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Degradation of respirable fibrils of poly( p ‐phenylene terephthalamide) by solar ultraviolet radiation
Author(s) -
Knoff Warren F.
Publication year - 1994
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.1994.070521207
Subject(s) - degradation (telecommunications) , poly(p phenylene) , ultimate tensile strength , materials science , ultraviolet , polymer , fibril , brittleness , composite material , modulus , polymer chemistry , chemical engineering , chemistry , optoelectronics , telecommunications , biochemistry , computer science , engineering
After ∼ 160 days in the environment, the polymer in a respirable‐size poly( p ‐phenylene terephthalamide) fibril (diameter = 0.3 μm) is expected to degrade, due to solar ultraviolet radiation, from an initial molecular weight of ∼ 20,000 to less than 400. This estimate is based on ultraviolet absorption characteristics, photolytic degradation kinetics, and judgments regarding how these translate into actual time in the environment. Degradation to this molecular weight level will cause the fibril tensile strength and modulus to decrease to ∼ 1% of their initial values. Mechanically, such a degraded fibril will be weak and brittle with properties similar to those of uncooked spaghetti. © 1994 John Wiley & Sons, Inc.