No abstract

Summary: New epoxy materials are needed with low dielectric constants (Dk or εr), low loss (Df or tan δ) in the giga‐hertz frequency range and high glass transition temperatures (Tgs) for next generation fiber reinforced printed circuit boards. In this work, the incorporation of adamantane into an epoxy network has been investigated. In particular, this has been achieved by means of a new adamantane‐based, tetra‐functional crosslinking agent (1,3,5,7‐tetrakis(4‐aminophenyl)adamantane or TAPA) which was specifically synthesized and subsequently characterized for this study. The properties of EPON Resin 828 cured with the newly synthesized TAPA have been compared with the commonly used commercial curing agent 4,4′‐diaminodiphenylsulfone (DDS). It was found that the epoxy polymer cured with TAPA exhibited superior thermal properties as well as a good dielectric performance at high frequencies. magnified image

Silica-coated BaSO4 submicronic particles, modified on the surface by treatment with stearic acid, have been characterized by means of 29Si, 13C, and 1H magic-angle-spinning (MAS) high-resolution techniques, and low-resolution 1H-FID analysis. Two types of adsorbed water were identified; adsorbed either inside or on the surface of BaSO4, most of the latter being removed by the silica coating. Evidences of silica-stearic acid interactions were found involving either carboxylic acid or carboxylate functional groups, and occurring by means of hydrogen and/or covalent bonds. Stearic acid was present as monolayer only, its chain being mostly rigid, even though a small fraction was subjected to fast inter-conformational motions.