(217ez) Biocomposites of Thermoplastic Starch and Ginger Residues

Biocomposites made from natural fibers and bio-based or biodegradable polymers have been received much attention due to the ecological concerns and the approaching depletion of fossil fuels.  These biocomposites are sometimes defined as green composites.  Similar to conventional composites, biocomposites are attractive in terms of lightweight structures with high stiffness.  In addition, green composites are also fully biodegradable after use.  Thermoplastic starch (TPS) is one of the most interesting bio-based and biodegradable materials since it is produced from starch, which is naturally abundant, cheap, renewable, non-toxic, biodegradable and compostable.  However, the applications of TPS are still restricted by their high moisture/water adsorption and poor mechanical properties.  These limitations are considered as major drawbacks when compared to conventional plastics.  Fabrication of TPS composites with natural reinforcements is an alternative strategy not only to improve the properties of TPS, but also to provide a 100% bio-based materials.  Ginger residue - a solid waste material obtained from the ginger extraction process - contains not only starch, proteins, fats, inorganic materials, moisture and essential oils, but also fibers.  A large amount of ginger residue has been discarded as waste every year.  The utilization of agricultural residue as an additive for bio-based plastics is a challenging task for achieving sustainable and competitive materials and also adding the value of waste residue.  Therefore, the aim of the present work is to study the influence of ginger residue on properties of TPS.  TPS/ginger residue composites with various contents of ginger residue, i.e. 0, 2.5, 5.0 and 10.0% w/w were prepared by a twin-screw extruder.  The obtained TPS/ginger residue composites showed lower degree of mold shrinkage, greater water vapor barrier property (~ 37–53 %), higher glass transition temperature (~ 3–13 °C), higher melting temperature (~ 20–25 °C), and better tensile property (tensile strength ~ 842–2,929 % and modulus ~ 17.6–454.0 MPa) than TPS.  The resulting TPS/ginger residue biocomposites are promising bio-based material which could be used as a partial substitute for petroleum-based plastics or high-cost biodegradable plastics in the plastic injection molding industry.