Study on the polymer layered silica nanocomposites of a few typical high performance plastic resins

High performance plastic resins PEK-C, PES, PEI and PSU were mixed with organoclay CH₃ (CH₂)₁₇ (CH₃)₃N₃⁺-Montmorillonite in solution. The XRD results revealed that the PEK-C and PES were very easy to intercalate into the clay and drove the clay to exfoliate, as a result, exfoliated polymer/clay nanocomposites were obtained. On the contray, PEI and PSU could not intercalate into the clay. The possible reasons caused these different results might be that the interaction between the former two polymers and clay were strong while the interaction between the latter two polymers and clay were weak. The T_gs of PEK-C/clay and PES/clay nanocomposites were 210°C and 229°C, much lower than that of pure PEK-C and PES, which were 227°C and 237°C, respectively. But the decomposing temperatures T_d of PEK-C and PES rose from 469°C to 507°C and from 514°C to 579°C after mixed with clay, increased 38°C and 65°C, respectively. For the polymer PEI and PSU, which could not intercalate into the clay, both their T_g and T_d changed little after mixed with the clay. The positron annihilation life time spectroscopy results indicated that larger free volumes formed as PEK-C combined with clay, which was supposed to be responsible for the decreases of its T_g.