SCI和EI收录∣中国化工学会会刊

Chin.J.Chem.Eng. ›› 2013, Vol. 21 ›› Issue (12): 1410-1418.DOI: 10.1016/S1004-9541(13)60543-1

• MATERIALS AND PRODUCT ENGINEERING • Previous Articles     Next Articles

In-situ Polymerization-modification Process and Foaming of Poly(ethylene terephthalate)

ZHONG Hua, XI Zhenhao, LIU Tao, ZHAO Ling   

  1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
  • Received:2012-08-01 Revised:2013-01-18 Online:2013-12-27 Published:2013-12-28
  • Contact: ZHAO Ling
  • Supported by:

    Supported by the National Natural Science Foundation of China (21176070), the National High Technology Research and Development Program of China (2012AA040211), the Joint Research Project of Yangtze River Delta (12195810900), the Specialized Research Fund for the Doctoral Program of Higher Education (20120074120019) and the Fundamental Research Funds for the Central Universities.

In-situ Polymerization-modification Process and Foaming of Poly(ethylene terephthalate)

仲华, 奚桢浩, 刘涛, 赵玲   

  1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
  • 通讯作者: ZHAO Ling
  • 基金资助:

    Supported by the National Natural Science Foundation of China (21176070), the National High Technology Research and Development Program of China (2012AA040211), the Joint Research Project of Yangtze River Delta (12195810900), the Specialized Research Fund for the Doctoral Program of Higher Education (20120074120019) and the Fundamental Research Funds for the Central Universities.

Abstract: Most of traditional linear poly(ethylene terephthalate) (PET) resins of relatively low molecular mass and narrow molecular mass distribution have low melt strength at foaming temperatures, which are not enough to support and keep cells. An in-situ polymerization-modification process with esterification and polycondensation stages was performed in a 2 L batch stirred reactor using pyromellitic dianhydride (PMDA) or pentaerythritol (PENTA) as modifying monomers to obtain PETs with high melt strength. The influence of amounts of modifying monomers on the properties of modified PET was investigated. It was found that the selected modifying monomers could effectively introduce branched structures into the modified PETs and improve their melt strength. With increasing the amount of the modifying monomer, the melt strength of the modified PET increased. But when the amount of PENTA reached 0.35% or PMDA reached 0.9%, crosslinking phenomenon was observed in the modified PET. Supercritical carbon dioxide (ScCO2) was employed as physical foaming agent to evaluate the foaming ability of modified PETs. The modified PETs had good foaming properties at 14 MPa of CO2 pressure with foaming temperature ranging from 265 ℃ to 280 ℃. SEM micrographs demonstrated that both modified PET foams had homogeneous cellular structures, with cell diameter ranging from 35 μm to 49 μm for PENTA modified PETs and 38 μm to 57 μm for PMDA modified ones. Correspondingly, the cell density had a range of 3.5×107 cells·cm-3 to 7×106 cells·cm-3 for the former and 2.8×107 cells·cm-3 to 5.8×106 cells·cm-3 for the latter.

Key words: poly(ethylene terephthalate), in-situ polymerization-modification, supercritical carbon dioxide, molten-state foaming

摘要: Most of traditional linear poly(ethylene terephthalate) (PET) resins of relatively low molecular mass and narrow molecular mass distribution have low melt strength at foaming temperatures, which are not enough to support and keep cells. An in-situ polymerization-modification process with esterification and polycondensation stages was performed in a 2 L batch stirred reactor using pyromellitic dianhydride (PMDA) or pentaerythritol (PENTA) as modifying monomers to obtain PETs with high melt strength. The influence of amounts of modifying monomers on the properties of modified PET was investigated. It was found that the selected modifying monomers could effectively introduce branched structures into the modified PETs and improve their melt strength. With increasing the amount of the modifying monomer, the melt strength of the modified PET increased. But when the amount of PENTA reached 0.35% or PMDA reached 0.9%, crosslinking phenomenon was observed in the modified PET. Supercritical carbon dioxide (ScCO2) was employed as physical foaming agent to evaluate the foaming ability of modified PETs. The modified PETs had good foaming properties at 14 MPa of CO2 pressure with foaming temperature ranging from 265 ℃ to 280 ℃. SEM micrographs demonstrated that both modified PET foams had homogeneous cellular structures, with cell diameter ranging from 35 μm to 49 μm for PENTA modified PETs and 38 μm to 57 μm for PMDA modified ones. Correspondingly, the cell density had a range of 3.5×107 cells·cm-3 to 7×106 cells·cm-3 for the former and 2.8×107 cells·cm-3 to 5.8×106 cells·cm-3 for the latter.

关键词: poly(ethylene terephthalate), in-situ polymerization-modification, supercritical carbon dioxide, molten-state foaming