Starch-based Films Plasticized with Glycerol and Lignin from Piassava Fiber Reinforced with Nanocrystals from Eucalyptus

Effects of silane hydrolysis time on the physicochemical properties of bioplastics based on starch and epoxidized soybean oil

This work investigated the effects of 3-aminopropyl triethoxy silane (APTES) hydrolysis time on the physicochemical properties of the resulting starch/epoxidized soybean oil (ESO) bioplastics comprehensively. FTIR analysis confirmed that APTES hydrolyzed for 4 h had the best modification effect on starch. The results of XRD and TGA demonstrated the successful silylation of starch by APTES despite hydrolysis time. Silylation treatment reduced the thermal stability of starch slightly, but enhanced the thermal stability of the resultant bioplastics, revealing better interaction between silylated starch and ESO. The interfacial adhesion of starch and ESO in the bioplastics was obviously enhanced when APTES was hydrolyzed for 2-24 h. The bioplastics with APTES hydrolyzed for 2-4 h showed more desirable tensile properties as the silane hydrolysis was complete and self-condensation of hydrolyzed silanes was avoided. The bioplastics containing silylated starch still showed superior opacity and biodegradability.

The physical, mechanical, thermal and barrier properties of starch nanoparticle (SNP)/polyurethane (PU) nanocomposite films synthesised by an ultrasound-assisted process

This article reports on the ultrasound-assisted acid hydrolysis for the synthesis and evaluation of starch nanoparticles (SNP) as nanofillers to improve the physical, mechanical, thermal, and barrier properties of polyurethane (PU) films. During the ultrasonic irradiation, dropwise addition of 0.25 mol L^-1 H₂SO₄ was carried out to the starch dispersion for the preparation of SNPs. The synthesized SNPs were blended uniformly within the PU matrix using ultrasonic irradiation (20 kHz, 220 W pulse mode). The temperature was kept constant during the synthesis (4 °C). The nanocomposite coating films were made with a regulated thickness using the casting method. The effect of SNP content (wt%) in nanocomposite coating films on various properties such as morphology, water vapour permeability (WVP), glass transition temperature (Tg), microbial barrier, and mechanical properties was studied. The addition of SNP to the PU matrix increased the roughness of the surface, and Tg by 7 °C, lowering WVP by 60% compared to the PU film without the addition of SNP. As the SNP concentration was increased, the opacity of the film increased. The reinforcement of the SNP in the PU matrix enhanced the microbial barrier of the film by 99.9%, with the optimal content of SNP being 5%. Improvement in the toughness and barrier properties was observed with an increase in the SNP content of the film.

Can Sustainable Packaging Help to Reduce Food Waste? A Status Quo Focusing Plant-Derived Polymers and Additives

The promotion of sustainable packaging is part of the European Green Deal and plays a key role in the EU’s social and political strategy. One option is the use of renewable resources and biomass waste as raw materials for polymer production. Lignocellulose biomass from annual and perennial industrial crops and agricultural residues are a major source of polysaccharides, proteins, and lignin and can also be used to obtain plant-based extracts and essential oils. Therefore, these biomasses are considered as potential substitute for fossil-based resources. Here, the status quo of bio-based polymers is discussed and evaluated in terms of properties related to packaging applications such as gas and water vapor permeability as well as mechanical properties. So far, their practical use is still restricted due to lower performance in fundamental packaging functions that directly influence food quality and safety, the length of shelf life, and thus the amount of food waste. Besides bio-based polymers, this review focuses on plant extracts as active packaging agents. Incorporating extracts of herbs, flowers, trees, and their fruits is inevitable to achieve desired material properties that are capable to prolong the food shelf life. Finally, the adoption potential of packaging based on polymers from renewable resources is discussed from a bioeconomy perspective.

Applications of Lignocellulosic Fibers and Lignin in Bioplastics: A Review

Lignocellulosic fibers and lignin are two of the most important natural bioresources in the world. They show tremendous potential to decrease energy utilization/pollution and improve biodegradability by replacing synthetic fibers in bioplastics. The compatibility between the fiber-matrix plays an important part in the properties of the bioplastics. The improvement of lignocellulosic fiber properties by most surface treatments generally removes lignin. Due to the environmental pollution and high cost of cellulose modification, focus has been directed toward the use of lignocellulosic fibers in bioplastics. In addition, lignin-reinforced bioplastics are fabricated with varying success. These applications confirm there is no need to remove lignin from lignocellulosic fibers when preparing the bioplastics from a technical point of view. In this review, characterizations of lignocellulosic fibers and lignin related to their applications in bioplastics are covered. Then, we generalize the developments and problems of lignin-reinforced bioplastics and modification of lignin to improve the interaction of lignin-matrix. As for lignocellulosic fiber-reinforced bioplastics, we place importance on the low compatibility of the lignocellulosic fiber-matrix. The applications of lignin-containing cellulose and lignocellulosic fibers without delignification in the bioplastics are reviewed. A comparison between lignocellulosic fibers and lignin in the bioplastics is given.

Graphene Oxide Filled Lignin/Starch Polymer Bionanocomposite: Structural, Physical, and Mechanical Studies

In this study, graphene oxide (GO) was investigated as a potential nanoreinforcing agent in starch/lignin (ST/L) biopolymer matrix. Bionanocomposite films based on ST/L blend matrix and GO were prepared by solution-casting technique of the corresponding film-forming solution. The structures, morphologies, and properties of bionanocomposite films were characterized by Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), ultraviolet-visible (UV-vis), SEM, and tensile tests. The experimental results showed that content of GO have a significant influence on the mechanical properties of the produced films. The results revealed that the interfacial interaction formed in the bionanocomposite films improved the compatibility between GO fillers and ST/L matrix. The addition of GO also reduced moisture uptake (Mu) and water vapor permeability of ST/L blend film. In addition, TGA showed that the thermal stability of bionanocomposite films was better than that of neat starch film. These findings confirmed the effectiveness of the proposed approach to produce biodegradable films with enhanced properties, which may be used in packaging applications.