The Preparation And Performance For Highly Exfoliated Epoxy/Clay Nanocomposites

Two challenging tasks in the field of polymer/clay nanocomposites were explored in the thesis.One is how to obtain highly and disorderly exfoliation of clay in the polymer matrix,the other is how to build a stronger interface between the polymer matrix and the clay platelets.The main results are as follows:(1)A new “acetone-clay slurry compounding” approach has been developed to fabricate epoxy/clay nanocomposites.The chosen modifier with special functional groups was employed to modify pristine Na+-clay.The prepared organoclay-slurry,instead of being dried up as usual,was directly blended with epoxy resin and clay layers were exfoliated in epoxy prior to curing.And then a disorderly and highly exfoliated epoxy/clay nanocomposite was achieved.(2)The effect of different organic modifiers on the microstructure of nanocomposites and the mechanism of exfoliation of the organoclay in epoxy via the new method have been explored by monitoring the change of morphology of organoclay during each stage of processing with X-ray diffraction(XRD)and by TEM observation.When 2,4,6-tris(dimethylaminomethyl)phenol(DMP-30)and Jeffamine 230(D230)used as modifiers,both of which have strong hydrophilic group and reactive group and also have good compatibility with epoxy prepolymer,highly and disordered exfoliation can be formed.In the case of organoclay modified with hydroxyl-substituted quaternary ammonium ions(CC),which has stronger hydrophility but relatively week affinity with epoxy prepolymer,a mixture of ordered and disordered exfoliation can be obtained.When aliphatic alkyl ammonium(CTAB and ODA)used as surfactants,which are hydrophobic and bad in compatibility with epoxy prepolymer,the organoclay usually has a poor dispersion in epoxy and aggregation occasionally formed.They can only lead to a slightly increase in d-spacing but not to an exfoliation.(3)The influences of the type of modifiers on flexural strength,thermal stability and friction properties of epoxy/clay nanocomposites have been investigated.It revealed that the performance of nanocomposites prepared by organoclay(modified by DMP-30 and D230)with reactive functional groups were superior to those of nanocomposites prepared by organoclay modified by CTAB and ODA,which have on reactive functional groups.The related properties of nanocomposites fabricated by CC modified clay,which can form hydrogen bonds with epoxy,are in the moderate level.(4)In order to establish stronger interfacial interaction between organoclay and epoxy matrix,which would help improve the mechanical properties of nanocomposites,CC with hydroxyl group was used to modify the montmorillonite.A chemical reaction takes place between the epoxy and CC-MMT when DMP-30 as a catalyst,and then a strong chemical bonding was built up.The mechanical and thermal properties of epoxy/clay nanocomposite were improved significantly.The glass transition temperature has increased by 13?,the tensile strength increased by nearly 160%.