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Multiple endotherm melting behavior in relation to the morphology of poly[3,3‐ bis(ethoxymethyl) oxetane]
Author(s) -
Fay J. J.,
Murphy C. J.,
Sperling L. H.
Publication year - 1990
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.1990.070400724
Subject(s) - endotherm , differential scanning calorimetry , supercooling , crystallization , enthalpy of fusion , melting point , materials science , crystallography , fusion , morphology (biology) , enthalpy , annealing (glass) , crystal (programming language) , analytical chemistry (journal) , chemistry , thermodynamics , chromatography , organic chemistry , composite material , linguistics , physics , philosophy , genetics , biology , computer science , programming language
Two crystalline melting peaks have been observed by differential scanning calorimetry for low molecular weight poly[3,3‐bis(ethoxymethyl) oxetane] (polyBEMO) samples, M n < 1 × 10 4 g/mol, whereas only one melting peak has been observed for samples of higher molecular weight, M n < 1 × 10 4 g/mol. Crystallization of low molecular weight samples at large supercoolings produces the lower melting form while low supercooling or annealing favors the higher melting species. Enthalpy of fusion values obtained by DSC for a multiple melting endotherm sample range from 28 to 39 J/g for crystallization temperatures from 58 to 35°C, respectively. Optical microscopy studies indicate that the lower melting peak corresponds to a spherulitic type morphology and the higher melting peak correlates to a fine grained crystal structure. Wide angle X‐ray powder diffraction studies do not detect differences in the crystal structures of samples exhibiting either one or two melting peaks, which suggests that the multiple melting phenomenon is due to differences in morphology rather than the presence of different crystal forms.