Plasma polymerizaton coating of silica fillers for Epoxy Molding Compounds(EMCs)

摘要

Silica fillers for Epoxy Molding Compouds 9EMCs) were modified via plasma polymerizaton coating of acrylonitile,acrylic acid and dimethyl phosphite with RF plasma(13.56MHz).The resultign samples were characterized by DSC,FT-IR and contact angle measurements.EMC samples were prepared from silica fillers,biphenyl epoxy resin,phenol novolac an triphenyl phosphine,and cured at 175 deg C for 4 H.Flexural strength of the EMC samples was evaluated in a 3-point bending mode with an Instron 5567 at a crosshead speed of 1 mm/min both at RT and 250 degC,and failure surfaces were analyzed by SEM.Some samples were exposed to 121 degC, 2 atm pressure and 100% RH for 12,24 and 32h,and then to 250 degc for 10 min prior to testing at RT.?Plasma polymer coating of silca with acrylonitrile greatly improved the flexural strength of EMC at RT as well as at 250 degc,followed by acrylic acid and dimethyl phosphite.Exposing EMC samples to 121 degC,2 atm pressure and 100% RH for 32 h decreased th eflexural strength by 13% when the silica was coated with acrylonitrile plasmea polymer,compared to the 21% decrease in thecontrol sample.Plasma polymer coating of silica also increased the T_g of the EMC,and lowered water absorption and CTE in he rubgbery region.Therefore,enhanced properties by plasma polymer coating of silica with acrylonitrile or acrylic acid can be attributed to nitrile or carboxylic acid groups,as ocnfirmed by FT-IR,which acan react with epoxy groups in thebase resin,as evidenced by DSC analysis.