The Study Of Lower Dielectric Constant Of Porous Silica/CE Composites

Cyanate ester(CE) resin possesses very low dielectric constant(?) and dielectric loss(tan?) in a wide frequency and temperature range. It has also balanced heat resistanceand, low shrinkage and low moisture absorption rate. With the rapid development of the high frequency printed circuit boards(PCB) and high performance materials, polymer with lower ?, tan? and higher thermal and mechanical properties are demanded. Introduction of pores into polymer and reinforcement by porous inorganic filler are perspective routes to prepare high performance composites.The purpose of our work is to develop a new kind of CE-based composite with excellent dielectric, mechanical and thermal properties. CE composites filled with glycidyl polyhedral oligomeric silsesquioxanes(G-POSS), mesoporous silica(MPS) with inorganic mesoporous skeleton and functional POSS-MPS have been synthesized, and the microstructure and performance of porous silica/CE nanocomposites were investigated.The studies of G-POSS/CE composites suggest that the addition of G-POSS can obviously reduce the curing temperature of CE resin system. When the the content of G-POSS is 4phr, the curing peak temperature decreased from 287? to 252?. The conclusions reveal that the of CE composites decrease with improving of mass fraction of G-POSS, and also present stable ? across the wide frequency range. The ? of composites is reduced from 3.27 of pure CE to 3.05 containing 4phr of G-POSS. The mechanical of G-POSS/CE composites are also strengthened. The impact strength is strengthened to 23.8KJ/m2, increased by 158%. High content of G-POSS compromises the thermal properties and wet resistance of the composites.MPS with worm-hole framework was synthesized with ?, ?-polyoxypropylene diamine(D2000) as templates. All mesoporous silicas were employed as filler to prepare improved CE composites with lower ? and tan?, higher thermal and mechanical properties. It was found that all mesoporous silicas retained their mesostructure in MPS/CE composites to introduce a lot of voids into the composites. So, the ? of composites decreased with the loading of MPS increased. Specifically, with the addition of MPS to CE, the ? of the composite can be reduced from 3.27 of the pure CE to 3.02 by incorporating 1phr of MPS. When the the content of MPS is 1phr, the flexural strength and flexural modulus are strengthened to 120.85 MPa and 3.8GPa, increased by 22.4% and 15.9%, respectively. All the composites exhibited improved mechanical properties, glass transmission temperature(Tg) and thermal decomposition temperature(Td) in comparison to CE. All these differences in macro-properties are attributed to the different structure between MPS/CE composites and CE. When MPSs content are higher(MPS ? 2Phr), MPSs are easy to be agglomeration and settlement in matrix.The novel organic-inorganic particles(denoted POSS-MPS) were synthesized by the reaction of amino-functionalized mesoporous silica(AP-MPS) and G-POSS, and were employed as reinforcing agent to prepare POSS-MPS/CE composites. The ? and tan? of CE composites decrease with improving of mass fraction of POSS-MPS. The POSS-MPS/CE composites containing 4phr of POSS-MPS showed lower ?=2.78 and tan?=0.0079 in comparison to pristine CE with the value of 3.27 and 0.0119, respectively. Moreover, the composites exhibited enhancement in tensile strength, tensile modulus, Tg and Td in comparison to pristine CE, respectively. The results manifested that introduction of POSS-MPS improved the dielectric properties, mechanical properties and thermal properties of CE. The excellent improvement in dielectric properties, mechanical properties and thermal properties of the POSS-MPS/CE composites is ascribed to increase of voids volume and reinforcement of interfacial interaction between organic and inorganic phase in the composites.