Studies On Hydrophobic Casein Thermoplastic Modified Using Polyurethane Microparticles

Casein was modified by polyurethane prepolymer (PUP) via soild reaction, which was a new method of modification on casein. In this work, we studied the effects of processing condition and polyurethane structure on the structure/properties of modified casein.First, the effect of polyurethane content on the structure/properties of modified casein was studied. Results showed as compared with raw casein, the toughness and hydrophobicity of modified caseins were obviously improved. In addition, these properties were also improved with an increase of PUP content. It was to be noted that the PU content in modified casein was suitable controlled to20wt.%; this value amount was selected because it was represented optimum balance between performance and cost.Second, the effect of processing condition on the structure/properties of modified casein was studied. Results showed as compared with raw casein, the toughness and hydrophobicity of the modified caseins were significantly improved. However, modified caseins processed at different temperatures (60-90℃) showed similar properties.Third, the effect of isocyanate types on the structure/properties of modified casein was studied. Compared with raw casein, modified caseins showed improved toughness and hydrophobicity. Modified caseins processed at different isocyanate types showed similar properties.The properties of modified casein were associated with many factors. The PU content had more obviously affected on the properties of modified casein than that of reaction temperature and isocyanate types. Polyurethane prepolymer modified caseins via solid reaction, which showed convenient operation, reduced the use of organic solvent, and greatly improved the toughness and hydrophobicity of the modified caseins. In modifying casein, PU particles were formed under strong shear, and PU particles showed good compatibility with casein due to urethane linkages. The improved properties broadened application of modified casein, which had potential application in plastic and glue.