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Change and Convergence of Polymer Distribution During Nonrandom Degradation
Author(s) -
Tobita Hidetaka
Publication year - 2010
Publication title -
macromolecular reaction engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 32
eISSN - 1862-8338
pISSN - 1862-832X
DOI - 10.1002/mren.200900062
Subject(s) - breakage , dispersity , degradation (telecommunications) , bar (unit) , limiting , polymer , chain (unit) , distribution (mathematics) , thermodynamics , chemistry , convergence (economics) , materials science , mathematics , polymer chemistry , crystallography , physics , mathematical analysis , composite material , organic chemistry , computer science , telecommunications , economics , economic growth , mechanical engineering , astronomy , meteorology , engineering
The CLD development during nonrandom degradation is investigated, assuming the rate of bond scission depends on the chain length and the position of the bond within the chain. As the degradation proceeds, the polydispersity index $({\rm PDI} = \bar {P}_{\rm w} /\bar {P}_{\rm n} )$ usually approaches a fixed value pertinent to the degradation mechanism, independent of the initial distribution. The exact limiting values are presented for several cases. These values may be useful to estimate the degradation mechanisms. For example, if the limiting PDI is smaller than 2, the bonds in larger chains may be easier to break than shorter ones, and if it is smaller than 4/3, the size effect is not enough and the breakage may tend to occur in the middle of the chain.