Functionalized graphene/thermoplastic polyester elastomer nanocomposites by reactive extrusion‐based masterbatch: preparation and properties reinforcement

A reactive extrusion process was developed to fabricate polymer/graphene nanocomposites with good dispersion of graphene sheets in the polymer matrix. The functionalized graphene nanosheet (f‐GNS) activated by diphenylmethane diisocyanate was incorporated in thermoplastic polyester elastomer (TPEE) by reactive extrusion process to produce the TPEE/f‐GNS masterbatch. And then, the TPEE/f‐GNS nanocomposites in different ratios were prepared by masterbatch‐based melt blending. The structure and morphology of functionalized graphene were characterized by Fourier transform infrared, X‐ray photoelectron spectroscopy, X‐ray diffraction and transmission electron microscopy (TEM). The incorporation of f‐GNS significantly improved the mechanical, thermal and crystallization properties of TPEE. With the incorporation of only 0.1 wt% f‐GNS, the tensile strength and elongation at break of nanocomposites were increased by 47.6% and 30.8%, respectively, compared with those of pristine TPEE. Moreover, the degradation temperature for 10 wt% mass loss, storage modulus at ?70°C and crystallization peak temperature (T_cp) of TPEE nanocomposites were consistently improved by 17°C, 7.5% and 36°C. The remarkable reinforcements in mechanical and thermal properties were attributed to the homogeneous dispersion and strong interfacial adhesion of f‐GNS in the TPEE matrix. The functionalization of graphene was beneficial to the improvement of mechanical properties because of the relatively well dispersion of graphene sheets in TPEE matrix, as suggested in the TEM images. This simple and effective approach consisting of chemical functionalization of graphene, reactive extrusion and masterbatch‐based melt blending process is believed to offer possibilities for broadening the graphene applications in the field of polymer processing. Copyright © 2014 John Wiley & Sons, Ltd.     

Tensile,fatigue and thermomechanical properties of poly(ethylene-co-vinyl acetate) nanocomposites incorporating low and high loadings of pre-swelled organically modified montmorillonite

The production of exfoliated polymer/clay based nanocomposites is crucial to obtain an actual benefit of nanoscale reinforcement in the polymer matrix. In this project, the production of exfoliated polymer/clay nanocomposite was aimed through the use of poly(ethylene-co-vinyl acetate) (EVA) copolymer as matrix and organically modified montmorillonite (O-MMT) as nanofiller. The research work involved the use of pre-swelled technique through magnetic stirring and ultra-sonication to obtain more readily exfoliated and dispersed O-MMT nanofiller for EVA nanocomposite production. The aims were to allow the improvement in O-MMT exfoliation and dispersion when the nanofiller was incorporated in high loading (greater than 3 wt%) into the copolymer. The original and pre-swelled O-MMTs were employed to produce the EVA/O-MMT nanocomposites with 1, 3, 5, 7 and 9 wt% nanofiller by melt compounding technique. The results of TEM, tensile and fatigue tests, XRD, FTIR and DMA proved that the pre-swelling technique applied on the O-MMT before melt compounding with the EVA copolymer can bring positive impact to the performance of the nanocomposite. As opposed to the original O-MMT, the pre-swelled O-MMT has the ability to improve the tensile toughness, cyclic stability and storage modulus of the EVA copolymer even when high O-MMT loading (7 wt %) was employed. Improvement in the EVA - O-MMT interactions in the nanocomposite system was postulated to be the main reason for such observations.     

Effect of modified graphene and microwave irradiation on the mechanical and thermal properties of poly(styrene‐co‐methyl methacrylate)/graphene nanocomposites

The effect of modified graphene (MG) and microwave irradiation on the interaction between graphene (G) and poly(styrene‐co‐methyl meth acrylate) [P(S‐co‐MMA)] polymer matrix has been studied in this article. Modification of graphene was performed using nitric acid. P(S‐co‐MMA) polymer was blended via melt blending with pristine and MG. The resultant nanocomposites were irradiated under microwave at three different time intervals (5, 10, and 20 min). Compared to pristine graphene, MG showed improved interaction with P(S‐co‐MMA) polymer (P) after melt mixing and microwave irradiation. The mechanism of improved dispersion and interaction of modified graphene with P(S‐co‐MMA) polymer matrix during melt mixing and microwave irradiation is due to the presence of oxygen functionalities on the surface of MG as confirmed from Fourier transform infrared spectroscopy. The formation of defects on modified graphene and free radicals on P(S‐co‐MMA) polymer chains after irradiation as explained by Raman spectroscopy and X‐Ray diffraction studies. The nanocomposites with 0.1 wt% G and MG have shown a 26% and 38% increase in storage modulus. After irradiation (10 min), the storage modulus further improved to 11.9% and 27.6% of nanocomposites. The glass transition temperature of nanocomposites also improved considerably after melt mixing and microwave irradiation (but only for polymer MG nanocomposite). However, at higher irradiation time (20 min), degradation of polymer nanocomposites occurred. State of creation of crosslink network after 10 min of irradiation and degradation after 20 min of irradiation of nanocomposites was confirmed from SEM studies. Copyright © 2014 John Wiley & Sons, Ltd.     

Degradation of poly(ethylene terephthalate)/clay nanocomposites during melt extrusion: Effect of clay catalysis and chain extension

Organoclays with various contents of hydroxyl groups and absorbed ammonium were prepared and compounded with poly(ethylene terephthalate) (PET), forming PET/clay nanocomposites via melt extrusion. Dilute solution viscosity techniques were used to evaluate the level of molecular weight of PET/clay nanocomposites. Actually, a significant reduction in PET molecular weight was observed. The level of degradation depended on both the clay structure and surfactant chemistry in organoclays. The composites, based on clay with larger amount of hydroxyl groups on the edge of clay platelets, experienced much more degradation, because the hydroxyl groups acted as Brønsted acidic sites to accelerate polymer degradation. Furthermore, organoclays with different amounts of absorbed ammonium led to different extents of polymer degradation, depending upon the acidic sites produced by the Hofmann elimination reaction of ammonium. In addition, the composite with better clay dispersion state, which was considered as an increasing amount of clay surface and ammonium exposed to the PET matrix, experienced polymer degradation more seriously. To compensate for polymer degradation during melt extrusion, pyromellitic dianhydride (PMDA) was used as chain extender to increase the intrinsic viscosity of polymer matrix; more importantly, the addition of PMDA had little influence on the clay exfoliation state in PET/clay nanocomposites.     

Morphology and physical properties of poly(ethylene oxide) loaded graphene nanocomposites prepared by two different techniques

Organic–inorganic hybrids are artificially created structures presenting novel properties not exhibited by either of the component materials alone. In this contribution one addresses processing, morphology and properties of polymer nanocomposites reinforced graphene. First, synthesis routes to graphite oxide (GO) and foliated graphene sheets (FGS) are illustrated. Physical characterization of these graphene sheets were conducted using atomic force microscopy and X-ray diffraction techniques. Processing, structure and properties of graphene/poly(ethylene oxide) (PEO) nanocomposites are discussed. FGS was dispersed into PEO via two different composite manufacturing techniques: melt compounding and solvent mixing. Morphology of dispersed graphene and properties from different blending routes are compared. TEM showed that graphene distributed parallel to the composite surface using solvent method, while distributed randomly in melt blended method. Optical measurements indicated that the transparency of PEO/graphene prepared by solvent method is higher than that of melt blended method in the visible region. Electrical conductivity measurements are employed to evaluate threshold concentration for rigidity and connectivity percolation. The percolation concentration of the composites prepared by solvent method is less than those of melt blended method. The mechanical performance of the composites prepared by solvent method is higher than melt blended. Halpin–Tsai model has been used to confirm the distribution of the graphene into PEO by the two different processing techniques.     

Organo-modified montmorillonite/poly(?-caprolactone) nanocomposites prepared by melt intercalation in a twin-screw extruder

Nanocomposites based on biodegradable poly(?-caprolactone) organo-modified clay have been prepared by melt intercalation using a twin-screw extruder. The screw configuration developed allowed us to obtain an intercalated/exfoliated nanocomposite structure using a modified montmorillonite containing no polar groups, in contrast to previous work using mainly alkyl ammonium containing hydroxyl polar groups in poly(?-caprolactone). Montmorillonite nanocomposites were prepared using a specific extrusion profile from a 30 wt% masterbatch of organo-modified clay, which was then diluted at 1, 3 and 5%. Intercalated and/or exfoliated nanocomposites structures were assessed using rheological procedures and confirmed by transmission electron microscopy analysis. Mechanical and thermal properties were found to be strongly dependent on morphology and clay percentage. Crystallinity was only slightly affected by the clay addition. Effect of exfoliation on Young's modulus and thermal stability was investigated. Young's modulus increased significantly and onset degradation temperature measured by TGA was significantly reduced for an exfoliated nanocomposite composition containing 5 wt% organoclay.     

PREPARATION AND CHARACTERIZATION OF SOY PROTEIN ISOLATE(SPI)/MONTMORILLONITE(MMT) BIONANOCOMPOSITES

 The bionanocomposites of soy protein isolate (SPI)/montmorillonite (MMT) have been prepared successfully via simple melt mixing, in which MMT was used as nanofiller and glycerol was used as plasticizer. Their structures and properties were characterized with X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermogravimetric analysis and tensile testing. XRD、TEM and SEM results indicated that the MMT layers could be easily intercalated by the SPI matrix even by simple melt processing. The exfoliated MMT layers were randomly dispersed in the protein matrix as MMT content was low (less than 5 wt%), an incomplete exfoliation was evident from SEM results, and some primary particles were observed as the MMT content was high (from 5 wt% to 9 wt%). A significant improvement of the mechanical strength and thermal stability of SPI/MMT nanocomposites has been achieved. Our work suggests that simple melt processing is an efficient way to prepare SPI/MMT nanocomposites with exfoliated structure.     

Exfoliated high-impact polystyrene/MMT nanocomposites prepared using anchored cationic radical initiator-MMT hybrid

High-impact polystyrene (HIPS)/montmorillonite (MMT) nanocomposites were prepared via in-situ polymerization of styrene in the presence of polybutadiene, using intercalated cationic radical initiator-MMT hybrid. Incomplete exfoliation of the silicate layers in the HIPS nanocomposites was observed when a bulk polymerization was employed. On the other hand, the silicate layers were efficiently exfoliated in the PS matrix during a solution polymerization, due to the low extra-gallery viscosity, which can facilitate the diffusion of styrene monomers into the clay layers. The resulting exfoliated HIPS/MMT nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, particle size analysis, gel permeation chromatography, and dynamic mechanical analysis. The nanocomposites exhibited significant improvement in thermal and mechanical properties. For example, about 50% improvement in Young’s modulus was achieved with 5 wt% of clay, compared to the unmodified polymer counterpart.     

Exfoliation and Noncovalent Functionalization of Graphene Surface with Poly-N-Vinyl-2-Pyrrolidone by In Situ Polymerization

Heteroatom functionalization on a graphene surface can endow the physical and structural properties of graphene. Here, a one-step in situ polymerization method was used for the noncovalent functionalization of a graphene surface with poly-N-vinyl-2-pyrrolidone (PNVP) and the exfoliation of graphite into graphene sheets. The obtained graphene/poly-N-vinyl pyrrolidone (GPNVP) composite was thoroughly characterized. The surface morphology of GPNVP was observed using field emission scanning electron microscopy and high-resolution transmission electron microscopy. Raman spectroscopy and X-ray diffraction studies were carried out to check for the exfoliation of graphite into graphene sheets. Thermogravimetric analysis was performed to calculate the amount of PNVP on the graphene surface in the GPNVP composite. The successful formation of the GPNVP composite and functionalization of the graphene surface was confirmed by various studies. The cyclic voltammetry measurement at different scan rates (5–500 mV/s) and electrochemical impedance spectroscopy study of the GPNVP composite were performed in the typical three-electrode system. The GPNVP composite has excellent rate capability with the capacitive property. This study demonstrates the one-pot preparation of exfoliation and functionalization of a graphene surface with the heterocyclic polymer PNVP; the resulting GPNVP composite will be an ideal candidate for various electrochemical applications.     

Cold‐drawn induced microstructure in PVC‐bentonite nanocomposites

The mechanical properties and cold drawn‐induced micro and nanostructure of polyvinyl chloride (PVC)‐bentonite nanocomposites have been investigated. Molded sheets with 5 wt% concentration of bentonite and two processing additives were melt extruded and two‐roll‐milled processed. The flame retardant additive promoted polymer intercalation whereas a pigment dispersant promoted clay exfoliation, the polymer matrix showed isotropic orientation. The intercalated nanocomposite exhibited nanoplates oriented with their planes parallel to the molded sheet surface and the Young's modulus and yield stress were significantly enhanced relative to neat PVC. The strain at fracture (～144%) was slightly reduced relative to the matrix (～167%). Cold drawing induced molecular chain orientation along the tensile axis and preserved the orientation of the intercalated nanoclays. The fracture mechanism, as investigated via scanning electron microscopy (SEM) revealed plastic fracture mechanism (similar to neat PVC). On the other hand, the exfoliated nanocomposite did not show any improvement in mechanical properties but rather a significant decay of strain at fracture (～44%). The fractured region, as examined by SEM, exhibited microvoid morphology. Analysis of the fractured region showed PVC macromolecules oriented along the tensile axis but no preferred orientation of the nanoclays. The limited strain at fracture found for this material appears to be associated with the initially randomly oriented nanoclays being unable to orient under the tensile deformation. The nanoclays would act as stress concentrators leading to rapid material's failure due to loss of adhesion with the polymer matrix. The results suggest that exfoliated nanoclays could play a detrimental role when the nanocomposite is subjected to large deformations at temperatures well within the glassy regime. Copyright © 2009 John Wiley & Sons, Ltd.     

Thermal Degradation Kinetics and Modeling Study of Ultra High Molecular Weight Polyethylene (UHMWP)/Graphene Nanocomposite

The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (E_a) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.     

Poly(butylene succinate) and graphene nanoplatelet–based sustainable functional nanocomposite materials: structure-properties relationship

Sustainable functional polymer nanocomposites from renewable resources are extremely promising materials that can provide the next-generation of lightweight, multifunctional materials for several applications including energy storage, automotive, construction, defense, aerospace, consumer products, biomedical and functional coatings to name few. There is limited information on the use of sustainable polymers and graphene nanoplatelets (GNs), as well as the combinations of these two can provide reduced water permeability or enhanced electrical conductivity and improved thermal properties, and so on. Building upon this hypothesis, biobased poly(butylene succinate)/few-layer GN nanocomposites were prepared via a solventless melt-blending technique. Different characterization techniques such as differential scanning calorimetery, thermogravimetric analysis, dynamic mechanical analysis, dielectric spectroscopy, X-ray diffraction (XRD) and hot stage optical microscopy were used to study the thermal and structural characteristics. The melt blending was characterized by torque and temperature curves which showed that torque was reduced by up to 15 Nm, and melt temperature was improved by up to 5 °C. The improved crystallization of the composites in low concentrations of GN was observed. Graphene has been found to increase the crystallization temperature up to 10 °C and yielded pronounced spherulite structure, whereas peak shift was observed in XRD. High filler loading from 0.5 to 6.0 wt% was used to obtain more insights for few-layer graphene applications for thermoplastic polymer processing applications.     

Novel Poly(vinyl alcohol)/Chitosan/Modified Graphene Oxide Biocomposite for Wound Dressing Application

Rapid absorption of wound exudate and prevention of wound infection are prerequisites for wound dressing to accelerate wound healing. In this study, a novel kind of promising wound dressing is developed by incorporating polyhexamethylene guanidine (PHMG)‐modified graphene oxide (mGO) into the poly(vinyl alcohol)/chitosan (PVA/CS) matrix, conferring the dressing the required mechanical properties, higher water vapor transmission rate (WVTR), less swelling time, improved antibacterial activity, and more cell proliferation compared to the PVA/CS film crosslinked by genipin. In vivo experiments indicate that the PVA/CS/mGO composite film can accelerate wound healing via enhancement of the re‐epithelialization. PVA/CS/mGO composite film with 0.5 wt% mGO sheets displays the best wound healing properties, as manifested by the 50% higher antibacterial rate compared to GO and the wound healing rate of the mouse using this dressing is about 41% faster than the control group and 31% faster than the pure PVA/CS dressing. The underlying mechanism of the accelerated wound healing properties may be a result of the improved antibacterial ability to eradicate pathogenic bacteria on the wound area and maintain an appropriate moist aseptic wound healing environment to accelerate re‐epithelialization. These findings suggest that this novel composite PVA/CS/mGO film may have promising applications in wound dressing.     

Effective preparation of montmorillonite/polyurethane nanocomposites by introducing cationic groups into the polyurethane main chain

In this study, the effect of introducing a small amount of cationic groups into the polymer main chain on the exfoliation of montmorillonite (MMT) and the physical properties of the subsequent MMT/polymer nanocomposites were investigated. As a matrix polymer, a polyurethane cationomer (PUC) containing 3 mol% of quaternary ammonium groups was synthesized and MMT/PUC nanocomposites containing various amounts of MMT were prepared by the solution intercalation method. From the WAXS and TEM analyses, it was found that the MMT layers were completely exfoliated and dispersed in the PUC matrix. The Young’s modulus of the MMT/PUC nanocomposites significantly increased with increasing MMT content, but their elongation at break and maximum stress were maintained at a level close to that of the PU only at an MMT content of 1 wt% and decreased as the content of MMT increased above this level. The phase separation of the MMT/PUC nanocomposites was retarded with increasing content of MMT, due to the strong interactions between the PUC chains and the exfoliated MMT layers. It was found that the presence of small amounts of cationic groups in the main chain of the matrix polymer was very effective in facilitating the preparation of the MMT/polymer nanocomposites.     

Preparation and characterization of glass fiber–reinforced polyethylene terephthalate/linear low density polyethylene (GF‐PET/LLDPE) composites

Polyethylene terephthalate (PET) was melt blended with linear low density polyethylene (LLDPE) and subsequently compounded with glass fibers (GF) as reinforcements at percentages ranging from 15 to 45 wt% of LLDPE and 5 to 30 wt% of GF. Thermal, morphological, and mechanical properties of the prepared composites were investigated. It was found that compounding PET/LLDPE blends with GF would be beneficial in producing composites that are thermally stable with good mechanical properties. For example, the impact strength of the composites containing 85/15 wt% (PET/LLDPE) at relatively high loading of GF, ie, from 15 to 30 wt%, was higher than that of the GF‐reinforced neat PET. When increasing the percentage of LLDPE in the composites, the impact strength increased with increasing GF content, and this was also better than that of GF‐reinforced PET whose impact strength drastically decreased upon increasing the GF%. The improvement in mechanical properties of the composite, we suggest, should be correlated with the morphologies of the composites where the visualized interface adhesion tended to be better at higher loadings of both LLDPE and GF.     

Effect of new melamine-terephthaldehyde resin modified graphene oxide on thermal and mechanical properties of PVC

In this study a new melamine-terephthaldehyde resin modified graphene oxide was synthesized and used as a reinforcement of poly(vinyl chloride) (PVC). Characterization, morphology, thermal and mechanical properties of the nanocomposites were examined by means of attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray diffraction, field emission-scanning electron microscopy, thermogravimetric analysis, differential scanning calorimeter and tensile properties. The first hydrochloric acid releasing data of poly(vinyl chloride) was removed by incorporation of the modified graphene oxide as compare to the neat polymer. The temperatures at 2 wt% losses, main decomposition temperatures, maximum decomposition temperatures, also shift to higher temperature in the corresponding nanocomposites as compared to the neat PVC. The tensile strength and elongation at break of the nanocomposite films was increased as compared to the neat PVC. The interesting results in crystallinity of PVC were observed with adding 5 wt% of the modified graphene oxide.     

A dense graphene monolith with poloxamer prefunctionalization enabling aqueous redispersion to obtain solubilized graphene sheets

The realization of good aqueous dispersibility of commercial graphene products composed of exfoliated graphene sheets is of significance for downstream applications. However, the tap density of commercial graphene powder is quite low (0.03–0.1 kg/m³), meaning that 1 kg graphene powder occupies about 10–30 m³ in volume during transportation. And, the available content of commercial graphene dispersion/slurry in aqueous medium cannot exceed 5 wt%, although the density is high (≈ 1050 kg/m³). In this work, a graphene monolith was prepared by oven-drying of graphene sheets prefunctionalized with poloxamer surfactants. Our graphene monoliths not only have a high density (1500 kg/m³) and high graphene content (≈ 10 wt%), but also a full capability to be completely redispersed (≈ 100%) in water by bath sonication to obtain solubilized graphene sheets, whose lateral size and thickness are unchanged compared to as-exfoliated ones. Moreover, a simple empirical method was proposed to predict the redispersion capability of graphene monoliths using different poloxamers by contact angle measurements. Our results provide a universal approach to make exfoliated graphene-based products with better downstream availability and lower transportation cost.     

Covalent polymeric modification of graphene nanosheets via surface‐initiated single‐electron‐transfer living radical polymerization

Graphene nanosheets offer intriguing electronic, thermal, and mechanical properties and are expected to find a variety of applications in high‐performance nanocomposite materials. Dispersal of graphene nanosheets in polymer hosts and precise interface control are challenging due to their strong interlayer cohesive energy and surface inertia. Here, an efficient strategy is presented for growing polymers directly from the surface of reduced graphene oxide (GO). This method involves the covalent attachment of Br‐containing initiating groups onto the surface of hydrazine hydrate reduced GO via a diazonium addition and the succeeding linking of poly(tert‐butyl methacrylate) (PtBMA) chains (71.7 wt % grafting efficiency) via surface‐initiated single‐electron‐transfer living radical polymerization (SET‐LRP) to graphene nanosheets. The resulting materials were characterized by using a range of testing techniques and it was proved that polymer chains were successfully introduced to the surface of exfoliated graphene sheets. After grafting with PtBMA, the modified graphene sheets still maintained the separated single layers, and the dispersibility was improved significantly. The method is believed to offer possibilities for optimizing the processing properties and interface structure of graphene–polymer nanocomposites. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Facile solvothermal synthesis of graphene-MnOOH nanocomposites

In this paper, we report a facile solvothermal route capable of aligning MnOOH nanocrystals on graphene. X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations indicate that the exfoliated graphene sheets are decorated randomly by MnOOH nanocrystals, forming well-dispersed graphene-MnOOH nanocomposites. Dissolution-crystallization and oriented attachment are speculated to be the vital mechanisms in the synthetic process. The attachment of additives, such as MnOOH nanoparticles, are found to be beneficial for the exfoliation of GO as well as preventing the restack of graphene sheets. Moreover, cyclic voltammetry (CV) analyses suggest that the electrochemical reversibility is improved by anchoring MnOOH on graphene. Notably, the as-fabricated nanocomposites reveal unusual catalytic performance for the thermal decomposition of ammonium perchlorate (AP) due to the concerted effects of graphene and MnOOH. This template-free method is easy to reproduce, and the process proceeds at a low temperature and can be readily extended to prepare other graphene-based nanocomposites.     

Preparation and characterization of corn starch/soy protein biocomposite film reinforced with graphene and graphene oxide nanoplatelets

Corn starch (CS) and soy protein isolate (SPI), as inexpensive, abundant, and biodegradable materials, can chemically interact well with each other to produce biofilms. However, to overcome some of their physical and mechanical limitations, it is preferred to use their composite form, employing reinforcing materials. In this study, initially, graphene (G) and graphene oxide (GO) were synthesized by a green method. Then, to enhance the polymer blend final properties, the effects of adding G and GO in the range of 0.5 to 2 wt% on physical and mechanical properties of starch/protein blend were investigated. The results showed that the presence of 0.5‐wt% G and 2‐wt% GO significantly increased the modulus of starch/protein film from 252 to 578 and 449 MPa, respectively. In addition, the thermal stability of CS/SPI/GO (2 wt%) composite film was 50°C to 60°C more than that of the pure starch/protein film. On the other hand, G‐reinforced composite films tended to decline water diffusion compared with the pure polymer film. In addition, the composite film with 2‐wt% GO content had the lowest oxygen permeation rate (3.48 cm³ μm/m²d kpa) among the other composite films.