effective dynamic modulus. Test samples came from five lots of standard Y3333 r.ompound and from two lots of experimental Y3333. Tests of the four properties revealed that individual sheets of Y3333 were homogeneous. Since sheets from the same lot differed little in properties, normal process variations had minimal effect on properties. Although lot-to-lot variation of standard Y3333 was statistically significant, the coefficients of variation of 5% or less indicated a reasonable .consistency among the five lots tested. The two experimental lots of Y3333, made with known material and manufacturing variables, showed a response to the variations but maintained low coefficients of variation. After evaluating the Yerzley instrument, we decided that it demonstrated its worth for detec~ing differences among Y3333 cellular silicones.

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