Effects of asphodel tuber and dolomite on the properties of bio-hybrid films processed by a twin screw extruder

Abstract

Bio-hybrid granules made from asphodel tuber (AT), starch, polyvinyl alcohol (PVOH), and dolomite were formed using a twin-screw extruder. The granules were prepared using starch or AT as a raw material, glycerol as a plasticizer, TiO2 as a heat stabilizer, and dolomite as a filler. The films were fabricated from granules by hot-press moulding. The mechanical (e.g., tensile strength, elongation-at-break, and modulus of elasticity), physical (e.g., weathered, density, hardness, color, water absorption and solubility in different temperatures, water vapor permeability, and oxygen permeability), and chemical properties (e.g., carbonyl index and vinyl index) of the films were analysed. The properties of the films were noticeably enhanced with AT and dolomite. Asphodel tuber improved the water solubility, water absorption, and weight loss after weathered. Asphodel tuber could resist water diffusion into the films because of its hydrophobic property, like dolomite. Dolomite also exhibited strong mechanical properties and barrier properties to water and oxygen. Additionally, cross-linking most likely occurred with inter- or intramolecular interactions. The interactions among the AT, starch, dolomite, and plasticiser with PVOH were interpreted as esterification, etherification, hydrogen bonding, carbonyl bonding, and vinyl bonding in the molecular structure of the bio-hybrid films.