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Removal of ungrafted monomer from polypropylene‐graft‐maleic anhydride via supercritical carbon dioxide extraction
Author(s) -
Clark Kelly,
Lee Sunggyu
Publication year - 2004
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.20161
Subject(s) - maleic anhydride , supercritical carbon dioxide , thermogravimetric analysis , polypropylene , extraction (chemistry) , materials science , monomer , copolymer , methanol , supercritical fluid extraction , polymer chemistry , acetone , supercritical fluid , xylene , organic chemistry , chemical engineering , toluene , chemistry , polymer , engineering
The removal of spent initiator, excess initiator and unbound monomer from newly synthesized polypropylene‐graft‐maleic anhydride (PP‐g‐MA) has typically been carried out using Soxhlet extraction. Standard solvents used in the Soxhlet process are xylene, toluene, acetone or methanol. These chemicals are not only hazardous to some degree, but also lead to undesirable maleic anhydride (MA) ring opening. This paper establishes that supercritical carbon dioxide (scCO 2 ) extraction of residuals prevents anhydride ring opening and eliminates the need for post‐extraction vacuum‐drying of the copolymer product. An added benefit of this innovative process is that environmentally friendly carbon dioxide (CO 2 ) is used in place of harmful solvents. The successful extraction of the residuals is established by thermogravimetric analysis (TGA), whereas FTIR spectroscopy is used to compare the anhydride content of Soxhlet‐extracted PP‐g‐MA to that of scCO 2 ‐extracted copolymer. Polym. Eng. Sci. 44:1636–1641, 2004. © 2004 Society of Plastics Engineers.