JOURNAL OF APPLIED POLYMER SCIENCE
·
2022
·Vol. 139
·期 45
·e53021
·
IF 3.057
Mingzhe Li,Bin Cao,Ruiqi Shang,Hongwei Mei,Liming Wang
Silicone rubber is used as an antipollution flashover material in outdoor insulation, which is susceptible to aging and has a shorter service life than other candidates. Microcracks are a common aging phenomenon that are difficult to be detected and repaired. The microcapsule self-healing technology can be used to repair microcracks and extend the service life of silicone rubber. This study considers hydrogen silicone oil as a representative of the polydimethylsiloxane healing agent system. Poly(urea–formaldehyde) microcapsules containing the hydrogen silicone oil are synthesized by in situ polymerization. The effects of the emulsifier concentration, initial pH value, initial ratio of the core–shell material, and sodium chloride (NaCl) concentration on the synthesis are investigated. Accordingly, the properties of the microcapsules before and after long-term storage are analyzed. The results demonstrate that microcapsules synthesized using poly(ethylene-alt-maleic anhydride) (EMA)+ polyvinyl alcohol (PVA) as the emulsifier have satisfactory morphology and performance, where the best synthesis conditions are 0.13 wt% EMA, 0.05 wt% PVA, initial ratio of the core–shell material of 1.5:1–2.0:1, initial pH value of 3.5–4.0, and 2 wt% NaCl. In long-term storage, the core material is well protected by the shell material. The synthesized microcapsule can serve as a material in the self-healing system of silicone rubber.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2014
·Vol. 72
·期 2
·385-393
·
IF 1.547
Guo Ping,Zhai Shang-Ru,Xiao Zuo-Yi,Zhang Feng,An Qing-Da,Song Xiao-Wei
Fabrication of s uerhydrophobic materials towards oil/water separation and oil absorption has been receiving great attention nowadays, due to the significant increase of industrial oily wastewater and frequent accident of oil spill. In most previous studies, the usage of expensive precursors restricted the wide applications of prepared superhydrophobic materials. In this work, superhydrophobic filter paper, fabric and polyester sponges were fabricated by dip-coating the mixed solution of polystyrene and xerogels, which were prepared with tetraethoxysilane and polymethylhydrosiloxane, based on previous work. The as-fabricated fabric can effectively separate oil and water mixtures and possesses excellent reusability; more significantly, the materials maintained its good hydrophobic and excellent oil/water separation capacity even after ten cycles. Interestingly enough, the stability was provided, as a result, the fabric still exhibited superhydrophobic after 100 abrasion times and showed high repellency towards many liquids with different pH values. Additionally, the coated polyester sponges can quickly absorb various oil and organic liquid, which will offer a practical application for the treatment of seawater or oily wastewater. By contrast, this experiment process is simple and avoided using costly fluoro-chemicals or complicated fabrication process.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2017
·
IF 1.174
Yuedong Zhou,Fengfu Li,Junwei Liu,Zhi Yun,Xia Gui
The liquid phase ring-opening of octamethylcy-clotetrasiloxane (D 4 ) was investigated over Pt-H 2 SO 4 /Zr-montmorillonite catalyst. Montmorillonite (Mt), Zr-Mt, H 2 SO 4 /Mt, H 2 SO 4 /Zr-Mt and Pt-H 2 SO 4 /Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, nitrogen adsorption–desorption, NH 3 -TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst, Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D 4 , polymethylhydrosiloxane (D 4 H ) and hexamethyldisiloxane (MM) to low-hydro silicone oil. Relative to Zr-Mt, the acidity of H 2 SO 4 /Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D 4 conversion and yield of low-hydro silicone oil. To enhance the stability of H 2 SO 4 /Zr-Mt catalyst, a small amount of metals (Pt) was doped. The nitrogen adsorption–desorption results indicated that pore textural parameters of the Pt-H 2 SO 4 /Zr-Mt had not changed with larger specific surface area. Compared with H 2 SO 4 /Zr-Mt, the total acidity of Pt-H 2 SO 4 -Zr/Mt catalyst retained, but the content of the Brønsted acid increased and the content of the Lewis acid decreased. The Pt-H 2 SO 4 -Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization, the yield of low-hydro silicone oil decreased from 93% to 42% over H 2 SO 4 /Zr-Mt catalyst, while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H 2 SO 4 /Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H 2 SO 4 /Zr-Mt catalyst was detected. Furthermore, Pt-H 2 SO 4 /Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D 4 , D 4 H and MM to low-hydro silicone oil.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2024
·
IF 4.1
Shengqiang Wang,Zhenbo Peng,Yanhua Huang,Mingquan Zhu,Yayun Liu,Yong Zhang
Phenyl-containing polysiloxanes have better thermal stability, low-temperature flexibility, and room-temperature damping performance than polydimethylsiloxanes. Poly [dimethylsiloxane- co -methyl (phenyl)siloxane] and poly (dimethylsiloxane- co -diphenylsiloxane) were synthesized through a bulk copolymerization of octamethylcyclotetrasiloxane and methylphenylcyclosiloxane mixture or octaphenylcyclotetrasiloxane, and the structure and properties of the copolysiloxanes were comparatively studied. The phenyl content in poly [dimethylsiloxane- co -methyl (phenyl)siloxane] can be as high as 50 mol%. With the increment of the phenyl content, the thermal stability of the copolysiloxanes is dramatically improved as evaluated by thermal gravimetric analysis. At a given phenyl content, poly [dimethylsiloxane- co -methyl (phenyl)siloxane] has higher thermal stability than poly (dimethylsiloxane- co -diphenylsiloxane). The former is more difficult to crystalline at low temperatures and has lower room temperature viscosity than the latter as confirmed by differential scanning calorimetry and rotational rheometer. The copolysiloxanes is mixed with hydrogen-containing polysiloxane and silica, and vulcanized at elevated temperature to get copolysiloxane composites with good damping properties, oil resistance, and low-temperature resistance. This study not only enriches the fundamental academic research on functional polysiloxanes, but also provides useful technical references for practical applications of phenyl silicone rubber.
研究领域:
高分子科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）