| Due to its superior mechanical and chemical performances, epoxy resin has beenwidely used in many fields of human life. However, because of its intrinsic brittleness,the application of epoxy resin in some specific areas has been still limited. In order toovercome such challenges, people are seeking various rational methods to not onlyenhance epoxy resin’s strength and toughness, but also simultaneously keep its othersuperior performances, for example, thermal mechanical properties and modulus.Recently, nano-sized particles have been introduced into epoxy resin matrix forenhancing its toughness. It was found that even low filler content of nanoparticlescould largely improve the mechanical and thermal properties of epoxy resin due to thein-situ homogeneous dispersion in nanoscale of the filled particles in the matrix. Nanofiller of particles may open a new way to create multifunctional epoxy resin with highperformances. In this thesis, we introduced various rubber particles with differentsizes to act as filling materials and studied the relationship between the properties ofepoxy resin and the filled rubber nanoparitcles. Based on the experimentalinvestigations, the relevant toughening mechanisms were proposed. The main resultsare including:(1) A comparative study was carried out on epoxy composites filled withsub-micron or nano-sized rubber particles. It was found that the viscosities of uncuredepoxy resins increased after adding nano-sized rubbers particles, but decreased whenmixed with sub-micron ones. The glass transition temperatures of epoxy compositesincreased with nano-sized particles, but decreased with sub-micron ones. All rubberparticles resulted in decrease in the elastic modulus of composites obviously, butincrease in the elongations at break. At lower filler content, the tensile strength ofepoxy composites can be improved with nano-sized rubber particles. All rubberparticles exhibited significant toughening effect on epoxy resin. Based on themorphologies in micro-scale, the de-bonding behavior of rubber particles wasobserved for both rubber particles, and this promoted the local plastic deformationaround crack tips of the prepared composites. (2) In order to better understand the toughening mechanism of various rubberparticles, the performances of rubber-epoxy composites mixed with joint sub-micronand nano-sized sized particles were explored. The results revealed that the toughnessof epoxy resin mixed with joint particles was much higher than that of epoxy resinmixed with individual filler. The synergistic toughening effect could be ascribed to ade-bonding behavior, in which the two kinds of rubbers can promote the de-bondingbetween each other during fracture process and result in increased plastic deformationability of epoxy resin matrix. Therefore, the toughness improvement of epoxy resinmatrix could be explained by the enhancement of fracture energy due to de-bondingbehavior.(3) In this work, a new type of rubber particles (named VP401) was introduced toact as the filler for epoxy resin. The results revealed that both the toughness andthermal performance could be improved significantly. The mechanism was attributedto the strong interaction between the special rubber nanoparticle and epoxy resinmatrix. |
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