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Crystallinity in secondary cellulose esters
Author(s) -
Boy R. E.,
Schulken R. M.,
Tamblyn J. W.
Publication year - 1967
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.1967.070111205
Subject(s) - cellulose , crystallinity , acetone , cellulose triacetate , differential thermal analysis , crystallization , acetic anhydride , melting point , polymer chemistry , thermal analysis , chemistry , cellulose acetate , acetic acid , precipitation , organic chemistry , materials science , nuclear chemistry , crystallography , diffraction , thermal , physics , meteorology , catalysis , optics
Cellulose esters which have a high degree of esterification are readily crystallizable by simple heat treatments. Such esters include cellulose triacetate, cellulose tripropionate, and mixed cellulose triesters. X‐ray diffraction analysis shows distinct crystal patterns for these crystalline cellulose esters, and differential thermal analysis shows strong melting peaks. X‐ray diffraction analysis of secondary cellulose esters, that is, esters having a substantially lower degree of esterification, shows very diffuse patterns which are only slightly indicative of crystalline structure. Differential thermal analysis, on the other hand, shows strong endothermic peaks which appear to indicate melting of crystalline material. Once melted, secondary cellulose esters cannot be recrystallized easily by simple heat treatments, but it has been found that treatment with certain solvents will induce crystallization. For instance, precipitation of secondary cellulose acetate from acetic acid gave a material which showed two melting peaks by differential thermal analysis, and precipitation from acetone gave a material which showed a single melting peak. A secondary mixed ester, cellulose acetate butyrate, precipitated from acetone had three melting peaks. The coincidence of two of the peak temperatures of this ester with those of the separate triesters of acetic and butyric acids indicated a block rather than a random substitution into the cellulose chain.