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Modified hollow glass microsphere (HGM) particles have been prepared by surface treatment. Coupling agents such as γ‐aminopropyltriethoxysilane (APTES), di(dioctylpyrophosphato) ethylene titanate (NDZ‐311), and glutaraldehyde (GA) were used as modifiers to improve the hydrophobicity of HGM. Compared with pristine HGM, the modified HGM, especially the particles coupled with APTES‐GA, show better properties on flexural strength, fracture toughness, and dynamic mechanical properties of phenolic syntactic foams. It is revealed that the coupling agent coating layer grafted onto the surface of HGM reduces the polarity of particles, avoiding agglomeration of HGM in phenolic matrix and exhibiting good interfacial interaction between HGM and phenolic matrix. The remarkable improvement of interfacial adhesion between APTES‐GA modified HGM and phenolic matrix is mainly due to the covalent linkage with phenolic resin while the physical entanglement of molecular chains dominates the linkage between other modified HGM and phenolic matrix. APTES‐GA treatment is a more appropriate surface modification method for inorganic particle reinforced phenolic matrix composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44415.

Epoxy syntactic foams were prepared with diglycidyl ether of bisphenol-A (DGEBA) epoxy resin, 2.4.6-tri(dimethylaminomethyl)phenol (DMP-30), coupling treated microsphere and short carbon fiber. The density of the foam was maintained between 0.56 and 0.91 g/cm 3 for all compositions. Compressive, flexural, tensile and dynamic mechanical properties of the foams were investigated with respect to hollow glass microsphere (HGM) and carbon fiber (CF) content. A considerable improvement in the mechanical properties viz. compressive, flexural and tensile strengths was observed for the foams on incorporation of a small quantity of CF. The storage modulus were higher for the foam composites containing CF. The presence of HGM has significant influence on T g of the syntactic foams, spherical filler diminished the T g of the syntactic foams due to the plasticizing effect of the coupling treatment of HGM, that is helpful for enhancing damping properties of syntactic foams.

A thickness gradient interpenetrating polymer network (IPN) was easily created that takes advantage of the relatively poor compatibility and curing rates discrepancy between epoxy (EP) and polyurethane (PU). Ultraviolet absorption spectrum (UV-Vis), thermogravimetric (TG), Differential scanning calorimetry (DSC), Dynamic thermomechanical analysis (DMA), Atomic force microscope (AFM) and water contact angle were adopted to characterize this IPN structure. We found that the absorption in visible light region, glass-transition temperatures (T g ), thermal decomposition temperatures (T d ) and Derjaguin-Muller-Toporov (DMT) modulus were increasing along with the gradient direction from bottom side to top side of the IPN. While the absorption in ultraviolet region and adhesion force were decreasing along with the gradient direction from bottom side to top side of the IPN. DMA analysis demonstrates that this continuous gradient IPN has a good balance between the damping temperature range and the loss factor which is suitable for using as a self-supporting damping structure.

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