Highly Populated and Nearly Monodispersed Nanosilica Particles in an Organic Medium and Their Epoxy Nanocomposites

Abstract

An organic aminopropyl-functionalized nanosilica sol was synthesized in the presence of ethyl silicate, γ-(aminopropyl)triethoxysilane (KH550), and N,N-dimethylformamide (DMF) via a sol-gel technique and then used to prepare epoxy nanocomposites. Structure and morphology analyses of the obtained aminopropyl-functionalized nanosilicas were observed by dynamic light scattering (DLS), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). TEM and DLS showed that modified nanosilicas with an average diameter of 30 nm dispersed homogeneously in DMF. The effects of the aminopropyl-functionalized nanosilica particles on the flexural modulus, impact strength, glass transition temperature (Tg), and bulk resistivity (ρv) of the epoxy nanocomposites were investigated. The toughening mechanisms and microstructures were determined in terms of the impact fracture surface morphology using scanning electron microscopy.

Simultaneous improvement in strength, toughness, and thermal stability of epoxy/halloysite nanotubes composites by interfacial modification

“…T g characterizes the chain segmental mobility which is determined mainly by the chemical structure and also is related to the interfacial interaction for nanocomposites. The T g variation of epoxy nanocomposites is proposed to be a result of two competitive factors: the enhanced interaction and the decreased cross‐linking density of epoxy . Compared with the unmodified HNTs, the enhanced interaction between the A‐HNTs and epoxy restricted the motion of chain segments.…”

Simultaneous reinforcement and toughness improvement of an epoxy–phenolic network with a hyperbranched polysiloxane modifier

“…Over the past few decades, tremendous efforts have been made and different kinds of modiers have been developed to improve the toughness of epoxy resins, such as liquid rubber or rubber particles, 5,6 thermoplastics, 7 and nanoparticles. [8][9][10] In most cases, blending modiers into the epoxy matrix brings about the improvement of toughness but oen signicantly compromises the thermal properties, 11,12 modulus and strength of the resins. 13,14 Moreover, phase separation before or during the curing process aer incorporation of these modiers may result in great difficulty in the design of interfacial chemistry and cure schemes to guarantee a proper morphology of the cured networks.…”

“…3(b), as the HBPSi-2 loading increases from 0% to 15%, T g of E-HBPSi-2 decreases stepwise. Various research groups [37][38][39][40][41][42] have reported a decrease in T g when silica or organosilicone are added to epoxy or some other matrix. Generally, this behavior has been attributed to plasticizing effect or to a limited amount of unreacted reactant.…”

Thermal and Mechanical Properties of Epoxy Composites Using Silica Powder

“…이러한 이유로 에폭 시 복합재료의 내충격성 및 열안정성을 개선하기 위 한 다수의 연구가 진행되고 있다. 에폭시 수지에 보다 유연한 물성의 고무, PMMA계(Polymethylmethacrylate) 코어-셀(core-shell), CTBN (carboxyl terminated acrylonitrile butadiene)과 같은 탄성체를 도입하거나 [2], 나노 클레이(Montmorillonite, MMT) [4], 탄소나노튜브(Carbon Nano Tube, CNT) [5][6][7], HNT (Halloysite Nano Tube) [8,9], Carbon [10], SiO2 [11][12][13] Figure 5에 neat epoxy, epoxy/CA0030_70%, epoxy/ CA0030+APTES2%_70%, CA0030, CA0030+APTES 2% 를 TGA thermogram을 나타내었다. …”