Starch-based Nanocomposite Films Research Articles

Enhanced optical, dielectric, and mechanical properties of starch-based nanocomposite films reinforced with layered double hydroxide

In this study, we present the optical, electrical, dielectric, and mechanical properties of nanocomposite films containing different inorganic filler content. Starch is used as the biopolymer while the carbonate intercalated Mg-Al layered double hydroxide (LDH) is used as the inorganic filler. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDS) are used to characterize and evaluate the dispersion of LDH in the biopolymer matrix. Increasing the filler content was found to improve the optical properties by increasing the light absorption coefficients, reducing the optical gap energy and increasing the refractive index. Improved dielectric properties were demonstrated by the significant decrease in the dielectric energy dissipation with increasing filler content. In addition, mechanical properties were enhanced by increasing the Young’s modulus when the filler content reached 5 wt %.

Characteristics of nanocomposite film based on elephant foot-yam starch (Amorphophallus paeoniifolius) with different nanocrystalline cellulose concentration

ABSTRACTBionanocomposite film is composed of renewable materials such as polymer with the addition of nanofiller in the form of nanocrystal cellulose (NCC). Biopolymer serves as a matrix, while nanofiller is dispersed to improve the functional properties. NCC is a nanoparticle commonly used in the production of bioplastics, and the addition to nanocomposite film can enhance the mechanical and barrier properties. Therefore, this study aimed to determine the physio-chemical, mechanical, and permeability characteristics of elephant foot-yam starch-based nanocomposite films by adding different concentrations of NCC at 3, 5, and 7 wt.%. The experiment used elephant foot-yam starch, NCC, sorbitol, and carboxymethyl cellulose (CMC) as biopolymer, nanofiller, plasticizer, and stabilizer, respectively. The results showed that the optimum concentration was 7 wt.% NCC, showing tensile strength, elongation, WVTR, and thickness consistent with the Japanese Industrial Standard. NCC dispersion showed favorable water solubility and excellent biodegradability, yielding optimal SEM and FTI-R results. SEM analysis showed a well-dispersed structure, while FTI-R showed sharper spectra in specific functional groups. Moreover, XRD showed several diffraction peaks with strong intensity at 2θ = 17.12°(101̅), 22.75° (002), and 35.0° (040), confirming the presence of NCC in the film matrix. Based on the results, this nanocomposite had great potential to be developed into environmentally friendly packaging.

The Role of Virgin Coconut Oil in Corn Starch/NCC-Based Nanocomposite Film Matrix: Physical, Mechanical, and Water Vapor Transmission Characteristics.

Corn starch-based nanocomposite films usually have low moisture barrier properties. Adding virgin coconut oil (VCO) as a hydrophobic component can improve the nanocomposite film's characteristics, especially the film's permeability and elongation properties. This study aimed to determine the role of VCO with various concentrations (0, 3, 5 wt%) on the physical, mechanical, and water vapor transmission characteristics of corn starch/NCC-based nanocomposite films. Adding 3% VCO to the film showed the lowest WVTR value by 4.721 g/m2.h. At the same time, the value of tensile strength was 4.243 MPa, elongation 69.28%, modulus of elasticity 0.062 MPa, thickness 0.219 mm, lightness 98.77, and water solubility 40.51%. However, adding 5 wt% VCO to the film increased the film's elongation properties by 83.87%. The SEM test showed that adding VCO formed a finer structure with pores in several areas. The FTIR films showed that adding VCO caused a slightly higher absorption peak shift at the O-H groups and new absorption peaks at wave numbers 1741 cm-1 and 1742 cm-1. The results of this study may provide opportunities for the development of nanocomposite films as biodegradable packaging in the future.

A Review on Reinforcements and Additives in Starch-Based Composites for Food Packaging.

The research of starch as a matrix material for manufacturing biodegradable films has been gaining popularity in recent years, indicating its potential and possible limitations. To compete with conventional petroleum-based plastics, an enhancement of their low resistance to water and limited mechanical properties is essential. This review aims to discuss the various types of nanofillers and additives that have been used in plasticized starch films including nanoclays (montmorillonite, halloysite, kaolinite, etc.), poly-saccharide nanofillers (cellulose, starch, chitin, and chitosan nanomaterials), metal oxides (titanium dioxide, zinc oxide, zirconium oxide, etc.), and essential oils (carvacrol, eugenol, cinnamic acid). These reinforcements are frequently used to enhance several physical characteristics including mechanical properties, thermal stability, moisture resistance, oxygen barrier capabilities, and biodegradation rate, providing antimicrobial and antioxidant properties. This paper will provide an overview of the development of starch-based nanocomposite films and coatings applied in food packaging systems through the application of reinforcements and additives.

Biodegradability of Starch Nanocomposite Films Containing Different Concentrations of Chitosan Nanoparticles in Compost and Planting Soils

Starch-based nanocomposite films containing chitosan nanoparticles (S/CNP films) are biodegradable and promising alternatives for non-biodegradable synthetic plastics. Nonetheless, limited work has been conducted to investigate the biodegradability of the films in soil. Thus, this work is aimed at investigating the biodegradation of starch-based films containing different concentrations of CNP (0, 10, 15, 20, 25% w/w solid starch) via a soil burial test using compost and planting soils. The biodegradability was investigated in terms of weight loss, visual appearance, morphology, and structural changes. It was found that S/CNP films biodegraded slower than neat starch films, and the degradation rate was reduced by 46 and 44% in compost and planting soils, respectively, with the increase in the concentrations of CNP from 10 to 25% w/w incorporated into the films. The degradation rate of films in compost soil after 8 days was found to be higher (0.0617 g/day) than in planting soil (0.0266 g/day). Visual appearance, morphology, and structural change results also supported these findings. The biodegradable S/CNP films can be used to reduce the usage of synthetic plastic.

Nanocomposite starch films: Cytotoxicity studies and their application as cheese packaging

This work focuses on the development of starch-based nanocomposite films containing AgNPs obtained by different green synthesis techniques, the characterization of their relevant properties, the study of their cytotoxicity and their application as food packaging on cheese.AgNPs were obtained by different green synthesis techniques: AgNP in situ and AgNP L. The incorporation of AgNP L improved the barrier properties of nanocomposite films, since water vapor permeability decreased (0.63 ± 0.07 × 10−10 g/m s Pa) compared to films containing AgNPs in situ (1.9 ± 0.1 × 10−10 g/m s Pa), while the UV–vis barrier capacity was higher (371.5 ± 15.6 and 314.1 ± 14.7, respectively). Films with AgNPs synthesized in situ were less cytotoxic for the Caco-2/TC7 line (90% viability) in comparison with films containing AgNPs synthesized with lemon juice (AgNP L). Vero cells were susceptible to adhesion problems on both control and nanocomposite films. Likewise, the differences observed between monocytes and macrophage THP-1 cells may be associated with the expression of different markers. Then, active packages were developed by thermo-sealing the films. The nanocomposite samples were able to extend the shelf life of cheese by 7 days, but the CL and AgNP L films were more effective, probably due to the synergistic effect of the active compounds present in the lemon juice and the low pH of the film-forming suspension. Finally, production costs and the current legislative framework for this type of material were revised.

Morphological and thermo-mechanical characterization of sweet potato starch based nanocomposites reinforced with barley starch nanoparticles.

The aim of present study was to develop and characterize the biodegradable sweet potato starch-based nanocomposite films reinforced with barley starch nanoparticles (SNP). Sweet potato starch-based films with varying concentrations of barley SNP (5-25% w/w) were manufactured by adopting solution casting method using glycerol as a plasticizer. The morphology, thickness, transparency, water solubility, water vapor transmission rate (WVTR), tensile strength, elongation at break and thermal stability properties of nanocomposite films were evaluated. The results showed that the incorporation of barley SNP led to a significant increase in tensile strength from 2.63 (control film) to 8.98MPa (nanocomposite with 15% (w/w) SNP). Compared with the native starch film, the surface of the nanocomposite films became more rough and uneven with the increasing concentration of nanofillers. High concentration of SNP (upto 25%, w/w) significantly decreased the transparency and WVTR, and water solubility (upto 20%, w/w) of nanocomposite films. The WVTR decreased from 3294.53 to 349.06g/m2/24h. In addition, the thermal stability of nanocomposites got improved after incorporation of SNP into starch-film matrix.

Pearl millet starch-based nanocomposite films reinforced with Kudzu cellulose nanocrystals and essential oil: Effect on functionality and biodegradability

This paper documents the preparation of three biopolymer films: 1) pearl millet starch (PMS) films, 2) PMS films reinforced with cellulose nanocrystals (CNCs), and 3) PMS films reinforced with CNCs stabilized Pickering emulsion of clove bud oil (CBO) and a comparison of their mechanical and water barrier properties and biodegradation behavior in soil. Reinforcing PMS films with Kudzu CNCs/CBO significantly increased tensile strength (from 3.9 to 16.7 MPa) and Young's modulus (from 90 to 376 MPa) but reduced the elongation (54.2 to 30 %) at the break of nanocomposite films. Also, the water vapor permeability of nanocomposite films decreased (from 9.60 to 7.25 × 10−10gm−1s− 1Pa−1) with the incorporation of Kudzu CNCs/CBO. The fastest biodegradation was observed for PMS films (98% in 15 days), followed by PMS films reinforced with Kudzu CNCs (96% in 18 days), followed by PMS films reinforced with Kudzu CNCs stabilized Pickering emulsions (94% in 21 days). The morphological analysis found hyphae-like structure formation due to microbial action, which increased over time. In general, all three biopolymer films showed good biodegradation behavior, and they all degraded between 15 and 21 days, suggesting that starch-based films reinforced with Kudzu CNCs provide a technique for the production of biodegradable packaging material.

Preparation and characterization of starch-based nanocomposites reinforced by graphene oxide self-assembled on the surface of silanecouplingagent modified cellulose nanocrystals.

The dispersion of cellulose nanocrystal (CNC) in starch matrix limited its application. In this study, CNC modified by silanecouplingagent before graphene oxide (GO) self-assembled on the surface of modified CNC, then CNC-GO as a filler was used to prepare starch-based nanocomposite films (CS/CNC-GO). The structure of CNC-GO and CS/CNC-GO films and the properties of CS/CNC-GO films were studied by FT-IR, Raman, SEM, surface potential, UV-Vis, moisture absorption and tensile tests. The results showed that GO was successfully self-assembled on the surface of CNC modified by silanecouplingagent. CNC-GO was superior to CNC in reinforcing the strength of starch film, improving the transmittance of starch film and decreasing moisture rate of starch film. Tensile strength, elongation at break and transmittance of CS/CNC-GO film with 5wt% CNC-GO reached maximum, which was 53.96MPa, 3.72% and 38.76%, respectively. Moisture rate of CS/CNC-GO film with 3wt% CNC-GO reached minimum that was 12.13%. These were assigned to the more uniform dispersion of CNC-GO in the starch matrix and the stronger interfacial interaction between starch and CNC-GO.

Preparation and characterization of cross-linked starch nanocrystals and self-reinforced starch-based nanocomposite films

In this study, starch-based nanocomposite films reinforced by cross-linked starch nanocrystals (CSNCs) were successfully prepared. CSNCs were obtained by cross-linking reaction between starch nanocrystals (SNCs) and sodium hexametaphosphate (SHMP). Through the characterization and comparison of SNCs and CSNCs in microscopic morphology, degree of substitution, swelling degree, XRD spectrum, and FTIR spectrum, the successful progress of the cross-linking reaction was confirmed. Besides, the effects of adding CSNCs on physiochemical properties of the nanocomposite films including mechanical properties, water vapor permeability, and contact angle were studied. The results confirmed that CSNCs had good enhancement effects on the physicochemical properties of starch-based films due to the self-reinforcing effect, and when the CSNCs content reached 10%, the nanocomposite film had the best overall performance. We further evaluated the cytotoxicity of the nanocomposite. Taken together, it is believed that the reported self-reinforced starch-based films are very promising for food packaging and preservation.

Effects of Plasticizers and Clays on the Physical, Chemical, Mechanical, Thermal, and Morphological Properties of Potato Starch-Based Nanocomposite Films.

Biodegradable polymeric films have great potential as alternatives to synthetic polymeric films to reduce environmental pollution. Plasticizing agents and nanofillers can improve the mechanical properties of polymer-based composites, resulting in materials with better flexibility and extensibility. Starch, a natural polymer, can be produced at low cost and on a large scale from abundant and inexpensive agricultural resources like potatoes. The aim of the present work was to fabricate mechanically strong and thermally stable potato starch films reinforced with different types of plasticizers and nanoclays at different concentrations. Different types of plasticizers such as water, glycerin, ethylene glycol, sorbitol, and formamide and three types of clays such as montmorillonite, hectorite, and kaolinite at various concentrations were used to prepare potato starch-based nanocomposite films. The films were prepared using a very simple solution casting process. The mechanical properties and thermal stabilities of nanocomposite films significantly improved using montmorillonite, hectorite, and kaolinite clays. The water uptake percentage of the fabricated films decreased with addition of plasticizers and further decreased with addition of different types of clays. The structural and morphological changes of the fabricated films in the presence of plasticizers and nanoclays were correlated in detail with their mechanical properties, crystallinity, biodegradability, thermal stability, and water absorption capacities.

Cellulose nanocrystals from grape pomace and their use for the development of starch-based nanocomposite films

Nanocomposite films prepared from starch (ST) in the presence of cellulose nanocrystals (CNCs) was performed using grape pomace as raw material. CNCs were obtained by acid hydrolysis and added to filmogenic solutions (1, 2, 5, 10 and 15 g/100 g of ST). Cellulose, CNCs and Nanocomposites were characterized. Amorphous non-cellulosic materials were removed from the grape pomace presented values for CrI 64% and 71% and yield 12 and 70% in Cellulose and CNCs, respectively. Nanocomposites showed smaller permeability and the addition of 5 to 15% CNCs formed more opaque films and had improved tensile strength and Young’s modulus. The addition of CNCs from 5 to 15% proved to be effective in improving mechanical properties and decreasing water vapor permeability, important characteristics in food packaging materials. This study provided an effective method to obtain CNCs from the agroindustrial waste and open the way to produce high-value starch based nanocomposites.

Effects of different gums on tensile properties of cellulose nanofibrils (CNFs)-reinforced starch

This research is focused on the development of a new starch-based nanocomposite films reinforced with cellulose nanofibrils (CNFs) for food packaging purposes. A series of starch films were produced by the solution casting method with various concentrations of glycerin, CNF, and citric acid (CA). Mechanical properties of the films were investigated using tensile tests. Based on the results, the best formulation with optimal mechanical properties was introduced by different amounts of various gums to study the effects of the gums on tensile properties of the samples. Fourier-transform infrared analysis was performed to study posttreatment chemical structure of the sample to confirm the cross-linking and esterifying of the nanocomposite films. Results revealed that the tragacanth gum had a negative impact on the mechanical properties, while the frankincense gum (F-gum) and Arabic gum positively influenced the mechanical properties through strengthening the network structure. The sample containing 0.3 g of F-gum (10% w/w, relative to the starch weight) showed the best results compared to the control films.

Antimicrobial properties of starch films incorporated with chitosan nanoparticles: In vitro and in vivo evaluation

Chitosan nanoparticles (CNP) were synthesized via ionic gelation and used for the preparation of starch-based nanocomposite films containing different concentration of CNP (0, 5, 10, 15, 20% w/w). Antimicrobial properties of starch/CNP films was evaluated via in vitro (disc diffusion analysis) and in vivo (microbial count in wrapped cherry tomatoes) study. It was found that inhibitory zone of the 15 and 20% of starch/CNP films were clearly observed for all the tested bacteria including Bacillus cereus, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. In vivo study revealed that the starch/CNP film (15% w/w) was more efficient to inhibit the microbial growth in cherry tomatoes (7 × 102 CFU/g) compared to neat starch film (2.15 × 103 CFU/g) thus confirmed the potential application of the films as antimicrobial food packaging.

The co-plasticization effects of glycerol and small molecular sugars on starch-based nanocomposite films prepared by extrusion blowing

In this study, starch-based nanocomposite films (SNF) made with small molecular sugars (sucrose, fructose and glucose) and glycerol as co-plasticizers were prepared by extrusion blowing. The incorporation of sugars into SNF inhibited the formation of intercalated structures, as shown by X-ray diffraction (XRD) data. XRD analysis also showed that the relative crystallinity of the films decreased after the addition of sugars. Compared to control films, SNF made with sugars showed higher water vapor permeability (WVP, 4.78 × 10−10 g.m/m2.s.Pa), as well as a lower tensile strength and glass transition temperature (Tg, −14.2 °C). Fourier transform infrared (FTIR) analysis revealed that there were high levels of hydroxyl groups and water molecules aggregated around the starch polymer chains. Sugars played an important role in the melting and fracturing of starch granules, as confirmed by scanning electronic microscopy (SEM) data. For the films with sugars especially for glucose, the vertical elongation at break achieved 142%, representing approximately 76% enhancement in elongation at break value compared to the control film, which has almost reached basic standard of traditional plastics (V/H-E ≥ 150%). Thermoplastic starch films co-plasticized with sucrose (TPS-suc) presented better performance than those co-plasticized with fructose (TPS-fru) or glucose (TPS-glu).

Banana starch nanocomposite with cellulose nanofibers isolated from banana peel by enzymatic treatment: In vitro cytotoxicity assessment

The potential use of cellulose nanofibers (CNFs) as a reinforcing agent in banana starch-based nanocomposite films was investigated. CNFs were isolated from banana peel (Musa paradisiaca) by enzymatic hydrolysis. Banana starch-based nanocomposite films were prepared with CNFs using the casting method. CNFs effect on cell viability and on nanocomposite films properties’ was investigated. The cytotoxicity of CNFs was assessed on Caco-2 cell line. CNFs were not cytotoxic at 50–2000 μg/mL. However, CNFs above 2000 μg/mL significantly decreased cell viability. Topography analysis showed that the incorporation of CNFs modified the film structure. The nanocomposites exhibited a complex structure due to strong interactions between CNFs and starch matrix, promoting a remarkable improvement on mechanical and water barrier properties, opacity and UV light barrier compared to the control film. CNFs can offer a great potential as reinforcing material for starch-based nanocomposite films, producing a value-added food packaging from a waste material.

Cellulose nanocrystals from Miscanthus fibers: insights into rheological, physico-chemical properties and polymer reinforcing ability

Cellulose nanocrystals (CNC) were extracted from Miscanthus (MST) fibers using a sulfuric acid hydrolysis process. The results showed that the obtained CNC exhibit a needle-like shape with an average aspect ratio of 37. The surface charge density was measured at 1.99 sulfate groups per 100 anhydroglucose units while the zeta potential value was found to be -38 mV. The crystallinity of the extracted CNC was 76%, and the cellulose I type crystal structure was predominant. Due to its high importance for potential application of CNC in aqueous systems, the rheological behavior of CNC aqueous suspensions at various CNC concentrations was determined. The CNC suspensions showed gel-like behavior at very low CNC concentrations ranging from 0.1 wt% up to 0.6 wt%, as confirmed by the steady shear viscosity measurements and the oscillatory dynamic tests. The dynamic rheological parameters of CNC suspensions were slightly affected by the temperature profile. At high temperature up to 80 °C a stronger CNC network is formed by increasing the relative motion resistance of CNC macromolecules and the entanglement. In order to identify the reinforcing ability of the newly extracted CNC, starch-based nanocomposite films were produced with various CNC contents (1, 3, 5 and 8 wt%) and their tensile properties were investigated. It was found that the addition 8 wt% CNC within starch matrix increased the Young’s modulus by 150% and the tensile strength by 118%, resulting in mechanically strong and eco-friendly nanocomposite materials.

A comparative study of gelatin and starch-based nano-composite films modified by nano-cellulose and chitosan for food packaging applications

Environmental concerns have led to extensive research for replacing polymer-based food packaging with bio-nano-composites. In this study, incorporation of nano-cellulose into gelatin and starch matrices is investigated for this purpose. Chitosan is used to improve mechanical, anti-fungal and waterproof properties. Experiments are designed and analyzed using response surface methodology. Nano-Cellulose is synthesized via acid hydrolysis and incorporated in base matrices through wet processing. Also, tensile strength test, food preservation, transparency in visible and UV and water contact angle are performed on the nano-composite films. DSC/TGA and air permeability tests are also performed on the optimal films. The results show that increasing nano-cellulose composition to 10% leads to increase the tensile strength at break to 8121 MN/m2 and decrease the elongation at break. Also, increasing chitosan composition from 5% to 30% can enhance food preservation up to 15 days.

Tunable d-Limonene Permeability in Starch-Based Nanocomposite Films Reinforced by Cellulose Nanocrystals.

In order to control d-limonene permeability, cellulose nanocrystals (CNC) were used to regulate starch-based film multiscale structures. The effect of sphere-like cellulose nanocrystal (CS) and rod-like cellulose nanocrystal (CR) on starch molecular interaction, short-range molecular conformation, crystalline structure, and micro-ordered aggregated region structure were systematically discussed. CNC aspect ratio and content were proved to be independent variables to control d-limonene permeability via film-structure regulation. New hydrogen bonding formation and increased hydroxypropyl starch (HPS) relative crystallinity could be the reason for the lower d-limonene permeability compared with tortuous path model approximation. More hydrogen bonding formation, higher HPS relative crystallinity and larger size of micro-ordered aggregated region in CS0.5 and CR2 could explain the lower d-limonene permeability than CS2 and CR0.5, respectively. This study provided new insight for the control of the flavor release from starch-based films, which favored its application in biodegradable food packaging and flavor encapsulation.

Hydrophilic modification of cellulose nanocrystals improves the physicochemical properties of cassava starch-based nanocomposite films

Carboxymethyl cellulose nanocrystals (N-CMCs) were produced by carboxymethylation of cellulose nanocrystals (CNCs) that derived from sweet potato residue. Transmission electron microscopy showed that the N-CMCs which had a porous surface structure were more loosely packed and slightly larger with a uniform diameter ranging from 30 nm to 50 nm. N-CMCs with low viscosity (<25 mPa s) and nano-sized scale were used as reinforcement for preparing cassava starch-based films. Effect of N-CMCs varying 0.2 g/100 mL −0.5 g/100 mL was studied on physicochemical properties of N-CMCs/cassava starch films. N-CMCs/cassava starch film with 0.4 g/100 mL N-CMCs exhibited a 554% increase in tensile strength, 41% increase in elongation at break, and 123% increase in water solubility compared with the CNCs/cassava starch film. Moreover, the water vapor permeability and moisture absorption of the N-CMCs/cassava starch film decreased by 42.7% and 15.9%, respectively. Better mechanical properties, water barrier properties and water solubility was achieved for the N-CMCs/cassava starch film than for the CNC/cassava starch film, indicating N-CMCs after carboxymethylation were beneficial for reinforcement of cassava starch-based films. The moisture absorption abilities of both cassava starch nanocomposite films were comparable. The results may be applied to the development of water-soluble and biodegradable edible films for food packaging.