Preparation And Properties Of Acrylate/Epoxy Nanocomposites Based On Inorganic Layered Materials By In-Situ Polymerization

In recent years,ion-exchange process and covalent-graft method have been developed to organo-modify inorganic layerd materials,thus making them more organophilic and have better compability with polymer matrix.In this thesis,we demonstrated a novel method for the preparation of exfoliated nanocomposite based on the organo-modified clay with reactive acrylate group grafted to the clay layer by covalent bonds and also on organo-modified layered double hydroxide.The epoxy nanocomposites based on the ternary system of DGEBA,hyperbranched epoxy and LDH was also prepared.Furthermore,we aim to explore possible applications of these functionalized layered materials in high performance nanocomposites.1.The half adduct of isophorone diisocanate and 2-hydroxyethyl acrylate (IPDI-HEA),as a reactive organic modifier,was used to functionalize Na-montmorillonite(Na-MMT) clay.Unlike the electronic interaction in the conventional cation-exchange method,the driving force for the organic modification came from the chemical reaction between IPDI-HEA and framework hydroxyl groups on the surface of clay.With high degree of organic modification(48%),the d-spacing of clay layer was greatly enlarged to 3.32 nm,and the clay became more organophilic.After in situ photopolymerization among the IPDI-HEA grafted MMT clay,monomers and oligomers,the exfoliated polymer/clay nanocomposites were obtained. X-ray diffraction and transmission electron microscopy were used to detect the structure and morphology of the clay dispersed in the polymer matrix. Compared with the pure polymer materials,the exfoliated polymer/clay nanocomposites exhibited enhancements in mechanical and thermal properties.2.The thermal and mechanical properties of UV curing coatings consisted of urethane acrylates as an oligomer and a diacrylate monomer were reinforced by using layered double hydroxide(LDH).The LDH was organically modified by an ion-exchange process,in which the nitrate anions were replaced by long alkyl sulfate anions.With organic modification,the d-spacing of inorganic LDH layers was greatly enlarged to 2.75 nm from 0.78 nm,leading the LDH to be organophilic.During in situ photopolymerization process,the d-spacing of LDH layers was further enlarged to 4.29 nm,indicating the intercalation of polymer chains.For comparison,polymer/LDH nanocomposite filled with un-modified LDH was also prepared,and showed less enhancement in thermal and mechanical properties.3.The effects of organically modified layered double hydroxide(O-LDH) and epoxy functionalized hyperbranched aliphatic polyester(E1),on the mechanical strength,thermal property and toughness of diglycidyl ether of bisphenol A(DGEBA) epoxy resin were studied in details.The crystalline structure and morphology of the nanocomposites composed of DGEBA/O-LDH and DGEBA/E1/O-LDH were investigated by wide angle X-ray diffraction analysis and transmission electron microscopy observation. Both results showed that the LDH nanosheets were sufficiently exfoliated and randomly dispersed in the epoxy matrix.The thermal and mechanical properties were compared with the corresponding neat polymer matrix.The enhancement in strength and toughness was achieved by the addition of O-LDH and E1,respectively,and confirmed in terms of fracture surface analysis by scanning electron microscopy.