Abstract: IPN's of polybutyl acrylate (PBA) and PS(OH), a copolymer of styrene and HFMS (a hydroxyl-containing monomer) were prepared by a sequential process, DSCand TEMshow that all the IPN' s display two-phase structure even when the hydroxyl content in PS (OH) reached 30 mol%.The compositions of the two phases were calculated from the T_g values based on the “copolymerization equation”.It is found that there is no composition change of the two phases when the content oi PS(OH) in the IPN' s is less than 50%.Apparent T_g increase of the PBA-rich phase is found when the hydroxyl content in PS (OH) is as high as 30 mol% and PS (OH) becomes the major component in the IPN' s(>60%).This indicates that PS(OH) can be partially solubilized in the PBA-rich phase only when there are enough hydrogen bonds existing.The relative modulus of the IPN' s as a function of the total composition shows that in the composition range of PS(OH) about 30%-50% there is a drastic change of the modulus accompanying the variation of the phase structure.The modulus data are in good agreement with the Budi-ansky equation rather than the Kerner equation implying some extent of phase continuity.

Key words: Interpenetrating polymer network(IPN), Hydrogen bond, Miscibility, Morphology, Modulus