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Poly( L ‐lactic acid) with added α‐tocopherol and resveratrol: optical, physical, thermal and mechanical properties
Author(s) -
Hwang Sung Wook,
Shim Jin Kie,
Selke Susan EM,
SotoValdez Herlinda,
Matuana Laurent,
Rubino Maria,
Auras Rafael
Publication year - 2012
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.3232
Subject(s) - materials science , rheology , glass transition , compounding , tocopherol , viscosity , chemical engineering , composite material , compression molding , polymer , chemistry , organic chemistry , antioxidant , vitamin e , mold , engineering
Poly( L ‐lactic acid) (PLLA) films containing various concentrations of two natural antioxidants, α‐tocopherol and resveratrol, were fabricated by a melt compounding and compression molding process. The influence of the antioxidants on the optical properties such as color and UV‐visible light transmission was analyzed. The thermal, mechanical, rheological and physical properties of PLLA films with added antioxidants were assessed. PLLA films with added α‐tocopherol and resveratrol showed a yellowish brown color and the lightness was influenced by the presence of the antioxidants. The glass transition and melting temperatures were significantly reduced with the addition of antioxidants while enhanced thermal stability was observed, which could be a benefit and important for processing and production. PLLA films with added antioxidants were slightly more hydrophobic than neat PLLA. The combination effect of plasticizing and enhancement of the elastic modulus with differing concentrations of two antioxidants played a critical role in the mechanical and thermomechanical properties of PLLA films. The melt viscosity of the PLLA films with added antioxidants was substantially higher than that of neat PLLA. The higher melt viscosity and G ′(ω) could be an indication of formation of entanglement between PLLA and the two antioxidants. Copyright © 2012 Society of Chemical Industry