Journal of the American Oil Chemists' Society

, Volume 78, Issue 8, pp 867–872

Thermal and mechanical properties of plastics molded from urea-modified soy protein isolates


DOI: 10.1007/s11746-001-0357-1

Cite this article as:
Mo, X. & Sun, X. J Amer Oil Chem Soc (2001) 78: 867. doi:10.1007/s11746-001-0357-1


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.

Key Words

Denaturation dynamic mechanical property mechanical properties protein modification soy protein thermal property 

Copyright information

© AOCS Press 2001

Authors and Affiliations

  1. 1.Depatment of Grain Science and IndustryKansas State UniversityManhattan

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