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Properties and morphology of poly(lactic acid)/soy protein isolate blends
Author(s) -
Fang Kun,
Wang Biaobing,
Sheng Kuichuan,
Sun Xiuzhi Susan
Publication year - 2009
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.30446
Subject(s) - ultimate tensile strength , differential scanning calorimetry , soy protein , lactic acid , materials science , chemistry , chemical engineering , nuclear chemistry , composite material , food science , physics , genetics , biology , bacteria , engineering , thermodynamics
Poly(lactic acid) (PLA)/soy protein isolate (SPI) blends with and without modifier were melt compounded in a intensive mixer. Tensile strength of PLA/SPI simple blends decreased more than pure PLA because the dispersed SPI granules acted as the stress concentration; tensile strength was improved by loading of sodium bisulfite (NaHSO 3 ). At 0.5 wt % NaHSO 3 loading, the blend gave 43.9 MPa of tensile strength. Blends containing both methylene diphenyl diisocyanate (MDI) and NaHSO 3 displayed a significant improvement in tensile strength, which increased by 38% at 4 wt % MDI, compared with the PLA/SPI/NaHSO 3 blend. The scanning electron microscopic observation demonstrated that incorporating NaHSO 3 and MDI improved compatibility between PLA and SPI. The differential scanning calorimetry indicated that SPI induced and accelerated cold crystallization of PLA in the blends, which was also affected by the presence of NaHSO 3 and MDI. The PLA/SPI blend containing both NaHSO 3 and MDI displayed higher water resistance than the PLA/SPI/NaHSO 3 blend. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009