title: Flexible starch-polyurethane films: Physiochemical characteristics and hydrophobicity.
abstract: Starch-polyurethane (PU) composite films with improved mechanical and hydrophobic properties were developed in this work. A simple and effective microwave-aided starch gelatinisation instrument was used to prepare glycerol plasticized high amylose starch (HAGS) material. Polyethylene glycol-isocyanate (PEG-iso) linker was prepared by reacting PEG 1000 with hexamethylene diisocyanate (HMDI). PEG-iso linker was then grafted into HAGS forming three dimensional urethane networks (PEG-PU). HAGS-PEG-PU composite blends were prepared and dried at ambient temperature to obtain HAGS-PEG-PU films. The mechanical properties and hydrophobicity (as contact angle, CA) of the HAGS-PEG-PU films were measured and analysed. Fourier transform infrared spectroscopy showed good grafting of PEG-iso into starch structure. Increase of PEG-iso concentration up to 20% (w/w) improved the molecular mixing and interpenetration between the starch and PEG-PU. The HAGS-PEG-PU films had improved hydrophobicity as indicated by CA values ranging from 51 to 110°and very high flexibility as evidenced from elongation at break (εB) values from 17 to 1000%. The HAGS-PEG-PU film formulation containing 20% (w/w) PEG-iso provided the best flexibility (εB>1000%) and hydrophobicity (CA>110°).
authors.affiliation: School of Science, RMIT University, Melbourne, VIC 3083, Australia; CSIRO Materials Science and Engineering, Clayton South, VIC 3169, Australia.
authors.forename: N L
authors.initials: NL
authors.lastname: Tai
authors.affiliation: CSIRO Materials Science and Engineering, Clayton South, VIC 3169, Australia.
authors.forename: Raju
authors.initials: R
authors.lastname: Adhikari
authors.affiliation: School of Science, RMIT University, Melbourne, VIC 3083, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Shanks
authors.affiliation: School of Science, RMIT University, Melbourne, VIC 3083, Australia; CSIRO Materials Science and Engineering, Clayton South, VIC 3169, Australia. Electronic address: benu.adhikari@rmit.edu.au.
authors.forename: Benu
authors.initials: B
authors.lastname: Adhikari
mesh_terms: D000688:Amylose / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D011092:Polyethylene Glycols; D011140:Polyurethanes / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013213:Starch / Q000737:chemistry*
chemical_list: D011140:Polyurethanes; D011092:Polyethylene Glycols; D013213:Starch; D000688:Amylose
keywords: Flexibility; High amylose starch; Hydrophobicity; Packaging films; Polyethylene glycol-isocyanate; Polyurethane