Structural modifications in bivoltine silk fiber under thermal treatment

✍ Scribed by G. Ramgopal; R. Ramani; P. Ramachandra; C. Ranganathaiah

• Book ID: 101249546
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 147 KB
• Volume: 63
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19970118)63:3<395::aid-app16>3.0.co;2-#

✦ Synopsis

The microstructural changes of semicrystalline bivoltine silk fibers annealed between 27 to 260ЊC were measured using positron annihilation lifetime spectroscopy (PALS). Measured lifetime and intensity as a function of temperature reveals the removal of water molecules until 60ЊC. Present results indicate a T g of 140ЊC, 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 205ЊC, respectively. Degradation of the fibers occur around 240ЊC. 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.