Preparation And Characterization Of Unsaturated Polyester/Montmorillonite Composites

Polymer/montmorillonite composites are a kind of novel composites due to the excellent properties as well as their wide applications in the future. The aims of this study on unsaturated polyester(UP)/montmorillonite composites are to improve the thermal properties and to provide valuable instructions for thermosetting resin systems.Unsaturated polyester/montmorillonite composites were prepared by in-situ intercalation polymerization with methyl ethyl ketone peroxide (MEKP) as initiator, cobalt naphthenate as accelerant and phenylethylene as diluting agent. Influence of amount of ethylene glycol, mole ratio of phenylethylene and maleic anhydride, added time of montmorillonite, kind of dihydroxy alcohol and content of montmorillonite was investigated. It is concluded that composite with high thermal properties can be gained under following optimal experiment conditions: amount of excessive ethylene glycol 7%, mole ratio of phenylethylene and maleic anhydride 1.8:1,adding montmorillonite before reaction and content of montmorillonite 1%. Thermal stability of composite prepared from ethylene glycol is superior to that prepared from 1,2-propanediol.It is proved that montmorillonite exists in composites and strong interaction is formed by FT-IR.XRD results indicate that 001 peak is transferred to 2θvalue of 3.8°corresponding to an interbedded space of 2.325nm when montmorillonite is organized. After compounded with UP, the peak disappears within the range of diffraction observed. It was the reason that interbedded space of organic montmorillonite was expanded and organic montmorillonite had good compatibility with UP. So UP could be solidified into the space of montmorillonite easily and slices were further expanded. Then composites were formed. TEM results show that most of montmorillonite slices are still existed in polyester matrix in the form of aggregate.Thermal decomposition kinetics of UP/montmorillonite composites under nitrogen was studied and compared with UP. Apparent activation energy E of composites and UP were all obtained by differential method. The results indicate that composite UP11 prepared from ethylene glycol is further steadier than pure UP1 and composite UP21 prepared from 1,2-propanediol.