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Electron Beam Radiation Modification on Chemical, Thermal and Crystalline Properties of Poly (L-lactic acid)

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Title Electron Beam Radiation Modification on Chemical, Thermal and Crystalline Properties of Poly (L-lactic acid)
 
Creator Rao, N Rajeswara
Rao, T Venkatappa
Rao, B Sanjeeva
Shanmukhi, P S V
 
Subject Electron beam
Component spectra
Glass-Transition temperature
Degree of crystallinity
Micro-Cracks
 
Description 715-722
The paper presents the effect of electron beam (EB) irradiation on poly (L-Lactic acid) (PLLA). The resultant physicochemical properties were investigated using Electron spin resonance spectrometer (ESR), Fourier transform infrared spectrometer (FTIR), Differential scanning calorimetry (DSC), X-ray Diffraction (XRD) and Scanning electron microscopy (SEM). The results suggest that PLLA undergoes random chain scission producing two types of free radicals ~Ċ(CH3)~ (I) and ĊH(CH3)~ (II) at room temperature. Presence of these free radicals has been confirmed by the ESR method and computer simulation studies using easyspin tool. FTIR results depict that the intensity of the absorption band 1745 cm-1 is reduced by 12% for 90 kGy dose. DSC studies indicate that both glass transition temperature (Tg) and melting temperature (Tm) of PLLA decrease following radiation dose. However melting enthalpy (ΔH) and degree of crystallinity (XC) increased initially up to 30 kGy of radiation dose followed by a decrease after 30 kGy. These results confirm the existence of two types of crystalline lamellar are present in PLLA. Measurements of XC by XRD also confirm the same aspect. The surface of PLLA is composed of micro-cracks when exposed to higher radiation doses.
 
Date 2021-10-20T08:54:06Z
2021-10-20T08:54:06Z
2021-10
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://nopr.niscair.res.in/handle/123456789/58308
 
Language en
 
Publisher NIScPR-CSIR, India
 
Source IJPAP Vol.59(10) [October 2021]