Acta Phys. -Chim. Sin. ›› 2005, Vol. 21 ›› Issue (08): 873-877.doi: 10.3866/PKU.WHXB20050810

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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

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