Polyethylene Nanocomposite Films Research Articles

Facile fabrication of ultrastrong polyethylene nanocomposite films with low filler content via flow-driven graphene re-dispersion assisted crystallization

Fabrication of polymer films with superb mechanical properties is far from mature compared to that of fibers, hampering the further engineering applications of lightweight polymer materials. Herein, high density polyethylene (HDPE) films reinforced with re-dispersed or refined reduced graphene oxide (rGO) are prepared via a facile melt-stretching strategy. The incorporation of only 0.2 wt% rGO is demonstrated to endow the melt-stretched film (80× stretch ratio) with ultrahigh Young's modulus of 2.9 GPa and tensile strength of 162.2 MPa, which are comparable to many engineering plastics and also significantly superior to the existing HDPE/graphene composites. More importantly, these modulus and strength values are increased by 71 and 65% compared to the neat PE (80×), respectively, far more than the theoretical prediction with the mixing rule. Experimental characterizations indicate that the high-efficient mechanical enhancement is attributed to the strong synergy of melt stretching-driven crystallization and rGO re-dispersion or refinement in constructing the compact and robust shish-kebabs crystal network. Such microstructural characteristics greatly promote the load transfer along the covalently bonded molecular chains, and also from polymer to rigid fillers under loading. Furthermore, the excellent puncture resistance and thermo-mechanical properties of PE/rGO films have been demonstrated. This work provides a feasible way towards scalable manufacturing of high-performance polymer nanocomposite films from general plastics and carbonaceous nanomaterials.

Evaluation of bioactive low‐density polyethylene (LDPE) nanocomposite films in combined treatment with irradiation on strawberry shelf‐life extension

A low-density polyethylene (LDPE) film reinforced with cellulose nanocrystals (CNCs) with an encapsulated bioactive formulation (cinnamon essential oil+silver nanoparticles) was developed for preservation of fresh strawberries. Antimicrobial activity of the active LDPE films was tested against Escherichia coli O157:H7, Salmonella typhimurium, Aspergillus niger, and Penicillium chrysogenum by agar volatilization assay. The optimal condition of the films showed ≥75% inhibitory capacity against the tested microbes. Strawberries were stored with different types of films: Group 1 (control): (LDPE+CNCs+Glycerol), Group 2: (LDPE+CNCs+Glycerol+AGPPH silver nanoparticles), Group 3: (LDPE+CNCs+Glycerol+cinnamon), Group 4: (LDPE+CNCs+Glycerol+active formulation), and Group 5: (LDPE+CNCs+Glycerol+active formulation+0.5kGy γ-radiation) at 4°C for 12 days. Weight loss (WL) (%), decay (%), firmness (N), color, and total phenolics and anthocyanin content of the strawberries were measured. Results showed that the most effective LDPE-nanocomposite film for reducing the microbial growth was LDPE+CNCs+Glycerol+active formulation film (Group 4). When combined with γ-irradiation (0.5kGy), the LDPE+CNCs+Glycerol+active formulation (Group 5) significantly reduced both decay and WL by 94%, as compared to the control samples after 12 days of storage. Total phenols (from 952 to 1711mg/kg) and anthocyanin content (from 185 to 287mg/kg) increased with storage time under the different treatments. The mechanical properties, water vapor permeability (WVP), and surface color of the films were also tested. Though the WVP of the films were not influenced by the types of antimicrobial agents, they did significantly (p≤0.05) change color and mechanical properties of the films. Therefore, combined treatment of active film and γ-irradiation has potential as an alternative method for extending the shelf-life of storage strawberries while maintaining fruit quality. PRACTICAL APPLICATION: Bioactive Low-density polyethylene (LDPE) nanocomposite film was developed in the study by incorporating active formulation (essential oil and silver nanoparticle) to extend the shelf life of stored strawberries. The bioactive LDPE-based nanocomposite film along with γ-irradiation could be used to preserve fruits for long-term storage by controlling the growth of foodborne pathogenic bacteria and spoilage fungi.

Development of linear low‐density polyethylene nanocomposite films for storage of sugarcane juice

AbstractSugarcane juice is a cheap and popular product in the beverage industry, with colors varying from light gray to dark green containing abundant amounts of polyphenolic compounds, ascorbic acid, minerals, and pigments. With ample sucrose content, sugarcane juice has evolved as the primary raw material for manufacturing 70% of the world's sugar content. Despite having high nutritional value, the shelf life of juice is a severe concern owing to the onset of microbial activities, which speeds up the fermentation process immediately after the extraction, which calls for appropriate packaging for delaying the qualitative degradation. For this purpose, the physicochemical properties, microbial stability, and color properties of “Mandya” variety sugarcane juice was ascertained upon storage in developed nanocomposite films made of linear low‐density polyethylene (LLDPE) by varying the levels of compatibilizer, nanoclay, and thickness. Upon evaluating the results, it was observed that the critical physicochemical attributes, namely, total soluble solids (TSS), pH, total sugars, and overall acceptability, were found to decrease with an increase in the level of nanoclay and compatibilizer and decrease in film thickness. Zero plate counts were observed till day 15 of storage, and a gradual increase was noticed in the further days. Correspondingly, an increase in the overall color difference with the progression of storage also occurred. It was concluded from the analysis that film of 100 μm thickness prepared from a combination of 93% LLDPE, 5% compatibilizer, and 2% nanoclay gave superior shelf life, minimum change in quality parameters, and least microbial population in sugarcane juice.Practical ApplicationFruit juice industries are interested in using packaging films with high tensile strength and low permeability instead of expensive glass bottles. Nanocomposite technology could be an effective tool for developing high‐barrier packaging material. LLDPE has many applications for developing both rigid form and flexible films. Most research studies on sugarcane juice preservation are confined to bottling, and there is a scarcity of information on the storage of sugarcane juice in pouches. In this context, the goal of the present study is to develop a cost‐effective packaging technology for the storage of sugarcane juice.

Silver-titanium polymeric nanocomposite non ecotoxic with bactericide activity.

In view of the intense interest in applications of silver nanoparticles in products for the medical field and in food preservation packaging due to their antimicrobial properties, the ecotoxicology of silver nanocomposites was evaluated in films. Test with the sea urchin Echinometra lucunter, to evaluate embryonic development and contamination by the action of silver and titanium nanoparticles in polyethylene nanocomposite films presents new results. The silver nanoparticle’s stability in polymeric materials can be enhanced by adding carriers, such as titanium dioxide and montmorillonite clay (MMT) without to producing one unfriendly material. For this research, low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE) were used processed in a twin-screw extruder, followed by gamma irradiation with 25 kGy and characterized by ecotoxicology assays, field emission scanning electron microscopy (FESEM), scanning electron microscopy and energy dispersive spectroscopy (SEM–EDX), differential scanning calorimetry (DSC), thermogravimetric analysis (TG), Raman spectroscopy (SERS) and mechanical properties. The antibacterial properties of the LDPE films were investigated against Escherichia coli and Staphylococcus aureus. The gamma irradiation had an important effect in the synthesis of silver nanoparticles resulting in bactericidal activity and the death of 100% of the tested bacteria. The evaluation of the environment was considered with the ecotoxicological investigation carried out. The results indicated that the polymeric films with silver nanoparticles and TiO2 do not contaminate the environment and neither interfere with the larval development of Echinometra lucunter. The obtained materials can be used in various applications with antimicrobial properties.Graphical

Photoresponsive Biomimetic Soft Robots Enabled by Near‐Infrared‐Driven and Ultrarobust Sandwich‐Structured Nanocomposite Films

Soft robots, intelligent structures built up of smart soft materials, are capable of being programmed to perform delicate work. Recently, plenty of biomimetic soft robots with functionalities of grasping, sensing, searching, and transporting have been exploited by emulating activities of living creatures adapting to ecological environments. However, mass production of biomimetic soft robots has remained a grand challenge while maintaining stable pre‐engineered functionalities under distinct circumstances, which significantly constrains their practical applications. To this end, a facile and scalable approach that can be utilized for mass‐producing sandwich‐structured photoresponsive polyimide (PI)/Au/low‐density polyethylene (LDPE) nanocomposite films is reported. Attributed to the remote and precise‐driven mode, reversible and stable actuation behavior, and the ultrarobust mechanical properties of the sandwich‐structured PI/Au/LDPE nanocomposite films, it was possible to devise a variety of photoresponsive biomimetic soft robots such as artificial flytrap, directionally moveable caterpillar‐inspired walker, and dolphin‐like cruisable and loadable swimmer via simply tailoring them into predesigned geometries.

Alkaline halloysite nanotubes/low density polyethylene nanocomposite films with increased ethylene absorption capacity: Applications in cherry tomato packaging

Halloysite nanotubes (HNTs) are hollow tubular clay nanoparticles used as nanofillers to remove or minimize the production of ethylene gas. The presence of ethylene gas leads to reduced shelf life in fruits and vegetables by accelerating postharvest softening and aging. Alkaline solution-treated HNTs have increased ethylene adsorption capacity due to an increased number of OH groups on the HNTs external surface. This study reports on the thermal, morphological, and mechanical properties of alkaline HNTs (ALK-HNTs) loaded into a low-density polyethylene (LDPE) matrix. Our results indicate that, although the mechanical properties of the LDPE matrix films were not improved with loading ALK-HNTs, the oxygen barrier property were improved and ethylene gas adsorption increased by 220 %. Cherry tomatoes packaged in a 3% ALK-HNTs/LDPE nanocomposite film and stored at 8 °C for 21 days showed a reduction in loss of firmness and weight by 17.0 % and 36.7 %, respectively.

Application of clay-TiO2 nanocomposite packaging films on pears (Prunus communis L. cv. Williams) under cold storage

Today, nanomaterials are presenting novel characteristics can be applied in developing new packaging with modified preferred properties. These are including the development of packaging with improved barrier characteristics which will extend the storage life of a product. In the present study, the effect of three types of developed low-density polyethylene nanocomposite films with two types of TiO2 (anatase and rutile) and clay (Closite 20A) nanoparticles were evaluated on the quality parameters of pear fruit (cv. ‘Williams’) during 48 days of storage at 4 °C. The Mechanical test revealed that the reinforcement in the presence of the nanocomposites was more than that with their conventional counterparts. The barrier properties against oxygen, carbon dioxide and water vapor of nanocomposite films were significantly decreased. The results showed that nanocomposite packaging film (NPFs) was a promising oxygen, carbon dioxide and water vapor barrier. Weight loss, firmness and the total solids content of pear in clay/TiO2-nanocomposite film decreased at the rates of 50%, 39% and 13%, respectively due to the modified atmosphere. Higher ascorbic acid content, lower ethylene production, reducing sugar content and PPO activity and higher POD of the packed fruits were observed in clay/TiO2-nanocomposite film. The single use of clay and TiO2 nanoparticles was not as effective as both of them in increasing durability of pear fruits. So, clay/TiO2-nanocomposite film can be considered as a practical approach to reduce the risk of pathogens, contamination and to improve the maintenance quality of pear fruit during the storage.

Characterization and tribological analysis of graphite/ultra high molecular weight polyethylene nanocomposite films

Wear of Ultra-High Molecular Weight Polyethylene (UHMWPE) plays an important role in medical industry. In this work the UHMWPE was reinforced with graphite nanoparticles at different concentrations. The nanocomposite films were prepared by cryo-milling followed by sintering. The mechanical test results showed that with increasing the graphite concentrations, Hardness, Young's modulus and the yield strength of the Graphite/UHMWPE composite increased, but the strain at fracture decreased. Hot pressed composite structures were characterized for their tribological behavior in a ball-on-disk tribometer using a normal load of 30 N. Graphite nanoplates reinforcement improved on the wear resistance, which is a combined effect of lubrication as well as toughening offered by graphite nanoplates. The best wear responses seen at lower concentrations of graphite viz. 0.1, 0.3 and 0.5 wt%. The prepared Graphite/UHMWPE composites could be an appropriate candidate to be used in joint articulations, where low friction and high wear resistance are required.

Cetylpyridinium bromide-modified montmorillonite as filler in low density polyethylene nanocomposite films

The development of clay polymer nanocomposites has been presented as an interesting alternative for design of new active food packaging materials. In this work, low density polyethylene (LDPE) nanocomposites with cetylpyridinium bromide (CPB) – modified montmorillonite (Mt) were developed. In a first stage, Mt. was modified with different CPB proportions based on cation exchange capacity (1:1 and 2:1), resulting in two different organoclays. These modified clays were hydrophobic and presented a good thermal stability that favored their capacity for extrusion to develop LDPE nanocomposites. Based on the incorporated organoclay, nanocomposite films showed important changes in morphology, and differences in mechanical properties, crystallinity, and gas permeability in comparison to polyethylene. All nanocomposites showed greater opacity than LDPE, however, their color changes did not exceed the visual perception limit. Finally, electrical conductivity (EC) measurements showed that CPB was able to migrate from the nanocomposite films to an aqueous food simulant. This behavior was dependent on the availably of free CPB in the matrix, its disposition in the organoclay and the organoclay distribution into the polymer matrix. These results highlight the migration of the surfactant from LDPE nanocomposites with Mt./CPB organoclays, making montmorillonite a potential surfactant carrier that increases compatibility and function in polymers allowing the generation of novel materials that could be used in the design of food packaging.

Fabrication and Characterization of Polyethylene Nanocomposite Films Containing Zinc Oxide (ZnO) Nanoparticles Synthesized by a Cost-Effective and Safe Method

ZnO nanoparticles were synthesized through a cost-effective and safe method followed by fabrication and characterization of polyethylene/ZnO nanocomposite films and investigation of their properties. The morphology and size of the synthesized nanoparticles were evaluated by field emission scanning electron microscopy (FE-SEM). It was found that nanoparticles with a plate-like morphology with an average thickness of 50-70 nm were synthesized. The nanocomposites were characterized by using Fourier transform infrared analysis (FTIR) and ultraviolet–visible spectroscopy (UV-VIS). In addition, the effects of the amount of zinc oxide nanoparticles (ZnO-NPs) on the mechanical properties of the films and particles and their antibacterial properties against a gram-negative bacterium (Escherichia coli) and gram-positive bacteria (Staphylococcus aureus) were investigated. In the case of nanoparticles, one more gram-positive bacterium (Staphylococcus aureus) was studied. The results demonstrated an inhibition of growth of all bacteria in a broth medium for both the nanoparticles and nanocomposites. The FE-SEM micrographs revealed that by increasing the nanofiller content an inferior quality of dispersion was obtained which was reflected in the lower tensile strength of the nanocomposites compared to the pure PE. It was demonstrated that the addition of poly ethylene graft maleic anhydride (PE-g-MA), as compatibiliser, improved the dispersion state of the nanoparticles and, consequently, the ultimate mechanical properties. In addition, it was shown that the fabricated nanocomposites exhibited considerable UV-shielding properties.

Innovative Linear Low Density Polyethylene Nanocomposite Films Reinforced with Organophilic Layered Double Hydroxides: Fabrication, Morphology and Enhanced Multifunctional Properties

Herein, we reported the successful development of novel nanocomposite films based on linear low density polyethylene (LLDPE) with enhanced anti-drop, optical, mechanical, thermal and water vapor barrier properties by introducing organophilic layered double hydroxides (OLDHs) nanosheets. OLDHs loadings were varied from 0–6 wt.%. Structural analyses using the Fourier transform infrared spectrum (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) indicated that the OLDHs nanosheets were homogeneously dispersed with an ordered alignment in the LLDPE matrix. The LLDPE film containing 2 wt.% OLDHs (denoted as OLDHs-2) showed the optimal mechanical, thermal and water vapor barrier properties, whilst the anti-drop and optical performance of the films improved with increasing OLDHs content. The enhanced antidrop properties of the composite films relative to pristine LLDPE can be expected to effectively reduce agricultural losses to disease when the films are applied as agricultural films, whilst the superior light transmittance and water-retaining properties of the composite films will boost agricultural production. Results presented suggest that multifunctional LLDPE/OLDHs nanocomposites show great promise as low cost agricultural plastic films.

Nanocomposite films containing organoclay nanoparticles as an antimicrobial (active) packaging for potential food application

Polyethylene nanocomposite films containing combinations of organoclay (OC) nanoparticles were prepared using extrusion molding method. The physical (X-ray diffraction [XRD] and scanning electron microscopy [SEM]), mechanical (tensile strength [TS] and elongation at break [E]) and antibacterial properties of the films against gram positive and gram negative bacteria were evaluated. XRD results showed an increase in basal reflection and intercalated-exfoliated structure prepared. SEM images revealed that Cloisite 20A had better compatibility with the polyethylene matrix in such way that it distributed homogenously in the matrix. Incorporating nanoparticles into polyethylene matrix significantly improved mechanical properties of the films in terms of TS and E parameters. Among used organoclays, Cloisite 30B, and Cloisite 15A had the most and the least antibacterial effect, respectively. A combination of three studied OCs revealed a more pronounced antibacterial effect than that of single or binary mode. Furthermore, its effect on gram negative Escherichia coli, was more pronounced than gram positive Staphylococcus aureus. Practical applications Nanocomposite films studied in this research provide bacteriostatic activities with improving mechanical properties. The main feature of this study was to use a mixture of nanoparticles for an enhanced antibacterial effect and, therefore, to reduce metallic nanoparticles' concentration in the obtained active films. Thus, such packaging material is suggested for potential use as an optimal choice for antimicrobial food packaging applications.

Rheological, structural, ultraviolet protection and oxygen barrier properties of linear low- density polyethylene films reinforced with zinc oxide (ZnO) nanoparticles

Abstract Linear low-density polyethylene (LLDPE) and zinc oxide (0–10%, w/w) nanocomposite (NC) films were produced through melt-mixing extrusion process. Both LLDPE and LLDPE/ZnO NC exhibited predominating liquid-like property in the lower frequency range, however, a distinct gel point was detected at higher frequency. At 10% loading of ZnO to LLDPE followed the time-temperature-superposition (TTS) principle adequately in the selected temperature range (140–170 °C). Tensile strength (TS) of the NC increased whereas the elongation at break (EAB) decreased with increasing loading concentration of ZnO. NC films showed lower transparency, b*-values (yellowness), and ΔE*-values (total color difference) than the control LLDPE film. Incorporation of ZnO improved the ultraviolet (UV) barrier properties whereas the oxygen transmission rate decreased significantly from about 11,000 to 8000 cm 3 /(m 2 24 h). X-ray diffraction (XRD) analysis confirmed the crystalline structure of the NC films, and an improvement in thermal stability was detected through thermogravimetric analysis. Scanning electron microscopy (SEM) exhibited well dispersion of nanoparticles in the NC matrix with a coarse film surface. Thus, LLDPE/ZnO nanocomposite films could be used as a food packaging material to prevent oxygen and UV induced lipid oxidation in food materials.

Mechanical and morphological investigation of virgin polyethylene and silver nanoparticle-loaded nanocomposites film: comprehensive analysis of kinetic models for non-isothermal crystallization

This research was accomplished to examine the mechanical, morphological and crystallization kinetics study of polyethylene/silver nanoparticles (Ag-NPs) nanocomposite films. In this research, low-density polyethylene (LDPE) nanocomposite films were prepared containing Ag-NPs using maleic-anhydride-grafted low-density polyethylene (LDPE-g-MAH) as a compatibilizer by the melt mixing process. From mechanical property evaluation, it is revealed that the LDPE/LDPE-g-MAH/Ag-NPs nanocomposite films showed decreased tensile strength as compared with virgin LDPE matrix. Thermal characteristics of the prepared virgin LDPE and its nanocomposite films were studied by differential scanning calorimetry (DSC). Comprehensive analysis of different kinetic models such as the Avrami and Mo model on non-isothermal crystallization kinetics was performed in order to correlate the rate of crystallization and its various kinetic parameters. Further, the macrokinetic equation as proposed by Malkin has been applied to describe the kinetics of crystallization in the light of the Avrami equation. Concerning virgin LDPE and Ag-NP-reinforced LDPE, the former shows primary crystallization, whereas the later exhibits both primary and secondary crystallization with varying Avrami exponents. Kinetic parameters are recognized, and confirm the influence of Ag-NPs on crystallization kinetics. X-ray diffraction spectroscopy and transmission electron microscopic analysis of the nanocomposite films were conducted to verify the dispersion of inorganic filler particles in the resulting hybrids.

Halloysite nanotubes reinforced ultrahigh molecular weight polyethylene nanocomposite films with different filler concentration and modification

Halloysite nanotube/ultrahigh molecular weight polyethylene (HNT/UHMWPE) nanocomposite films were prepared by melt extrusion and thermal extension methods, and the morphology, microstructure, thermal properties, mechanical properties and wettability of these nanocomposite films were investigated with respect to the effects of HNT concentration and modification. HNTs were homogenously distributed and formed self entangled network structures in the UHMWPE matrix. The incorporation of HNT obviously accelerates the crystallization and enhances the thermal stability, mechanical strength and wettability of UHMWPE. However, after HNT concentration exceeds a critical value, the crystallinity and mechanical strength of UHMWPE decrease due to the restriction of HNT obstacles and the existence of large HNT agglomerates. Surface modification of HNT is a good method to further improve the crystallization, thermal stability and mechanical property of UHMWPE nanocomposites, with reduction of nanotube aggregation and strengthening of interfacial bonding between nanotubes and matrix.

Barrier, Biodegradation, and mechanical properties of (Rice husk)/(Montmorillonite) hybrid filler-filled low-density polyethylene nanocomposite films

Rice husk (RH)/montmorillonite (MMT) hybrid filler-filled low-density polyethylene nanocomposite films were prepared by extrusion blown film. RH was used as a biodegradable filler in various concentrations (2, 5, and 7 parts per hundred composite), while the amount of MMT was held constant at 2 wt%. Delamination of MMT platelets and distribution of RH were investigated by X-ray diffraction and scanning electron microscopy. Diffractograms revealed the formation of intercalated structures, regardless of the RH content. Barrier properties revealed that MMT platelets have the potential to retard the diffusion of permeating molecules while, on the other hand, barrier efficiency of MMT is balanced by the subsequent incorporation of RH in RH/MMT hybrid filler-filled composite films. Despite an increase in permeability, the selectivity ratio (CO2/O2 permeability) increased with increasing RH contents in the hybrid filler-filled composite films showing the potential of these films in the development of modified atmosphere for fresh fruits and vegetables. The colonization of fungus and formation of holes as observed in micrographs of the test samples subjected to soil burial revealed that the biodegradation rate increased with the incorporation of RH in the hybrid composites. The composite films with higher contents of RH in hybrid filler are also more biodegradable than those having lower contents. Addition of RH contents in the hybrid filler increased the tensile modulus, while decreasing the tensile and tear strength. Addition of RH in the hybrid filler increased the melting and crystallization temperatures of the resulting nanocomposite films as well. J. VINYL ADDIT. TECHNOL., 23:162–171, 2017. © 2015 Society of Plastics Engineers

Effects of a combination of antimicrobial silver low density polyethylene nanocomposite films and modified atmosphere packaging on the shelf life of chicken breast fillets

Low-density polyethylene (LDPE) nanocomposite films containing different concentrations of silver (Ag) nanoparticles (NPs) (0.5 and 1% of polymer weight, w/w) were manufactured via extrusion and subsequently characterised. The microbiological quality of chicken breast fillets wrapped with Ag/LDPE nanocomposite films, followed by modified atmosphere packaging (using conventional laminates and employing a gas mix of 40% CO2:60% N2) were assessed. The tensile strength of Ag/LDPE nanocomposite films were significantly lower (p < 0.05) than control films (without Ag NPs), indicating that the presence of Ag NPs reduced the film strength. Independent of the concentration of Ag NPs used, Ag/LDPE nanocomposite films extended the shelf life of the chicken breast fillets and significantly (p < 0.05) enhanced oxidative stability compared to control films. The results indicated that LDPE nanocomposite films containing Ag NPs could potentially be used as antimicrobial packaging for food applications.

An investigation of the effects of organomodified-fluoromica on mechanical and barrier properties of compatibilized high density polyethylene nanocomposite films

Nanocomposite sheets based on high density polyethylene and containing organically modified fluoromica and three different compatibilizers (ethylene vinyl acetate copolymer and two maleic anhydride grafted high density polyethylene (HDPE-g-MA) grades with different melt flow indices) were prepared by melt mixing processing in an internal mixer. In order to evaluate the direct relationship between different properties of compression molded sheets and their microstructures, mechanical and barrier properties of the final nanocomposites were examined. Fluoromica content, compatibilizer type, and compatibilizer to clay ratio were changed to study the effects of different material variables on the final nanocomposite properties. A second-order polynomial function fitted well on experimental results and showed that the compatibilizer molecular weight played an important role in the morphology and consequently, the nanocomposite properties. Reducing the compatibilizer molecular weight resulted in better delamination and subsequent enhancement in mechanical and barrier properties. Optimization of various properties was done over the 16 designed experiments and 42% improvement in Young’s modulus and 30% reduction of permeability, compared to pristine high density polyethylene, were obtained for the optimal sample.

Preparation and Application of LDPE/ZnO Nanocomposites for Extending Shelf Life of Fresh Strawberries.

Strawberries have a very short post-harvest life mostly due to their relatively high water content, intense metabolic activity and susceptibility to microbial rot. Antimicrobial low-density polyethylene nanocomposite films containing ZnO nanoparticles at different mass fractions were prepared by melt mixing and followed by compression moulding using a hot press machine. Fresh strawberries were packed in nanocomposite films and stored at 4 °C. Their microbial stability, ascorbic acid content and titratable acidity were evaluated after 0, 4, 8, 12 and 16 days of storage. Microbial growth rate was significantly reduced up to 16 days as a result of the use of nanocomposite packaging material containing ZnO nanoparticles. By increasing the ZnO nanoparticle mass fraction to 5%, the antimicrobial activity of the film increased. All packages containing the ZnO nanoparticles kept the microbial load of fresh strawberries below the level that affects shelf life (5 log CFU/g) up to 16 days. The lowest degradation of ascorbic acid content (6.55 mg per 100 g), and loss of acidity (0.68%) were observed in packages containing 3% of ZnO nanoparticles with 10% polyethylene-grafted maleic anhydride.

Improved mechanical and barrier properties of low-density polyethylene nanocomposite films by incorporating hydrophobic graphene oxide nanosheets

The successful conversion from hydrophilic GONSs to hydrophobic ODA–GONSs imparts LDPE nanocomposite films with enhanced mechanical and barrier performances for potential packaging materials.