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Crystallinity index of poly(ethylene terephthalate) by x‐ray diffractometry and differential scanning calorimetry
Author(s) -
Wakelyn N. T.,
Young P. R.
Publication year - 1966
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.1966.070101004
Subject(s) - crystallinity , differential scanning calorimetry , annealing (glass) , ethylene , materials science , poly ethylene , analytical chemistry (journal) , polymer chemistry , composite material , thermodynamics , chemistry , physics , chromatography , organic chemistry , catalysis
The crystallinity of a variety of poly(ethylene terephthalate) (PET) specimens, produced by thermal annealing, has been measured by three x‐ray diffractometric index methods and by an index method for differential scanning calorimetric data. The measurement procedures are termed indices since they involve various methods of ranking specimens in a relative manner between maximum and minimum crystallinity standards. Statistically different index values are determined by the various physical methods and procedures of calculation for many types of specimens. The integral index method, which utilizes x‐ray diffractometric data, corresponds in a more precise manner to the calorimetric index than to the other two x‐ray methods, for the cases in which oriented film is annealed in a vacuum oven and is subject to a continuous pumping environment. This treatment also produces a threefold increase in number‐average molecular weight of PET film. Annealing in sealed ampules, M n constant, produces substantially the same results for all three x‐ray methods but different results for the calorimetric procedure. A relatively simple two‐point procedure yields virtually the same trend as the more complicated indicial methods.