Advanced Search

Citation: CHIANG YIN-YEN, LIN I, TANG LAN-SEN, GAI TAI-HO. STUDIES ON POLYORGANOSILOXANES——Ⅶ. ROOM TEMPERATURE VULCANIZATION OF SILICONE RUBBER AND THE THERMAL DEGRADATION OF THE VULCANIZATE[J]. Acta Polymerica Sinica, ;1964, 6(5): 342-349. shu

STUDIES ON POLYORGANOSILOXANES——Ⅶ. ROOM TEMPERATURE VULCANIZATION OF SILICONE RUBBER AND THE THERMAL DEGRADATION OF THE VULCANIZATE

  • Polydimethylsiloxane containing hydroxyl end groups can be vulcanized at room tern-perature by using ethyl orthosilicate as crosslinking agent and dibutyltin dilaurate as catalyst．The generally accepted mechanism of the vulcanization is given in Eq．(1)．However，in actual practice，the relative quantity of ethyl orthosilicate to hydroxysiloxane used is always many times larger than the stoichiometric ratio．The excess of ethyl orthosilicate should render the chain terminal unreactive toward the crosslinking reaction as shown in Eq．(2)，thus questioning the validity of the proposed mechanism．In our experiments carried out in moist air(Table 1)，the rate of vulcanization in-creased with the increase of the amount of ethyl orthosilicate，and the reverse was true when vulcanization took place in dry sealed tubes(Table 2)．This indicates that under dry condition，the excess ethyl orthosilicate retardS the crosslinking action as expected，while，in the presence of water，ethyl orthosilicate is hydrolysed to form polyethylsilicate having increased opportunity for the crosslinking．Consequently，the vulcanization should proceed according to Eqs．(3) and (4) where polyethylsilicate，instead of ethyl ortho-silicate，is the real crosslinking agent，as is generally proposed．When heated to 250℃ in air，the tensile strength of the room temperature vul-canized silicone rubber dropped to almost zero within an hour，and then gradually re-covered on prolonged heating (Fig．1b)．The recovery was not observed in N2 atmosphere (Fig．1c)．Similar results were obtained when polydimethylsiloxane alone was heated with dibutyltin dilaurate．In air，the viscosity at first dropped and then rose again (Fig．3a)，whereas，in N2，there was no such increase in viscosity after the initial drop (Fig．3b)．A small amount (0.1％) of dibutyltin dilaurate caused a significant decrease of molecular weight of polydimethylsiloxane on heating，while further increase of the catalyst produced only a small effect (Fig．4)．However，when water was added，great decrease in molecular weight was noted (Fig．5)．The effect of increasing amount of laurie acid on the molecular weight is shown in Fig．6．All these seem to indicate that the initial drop of the tensile strength of the room temperature vulcanized silicone rubber is due t0 the breaking of the Si—O—Si bond of polydimethylsiloxane by a trace of water in the system under the catalytic action of laurie acid or of dibutyhin dilaurate (Eq．5)．The recovery of the tensile strength when heated jn air for a long time iS caused bv the oxidation of the methyl group of the dimethylsiloxane in the presence of dibutyltin dilaurate to form new crosslinking units．
  • 加载中
  • 加载中
    1. [1]

      Jiashuang Lu ,  Xiaoyang Xu ,  Youqing He ,  Mingyue Wu ,  Ruixin Shi ,  Wenfang Yu ,  Hang Lu ,  Ji Liu ,  Qingzeng Zhu . 生命健康中的有机硅高分子. University Chemistry, 2025, 40(8): 169-180. doi: 10.12461/PKU.DXHX202409143

    2. [2]

      Yerong Chen ,  Bingbin Yang ,  Xinglei He ,  Yuqi Lin ,  Keyin Ye . Enzyme-Directed Evolution Enables Bioconversion of Organosilicon Compounds. University Chemistry, 2025, 40(10): 121-129. doi: 10.12461/PKU.DXHX202411054

    3. [3]

      Ruige ZHANG , Zhe ZHANG , He ZHENG , Zhan SHI . Recent advances of metal-organic frameworks for alkaline electrocatalytic oxygen evolution reaction. Chinese Journal of Inorganic Chemistry, 2025, 41(10): 2011-2028. doi: 10.11862/CJIC.20250185

    4. [4]

      Hongxia Yan ,  Rui Wu ,  Weixu Feng ,  Yan Zhao ,  Yi Yan . Innovation Inspired by Classical Chemistry: Luminescent Hyperbranched Polysiloxanes. University Chemistry, 2025, 40(4): 154-159. doi: 10.12461/PKU.DXHX202409010

    5. [5]

      Xiaohang JIN , Qi LIU , Jianping LANG . Room‑temperature solid‑state synthesis, structure, and third‑order nonlinear optical properties of phosphine‑ligand‑protected silver thiolate clusters. Chinese Journal of Inorganic Chemistry, 2025, 41(8): 1505-1512. doi: 10.11862/CJIC.20250125

    6. [6]

      Hao Chen , Dongyue Yang , Gang Huang , Xinbo Zhang . Progress on Liquid Organic Electrolytes of Li-O2 Batteries. Acta Physico-Chimica Sinica, 2024, 40(7): 2305059-0. doi: 10.3866/PKU.WHXB202305059

    7. [7]

      Guanghui Wang ,  Chen Qian ,  Zhiyong Ma . Preparation and Characterization of 7H-Benzo[C]Carbazole Based Ultra-Long Organic Room Temperature Phosphorescence Material. University Chemistry, 2025, 40(11): 289-299. doi: 10.12461/PKU.DXHX202412062

    8. [8]

      Yuanqing Wang , Yusong Pan , Hongwu Zhu , Yanlei Xiang , Rong Han , Run Huang , Chao Du , Chengling Pan . Enhanced Catalytic Activity of Bi2WO6 for Organic Pollutants Degradation under the Synergism between Advanced Oxidative Processes and Visible Light Irradiation. Acta Physico-Chimica Sinica, 2024, 40(4): 2304050-0. doi: 10.3866/PKU.WHXB202304050

    9. [9]

      Yachao HUANG , Chuanwang ZENG , Guiyong LIU , Jinming ZENG , Chao LIU , Xiaopeng QI . Oxygen vacancies and phosphorus doping enhanced metal-organic framework derived nitrogen-doped carbon-coated Co3O4 bifunctional electrocatalyst. Chinese Journal of Inorganic Chemistry, 2025, 41(11): 2251-2260. doi: 10.11862/CJIC.20250133

    10. [10]

      Tianyun Chen ,  Ruilin Xiao ,  Xinsheng Gu ,  Yunyi Shao ,  Qiujun Lu . Synthesis, Crystal Structure, and Mechanoluminescence Properties of Lanthanide-Based Organometallic Complexes. University Chemistry, 2024, 39(5): 363-370. doi: 10.3866/PKU.DXHX202312017

    11. [11]

      Aiai WANG , Lu ZHAO , Yunfeng BAI , Feng FENG . Research progress of bimetallic organic framework in tumor diagnosis and treatment. Chinese Journal of Inorganic Chemistry, 2024, 40(10): 1825-1839. doi: 10.11862/CJIC.20240225

    12. [12]

      Ran HUO , Zhaohui ZHANG , Xi SU , Long CHEN . Research progress on multivariate two dimensional conjugated metal organic frameworks. Chinese Journal of Inorganic Chemistry, 2024, 40(11): 2063-2074. doi: 10.11862/CJIC.20240195

    13. [13]

      Xiaofang DONG , Yue YANG , Shen WANG , Xiaofang HAO , Yuxia WANG , Peng CHENG . Research progress of conductive metal-organic frameworks. Chinese Journal of Inorganic Chemistry, 2025, 41(1): 14-34. doi: 10.11862/CJIC.20240388

    14. [14]

      Jiajie Li ,  Xiaocong Ma ,  Jufang Zheng ,  Qiang Wan ,  Xiaoshun Zhou ,  Yahao Wang . Recent Advances in In-Situ Raman Spectroscopy for Investigating Electrocatalytic Organic Reaction Mechanisms. University Chemistry, 2025, 40(4): 261-276. doi: 10.12461/PKU.DXHX202406117

    15. [15]

      Lewang Yuan , Yaoyao Peng , Zong-Jie Guan , Yu Fang . Insights into the development of 2D covalent organic frameworks as photocatalysts in organic synthesis. Acta Physico-Chimica Sinica, 2025, 41(8): 100086-0. doi: 10.1016/j.actphy.2025.100086

    16. [16]

      Xinxin YU , Yongxing LIU , Xiaohong YI , Miao CHANG , Fei WANG , Peng WANG , Chongchen WANG . Photocatalytic peroxydisulfate activation for degrading organic pollutants over the zero-valent iron recovered from subway tunnels. Chinese Journal of Inorganic Chemistry, 2025, 41(5): 864-876. doi: 10.11862/CJIC.20240438

    17. [17]

      Lu XU , Chengyu ZHANG , Wenjuan JI , Haiying YANG , Yunlong FU . Zinc metal-organic framework with high-density free carboxyl oxygen functionalized pore walls for targeted electrochemical sensing of paracetamol. Chinese Journal of Inorganic Chemistry, 2024, 40(5): 907-918. doi: 10.11862/CJIC.20230431

    18. [18]

      Lin′an CAO , Dengyue MA , Gang XU . Research advances in electrically conductive metal-organic frameworks-based electrochemical sensors. Chinese Journal of Inorganic Chemistry, 2025, 41(10): 1953-1972. doi: 10.11862/CJIC.20250160

    19. [19]

      Xiangyu CHEN , Zhenzhen MIAO , Ligang XU , Guangbao WU , Zhuang LIU , Wenzhen LÜ , Runfeng CHEN . Research progress on low-dimensional organic-inorganic hybrid metal halide optoelectronic materials. Chinese Journal of Inorganic Chemistry, 2025, 41(11): 2201-2217. doi: 10.11862/CJIC.20250056

    20. [20]

      Wenli FENG , Lu ZHAO , Yunfeng BAI , Feng FENG . Research progress on ultralong room temperature phosphorescent carbon dots. Chinese Journal of Inorganic Chemistry, 2025, 41(5): 833-846. doi: 10.11862/CJIC.20240308

Get Citation
PDF
XML
Metrics
  • PDF Downloads(0)
  • Abstract views(213)
  • HTML views(2)

通讯作者: 陈斌, bchen63@163.com
  • 1. 

    沈阳化工大学材料科学与工程学院 沈阳 110142

  1. 本站搜索
  2. 百度学术搜索
  3. 万方数据库搜索
  4. CNKI搜索
Address：Zhongguancun North First Street 2,100190 Beijing, PR China Tel: +86-010-82449177-888
Powered By info@rhhz.net

/

DownLoad:  Full-Size Img  PowerPoint
Return