The use of an eight-experiment Plackett-Burman method can assess six experimental variables and eight responses in a polysiloxane-glass microsphere syntactic foam. The approach aims to decrease the time required to develop a tunable polymer composite by identifying a reduced set of variables and responses suitable for future predictive modeling. The statistical design assesses the main effects of mixing process parameters, polymer matrix composition, microsphere density and volume loading, and the blending of two grades of microspheres, using a dummy factor in statistical calculations. Responses cover rheological, physical, thermal, and mechanical properties. The cure accelerator content of the polymer matrix and the volume loading of the microspheres have the largest effects on foam properties. These factors are the most suitable for controlling the gel point of the curing foam, and the density of the cured foam. The mixing parameters introduce widespread variability and therefore should be fixed at effective levels during follow-up testing. Some responses may require greater contrast in microsphere-related factors. Compared to other possible statistical approaches, the run economy of the Plackett-Burman method makes it a valuable tool for rapidly characterizing new foams.

Sylgard® 184 and Sylgard® 186 silicone elastomers form Dow Corning® are used as potting agents across the Nuclear Weapons Complex. A standardized mixing procedure is required for filled versions of these products. The present study is a follow-up to a mixing study performed by MST-7 which established the best mixing procedure to use when adding filler to either 184 or 186 base resins. 2 The most effective and consistent method of mixing resin and curing agent for three modified silicone elastomer recipes is outlined in this report. For each recipe, sample size, mixing type, and mixing time was varied over 10 separate runs. The results show that the THINKY™ Mixer gives reliable mixing over varying batch sizes and mixing times. Hand Mixing can give improved mixing, as indicated by reduced initial viscosity; however, this method is not consistent.

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The copper component of the microclad system was chemically characterized for purity via inductively coupled plasma mass spectrometry (ICP-MS). The copper purity was determined by measuring the impurities. The main impurities detected were tin and palladium which are the catalysts for the electroless plating process. Therefore, they were not considered in the purity calculation. Several minor differences were determined including copper weight percent of the microclad and impurity level. The purity results for all lots analyzed varied from 99.9986-99.9992%. Therefore, there is a high degree of similitude in the purity of the copper across the lots.