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Open AccessArticle

Supercritical CO2 Foaming of Radiation Cross-Linked Isotactic Polypropylene in the Presence of TAIC

1
Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Jialuo Road 2019, Jiading, Shanghai 201800, China
2
University of China Academy of Sciences, Beijing 100049, China
3
School of Physical Science and Technology, ShanghaiTech University, Haike Road 100, Pudong, Shanghai 201210, China
*
Author to whom correspondence should be addressed.
Academic Editor: Yu Yang
Molecules 2016, 21(12), 1660; https://doi.org/10.3390/molecules21121660
Received: 17 October 2016 / Revised: 27 November 2016 / Accepted: 29 November 2016 / Published: 7 December 2016
(This article belongs to the Special Issue Sub- and Supercritical Fluids and Green Chemistry)
Since the maximum foaming temperature window is only about 4 °C for supercritical CO2 (scCO2) foaming of pristine polypropylene, it is important to raise the melt strength of polypropylene in order to more easily achieve scCO2 foaming. In this work, radiation cross-linked isotactic polypropylene, assisted by the addition of a polyfunctional monomer (triallylisocyanurate, TAIC), was employed in the scCO2 foaming process in order to understand the benefits of radiation cross-linking. Due to significantly enhanced melt strength and the decreased degree of crystallinity caused by cross-linking, the scCO2 foaming behavior of polypropylene was dramatically changed. The cell size distribution, cell diameter, cell density, volume expansion ratio, and foaming rate of radiation-cross-linked polypropylene under different foaming conditions were analyzed and compared. It was found that radiation cross-linking favors the foamability and formation of well-defined cell structures. The optimal absorbed dose with the addition of 2 wt % TAIC was 30 kGy. Additionally, the foaming temperature window was expanded to about 8 °C, making the handling of scCO2 foaming of isotactic polypropylene much easier. View Full-Text
Keywords: polypropylene; TAIC; radiation cross-linking; supercritical carbon dioxide; foaming polypropylene; TAIC; radiation cross-linking; supercritical carbon dioxide; foaming
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MDPI and ACS Style

Yang, C.-G.; Wang, M.-H.; Zhang, M.-X.; Li, X.-H.; Wang, H.-L.; Xing, Z.; Ye, L.-F.; Wu, G.-Z. Supercritical CO2 Foaming of Radiation Cross-Linked Isotactic Polypropylene in the Presence of TAIC. Molecules 2016, 21, 1660.

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