Accelerating the crosslinking process of hyperbranched polycarbosilane by UV irradiation |
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| Affiliation: | 1. National Engineering Laboratory of Carbon Fiber Preparation Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, PR China;2. College of Material Science and Chemical Engineering,Ningbo University, Ningbo 315211, PR China;3. Engineering Laboratory of Specialty Fibers and Nuclear Energy Materials, Ningbo Institute of Materials Engineering and Technology, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, PR China;1. Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, India;2. FRP Institute, Chennai 600032, India;3. Materials Science Division, CSIR-National Aerospace Laboratories, Bangalore 560017, India;1. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China;2. Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China;3. Graduate University of Chinese Academy of Sciences, Beijing 100049, China;4. Shanghai Institute of Materials Genome, Shanghai 200050, China |
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| Abstract: | A liquid hyperbranched polycarbosilane (LHBPCS) with stoichiometric C/Si ratio but without unsaturated groups was synthesized. Different from traditional thermal crosslinking, ultraviolet (UV) irradiation crosslinking was taken. The molecular weight, the consumption of  SiH group and ceramic yield of LHBPCS showed an increase trend with increasing the UV irradiation time. After 30 min of UV irradiation, 71.8 wt% ceramic yield was obtained. In addition, extra divinyldimethylsilane was added into LHBPCS. Under UV irradiation, both the SiH group and vinyl group of divinyldimethylsilane were consumed. But the reaction extend of vinyl group was much faster than that of SiH group. Compared with pure LHBPCS, the mixture of LHBPCS and 5 wt% divinyldimethylsilane gave a higher ceramic yield of 79 wt% after 30 min of UV irradiation. By heating the crosslinked LHBPCS to 1000 °C, a near stoichiometric SiC ceramic was got. It exhibited excellent thermal stability at 1400 °C in air. |
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| Keywords: | Liquid hyperbranched polycarbosilane UV irradiation Divinyldimethylsilane Ceramic yield SiC ceramic |
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