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Structural modifications in bivoltine silk fiber under thermal treatment
Author(s) -
Ramgopal G.,
Ramani R.,
Ramachandra P.,
Ranganathaiah C.
Publication year - 1997
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/(sici)1097-4628(19970118)63:3<395::aid-app16>3.0.co;2-#
Subject(s) - silk , materials science , voltinism , composite material , polymer science , fiber , fibroin , thermal , biology , ecology , thermodynamics , physics , larva
The microstructural changes of semicrystalline bivoltine silk fibers annealed between 27 to 260°C were measured using positron annihilation lifetime spectroscopy (PALS). Measured lifetime and intensity as a function of temperature reveals the removal of water molecules until 60°C. Present results indicate a T g of 140°C, which is further confirmed by differential scanning calorimetry (DSC). The structural changes like random‐coil to alpha and then to beta form are observed in the crystalline and amorphous domains at 100 and 205°C, respectively. Degradation of the fibers occur around 240°C. As an extension of the present measurements, we have estimated the activation energy of 8.0 KJ/mol in the disordered domain of the fiber, based on Goldanskii's kinetic relations. © 1997 John Wiley & Sons, Inc.