Search

In this study, a kind of novel heat-insulating material composed by the vinyl-functionalized polyborosiloxane (BSiO) and hollow glass microspheres (HGM) was successfully prepared. Under solvent-free condition, the BSiO was synthesized by reacting triethoxyvinylsilane (VTEOS) and boric acid by one-pot method and characterized by GPC, FT-IR, NMR-29Si, NMR-11B and TGA analysis. The results indicated that the monomer feed ratio of the reactant made a great difference on the molecular structure and thermal stability of the BSiO and the BSiO-2 showed the best thermal stability when the feeding ratio of VTEOS and BA was 1.5. Moreover, the ceramic conversion analysis indicated that the BSiO-2 tended to form the inorganic SiBOC nanocomposite. Properties, such as the microstructure, density, linear shrinkage, compressive strength and thermal conductivity, burning behavior and flame retardancy of the BSiO-2/HGM composites after different heat treatment, were studied. The SEM results showed that the BSiO-2 could effectively wet the surface of HGM and the HGM was glued together firmly. With the increase in heat treatment temperature, the density and thermal conductivity of BSiO-2/HGM composites reached the minimum value at 600 °C, while the compressive strength reached the maximum value. The result of flame retardancy study showed that the composites possessed high LOI value (> 50%) and hardly any smoke could be observed during the burning process. This indicated that the BSiO-2/HGM composites possessed excellent flame-retardant property and fire safety. This paper will provide ideas for the design and preparation of heat-insulating materials with polyborosiloxane as heat-resistant binder.

The purpose of this study is to improve the interfacial adhesion property between epoxy resin (EP) and addition-curable liquid silicone rubber (AL-SR). A novel surface treatment agent, borosiloxane oligomers (BSiO), was synthesized, and the major chemical structure was evaluated by gel permeation chromatography, Fourier transform infrared spectra, nuclear magnetic resonance spectroscopy (29Si- and 11B-NMR), and thermogravimetric analysis. BSiO served as surface treatment agent for EP to improve interfacial adhesion characteristics of EP and AL-SR. The adhesion strength between EP and AL-SR was measured by pull-out test, and the results indicated that the adhesion strength increased from 0.02 MPa for EP/AL-SR to 0.18 MPa for BSiO-EP/AL-SR with the failure mode from EP posts dislodgement for EP/AL-SR to rubber breakage for BSiO-EP/AL-SR. Furthermore, adhesive mechanism was analyzed and concluded that the improvement of adhesion characteristics of EP/AL-SR through the oligomers surface treatment was a result of chemical and physical bonding. The BSiO acted as binder by reacting with amino groups on EP surface through the active epoxy groups and absorbing electron clouds of phenyl groups of AL-SR chains through the boron atoms. This feature makes BSiO a superior candidate to improve the adhesion and reduce the dislodgement or exfoliation of silicone rubber or other materials possessing electron-rich groups on the molecular chains from EP in the future.

In this study, under solvent-free condition, the vinyl-functionalized polyborosiloxane (BSiOVi) was synthesized by reacting triethoxyvinylsilane (VTEOS) and boric acid (BA) and the chemical structures were characterized by GPC and FT-IR. The results indicated that the BSiOVi containg Si-O-B bonds and vinyl groups was successfully synthesized. Moreover, the thermal stability and compressive strength after heat treatment were studied. TG-DTG result indicated that the BSiOVi with more Si-O-B high energy bonds possessed the better thermal stability than that of silicone rubber only possessing Si-O-Si bonds. The results of mechanical property of BSiOVi showed that the BSiOVi after heat treatment possessed the higher compressive strength than that of silicone rubber. This is because that the polymerization of Si-CH=CH2 groups could improve the crosslinking density, and the ceramic transformation of BSiOVi after heat treatment tend to the formation of dense SiBOC nanocomposites. We believed that the BSiOVi could be effectively served high temperature resistant matrix resin for ceramic matrix.

In this paper, (3-mercaptopropyl)trimethoxysilane (MPTS)- and copper-coated carbon fiber (M–Cu-CF) was obtained by electroless plating method. The M–Cu-CF was evaluated by FTIR, XRD, TGA, and SEM. It was found that the MPTS and Cu were coated on the fiber surface successfully. The M–Cu-CF was utilized as a conductive filler in silicone rubber (SR) for thermal and electrical conductivity applications and exhibited good dispersion and compatibility with the matrix. The effect of M–Cu-CF content on the thermal conductivity and volume resistivity of silicone rubber composites was investigated. The results showed that the thermal conductivity of the M–Cu-CF/SR composites reached 1.99 W (m K)−1 with only 4.0 wt% filler loading, approximately 2.10 times higher than that of raw-CF/SR composites at the same loading. And with the increase of M–Cu-CF loading, the least volume resistivity of M–Cu-CF/SR composites was 3.5 × 103 Ω cm.