Properties Of Nanocomposite Films Research Articles

Photo-producible and photo-degradable starch/TiO2 bionanocomposite as a food packaging material: Development and characterization

In current study, starch/TiO2 bionanocomposites were produced by photochemical reactions as a biodegradable food packaging material. Physical, mechanical, thermal and water-vapor permeability properties were investigated. Then, the photo-degradation properties of nanocomposite films were studied. This is the first report of the photo-producible and photo-degradable bionanocomposite as a food packaging material. Film-forming solutions were exposed to ultraviolet A (UV-A) for different times. Our results showed that UV-A irradiation increased the hydrophobicity of starch films. With increasing UV-A exposure time, tensile strength and Young’s modulus of the specimens were decreased. On the other hand, elongation at break of the films was increased with increasing UV-A irradiation. The glass transition temperature and melting point of the films were increased by increasing UV-A exposure time. Nevertheless, the results showed that photo-degradation properties of photo-produced starch/TiO2 nanocomposite were significantly higher than virgin starch and virgin starch/TiO2 films. According to obtain results and bibliography a schema was developed to describe the mechanism of photo-production and photo-degradation of starch/TiO2 by UV-A ray. It can be concluded, the modification of starch based biopolymer by UV-A and nano-TiO2, is an easy and accessible process to improve the packaging properties and photo-degradability of biopolymer based films.

Effect of oxidized chitin nanocrystals isolated by ammonium persulfate method on the properties of carboxymethyl cellulose-based films

Oxidized chitin nanocrystals (ChNCs) were isolated from crab shell chitin using ammonium persulfate (APS) method. The oxidized ChNCs were in needle shape with a diameter of 15nm, the length of 400–500nm, and crystallinity index of 93.5%. Carboxymethyl cellulose (CMC)-based films reinforced with the ChNCs (0, 1, 5, and 10wt.%) were flexible and transparent. The mechanical strength of the CMC film increased significantly (p<0.05) after blending with the ChNCs. The tensile strength (TS) and elastic modulus (EM) increased by 88% and 243% when 10wt.% of ChNCs were incorporated. Water vapor barrier property of the composite films decreased and the hydrophilicity increased compared with the neat CMC film. The oxidized ChNCs obtained using the APS method have a high potential for being used as a reinforcing filler to improve the mechanical properties of nanocomposite films for the application in food packaging, nano-papers, hydrogels as well as biomedical applications.

Physicochemical properties of nanocomposite films made from sorghum‐oxidized starch and nanoclay

The aim of this study was to evaluate the incorporation of nanoclay in the polymer matrix of native and oxidized sorghum starches films. The nanocomposite films were prepared by the casting technique and the physicochemical, water vapor barrier, mechanical, and morphological properties, as well the contact angle with water and the distribution of the nanoclay in the film were evaluated. The oxidized starch films showed a higher tensile strength, stiffness, and angle of contact with water, as well as a greater morphological homogeneity on the cross section when compared to native starch films. The nanoclay resulted in a significant (p ≤ 0.05) decrease in tensile strength, elongation, and stiffness in the films. The water vapor permeability was reduced with the addition of nanoclay to the native starch films; however, the oxidized starch film did not change. The nanoclay in the native starch films increased the contact angle from 19.2 to 26.1° at 7.5% of nanoclay. However, in the oxidized starch films the contact angle reduced from 29.1 to 18.3° with 7.5% of nanoclay and increased the presence of microfissures. The sorghum starches and nanoclay films have good potential for use in packaging, due to the good water vapor barrier, morphological properties, and an overall good appearance. The addition of nanoclay in sorghum starch films can contribute to the development of more water‐resistant films to be applied in food with high moisture.

Novel poly(vinyl chloride) nanocomposite films containing α-Al2O3 nanoparticles capped with vitamin B1: preparation, morphological, and thermal characterization

Many studies have been accomplished in the field of nanocomposite (NC) preparation to control the adhesion and spatial dispersion of nano-fillers and effect of these on attributes of the polymer matrix. In this investigation, surface modification of α-Al2O3 nanoparticles (NPs) was performed by vitamin B1 (VB1) as biodegradable and environmentally friendly modifier agent. Poly(vinyl chloride) (PVC) NCs were prepared with several contents of modified α-Al2O3 NPs (3, 5, and 7 wt.%) by ultrasonication method. Then, many standard techniques were used to study the properties of NC films. The results demonstrated that PVC/α-Al2O3–VB1 NC films had better thermal stability and stress strength properties than pure PVC. Morphology images of PVC/α-Al2O3–VB1 NCs showed the good dispersion of NPs in the polymer matrix in nanometer scale. They revealed that the α-Al2O3 NPs have sphere-like morphology. The mechanical properties of PVC/α-Al2O3–VB1 NCs were improved by adding different amounts of α-Al2O3–VB1 into the matrix of PVC. Water contact angle analysis showed increase in hydrophilicity of PVC/α-Al2O3–VB1 NCs.

Enhanced mechanical properties of hydrothermal carbamated cellulose nanocomposite film reinforced with graphene oxide

Cellulose carbamate (CC) was synthesized via hydrothermal process and mixed with graphene oxide (GO) to form a homogeneous cellulose matrix nanocomposite films. The properties of CC/GO nanocomposite films fabricated using simple solution-mixing method with different GO loadings were studied. Transmission electron microscope analysis showed the exfoliation of self-synthesized GO nanosheets within the CC matrix. X-ray diffraction results confirmed the crystalline structure of CC/GO films as the CC/GO mass ratio increased from 100/0 to 100/4. The mechanical properties of CC/GO film were significantly improved as compared to neat CC film. From thermogravimetric analysis result, the introduction of GO enhanced the thermal stability and carbon yields. The 3D homogeneous porous structures of the CC/GO films were observed under Field emission scanning electron microscope. These improvements in nanocomposite film properties could be confirmed by Fourier transform infrared spectroscopy due to the strong and good interactions between CC and GO.

Effect and mechanism of cellulose nanofibrils on the active functions of biopolymer-based nanocomposite films

Cellulose nanofibrils (CNFs) are superfine cellulose fibrils with a nanoscale diameter and have gained increasing attention due to their great potential in the food industry. However, the applications of CNFs in active food packaging are still limited. The objectives of this study were to develop biopolymer-based edible nanocomposite films using CNFs, corn starch, and chitosan, and to investigate the effect and mechanisms of CNFs on the active functions and properties of the nanocomposite films. Important functional properties of the films were measured and the films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Zetasizer. The results demonstrate that CNFs increased the rigidity of the films due to more hydrogen bonds being induced by CNFs (≥60%). Incorporating a high content of CNFs (≥60%) in the film resulted in enhanced filling effect on the structure of the biopolymer films, which significantly improved the light barrier, oxygen barrier and water vapor barrier capacities. As CNF content increased to 100%, the film opacity increased by 59%, while the peroxide value of corn oil protected with edible films was reduced by 23%. Furthermore, the antimicrobial properties of the edible films with 80% and 100% CNFs were increased by up to 2logCFU/g on day 8 in a beef model, due to more positive charges in the films and improved blocking effects on oxygen. These results demonstrate that CNFs can effectively enhance the antimicrobial effect and barrier properties of biopolymer-based nanocomposite films and have great potential in applications of active packaging for food products.

Eco-friendly soluble soybean polysaccharide/nanoclay Na+ bionanocomposite: Properties and characterization

The impact of montmorillonite (MMT) as a nanofiller at different concentrations (5, 10, 15wt.%) on the physicochemical and functional properties of nanocomposite film based on soluble soybean polysaccharide (SSPS) was investigated. The results showed that an increase in MMT concentration was accompanied by a decrease in water solubility, thickness, and elongation at break. Furthermore, tensile strength increased when MMT concentration was increased to 10wt.%. Atomic force and scanning electron micrographs showed a significant agglomeration at MMT 15wt.%. With added MMT, the level of whiteness, greenness, and yellowness of SSPS film increased (P<0.05). Dynamic mechanical thermal analysis indicated that the storage modulus of nanocomposites increased when the MMT was increased to 10wt.%. Furthermore, Fourier transform infrared spectrophotometry demonstrated that no considerable changes occurred in the functional groups of the SSPS when MMT was added. Antimicrobial tests revealed that antibacterial and anti-mold activities were unlikely from reinforced nanocomposites.

Chitosan–graphene oxide nanocomposites: Effect of graphene oxide nanosheets and glycerol plasticizer on thermal and mechanical properties

ABSTRACTIn this study, graphite oxide (GO) is synthesized from natural graphite flakes by the modified Hummers method. Characterization by Fourier transform infrared, X‐ray photoelectron, Raman and ultraviolet‐visible spectroscopies, X‐ray diffraction, and thermogravimetric analysis is conducted on GO to confirm the oxidation of graphite. Unplasticized and glycerol plasticized chitosan/graphene oxide (CS/GO) nanosheets nanocomposites with different GO loadings are prepared by solution casting. The combined effect of GO and glycerol on structure, thermal and mechanical properties of nanocomposite films is studied. GO nanosheets are well dispersed throughout the CS matrix due to the hydrogen bonding and electrostatic interactions between CS and GO nanosheets. The incorporation of GO within the CS matrix results in a decrease of the crystallinity, an improvement of thermal stability, and a significant enhancement of the stiffness and tensile strength that is emphasized by the glycerol. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45092.

Significantly enhanced electroactive β phase crystallization and UV-shielding properties in PVDF nanocomposites flexible films through loading of ATO nanoparticles: Synthesis and formation mechanism

In this work, we report on the preparation and characterization of a poly(vinylidene fluoride) (PVDF) film filled with antimony tin oxide nanoparticles (ATO-NPs), films were prepared via a facile solution casting method to investigate the electroactive β-polymorph formation mechanism and the optical properties of the (ATO/PVDF) nanocomposite films. The impact of the ATO loading on the structural and morphological properties of PVDF were investigated by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy techniques. Designing nanocomposites with a combination of the advantages of both PVDF and ATO nanofiller leads to a feasible route to a remarkable increase of the electroactive phase enriched PVDF films. The (0.05) ATO/PVDF composite film exhibits a maximum β-phase fraction of 86% compared with other loadings this may be assigned to the presence of interfacial interactions at the interface between NPs surface and CH2/CF2 dipoles of PVDF inducing the electroactive phases. Furthermore, the thermal properties of the composites were investigated by differential scanning calorimetry technique revealed the effect of the ATO loading on the structural and morphological properties of PVDF. Studying the optical properties of the nanocomposite films exhibit a strong absorbance in the entire UV region compared with neat PVDF, which is very appealing for UV blocking properties.

Nanocomposites films obtained from protein isolates of mechanically deboned chicken meat added with montmorillonite

Abstract The aim of this study was to evaluate the properties of nanocomposite films of protein isolates from mechanically deboned chicken meat with organoclay (montmorillonite). For the film development, a 23 experimental design was performed with three levels, protein isolate (2, 3.5, 5 g.100 mL-1 of solution), montmorillonite (0.3, 0.5, 0.7 g.100mL-1 of solution) and glycerol (25, 30, 35 g.100 mL-1 CPI). The tensile strength varied between 6.7 and 9.1 MPa, elongation to break from 26-66%, opacity of 13.1 to 35.7 and solubility from 38.5% to 81.8%. Assessing the structural properties, interleaving of the isolate and montmorillonite can be noted. The results obtained in the experimental design indicate that 2.0 g of CPI.100 g-1 of solution, 0.8 g of MMT.100 g-1of solution and 0.2 g of glicerol.100 g-1CPI are the ideal parameters for preparing nanocomposite films.

Improved Dielectric Properties of Polyvinylidene Fluoride Nanocomposite Embedded with Poly(vinylpyrrolidone)-Coated Gold Nanoparticles.

A novel nanocomposite dielectric was developed by embedding polyvinylpyrrolidone (PVP)-encapsulated gold (Au) nanoparticles in the polyvinylidene fluoride (PVDF) polymer matrix. The surface functionalization of Au nanoparticles with PVP facilitates favorable interaction between the particle and polymer phase, enhancing nanoparticle dispersion. To study the effect of entropic interactions on particle dispersion, nanocomposites with two different particle sizes (5 and 20 nm in diameter) were synthesized and characterized. A uniform particle distribution was observed for nanocomposite films consisting of 5 nm Au particles, in contrast to the film with 20 nm particles. The frequency-dependent dielectric permittivity and the loss tangent were studied for the nanocomposite films. These results showed the effectiveness of PVP ligand in controlling the agglomeration of Au particles in the PVDF matrix. Moreover, the study showed the effect of particle concentration on their spatial distribution in the polymer matrix and the dielectric properties of nanocomposite films.

Facile synthetic route for the preparation of PVC/α-MnO2-PVA nanocomposites: morphology, thermal, mechanical and Cd(II) adsorption properties

This study deals with the effect of α-MnO2-PVA as filler for improving the optical, mechanical, thermal, adsorption capacity and self-extinguishing properties of poly(vinyl chloride) (PVC) matrix. Therefore, α-MnO2 nanorods were obtained successfully by a hydrothermal method and were modified with poly(vinyl alcohol) (PVA) to increase compatibility of α-MnO2 with the organic PVC matrix and reduce the accumulation. Accordingly, PVC/α-MnO2-PVA nanocomposites (NCs) were fabricated with different amounts of modified nanorods (1, 3 and 5 wt%) by ultrasonic irradiation technique. Samples were characterized by instrumental analyses such as FT-IR, XRD, FE-SEM and TEM. Properties of NC films and neat PVC were evaluated with different techniques. Also, the PVC/α-MnO2-PVA NC was used as an efficient adsorbent for the removal of cadmium. It was found that PVC/α-MnO2-PVA NCs have better thermal, optical, tensile and self-extinguishing properties relative to pure PVC. The results from adsorption experiment showed that prepared NC is an effective adsorbent for the removal of Cd ions from aqueous solutions.

COST-FP1105: Properties of PLA films reinforced with unmodified and acetylated freeze dried nanofibrillated cellulose

Abstract Freeze dried nanofibrils were acetylated in a heterogeneous system with acetic anhydride, pyridine, and dimethylformamide and the obtained acetylated cellulose nanofibrils (CNFac) were combined with poly(lactic acid) (PLA) to a composite. CNFac with its partially hydrophobic surface showed a good compatibility with PLA resulting in composite films with improved properties. Tensile strength (TS), modulus of elasticity (MOE), and elongation at break (EB) of PLA/CNF increased significantly when 2–5% of CNFac was added to the PLA matrix, while the addition of 10% and higher amounts CNFac decreased the EB at a higher TS and MOE. Mechanical parameters did not improve in the case of unmodified CNF addition. The addition of CNFac maintained transparency and had absorbance values between those of pure PLA film and PLA film with 2% CNF, while films formed with the addition of 5 and 10% of CNF were less transparent. The addition of CNF did not essentially affect the thermal properties of nanocomposite films. The addition of 2–10% of CNFac increased the enthalpy and maximal temperature of cold crystallization as opposed to higher loading of CNFac. The results of differential scanning calorimetry (DSC) coincide with those of the mechanical properties. Tailoring properties of PLA/CNF are only reproducible in case of homogenously distributed CNF within the PLA matrix and by an improved interphase adhesion between PLA and CNFac.

Polymer Nanocomposite Film with Metal Rich Surface Prepared by In Situ Single-Step Formation of Palladium Nanoparticles: An Interesting Way to Combine Specific Functional Properties.

This paper presents a continuous single-step route that permits preparation of a thermostable polymer/metal nanocomposite film and to combine different functional properties in a unique material. More precisely, palladium nanoparticles are in situ generated in a polyimide matrix thanks to a designed curing cycle which is applied to a polyamic acid/metal precursor solution cast on a glass plate. A metal-rich surface layer which is strongly bonded to the bulk film is formed in addition to homogeneously dispersed metal nanoparticles. This specific morphology leads to obtaining an optically reflective film. The metal nanoparticles act as gas diffusion barriers for helium, oxygen, and carbon dioxide; they induce a tortuosity effect which allows dividing the gas permeation coefficients by a factor near to 2 with respect to the neat polyimide matrix. Moreover, the ability of the in situ synthesized palladium nanoparticles to entrap hydrogen is evidenced. The nanocomposite film properties can be modulated as a function of the location of the film metal-rich surface with respect to the hydrogen feed. The synthesized nanocomposite could represent a major interest for a wide variety of applications, from specific coatings for aerospace or automotive industry, to catalysis applications or sensors.

Novel nanofibrillated cellulose/polyvinylpyrrolidone/silver nanoparticles films with electrical conductivity properties

Nanofibrillated cellulose (NFC) isolated from rice straw pulp was used with polyvinylpyrrolidone (PVP) and silver nanoparticles (AgNPs) to prepare nanocomposites in the form of flexible films. The later films have promising mechanical and electrical conductivity properties. The isolated cellulose nanofibers were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Silver nanoparticles prepared via in-situ reduction in PVP were characterized using TEM and UV–vis spectroscopy. Tensile properties, microscopic structure, and electrical properties of nanocomposites films were studied. TEM and UV–vis spectroscopy proved the in-situ formation of AgNPs in PVP matrix. Films with good flexibility and tensile strength properties could be obtained from NFC/PVP/AgNPs as revealed from the (SEM) images and tensile properties testing. The electrical conductivity of NFC/PVP/AgNPs supports this system to be an excellent choice for sensitive electronic components packing as it can be used as antistatic and electrostatic dissipative materials.

Influences of Space Irradiations on the Structure and Properties of MoS2/DLC Lubricant Film

This work aims at revealing the influences of space irradiations [including the atomic oxygen (AO) and ultraviolet (UV) irradiations] on the MoS2/DLC solid lubricating film. The changes on microstructure, mechanical and vacuum tribological properties of nanocomposite films after irradiations have been systematically investigated. It is found that the AO irradiation mainly induces the surface oxidation of the film, whereas some oxygen atoms can erode the bulk film along the defects highway; thus, the connectivity of carbon atoms is improved. In contrast, the UV irradiation may break the carbon bonds and functional groups, as well as induce a secondary radical formation, which accelerates the broken and recombination of the carbon chain scission. Specially, the films after irradiations exhibit much higher hardness (>19 GPa), lower friction coefficient (<0.02) and wear rate compared with the original one. The excellent tribological properties of the films after irradiations can be attributed to the synergistic effect of the high sp 3 C content and good crystallization of MoS2 in the film, which cause the lower carbon and higher MoS2 content in the wear debris at the contact interface.

Characterization of nanocomposite film based on chitosan intercalated in clay platelets by electron beam irradiation

Different electron beam doses (10, 20, 30 and 40kGy) were tested with the purpose of investigating their influences on chitosan/clay (cloisite 20A) nanocomposite film to improve its functional performance by providing a crosslinked matrix. Water resistance, water contact angle and water barrier property of nanocomposite film were increased up to 30kGy, and then drastically decreased at the level of 40kGy. Characteristic diffraction peak of chitosan shifted to low angle with an increase in the interlayer spacing of the nanoclay after 30kGy irradiation, indicating a superlative intercalation. Crystallinity degree of chitosan/clay nanocomposite was increased in the amorphous region as the irradiation dose increased up to 30kGy. However, irradiation at level of 40kGy was converted the crystalline region of nanocomposite film to the amorphous state with losing the chitosan crystallinity. Irradiation increased the film tensile strength due to crosslinking of chitosan chains, with more pronounced effect at 30kGy and decreased it by chain degradation at 40kGy. A glass transition temperature was detected in DSC thermogram of chitosan/clay film, and it shifted to higher temperatures as the irradiation dose increased. Moreover, cold-crystallization exothermic peak of the chitosan/clay film moved to the lower temperature after irradiation, suggesting a faster crystallization rate. FE-SEM showed that the chitosan chains were more intercalated between the nanoclay platelets with increasing the irradiation dose. A progressive decrease in the roughness parameters of 20 and 30kGy irradiated nanocomposite films revealed by atomic force microscopy, whereas irradiation at 40kGy increased roughness values.

Investigation of polyethylene‐grafted‐maleic anhydride presence as a compatibilizer on various properties of nanocomposite films based on polyethylene/ethylene vinyl alcohol/ nanoclay

High oxygen barrier films were prepared based on low‐density polyethylene (LDPE)/ethylene vinyl alcohol (EVOH)/ nanoclay and polyethylene‐grafted‐maleic anhydride (LDPE‐g‐MA) as a compatibilizer. Box–Behnken statistical experiment design methodology was employed to study the effects of nanoclay, LDPE‐g‐MA, and EVOH presence and their contents on various properties of the final films. The R2 parameter varied between 0.89 and 0.99 for all the obtained responses. The morphology of the samples was evaluated. Results of oxygen transfer rate (OTR) test indicated that the addition of EVOH up to 30 wt% to neat LDPE can decrease oxygen permeability significantly. The addition of nanoclay also decreased the permeability of resulting films but, LDPE‐g‐MA reduced the permeability of the films only at an optimal content. Elastic modulus was increased with the addition of nanoclay, EVOH, and LDPE‐g‐MA to the matrix. An increase in EVOH content in the samples improved the tensile strength. Effect of nanoclay on tensile strength was highly dependent on the presence of a compatibilizer. The addition of compatibilizer to the samples and increasing its content enhanced the tensile strength of the specimens. Incorporation of nanoclay, EVOH, and LDPE‐g‐MA to the LDPE matrix and increasing the amount of these components in the samples led to higher storage modulus, zero shear rate viscosity, and shear thinning exponent, but, lowered the terminal slope and the frequency of intersection point of storage modulus (G′) and loss modulus (G″). The only exception was that EVOH increment resulted in a lower shear thinning exponent. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Mechanical and Thermal Properties of Clay-poly(norbornene) Nanocomposites from Ruthenium Alkylidene-mediated Surface-initiated Polymerization

In this work, the mechanical and thermal properties of nanocomposite films prepared from the surface-initiated polymerization of norbornene mediated by a surface-bound ruthenium alkylidine catalyst were investigated. Thermal gravimetric and dynamic mechanical analyses revealed enhanced properties of the resulting nanocomposite films over that of the unfilled polymer.

Synthesis and photoluminescence enhancement of nano-PAA-ZnCl2 with controllable dimension and morphology

One kind of ZnCl2 nano-films with controllable dimension and morphology is successfully synthesized on the top surface of nano-porous anodic alumina membrane (nano-PAAM) by self-organized method. The nano-PAA-ZnCl2 composite films are characterized by field emission scanning electron microscopy, energy dispersive spectrometer, and laser confocal Raman spectroscopy. The results indicate that the concentration of initial ZnCl2 solution, the depth of nano-PAAM substrate and the growth time of ZnCl2 crystals have important influences on the properties of nano-composite films. Furthermore, the characteristics of nano-composites such as the photoluminescence (PL) spectra are investigated. Compared with the nano-PAAM substrate, at room temperature, all of the nano-PAA-ZnCl2 composite films have both the same excitation center (335nm) and emission center (430nm), no matter what the nano-composite morphologies being; and the PL intensity of nano-PAA-ZnCl2 composite films are all enhanced and the maximum enhancement is two times; after annealing at 500°C, the emission spectra of the nano-composite films stabilized at the 385nm, 402nm and 430nm. The research provides a new, simple, economical and practical technology to fabricate nano-PAA composite films with higher luminousintensity.