Papers by Keyword: Siloxane

Abstract: As an emerging subgroup of 2D materials, monoelemental layered materials and their hydrogenated analogues (Xanes) such as silicane and germanane, have attracted considerable interest due to their remarkable combination of physical, chemical, and (opto)electronic properties. On the other hand, changing the size and structure of two-dimensional materials result to nanostructures with new and unique properties. In this direction, here we present the transformation of germanane and siloxane sheets into nanoscrolls and nanodots respectively, towards the generation of novel 0D and 1D nanostructures.

Abstract: Epoxy-silicate modifiers were obtained by a sol-gel procedure from the alkali-silicate solutions and their effect on physico-mechanical properties of the coatings based on the binary epoxide binder were investigated. It is shown that pretreatment of the metal surface effects strength of adhesive bonding with the epoxide coating.

Abstract: Materials used on exterior spacecraft surfaces are subjected to many environmental threats which can cause degradation, atomic oxygen is one of the most threats. We prepared organic silicon atomic-oxygen-protection film using method of polymerization. This paper presented the effects on the film structure and its durability of the preparation processing, and analyzed the polymerization theory, the film structure and composition of the film. At last, we tested the film in our ground based atomic oxygen simulator, and indicated that the film worked well.

Abstract: In order to modify the properties of the epoxy composites, an alkali catalyzed biphenyldiol formaldehyde resin (BPFR) was synthesized and used to cure epoxy resin (ER). γ-Glycidoxypropyl trimethoxysilane (KH-560) was used as a reinforcer of the composites. Laminates of the BPFR/ER fiberglass reinforced composites with different (KH-560) contents were prepared. The influence of the KH-560 content on the glass transition temperature (T_g) and thermal degradation properties of the composites was researched by dynamic mechanical analyzer (DMA) and thermogravimetric analysis (TG). The mechanical, electrical properties of the composites were determined. The results showed that the interfacial bonding strength between resin matrix and fiberglass can be efficiently improved with the presence of KH-560. When the ratio of BPFR and ER is 3 : 7, the content of KH-560 is 5 ~7 wt%, the impact resistance of the fiberglass reinforced composites is 61.35~78.59 kJ/m², the tensile resistance is 150.37~162.54 MPa, which are all 30 % higher than that of no added; The dielectric constant ε and dielectric loss tanδ of the composites is between 0.50~0.68 and between 0.008~0.01, respectively.

Abstract: This work reports melamine resin was modified with siloxane, Polyvinyl alcohol (PVA) and polyethylene glycol (PEG) to improve its structure and properties, and accomplished a wide research and study on the effect of different reaction conditions, including temperature, PH and solid contents. Using infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and DSC to analyzed the samples and study their composition and performance. The results showed that siloxane, Polyvinyl alcohol and polyethylene glycol (PEG) modifier can make the performance of the melamine better than unmodified ones.

Abstract: The UV curing kinetics of coating containing siloxane modified polyurethane-acrylate were studied using photo-DSC (DPC). The effects of some factors such as incident light intensity, initiator concentration, reaction temperature on the curing kinetics have been analysized from DPC data. The curing kinetic parameters (k_p and k_t) for prepolymers have also been determinedv by combining steady state and non-steady state kinetics.

Abstract: The epoxy resin (ER) and 2,3-epoxypropoxypropytrimethoxysilane (KH-560) were used to prepare alkyd resin (AR) insulating coating. The modified waterborne alkyd resin insulating coating was prepared. The dynamic mechanical properties, thermal properties and electrical properties of the composites were characterized by DMA, TG, et al. The results show that the tertiary amine has a good catalyzing effect for this reaction. When the mass ratio of AR with ER is 1 : 1, the glass transform temperature T_g of material is 64.6 °C. When the content of KH-560 is 5% mass fraction of the alkyd resin, the T_g of composites increase 5.6 °C, the initial degradation temperature increased by 63.78 °C; The r_s and r_v of composites are between 10⁹ ~ 10¹² MΩ; the ε and tanδ is between 0.6553 ~ 0.9975 and 0.0025-0.0036, respectively. The pencil hard degree and the impact strength of coating film are all over 5H and 40N, respectively.

Abstract: In order increasing properties of polyurethane acrylate coating, the epoxy resin/ polyurethane acrylate coating was prepared by UV and thermal dual curing with diphenyliodonium salt. The curing reaction and kinetics was investigated by UV-radiation and DSC, and the influence of the siloxane of methylacryloylpropyl-trimethoxysilane (MAPTMS) content on the properties of coating was determined by DMA and other physical methods. The results showed the hardness and glass transition temperature T_g of the coating film increased with the increasing MAPTMS content and the coating has good adhesion. When the content of MAPTMS reach 12 wt%, the T_g is the highest, which is 8.2°C higher than the before; When the triethylene glycol divinyl ether (DVE-3) can change the reaction from UV free radical/cationic reaction into thermal radical/cationic reaction, and can be described by autocatalytic Šesták-Berggre model (S-B) and the average activation energy E_a is 70.55 kJ/mol.

Abstract: Impact of the addition of silane and siloxane based hydrophobic powders on cement based mortar was studied. Effect of powder addition on mechanical properties and water absorption of cement based mortar is described. Impact of accelerated ageing, including UV radiation, and rain-sun cycles on hydrophobic performance was assessed, demonstrating excellent durability of silane-based hydrophobic performance.

Abstract: This paper introduces one siloxane rejuvenation fluid used to rejuvenate aged XLPE cables and also studies the effects and the mechanism of the rejuvenation. Accelerated aging experiment was performed to obtain water tree aged samples. Inject the rejuvenation siloxane fluid into the aged cable samples with a pressure injection system. By comparing the dielectric loss factor and the breakdown voltage level of the samples before and after rejuvenation, inferred that the insulation level of the cable samples after rejuvenation is close to or higher than that of new cables. Additionally, through microscope, organic compounds created by chemical reaction were observed to fill the micro voids and eliminate the moisture in the XLPE layer of the samples. Finally, the electric field was simulated by Finite Element Method (FEM). Based on the results, it's further confirmed that the siloxane rejuvenation fluid can significantly enhance the aged cable insulation.