Location: Dairy and Functional Foods ResearchTitle: Performance enhancement of poly(lactic acid)/soy protein concentrate blends by promoting formation of network structure Author
Submitted to: Green Materials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2012
Publication Date: 2/1/2013
Publication URL: http://handle.nal.usda.gov/10113/60343
Citation: Liu, B., Guevara, G.Z., Zhang, J., Liu, L.S. 2013. Performance enhancement of poly(lactic acid)/soy protein concentrate blends by promoting formation of network structure. Green Materials. 1(3):176-185. Interpretive Summary: Because of its high strength and stiffness, poly (lactic acid) (PLA) is a potential alternative to petrochemical polymers in many applications. However, drawbacks such as low heat distortion temperature and relatively high cost limit the broad application of PLA. Soy protein concentrate (SPC) can be preformulated with water to gain a thread shape with a large length/diameter (L/D) value, which enables the formation of an interconnected structure between PLA and SPC, when both are blended. The resultant blends have improved thermal and mechanical properties. The method can be applied for the preparation of other blends from PLA and agricultural polymers.
Technical Abstract: In this work, the effects of water content in preformulated soy protein concentrate (SPC) and of SPC content on the thermal, rheological and mechanical properties and morphology of poly(lactic acid) (PLA)/SPC blends were studied. The blends were prepared by twin screw compounding and the test specimens were injection molded. Water in the preformulated SPC was a critical factor for the development of SPC phase structure in the blends. The results indicated that the preformulated SPC containing water experienced large deformation during compounding and formed interconnected network structure in the resulting blends. Dynamic mechanical analysis revealed that the addition of water in the preformulated SPC and increasing the SPC loading level greatly improved the storage modulus of the resulting PLA/SPC blends at elevated temperatures.