Value addition of rice straw cellulose fibers as a reinforcer in packaging applications

The potential use of agro-waste in food packaging applications is receiving remarkable attention due to its sustainable approach and biodegradable properties. As typical lignocellulosic biomass, rice straw (RS) is widely produced but is usually abandoned and burned, causing tremendous environmental concerns. The exploration of using RS as the source of biodegradable packaging materials is promising for economically converting this agricultural waste into packaging material, thereby providing a considerable solution for RS disposal and an alternative solution to synthetic plastic waste. Polymers have been infused with nanoparticles, fibers, and whiskers, along with plasticizers and cross-linkers, and fillers like nanoparticles and fibers. They have also been blended with natural extracts, essential oils, and other synthetic and natural polymers to improve RS properties. There is still much research to be done before this biopolymer can be applied at an industrial level in food packaging. In this respect, RS can be valued for packaging to add value to these underutilized residues. This review article focuses on the extraction methods and functionality of cellulose fibers and their nanostructured forms from RS and their utilization in packaging applications.

Extruded biocomposite films based on poly(lactic acid)/chemically-modified agricultural waste: Tailoring interface to enhance performance

In this work, a lignocellulosic filler, rice straw (RS), was thermoplasticized by acetylation modification process and compounded with plasticized poly(lactic acid) (PLA) through twin-screw extrusion process. The biocomposite films were prepared continuously by using a slit die for PLA/RS and PLA/acetylated RS (ARS) compounds. By the chemical reaction, thermoset microstructure of RS was changed to a more flexible one. Additionally, by the reaction, the interfacial adhesion of lignocellulosic filler/PLA matrix, filler hydrophobicity and PLA wettability was enhanced considerably. The miscibility of partially phase-separated PLA/poly(ethylene glycol) (PEG) mixtures was improved by adding RS-based microfillers, particularly by the acetylated RS. Compared with PLA/unmodified RS films, PLA/ARS biocomposites show better thermal stability, toughness, Young modulus and softening point, especially at certain filler loadings.

Evaluation of Physico-Mechanical Properties on Oil Extracted Ground Coffee Waste Reinforced Polyethylene Composite

The current work discusses ground coffee waste (GCW) reinforced high-density polyethylene (HDPE) composite. GCW underwent two types of treatment (oil extraction, and oil extraction followed by mercerization). The composites were prepared using stacking HDPE film and GCW, followed by hot compression molding with different GCW particle loadings (5%, 10%, 15% and 20%). Particle loadings of 5% and 10% of the treated GCW composites exhibited the optimum level for this particular type of composite, whereby their mechanical and thermal properties were improved compared to untreated GCW composite (UGC). SEM fracture analysis showed better adhesion between HDPE and treated GCW. The FTIR conducted proved the removal of unwanted impurities and reduction in water absorption after the treatment. Specific tensile modulus improved for OGC at 5 vol% particle loading. The highest impact energy absorbed was obtained by OGC with a 16% increment. This lightweight and environmentally friendly composite has potential in high-end packaging, internal automotive parts, lightweight furniture, and other composite engineering applications.

Novel Biodegradable Poly (Lactic Acid)/Wood Leachate Composites: Investigation of Antibacterial, Mechanical, Morphological, and Thermal Properties

This research aimed to investigate the effects of using wood leachate (WL) powder as a cost-effective filler added to novel poly (lactic acid) biocomposites and evaluate their mechanical, thermal, morphological, and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), tensile test, Charpy impact test, Shore hardness, scanning electron microscope (SEM), differential scanning calorimetry (DSC), contact angle, and bacterial growth inhibition tests were employed to characterize the developed biocomposites. The SEM results indicated a proper filler dispersion in the polymer matrix. WL powder improved the hydrophobic nature in the adjusted sample’s contact angle experiment. Markedly, the results showed that the addition of WL filler improved the mechanical properties of the fabricated biocomposites. The thermal analysis determined the development in crystallization behavior and a decline in glass transition temperature (Tg) from 60.1 to 49.3 °C in 7% PLA-WL biocomposites. The PLA-WL biocomposites exhibited an antibacterial activity according to the inhibition zone for Escherichia coli bacteria. The developed novel PLA-WL composites can be effectively utilized in various value-added industrial applications as a sustainable and functional biopolymer material.

Crosslinked starch-coated cellulosic papers as alternative food-packaging materials

In general, during the production of cellulosic materials for food-packaging applications, lignin and other amorphous components are usually removed via the pulping and multilevel bleaching process to entirely separate them from the fiber.

Applications of emerging botanical hydrocolloids for edible films: A review

In recent years, many studies have been conducted on the production of edible films from emerging gums, which are mostly made from botanical sources. However, each one interacts differently with the film compounds, producing films with different properties that may improve or hinder their utilization in food packaging. Therefore, the aim of this review was to investigate and compare the physical, mechanical, thermal and structural properties of edible films produced with these emerging gums. The results of this review showed that it is possible to produce edible films with desirable physical, mechanical and thermal properties by optimizing the amounts and type of compounds in film formulations such as plasticizers, nanoparticles, lipid compounds, crosslinkers and combination of gums with other biopolymers. The future trends of this research include the deepening of knowledge to understand the molecular structures of emerging gums and to address the shortcomings of films based on these gums for their industrial-scale application in food packaging.

Plasticized starch-based biocomposites containing modified rice straw fillers with thermoplastic, thermoset-like and thermoset chemical structures

In this work, rice straw (RS) as an abundant biomass was applied to prepare some renewable thermoplastic materials by using soda-pulping and benzylation processes. The obtained RS products including untreated RS, RS pulp, benzylated RS pulp and pulping liquor as well as benzylated RS were incorporated into the thermoplastic starch through a twin-screw extrusion process to obtain all green composites. The successful thermoplasticization reaction of RS products was confirmed by spectroscopy results and morphological observations. The interfacial adhesion between the plasticized starch matrix and the RS products is enhanced by the chemical modifications, which confirmed by investigating through the morphological observations and linear rheological responses. The partial phase miscibility of the plasticizer/starch mixtures is improved by adding the benzylated RS and RS pulp. The RS pulp having cellulosic microfibers enhances the Young modulus and tensile strength of the plasticized starch even more than untreated RS. However, their thermoset and thermoset-like structure leads to the brittle failure mode of the starch biocomposites, similar to the common natural fiber biocomposites. The thermoplasticization reaction changes the failure mode and significantly improves the toughness of the plasticized starch/RS product biocomposites owing to better phase miscibility.

Preparation and characterization of polylactic-co-glycolic acid/insulin nanoparticles encapsulated in methacrylate coated gelatin with sustained release for specific medical applications

This study aimed to examine the possibility of using insulin orally with gelatin encapsulation to enhance the usefulness of the drug and increase the lifespan of insulin in the body using polylactic-co-glycolic acid (PLGA) nanoparticles alongside gelatin encapsulation. In this regard, PLGA was synthesized via ring opening polymerization, and PLGA/insulin nanoparticles were prepared by a modified emulsification-diffusion process. The resulting nanoparticles with various amounts of insulin were fully characterized using FTIR, DSC, DLS, zeta potential, SEM, and glucose uptake methods, with results indicating the interaction between the insulin and PLGA. The process efficiency of encapsulation was higher than 92%, while the encapsulation efficiency of nanoparticles, based on an insulin content of 20 to 40%, was optimized at 93%. According to the thermal studies, the PLGA encapsulation increases the thermal stability of the insulin. The morphological studies showed the fine dispersion of insulin in the PLGA matrix, which we further confirmed by the Kjeldahl method. According to the release studies and kinetics, in-vitro degradation, and particle size analysis, the sample loaded with 30% insulin showed optimum overall properties, and thus it was encapsulated with gelatin followed by coating with aqueous methacrylate coating. Release studies at pH values of 3 and 7.4, alongside the Kjeldahl method and standard dissolution test at pH 5.5, and glucose uptake assay tests clearly showed the capsules featured 3-4 h biodegradation resistance at a lower pH along with the sustained release, making these gelatin-encapsulated nanoparticles promising alternatives for oral applications.[Figure: see text].

Preparation and characterization of antibacterial, eco-friendly edible nanocomposite films containing Salvia macrosiphon and nanoclay

Nowadays, food security is a vital issue and antimicrobial packaging could play an important role in this matter. In this regard, Salvia macrosiphon seed mucilage (SSM) and nanoclay, as new sources for the production of food-grade edible films were investigated. These edible films were prepared by incorporation of SSM with glycerol and different percentage of nanoclay. Upon addition of nanoclay up to 2% physical, mechanical and thermal properties were considerably improved and the composite films showed the lowest water vapor permeability (WVP), as well as highest elongation at break and tensile strength. The nanocomposite edible films also showed antibacterial activity due to the SSM nature. Addition of nanoclay, increased the hydrophobicity, which makes the films great alternatives for food packaging. This study revealed that these novel antimicrobial edible films could be a promising packaging option for a wide range of food products.

Poly(ε-caprolactone)/triclosan loaded polylactic acid nanoparticles composite: A long-term antibacterial bionanocomposite with sustained release

In this study, the antibacterial bionanocomposites of poly(ε-caprolactone) (PCL) with different concentrations of triclosan (TC) loaded polylactic acid (PLA) nanoparticles (30wt% triclosan) (LATC30) were fabricated via a melt mixing process in order to lower the burst release of PCL and to extend the antibacterial activity during its performance. Due to the PLA's higher glass transition temperature (Tg) and less flexibility compared with PCL; the PLA nanoparticles efficiently trapped the TC particles, reduced the burst release of TC from the bionanocomposites; and extended the antibacterial property of the samples up to two years. The melt mixing temperature was adjusted to a temperature lower than the melting point of LATC30 nanoparticles; therefore, these nanoparticles were dispersed in the PCL matrix without any chemical reaction and/or drug extraction. The sustained release behavior of TC from PCL remained unchanged since no significant changes occurred in the samples' crystallinity compared with that in the neat PCL. The elastic moduli of samples were enhanced once LATC30 is included. This is necessary since the elastic modulus is decreased with water absorption. The rheological behaviors of samples showed appropriate properties for melt electro-spinning. A stable process was established as the relaxation time of the bionanocomposites was increased. The hydrophilic properties of samples were increased with increasing LATC30. The proliferation rate of the fibroblast (L929) cells was enhanced as the content of nanoparticles was increased. A system similar to this could be implemented to prepare long-term antibacterial and drug delivery systems based on PCL and various low molecular weight drugs. The prepared bionanocomposites are considered as candidates for the soft connective tissue engineering and long-term drug delivery.

Preparation and characterization of interface-modified PLA/starch/PCL ternary blends using PLLA/triclosan antibacterial nanoparticles for medical applications

In this study, the antibacterial, interface-modified ternary blends based on polylactic acid/starch/polycaprolactone were prepared for medical applications.