Biodegradable Carbon-based Ashes/Maize Starch Composite Films for Agricultural Applications

Abstract

The aim of this work is the development and characterization of biodegradable thermoplastic recycled carbon ashes/maize starch (TPAS) composite films for agricultural applications. A proper plasticizer, that is, glycerol, was added to a commercial maize starch in an amount of 35 wt.%. Carbon-based ashes were produced by the biomass pyro-gasification plant CMD ECO 20, starting from lignocellulosic wastes. The ashes were added to glycerol and maize native starch at different amounts ranging from 7 wt.% to 21 wt.%. The composite was mixed at 130 °C for 10 min and then molded. The effect of the different amounts of carbon based ashes on the thermal and physical-mechanical properties of the composite was assessed by using several techniques, such as rheology, wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), moisture absorption, degradation and mechanical tests. The presence of the carbon waste ashes allows to improve thermal and durability performances of the thermoplastic starch (TPS) films. It reduces the water absorption of starch matrix and strongly decreases the deterioration of starch, independently from fillers amount, enhancing the lifetime of the TPS films in outdoor conditions. In addition, the waste carbon ashes/maize starch films present an advantage in comparison to those of neat starch; it can biodegrade, releasing the plant nutrients contained in the ashes into the soil. In conclusion, this approach for recycling carbon waste ashes increases the efficiency of industrial waste management, along with a reduction of its impact on the environment.

An Innovative Method for the Recycling of Waste Carbohydrate-Based Flours

“…By comparing the moisture absorption data recorded by Stasi et al [8], who developed compression-molded composite films of thermoplastic carbon-based ashes/maize starch, it is noticeable that the imbibition coefficient values determined for Type 1 and Type 2 bio-films are lower than those in presence of carbon ashes (with a percentage reduction in the interval of 13%-20%), even though the ashes do not contribute to the water absorption of the starch films [8].…”

“…For this reason, the polymer chains of the thermoplastic starch can recrystallize in several crystalline structures for the separation and migration of the plasticizer by causing a variation of the mechanical properties [2,5,6]. Successful procedures for the production of thermoplastic starch film by means of extrusion and compression molding were developed by Giuri et al [7] and Stasi et al [8], respectively. The method proposed by Giuri et al [7] involved a controlled, easy and cheap processing procedure by using an extrusion technique and by adding 50 wt % glycerol to the maize native starch.…”

“…Nevertheless, mechanical properties of the starch films were lower than those of the synthetic thermoplastic polymer films, and the hygroscopic behavior of the starch thermoplastic films was still high, irrespective of their composition [7]. Stasi et al [8] used compression molding to process native starch, in presence or absence of carbon-based waste ashes. They found that the presence of ashes decreases the biodegradability of the starch by 70%, independently of the filler amount.…”

“…In addition, the tensile tests showed a relevant stiffening effect of the filler, with an increase of about 20% in tensile modulus. Besides, the moisture absorption capacity of the thermoplastic starch films decreased by about 30% thanks to the presence of the waste carbon ashes [8].…”

Recent Applications of Biopolymers Derived from Fish Industry Waste in Food Packaging

“…Several polysaccharides have been added to chitosan for producing blended films with enhanced final properties for food applications. Among them, thanks to its low cost, wide availability and biodegradability, starch is one of the most common polysaccharides proposed for the production of chitosan-based biofilms [ 196 , 197 ].…”