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Role of hardener, crosslinker, and pH in bare process of urea–formaldehyde polymerization and for in situ encapsulation of linseed oil
Author(s) -
Kurt Çömlekçi G.,
Ulutan S.
Publication year - 2019
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.46947
Subject(s) - resorcinol , linseed oil , formaldehyde , urea , urea formaldehyde , nuclear chemistry , polymer chemistry , polymerization , scanning electron microscope , thermal stability , chemistry , acrylic acid , materials science , polymer , organic chemistry , copolymer , adhesive , composite material , layer (electronics)
ABSTRACT In this study, urea–formaldehyde polymerizations in bare process and for in situ encapsulation of linseed oil (LO) have been scrutinized either at pH 3.5 or in inherently developing acidic pH. The solid‐state carbon nuclear magnetic resonance ( 13 C‐NMR) revealed that the hardener and the crosslinker (NH 4 Cl and resorcinol) resulted in the formation of methylene linkage. The addition of NH 4 Cl and resorcinol slightly decreased the thermal stability of poly(urea formaldehyde) (PUF) resin. Optical microscopy (OM) images and scanning electron microscopy (SEM) micrographs show that most regular shapes of capsules were obtained when NH 4 Cl and resorcinol were used in the regular reaction medium. The increment of NH 4 Cl amount up to 0.124 mol resulted in a 41% decrement of capsule size, whereas increment resorcinol amount up to 0.062 mol increased the size by 14%. The capsule size range was found to be between 60 and 100 μm. The capsules had a hardness of 22–74 MPa and an elasticity of 0.5–1.5 GPa. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 46947.