物理化学学报 >> 2005, Vol. 21 >> Issue (08): 873-877.doi: 10.3866/PKU.WHXB20050810

研究论文 上一篇    下一篇

OH对聚二甲基硅氧烷乳液辐射效应的影响

彭静; 朱轶才; 翟茂林; 乔金梁; 魏根拴   

  1. 北京大学化学与分子工程学院, 应用化学研究所,北京 100871; 中国石化股份有限公司, 北京化工研究院,北京 100013
  • 收稿日期:2004-12-03 修回日期:2005-02-23 发布日期:2005-08-15
  • 通讯作者: 魏根拴 E-mail:gswei@pku.edu.cn

Influence of OH Radicals on the Radiation Effect of Polydimethylsiloxane Latex

PENG Jing; ZHU Yi-cai; ZHAI Mao-lin; QIAO JIN-liang; WEIG en-shuan   

  1. Institute of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871; SINOPEC, Beijing Research Institute of Chemical Industry, Beijing 100013
  • Received:2004-12-03 Revised:2005-02-23 Published:2005-08-15
  • Contact: WEI Gen-shuan E-mail:gswei@pku.edu.cn

摘要: 通过凝胶和溶胶分析与分子量测定的方法,研究了不同体系下,OH对PDMS乳液γ辐射效应的影响. 结果表明,OH不仅可引发聚二甲基硅氧烷的分子间交联,也能促进其降解. 对于纯PDMS乳液,在所研究的剂量范围内,OH对其辐射交联行为影响较小. 但若体系中加入H2O2、KIO4 和 N2O这些提高OH生成产额的添加剂时,OH对PDMS的促降解作用会随着吸收剂量增加而表现更明显,导致凝胶含量与纯乳液辐照情况相比下降较多. 即使加入交联剂-三羟甲基丙烷三甲基丙烯酸酯(TMPTMA),在过量的OH存在下,当吸收剂量大于40 kGy以上时,TMPTMA不仅没有提高交联度,反而会与OH协同,使PDMS的凝胶含量下降更显著,同时产生更多的小分子聚合物,并使PDMS的平均分子量分布变窄. 这可能是由于交联剂首先与OH作用,形成的产物会加快PDMS的降解.

关键词: OH自由基, 聚二甲基硅氧烷(PDMS)乳液, 辐射交联, 辐射降解, 交联剂

Abstract: By measuring the gel fraction and GPC spectra of irradiated polydimethylsiloxane (PDMS) samples, the radiation effect of PDMS in latex form was investigated. Results showed that the OH radical could not only initiate the radiation crosslinking of PDMS latex, but also accelerate the scission of PDMS molecular chain. For the PDMS latex without additives, the effect of OH on the crosslinking behavior is not obvious. However, the addition of H2O2 or KIO4 or N2O which could increase the concentration of OH would enhance the radiation degradation of PDMS. Moreover, with the increase of absorbed dose, the degradation is more predominant to lead to the drop of gel fraction. Particularly, in the presence of crosslinking sensitizer-trimethylol propane trimethacrylate (TMPTMA), when the dose was above 40 kGy, the excess OH radical accelerated remarkably the degradation of PDMS chain which resulted in the narrow polydispersity of molecular weight and increase in content of PDMS with low molecular weight, and decrease of gel fraction, comparing with those of irradiated PDMS latex without TMPTMA. This suggested that the synergetic interaction perhaps existed between TMPTMA and excess OH radical. This might be attributed to that the OH radicals react with TMPTMA firstly, the resulted product might accelerate the degradation of PDMS.

Key words: Hydroxyl radical, Polydimethylsiloxane latex, Radiation crosslinking, Radiation degradation, Crosslinking sensitizer