Synthesis and characteristic applications of silicon resins for the modifying agent in heat conduction

Heat energy retention and dissipation have become key points of global smart textiles in recent years. This study describes the designing of silicon resin by using a sol–gel process, which acts as the modifying agent for siloxane substrate. The modifying agent was effectively blocked by silicon resin mixed with the ethylene or aluminum bond group, to control the molecular weight. Advanced polymer chromatography confirmed that the number average molecular weight (Mn) of silicon resin is 41,301 g mol−1, the weight average molecular weight (Mw) is 47,982 g mol−1, and the molecular weight distribution is 1.1617, which is relatively narrow. When the addition of vinyl groups is 5%, the silicone resin Mn decreases to 18,906 g mol−1 and Mw decreases to 28,641 g mol−1. When the addition of aluminum bond groups is 5%, the silicone resin Mn decreases to 17,497 g mol−1 and Mw decreases to 27,114 g mol−1. The result of thermogravimetric analysis shows that the pyrolysis temperature rises from 265.43°C to 266.17°C after the ethylene is added to the silicon resin, and the index of heat tolerance increases from 179.14°C to 191.38°C. After the addition of aluminum bond groups, the pyrolysis temperature rises from 265.43°C to 309.37°C, and the index of heat tolerance increases from 179.14°C to 193.09°C, meaning the silicone resin has higher thermal stability.

Research on a Superhydrophobic Coating of Highly Transparent Wear-Resistant Inorganic/Organic Silicon Composite Resin

Transparent superhydrophobic materials can be used in car glass, curtain walls, mobile phone screens, and other items. However, the hydrophobicity, transparency, and abrasion resistance of the transparent superhydrophobic coating are mutually restricted, and it is difficult to prepare transparent superhydrophobic coating with good performance. In this article, taking the mobile phone screen transparent coating as the research object, the inorganic silicon resin crystal coating as the main material, and the organic silicon resin as the binder and the hardness regulator, with the addition of the hydrophobically modifying nano silica particles, a high-transparent, wear-resistant, and superhydrophobic coating is researched. Experiments showed that when the composition mass ratio of SJ-32F resin to 9825 resin is 9:1 and the mass ratio of modified nano silica is 1.7%, the coating has a hardness of 3H–4H suitable for mobile phone screens, the contact angle of the coating can reach more than 150°, the rolling angle is less than 10°, and the light transmittance of the coating remains high at 91–95%. The cross-hatch adhesion strength of the coating reaches 5B, and the average adhesion strength measured by the adhesion pull tester is about 5.4 MPa. When the rubbing times reached 100, the light transmittance of the coating remained above 80%, and the contact angle remained basically unchanged.

Preparation and high-temperature microwave absorbing properties of 6H-SiC/MWCNT/silicon resin composites

Microwave absorbing materials (MAMs) have been widely used in the military and industrial fields. Recently, considerable efforts have been made to develop hybrid composition, multilayer structure absorbers to meet requirements such as strong absorption characteristics, wide absorption frequencies, light weights and oxidation resistance. In this study, a series of flexible composites consisting of 6H-SiC powder (40–50 wt.%), silicon resin (60–50 wt.%) and multiwalled carbon nanotubes (MWCNTs, additional 0.05–0.2 wt.%) were prepared and applied to produce high-temperature microwave absorbers via the spray coating method. The prepared composites were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the microwave absorbing properties of the composites were measured in the 4–18 GHz frequency range by the free space measurement method. The TGA thermograms indicated that the thermal stabilities of the prepared composites increased with increases in the 6H-SiC content but were less affected by increases in the MWCNT content. The actual measurement results showed that the optimum composition was 50 wt.% 6H-SiC, 50 wt.% silicon resin and an additional 0.2 wt.% MWCNT. The minimum reflection loss (RL) value of –58.9 dB was observed at 9.7 GHz with a thickness of 1.6 mm, and the effective absorption bandwidth (RL < –10 dB, for 90% microwave absorption) reached 2.3 GHz. At a high temperature of 450 °C, the absorption peak was located at 10.0 GHz with a reflection loss of – 13.7 dB, and the effective frequency bandwidth still reached 1.6 GHz.

Influence of Water-Repellent Treatment with Silicon Resin on Properties of Concrete

Although studies on water-repellent properties of silicon resin (SR) on cement-based materials have received tremendous attention around the world in recent years, they mainly focus on individual properties of water-repellent concrete treated with SR such as strength and water permeability resistance. However, to date, a systematic and comprehensive investigation is missing. The current study therefore investigates the influence of SR on the durability properties of cementitious materials by adding SR emulsion into integral concrete mixture and coating concrete surface with SR. The microscopic and mechanical properties and the durability performance were tested on the integral SR water‐repellent concrete (C-ISR) and SR surface water-repellent concrete (C-SSR). The obtained results indicate that SR application has no impact on hydration reaction and corresponding composition of cement-based materials, while SR addition leads to a reduction in strength and early shrinkage of cement mortar because the added SR delays the hydration reaction. Water-repellent treatment via SR can significantly reduce the water permeability of concrete, which is more apparent for surface water-repellent treatment (SSR). Furthermore, the durability properties were investigated, and the results indicate that integral SR water-repellent treatment (ISR) possesses better properties than SSR, which suggests water-repellent treatment via surface coating as an effective means to improve concrete durability.

Millimeter Wave Absorbing Electromagnetic Properties of ZnO Whisker/Silicon Resin Coating Material

Wave-absorbing coating samples are fabricated with ZnO whisker, the absorbent and silicon resin coating as the binder.The influences of the content of ZnO whisker in the absorbing coating and the thickness of the coating on millimeter wave absorbing property are analyzed.With the increasing of the thickness, the absorbing performance of the sample is enhanced significantly , the results show that with a ZnO whisker mass of 50% and coating thickness of 2 mm, excellent absorption (R<-10dB) is observed in the wave band from 66 to 78 GHz (with a bandwidth of 12GHz) . When the ZnO whisker mass is reduced to 30% with the same thickness of 2mm, two absorption bands are obtained from 55 to 67 GHz (with a bandwidth 12GHz) and 100 to 110 GHz (with a bandwidth 10GHz). Maxwell equations and boundary conditions are used to analyze the absorbing mechanism of the coating.