Molecular weight distributions in novolac type phenol-formaldehyde polymerizations

Kumar, Anil ; Phukan, Uzzal K. ; Kulshreshtha, Alok K. ; Gupta, Santosh K. (1982) Molecular weight distributions in novolac type phenol-formaldehyde polymerizations Polymer, 23 (2). pp. 215-221. ISSN 0032-3861

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In the acid-catalysed condensation polymerization of phenol and formaldehyde, the ortho and para positions of the phenol ring are known to exhibit different reactivities. Along with this on polymer molecules, the internal sites have lower reactivity due to molecular shielding. To model the novolac formation, five reactive sites have been proposed and their reactivities are assumed to be completely determined by the site involved. To find the molecular weight distribution (MWD) of the polymer from this information, a given polymer chain has been assumed to consist of these sites in the same relative ratio as in the reaction mass. A mass balance, on polymer molecules of given size, has been made and solved numerically as a function of time. The sensitivity analysis has been carried out to show that the MWD is little affected by the variation of reactivities of the internal sites. The reactivity of para external positions and the ratio of phenol and formaldehyde, however, play a major role in determining the MWD.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Polymerization; Catalysis; Phenol; Formaldehyde; Condensation; Molecular Weight Distribution; Novolac
ID Code:14105
Deposited On:12 Nov 2010 09:06
Last Modified:02 Jun 2011 10:05

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