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Polymerization of melamine and formaldehyde in homogeneous continuous‐flow stirred‐tank reactors using functional group approach: Part B: Molecular weight distribution
Author(s) -
Kumar Anil
Publication year - 1987
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.1987.070340405
Subject(s) - formaldehyde , molar mass distribution , polymerization , polymer , polymer chemistry , melamine , chemistry , chemical engineering , end group , materials science , organic chemistry , engineering
Polymerization of melamine and formaldehyde in homogeneous continuous‐flow stirred‐tank reactors (HCSTRs) is reversible and leads to formation of branched polymer due to the hexafunctional nature of melamine. The reversed reaction of branched molecules depends upon the chain structure, and herein a simple model is presented to account for this. The functional group analysis of part A of this series has been extended and the molecular weight distribution (MWD) relations for HCSTRs have been solved. The MWD of the polymer is extremely sharp and the molecules are more branched compared to those for batch reactors and can be explained as follows. A given reacted bond can react with water as well as free formaldehyde through the reversed reaction, and the rate constant for the latter step is much larger. Consequently, the chain growth is limited as long as there is free formaldehyde in the reaction mass. Lower conversion of melamine and formaldehyde in HCSTRs is used to explain the behavior observed.