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Thermal and mechanical properties of plastics molded from urea‐modified soy protein isolates
Author(s) -
Mo Xiaoqun,
Sun Xiuzhi
Publication year - 2001
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-001-0357-1
Subject(s) - soy protein , urea , differential scanning calorimetry , plasticizer , ultimate tensile strength , denaturation (fissile materials) , materials science , glass transition , enthalpy , soy flour , chemistry , dynamic mechanical analysis , chemical engineering , composite material , polymer , nuclear chemistry , organic chemistry , food science , physics , quantum mechanics , engineering , thermodynamics
Soy protein has been considered as a potential alternative of some petroleum polymers in the manufacture of plastics. The purpose of this investigation was to characterize the thermal and mechanical properties of plastics made from urea‐modified soy protein. Soy protein isolate was separated from the defatted soy flour, modified with various urea concentrations, and compression‐molded into plastics. Differential scanning calorimetry showed that the temperatures of denaturation and the enthalpies of denaturation of the modified soy protein decreased as urea concentrations increased above 1 M. At the same urea concentration, molded plastics made from the modified soy proteins showed a similar temperature of denaturation as the modified soy protein, but a lower enthalpy of denaturation. Tensile strength and Young's modulus of the molded plastics from the modified soy proteins increased as urea concentration increased and reached their maximum values at 8 M urea modification. Both storage modulus and glass transition temperature of the plastics from the modified soy proteins increased as urea concentration increased. The plastics made from the 2 M urea‐modified soy proteins showed improvements in elongation, tough fracture behavior, and water resistance. The urea may function as a denaturant, a plasticizer, and a filler.