Thermal properties of water-resistant starch – polyvinyl alcohol films modified with cellulose nanofibers

Microbial load reduction in stored raw beef meat using chitosan/starch-based active packaging films incorporated with cellulose nanofibers and cinnamon essential oil

Food safety is a global concern due to the risk posed by microbial pathogens, toxins and food deterioration. Hence, materials with antibacterial and antioxidant properties have been widely studied for their packaging application to ensure food safety. The current study has been designed to fabricate the chitosan/starch-based film with cinnamon essential oil (CEO) and cellulose nanofibers for active packaging. The nanocomposite films developed in this study were characterized by using UV-Vis Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM), and Gas Chromatography-Mass Spectroscopy (GC-MS). The biodegradability, hydrodynamic, mechanical, antioxidant and antibacterial properties of the films were also evaluated. From the results, the addition of CEO and cellulose nanofibers was found to enhance the antimicrobial and material properties of the film. FE-SEM analysis has also revealed a rough and porous surface morphology for the developed nanocomposite film. FT-IR analysis further demonstrated the molecular interactions among the various components used for the preparation of the film. The film has also been shown to have antibacterial activity against Staphylococcus aureus and Escherichia coli. Furthermore, the film was found to reduce the bacterial load of the stored beef meat when used as a packaging material. The study hence provides valuable insights into the development of chitosan/starch-based films incorporated with CEO and cellulose nanofibers for active food packaging applications. This is due to its excellent antimicrobial and physicochemical properties. Hence, the nanocomposite film developed in the study can be considered to have promising applications in the food packaging industry.

Preparation of hydroxypropyl methylcellulose/pueraria-based modified atmosphere film and its influence on delaying the senescent process of postharvest Agaricus bisporus

Based on the key factor of spontaneous modified atmosphere packaging (MAP)-gas permeability, a spontaneous MAP film was created for the preservation of Agaricus bisporus by delaying the senescence of white mushrooms. Compared with other mixed films, hydroxypropyl methylcellulose (HPMC)/pueraria (P)-2 showed better mechanical properties, barrier properties and thermal stability energy. Applying the HPMC/P-2 film for preserving white mushrooms can spontaneously adjust the internal gas environment. Moreover, the O2 concentration in the package remained stable at 1-2 %, and the CO2 concentration was between 8 % and 14 %. The film can effectively reduce the respiration rate of white mushrooms, inhibit enzymatic browning, maintain their good color and texture, and delay their aging. In conclusion, the HPMC/P-2 film can be used not only for fruit and vegetables preservation but also provide theoretical basis for sustainable food packaging.

Enhancing the Mechanical Properties of Corn Starch Films for Sustainable Food Packaging by Optimizing Enzymatic Hydrolysis

The objective of this study was to investigate the effects of enzymatic hydrolysis using α-amylase from Bacillus amyloliquefaciens on the mechanical properties of starch-based films. The process parameters of enzymatic hydrolysis and the degree of hydrolysis (DH) were optimized using a Box-Behnken design (BBD) and response surface methodology (RSM). The mechanical properties of the resulting hydrolyzed corn starch films (tensile strain at break, tensile stress at break, and Young's modulus) were evaluated. The results showed that the optimum DH for hydrolyzed corn starch films to achieve improved mechanical properties of the film-forming solutions was achieved at a corn starch to water ratio of 1:2.8, an enzyme to substrate ratio of 357 U/g, and an incubation temperature of 48 °C. Under the optimized conditions, the hydrolyzed corn starch film had a higher water absorption index of 2.32 ± 0.112% compared to the native corn starch film (control) of 0.81 ± 0.352%. The hydrolyzed corn starch films were more transparent than the control sample, with a light transmission of 78.5 ± 0.121% per mm. Fourier-transformed infrared spectroscopy (FTIR) analysis showed that the enzymatically hydrolyzed corn starch films had a more compact and solid structure in terms of molecular bonds, and the contact angle was also higher, at 79.21 ± 0.171° for this sample. The control sample had a higher melting point than the hydrolyzed corn starch film, as indicated by the significant difference in the temperature of the first endothermic event between the two films. The atomic force microscopy (AFM) characterization of the hydrolyzed corn starch film showed intermediate surface roughness. A comparison of the data from the two samples showed that the hydrolyzed corn starch film had better mechanical properties than the control sample, with a greater change in the storage modulus over a wider temperature range and higher values for the loss modulus and tan delta, indicating that the hydrolyzed corn starch film had better energy dissipation properties, as shown by thermal analysis. The improved mechanical properties of the resulting film of hydrolyzed corn starch were attributed to the enzymatic hydrolysis process, which breaks the starch molecules into smaller units, resulting in increased chain flexibility, improved film-forming ability, and stronger intermolecular bonds.

Contribution of the Surface Treatment of Nanofibrillated Cellulose on the Properties of Bio-Based Epoxy Nanocomposites Intended for Flexible Electronics

The growing interest in materials derived from biomass has generated a multitude of solutions for the development of new sustainable materials with low environmental impact. We report here, for the first time, a strategy to obtain bio-based nanocomposites from epoxidized linseed oil (ELO), itaconic acid (IA), and surface-treated nanofibrillated cellulose (NC). The effect of nanofibrillated cellulose functionalized with silane (NC/S) and then grafted with methacrylic acid (NC/SM) on the properties of the resulted bio-based epoxy systems was thoroughly investigated. The differential scanning calorimetry (DSC) results showed that the addition of NCs did not influence the curing process and had a slight impact on the maximum peak temperature. Moreover, the NCs improved the onset degradation temperature of the epoxy-based nanocomposites by more than 30 °C, regardless of their treatment. The most important effect on the mechanical properties of bio-based epoxy nanocomposites, i.e., an increase in the storage modulus by more than 60% at room temperature was observed in the case of NC/SM addition. Therefore, NC's treatment with silane and methacrylic acid improved the epoxy-nanofiber interface and led to a very good dispersion of the NC/SM in the epoxy network, as observed by the SEM investigation. The dielectric results proved the suitability of the obtained bio-based epoxy/NCs materials as substitutes for petroleum-based thermosets in the fabrication of flexible electronic devices.

Thermal Stability, Dynamic Mechanical Analysis and Flammability Properties of Woven Kenaf/Polyester-Reinforced Polylactic Acid Hybrid Laminated Composites

This paper presents the thermal and flammability properties of woven kenaf/polyester-reinforced polylactic acid hybrid laminated composites. The effects of the fiber content and stacking sequences of hybrid composites were examined. The hybrid composites were fabricated using the hot press method. Thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and flammability properties of woven kenaf/polyester-reinforced polylactic hybrid composites were reported. The thermal results have demonstrated the effect of the hybridization of the composites on the thermal stability and viscoelastic properties of the laminates. The work also measured the burning rate of the hybrid composites during the flammability test. The S7 sample that consisted of all woven kenaf layers in composite recorded the highest char residue of 10%, and the S8 sample displayed the highest decomposition temperature among all samples. However, as for hybrid composites, the S5 sample shows the optimum result with a high char yield and exhibited the lowest burning rate at 29 mm/min. The S5 sample also shows the optimum viscoelastic properties such as storage and loss modulus among hybrid composites.

Mechanism and Compatibility of Pretreated Lignocellulosic Biomass and Polymeric Mixed Matrix Membranes: A Review

In this paper, a review of the compatibility of polymeric membranes with lignocellulosic biomass is presented. The structure and composition of lignocellulosic biomass which could enhance membrane fabrications are considered. However, strong cell walls and interchain hindrances have limited the commercial-scale applications of raw lignocellulosic biomasses. These shortcomings can be surpassed to improve lignocellulosic biomass applications by using the proposed pretreatment methods, including physical and chemical methods, before incorporation into a single-polymer or copolymer matrix. It is imperative to understand the characteristics of lignocellulosic biomass and polymeric membranes, as well as to investigate membrane materials and how the separation performance of polymeric membranes containing lignocellulosic biomass can be influenced. Hence, lignocellulosic biomass and polymer modification and interfacial morphology improvement become necessary in producing mixed matrix membranes (MMMs). In general, the present study has shown that future membrane generations could attain high performance, e.g., CO2 separation using MMMs containing pretreated lignocellulosic biomasses with reachable hydroxyl group radicals.

Recent advances in composites based on cellulose derivatives for biomedical applications

Cellulose derivatives represent a viable alternative to pure cellulose due to their solubility in water and common organic solvents. This, coupled with their low cost, biocompatibility, and biodegradability, makes them an attractive choice for applications related to the biomedicine and bioanalysis area. Cellulose derivatives-based composites with improved properties were researched as films and membranes for osseointegration, hemodialysis and biosensors, smart textile fibers, tissue engineering scaffolds, hydrogels and nanoparticles for drug delivery. The different preparation strategies of these polymeric composites as well as the most recent available experimental results were described in this review. General aspects such as structure and properties of cellulose extracted from plants or bacterial sources, types of cellulose derivatives and their synthesis methods were also discussed. Finally, the future perspectives related to composites based on cellulose derivatives were highlighted and some conclusions regarding the reviewed applications were drawn.

Effect of a Novel Chemical Treatment on the Physico-Thermal Properties of Sugarcane Nanocellulose Fiber Reinforced Epoxy Nanocomposites

In the present investigation, a novel chemical treatment was introduced for the extraction of nanocellulose fibers from sugarcane bagasse and applied as reinforcement material to enhance the physical properties and thermal stability of epoxy nanocomposites. Epoxy nanocomposites with different weight fractions were fabricated using a wet layup process followed by furnace heating to remove the residual moisture content. The influence of surface modified sugarcane nanocellulose fiber loading on morphological (transmission electron microscope) properties of epoxy nanocomposites was investigated. The porosity and water absorption increase with the increment in fiber weight fraction for both treated and untreated nanocellulose fiber-epoxy composites. Among the various treatment processes, the alkali-treated fibers reinforced epoxy composites showed better thermal stability and water absorption resistance under 10 wt.% of nanocellulose fiber reinforcement.

Composite Films with UV-Barrier Properties of Bacterial Cellulose with Glycerol and Poly(vinyl alcohol): Puncture Properties, Solubility, and Swelling Degree

The aim of this study was to develop composite films based on bacterial cellulose, glycerol, and poly(vinyl alcohol) with improved optical and mechanical properties and good UV-barrier property. The interaction among the compounds was analyzed using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry, and differential scanning calorimetry. The mechanical properties (toughness, burst strength, and distance to burst), solubility, water adsorption, and light barrier properties of the composite films were evaluated. Polynomial models obtained allowed us to predict the behavior of these properties. Poly(vinyl alcohol) showed a reinforcing effect on the bacterial cellulose matrix, while glycerol showed a noticeable plasticizing behavior. The bacterial cellulose-based composites showed toughness values ranging from 0.22 to 2.60 MJ/m³. The burst strength values obtained ranged between 43.74 and 2105.52 g. The distance to burst ranged from 0.39 to 4.94 mm. The film solubility on water ranged from 9.37 to 31.65%, and the water retention ranged from 78.26 to 364.78%. Glycerol decreased the transmittance in the UV region, improving the UV-barrier properties of the films, while poly(vinyl alcohol) improved the transparency and opacity values of the samples. The transmittance in the UV regions (A, B, and C) ranged from 1 to 48.51%, increasing with the poly(vinyl alcohol) concentration.

Comparative study on properties of starch films obtained from potato, corn and wheat using 1-ethyl-3-methylimidazolium acetate as plasticizer

Starch films are gaining attention as substitutes of synthetic polymers due to their biodegradability and low cost. Some ionic liquids have been postulated as alternatives to glycerol, one of the best starch plasticizers, due to their great capacity to form hydrogen bonds with starch and hence great ability of preventing starch retrogradation and increasing film stability. In this work, [emim⁺][Ac^-]-plasticized starch films were prepared from potato, corn and wheat starch. The effect of starch molecular structure in terms of granular composition (amylose and phosphate monoester contents) and molecular weight (M_w) on film properties was evaluated. Potato starch films were the most amorphous because of the higher M_w and phosphate monoester content of potato starch, both contributing to a lower rearrangement of the starch chains making the crystallization process difficult. In contrast, corn and wheat starches lead to more crystalline films because of their lower M_w, which may imply higher mobility and crystal growth rate, and lower phosphate monoester content. This more crystalline structure could be the responsible of their better mechanical properties. [emim⁺][Ac^-] can be considered suitable for manufacturing starch films showing corn and wheat starch films similar properties to synthetic low-density polyethylene, but involving a simple and environmentally-friendly process.

Composite Films with UV-Barrier Properties Based on Bacterial Cellulose Combined with Chitosan and Poly(vinyl alcohol): Study of Puncture and Water Interaction Properties

The present study describes the preparation and characterization of composite films from bacterial cellulose produced by Komagataeibacter xylinus combined with poly(vinyl alcohol) and chitosan. The unique bacterial cellulose structure provides an expanded surface area with high porosity, easing the combination with other soluble polymers by dipping. This blending method effectively reinforces the bacterial cellulose structure. Toughness, puncture strength, water solubility, and swelling degree were measured to assess the effect of poly(vinyl alcohol) and chitosan on the analyzed properties. The morphology and optical and thermal properties were evaluated by scanning electron microscopy, UV-vis spectral analysis, thermogravimetry, and differential scanning calorimetry, respectively. Results showed that the films have good UV-barrier properties and high thermal stability. Toughness values ranged from 0.26 to 7.18 MJ/m³, burst strength ranged from 58.88 to 3234.62 g, and distance to burst ranged from 0.39 to 3.24 mm. Poly(vinyl alcohol) affected the water solubility and increased the swelling degree.

Resource recovery of Eichhornia crassipes as oil superabsorbent

The elastic cellulose-based aerogels (CBAs) with highly porous (99.56%) and low-density (0.0065gcm^-1) were prepared using Eichhornia crassipes as cellulose source and polyvinyl alcohol directly as cross-linker via a facile and environment-friendly process. The prepared CBAs exhibited excellent oil/solvent sorption capacities (60.33-152.21gg^-1), super-hydrophobicity (water contact angle of 156.7°) as well as remarkable reusability. More importantly, the absorbed oil could be quickly recovered by simple squeezing without significantly structure damage (at least 16 times). All these merits make CBAs very promising materials for oil spillage cleaning.

Extraction and modification of cellulose nanofibers derived from biomass for environmental application

Cellulose nanofibers obtained from various plants and microbial sources, their extraction methods and various environmental applications are discussed.

Effect of Incorporation Nanocrystalline Corn Straw Cellulose and Polyethylene Glycol on Properties of Biodegradable Films

This work aimed to study the effect of nanocrystalline corn straw cellulose (NCSC) and polyethylene glycol (PEG) on the properties of biodegradable corn distarch phosphate (CDP) films. The mechanical properties and barrier properties were investigated. Meanwhile, the compatibility, crystallization, thermal stability, and morphological structure of the films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (X-RD), thermogravimetric (TGA), and scanning electron microscopy (SEM). In contrast with the CDP films, incorporation of NCSC in the films improved their tensile strength (TS) significantly, and incorporation of PEG improved their elongation at break (EAB) significantly else. PEG, CDP, and NCSC (P-CDP/NCSC) blend films had the best barrier properties. The thermal stability of the films was increased by the incorporation of NCSC. X-RD showed that CDP and NCSC (CDP/NCSC) films had higher crystallinity. SEM revealed that all films had smooth surface, while the films presented a uniform network structure through the incorporation of NCSC.