Mechanical Properties Of Films Research Articles

Effect of gamma irradiation on properties of the synthesized PANI-Cu nanoparticles assimilated into PS polymer for electromagnetic interference shielding application

Conductive polymer nanocomposites for electromagnetic interference (EMI) shielding are important materials that can be combat the increasingly dangerous radiation pollution arising from electronic equipment and our surrounding environment. In this work, we have synthesized polyaniline-copper nanoparticles (PANI-Cu NPs) by the copper salt based oxidative polymerization method at room temperature and then added with different concentration (0, 1, 3 and 5 wt%) in polystyrene polymer forming PS/ PANI-Cu nanocomposites films by means of the traditional solution casting technique. The formed PANI-Cu NPs were investigated by UV/Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and SEM/EDX elemental mapping techniques. On the other hand, the prepared PS/PANI-Cu nanocomposites films were evaluated by UV and SEM, the mechanical properties of the nanocomposites films were evaluated and showed an improvement by added PANI-Cu NPs up to 3 wt% and 50 kGy gamma exposure dose. The PS/PANI-Cu nanocomposites films were examined as electromagnetic interference shielding material. Electromagnetic shielding effectiveness of the produced nanocomposites were tested in the X-band of the radio frequency range namely from 8 to 12 GHz using the vector network analyzer (VNA) and a proper wave guide. All samples were studied before and after 50 kGy gamma-ray irradiation under the same condition of pressure and temperature. The results showed that the nanocomposites have improved shielding properties.

Design and evaluation of composite films for in situ synthesis and antibacterial activity of allicin vapour

AbstractAlthough allicin has potent antibiotic properties, its low stability, which is responsible for its persistent biological activity, has posed a significant challenge to its practical application in modern medicine. To harness the healing benefits of this phytochemical, known by humans for thousands of years, we propose a controlled in situ synthesis of allicin vapour near the site of infection. Considering the critical need for novel approaches to prevent pandemic scenarios caused by MDR bacteria, we suggest encapsulating and physically separating allicin precursors (substrate alliin and enzyme alliinase) in alginate-based films and spray-dried chitosan microparticles. The mechanical properties of the hydrogel films of various compositions were evaluated, as well as their ability to protect the encapsulated alliinase against thermal stress and control the overall rate of allicin release upon hydration. Furthermore, the non-contact antibacterial efficacy of free alliin/alliinase reaction mixture (aqueous solution) and three compartmentalised configurations, i.e. film-solution, film-particles, and double-film, were tested against selected bacterial strains, i.e. E. coli, S. epidermidis, and S. aureus. The results indicate that the formation of allicin vapour using the proposed compartmentalised systems addresses allicin’s stability issues and provides better control over the rate of allicin production. The observed antibacterial effect was comparable with directly formed allicin using higher initial amounts of both substances, which is given by diffusion limitations associated with encapsulation. These findings illustrate the potential of compartmentalised systems in developing nature-based wound dressings for infection prevention and promoting healing.

Fabrication and characterization of bacterial cellulose/carbon nanotube composite conductive film and its impact on the luminance of flexible electroluminescent devices as the bottom electrode

Flexible conductive films (BC/CNTs) were fabricated via a straightforward vacuum filtration method using bacterial cellulose (BC) as the substrate and single-walled carbon nanotubes (SWCNTs) as the conductive filler. The resulting BC/CNTs composite films were characterized for the morphology, structure, thermal properties and electrical conductivity using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and X-ray photoelectron spectroscopy (XPS). The study revealed that, the addition of SWCNTs significantly improved the mechanical properties of films. Among the BC/CNTs composite films, the one with the SWCNTs concentration of 0.36 wt% exhibited the best mechanical properties. Incorporating SWCNTs also enhanced the thermal stability and improved electrical conductivity of the composite films. Notably, higher SWCNTs concentrations led to better thermal stability and lower electrical resistance. Ultimately, these BC/CNTs composite films were successfully employed in flexible electroluminescent devices, demonstrating good luminescence.

Tunning the hydrophobic performance and thermal stability of pectin film by acetic anhydride esterification

Pectin, a polysaccharide found in plant cell walls, is characterized by a high abundance of hydroxyl groups and carboxylic acid groups, which results in a strong affinity for water and limits its suitability as a film material. This study aimed to modulate the esterification degree of PEC films by adjusting the concentration of acetic anhydride, and assess the impact of acetic anhydride esterification modification on the properties of the resultant PEC films. The results demonstrated successful grafting of acetic anhydride onto the galacturonic acid ring in the PEC molecule through the esterification process. The hydrophobicity, thermal stability, barrier properties, and mechanical properties of the esterified PEC films were investigated. Among the various concentrations tested, the E-PEC-0.25 film exhibited the highest contact angle of 103.46° and tensile strength of 33.44 MPa, showcasing optimal performance. The E-PEC-0.1 film achieved the highest esterification degree of 0.94 and elongation at a break of 21.11 %. It also exhibited the transparency of 11.66 and the lowest water vapor transmission rate of 0.56 g·mm/(m2·h·kpa). Additionally, TGA and DSC tests revealed enhanced thermal stability of the esterification-prepared films. These findings highlight the potential of acetic anhydride tuning as a promising strategy for optimizing pectin film production.

Development of Polymeric Films Based on Sunflower Seed Proteins and Locust Bean Gum.

Most polymeric food packaging materials are non-biodegradable and derived from petroleum, thus recent studies have focused on evaluating alternative biodegradable materials from renewable sources, with polysaccharides and proteins as the main types of employed biopolymers. Therefore, this study aimed to develop biopolymeric films based on sunflower proteins and galactomannans from locust bean gum. The influence of the galactomannan amount (0.10%, 0.30%, 0.50%, and 0.75% w/v) on the physicochemical, thermal, and mechanical properties of cast sunflower protein-based films was studied. Sunflower proteins gave rise to yellowish, shining, and translucid films. With the incorporation of locust bean gum-derived galactomannans, the films became more brown and opaque, although they still maintained some translucency. Galactomannans significantly changed the proteins' secondary structures, giving rise to films with increased tensile resistance and stretchability. Nevertheless, the increase in the galactomannan amount did not have a significant effect on the film's thermal stability. The protein/galactomannan-based films showed values of water vapor and oxygen permeability that were slightly higher than those of the pristine materials. Overall, blending locust bean gum galactomannans with sunflower proteins was revealed to be a promising strategy to develop naturally colored and translucid films with enhanced mechanical resistance while maintaining flexibility, fitting the desired properties for biodegradable food packaging materials.

Characterization of the Physical, Mechanical, and Morphological Properties of Films Generated from Cassava Pomace

The pollution of the environment caused by conventional packing materials such as plastic has driven the need for biodegradable alternatives. Although starch is an important component in the development of such materials, starch is not suited for use as a biodegradable packaging material due to global hunger challenges. The current study successfully utilized the major industrial waste of the cassava starch processing industry to develop biodegradable films. Three packaging materials were developed using the casting procedure, which involved combining various quantities of cassava pomace (CP) and plasticizer combinations. The developed films were analyzed to evaluate their characteristics, such as color, thickness, density, moisture content, solubility, swelling index, mechanical properties, microscopic, and FT-IR characteristics. In contrast, concerning multiple aspects, each of the films demonstrated unique characteristics. The film with the lowest CP (C1) appeared to be thinner and lighter in color; however, it tended to contain a greater amount of moisture. The C1 film exhibited an adhesive property that was wellsuited for use as cling film. The intermediate CP film (C2) stands out because of its excellent mechanical characteristics, including high tensile strength and elongation at break. These attributes make it particularly well-suited for packaging applications, such as the production of biodegradable bags. Conversely, the swelling index and thickness of the highest CP film (C3) outperform both other films, suggesting that it may have the capacity to absorb higher moisture content. The scanning electron microscopic images revealed a uniform surface for all three samples. However, the cross-sectional images of C3 indicated internal cracks that were consistent with the lowest mechanical characteristics and flexibility. Therefore, the C3 film is more suitable for packaging items like plates. These films can serve as a viable, environmentally friendly, and biodegradable alternative to conventional packaging materials. Keywords: Mechanical properties, cassava pomace, physical properties, biodegradable films, micro-structure properties

Effect of plasticizers on the rheological properties of xanthan gum - starch biodegradable films

The effect of plasticizers, namely glycerol, sorbitol, and citric acid, on the structural and mechanical properties of biodegradable films obtained from xanthan gum (XG) and starch was studied. The plasticizing effect of glycerol, sorbitol, and citric acid on XG-starch films is justified by the destruction of intermolecular contacts between starch and XG macromolecules and the redistribution of hydrogen bonds in the system as a result of the hydrotropic action of plasticizer molecules. The use of glycerol proved to be the most effective for regulating the deformation of films, while the use of sorbitol to preserve strength. The dependence of the film roughness on the type and concentration of plasticizers was characterized. The smallest values of protrusions on the surface of XG-starch films were found in the presence of sorbitol. Considering the effect of the concentration of plasticizers on the stickiness of the surface of XG-starch films and their structural and mechanical properties, 1.5 % concentration of glycerol, sorbitol and citric acid was determined as optimal.

Novel nanoemulsion-loaded hydroxyl propyl methyl cellulose films as bioactive food packaging materials containing Satureja khuzestanica essential oil

This study was conducted in response to a gap in the production of hydroxyl propyl methyl cellulose (HPMC) edible films from Satureja khuzestanica essential oil (SKEO) and to survey the preservation effect of natural edible films on the vapor phase. For these purpose varying concentrations of SKEO ranging from 1.25 % (EF1) to 7.5 % (EF5) led to producing different edible films for potential food packaging applications and the physicochemical, mechanical, and antimicrobial properties of edible films were evaluated across solid, liquid, and vapor phases. The incorporation of nanoemulsions into the polymer films led to an increase in thickness and opacity, while the addition of SKEO resulted in reduced water solubility without impacting film density. Notably, the antibacterial efficacy of the films was most pronounced against S. aureus, with a zone of inhibition measuring 41 ± 1 mm for EF5 on solid media. Time killing assays further demonstrated that specific formulations (EF3, EF4, and EF5) were capable of eradicating all microorganisms within 60 min. Moreover, SKEO edible films exhibited significant inhibitory effects against E. coli under refrigeration conditions (4 °C). These results highlighted the effect of herbal edible films in enhancing the functionality of bioactive food packaging technologies.

Conductive NR/PMMA-RAFT-CNT-rGO composites and their morphological, mechanical, and electrical properties

This study reports the synthesis of poly(methyl methacrylate) (PMMA)-carbon nanotube (CNT)-reduced graphene oxide (rGO) emulsions via reversible addition-fragmentation chain-transfer (RAFT)-mediated surfactant-free emulsion polymerization using a hydrophilic chain transfer agent. The rGO was prepared by the modified Hummers method and reduced with L-ascorbic acid. The effects of the CNT:rGO ratios and CNT and rGO contents on the conversion and stability of emulsion were investigated. Increasing the CNT and rGO contents from 1 to 4 wt% decreased the monomer conversion, while all the samples remained as colloidal dispersions. The morphology of PMMA-CNT-rGO composites showed the incorporated arrangement of a linear CNT portion connected with the rGO sheet dependent on the CNT:rGO ratio. Various PMMA-CNT-rGO filled natural rubber (NR) cast films were prepared. The NR/PMMA-CNT-rGO composite film with a 1 wt% filler loading at a CNT:rGO ratio of 1:1 presented a quite high modulus value (3.08 MPa) and sufficient intrinsic electrical conductivity (1.36 S/m) due to its strong filler-matrix interaction. Thus, the PMMA-RAFT-CNT-rGO composites at a very low filler content can be used as an effective reinforcement to enhance the mechanical and electrical properties of NR films with a high compatibility between the fillers and NR matrix.

The Effect of the DBD Cold Plasma Process on the Physicochemical, Mechanical, and Microbial Properties of the Biodegradable Packaging Film (Based on Gelatin-Sodium Alginate) Incorporated with AgNPs to Extend the Shelf Life of Trout Fish in the Refrigerator

The Effect of the DBD Cold Plasma Process on the Physicochemical, Mechanical, and Microbial Properties of the Biodegradable Packaging Film (Based on Gelatin-Sodium Alginate) Incorporated with AgNPs to Extend the Shelf Life of Trout Fish in the Refrigerator

Assessing the Effect of Twisting and Twisting Fatigue on ZnO:Al Thin Film Performance on PEN and PET Substrates

This study examines the electromechanical characteristics of aluminium-doped zinc oxide (AZO) films. The films were produced using the RF magnetron sputtering process with a consistent thickness of 150 nm on various polymer substrates. The study focuses on assessing the electro-mechanical failure processes of coated segments using flexible substrates, namely polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), with a specific emphasis on typical cracking and delamination occurrences. This examination involves conducting twisting deformation together with using standardised electrical resistance measurements and optical microscope monitoring instruments. It was found that the crack initiation angle is mostly dependent on the mechanical mismatch between the coating and substrate. Higher critical twisting angle values are observed for the AZO/PEN film during twisting testing. Relative to the perpendicular plane of the untwisted sample, it was found that cracks initiated at a twist angle equal to 42° ± 2.1° and 38° ± 1.7° for AZO/PEN and AZO/PET, respectively, and propagated along the sample length. SEM images indicate that the twisting motion results in deformation in the thin film material, leading to the presence of both types of stress in the film structure. These discoveries emphasise the significance of studying the mechanical properties of thin films under different stress conditions, as it can impact their performance and reliability in real-world applications. The electromechanical stability of AZO was found to be similar on both substrates during fatigue testing. Studying the electromechanical properties of various material combinations is important for selecting polymer substrates and predicting the durability of flexible electronic devices made from polyester.

Influence of Reduced Graphene Oxide and Carbon Nanotubes on the Structural, Electrical, and Photoluminescent Properties of Chitosan Films.

Chitosan is a biopolymer with unique properties that have attracted considerable attention in various scientific fields in recent decades. Although chitosan is known for its poor electrical and mechanical properties, there is interest in producing chitosan-based materials reinforced with carbon-based materials to impart exceptional properties such as high electrical conductivity and high Young's modulus. This study describes the synergistic effect of carbon-based materials, such as reduced graphene oxide and carbon nanotubes, in improving the electrical, optical, and mechanical properties of chitosan-based films. Our findings demonstrate that the incorporation of reduced graphene oxide influences the crystallinity of chitosan, which considerably impacts the mechanical properties of the films. However, the incorporation of a reduced graphene oxide-carbon nanotube complex not only significantly improves the mechanical properties but also significantly improves the optical and electrical properties, as was demonstrated from the photoluminescence studies and resistivity measurements employing the four-probe technique. This is a promising prospect for the synthesis of new materials, such as biopolymer films, with potential applications in optical, electrical, and biomedical bioengineering applications.

Characteristics of soy films as affected by transglutaminase cross-linking and inclusions of pectin and protein enhancers.

Previously, we showed that water extract (soymilk, except pH was increased to 8 from 6.5) of whole soybean could be used directly as a raw material for producing edible soy films by deposition of the film-forming solution (soy extract with enhancers). However, the strength of such soy films needed improvement because they were weak. The purpose of this study was to investigate how transglutaminase (TG) cross-linking reactions and film enhancers, including pectin (low- and high-methoxyl pectin), whey protein isolate (WPI), and soy protein isolate (SPI), improve the physical properties of soy films. Soy films prepared with TG had tensile strength (TS) of 3.01MPa and puncture strength (PS) of 0.78MPa, which were higher by as much as 51% and 30% than that of soy films without TG treatment, respectively. Pectin showed significant effects on the mechanical properties of TG-added soy films in terms of TS, PS, and % elongation. On the other hand, only TS and PS were increased by the addition of WPI or SPI. Heat curing had a significant effect on soy film's physical properties. TG treatment significantly reduced film solubility when soaked in water and various levels of acid (vinegar) and base (baking soda) solutions. Under the experimental conditions of 35 unit TG and 28min of reaction, the degrees of cross-linking were evidenced by the disappearance of individual protein subunits, except the basic subunit of glycinin, and the reduction of 21% of lysine residues of the proteins. HIGHLIGHTS: Edible soy films were made with transglutaminase and about 21% lysine cross-linked. The mechanical strength of soy films was increased by incorporating film enhancers. Transglutaminase enhanced the mechanical properties of soy films.

Clay Minerals and Biopolymers in Film Design: Overview of Properties and Applications

Research to replace petroleum-based plastics has been quite challenging. Currently, there is a lot of interest in biopolymers as an alternative. However, biopolymers do not have suitable mechanical properties when in film form, which limits their applications. To resolve this issue, clay minerals are being incorporated as a strategy. Clay minerals offer the films good barrier, thermal, rheological, optical, and mechanical properties. They can also work with other additives to promote antioxidant and antimicrobial activity. This brief review focuses on incorporating clay minerals with other nanofillers and bioactives to improve their physical, chemical, and functional characteristics. The synergy of these materials gives the films exceptional properties and makes them suitable for applications such as food coatings, packaging materials, dressings, and bandages for treating skin wounds.

A Stretchable and Tough Graphene Film Enabled by Mechanical Bond.

The pursuit of fabricating high-performance graphene films has aroused considerable attention due to their potential for practical applications. However, developing both stretchable and tough graphene films remains a formidable challenge. To address this issue, we herein introduce mechanical bond to comprehensively improve the mechanical properties of graphene films, utilizing [2]rotaxane as the bridging unit. Under external force, the [2]rotaxane cross-link undergoes intramolecular motion, releasing hidden chain and increasing the interlayer slip distance between graphene nanosheets. Compared with graphene films without [2]rotaxane cross-linking, the presence of mechanical bond not only boosted the strength of graphene films (247.3 vs 74.8 MPa) but also markedly promoted the tensile strain (23.6 vs 10.2 %) and toughness (23.9 vs 4.0 MJ/m3). Notably, the achieved tensile strain sets a record high and the toughness surpasses most reported results, rendering the graphene films suitable for applications as flexible electrodes. Even when the films were stretched within a 20 % strain and repeatedly bent vertically, the light-emitting diodes maintained an on-state with little changes in brightness. Additionally, the film electrodes effectively actuated mechanical joints, enabling uninterrupted grasping movements. Therefore, the study holds promise for expanding the application of graphene films and simultaneously inspiring the development of other high-performance two-dimensional films.

A Stretchable and Tough Graphene Film Enabled by Mechanical Bond

AbstractThe pursuit of fabricating high‐performance graphene films has aroused considerable attention due to their potential for practical applications. However, developing both stretchable and tough graphene films remains a formidable challenge. To address this issue, we herein introduce mechanical bond to comprehensively improve the mechanical properties of graphene films, utilizing [2]rotaxane as the bridging unit. Under external force, the [2]rotaxane cross‐link undergoes intramolecular motion, releasing hidden chain and increasing the interlayer slip distance between graphene nanosheets. Compared with graphene films without [2]rotaxane cross‐linking, the presence of mechanical bond not only boosted the strength of graphene films (247.3 vs 74.8 MPa) but also markedly promoted the tensile strain (23.6 vs 10.2 %) and toughness (23.9 vs 4.0 MJ/m3). Notably, the achieved tensile strain sets a record high and the toughness surpasses most reported results, rendering the graphene films suitable for applications as flexible electrodes. Even when the films were stretched within a 20 % strain and repeatedly bent vertically, the light‐emitting diodes maintained an on‐state with little changes in brightness. Additionally, the film electrodes effectively actuated mechanical joints, enabling uninterrupted grasping movements. Therefore, the study holds promise for expanding the application of graphene films and simultaneously inspiring the development of other high‐performance two‐dimensional films.

Stepwise reinforcement strategy for guar gum/sodium alginate based films: Introduction of carboxylated cellulose nanofibers by different methods and further calcium ion crosslinking

Insufficient mechanical, barrier and water resistance properties of guar gum (GG) films limit their application in food packaging field. Herein, the properties of GG films were enhanced by a stepwise modification strategy. The mechanical and water vapor barrier properties of GG films were initially reinforced by doping with a different type of polysaccharide (sodium alginate; SA). Next, carboxylated cellulose nanofibers (CCN) were introduced as a reinforcing agent to improve film properties via two methods (blending and layer-by-layer (LBL) assembly method). Finally, the water resistance of composite films was further enhanced by calcium ion cross-linking treatment. GG/SA composite films exhibited better mechanical strength and water vapor barrier capacity compared to pristine GG film. In addition, the introduction of CCN, either by blending or LBL method, improved the light barrier, water vapor barrier and tensile strength. The calcium ion cross-linking treatment further enhanced the water vapor barrier, thermal stability, tensile strength and water resistance capacity. The potential applications of GG/SA/CCN films in real food packaging were also explored. In short, this study presents a simple and feasible performance enhancement strategy for GG and other underperforming polysaccharide matrix films, with potential applications in the development of high-performance bio-based food packaging materials.

Low-thermal-budget electrically active thick polysilicon for CMOS-First MEMS-last integration

Low-thermal-budget, electrically active, and thick polysilicon films are necessary for building a microelectromechanical system (MEMS) on top of a complementary metal oxide semiconductor (CMOS). However, the formation of these polysilicon films is a challenge in this field. Herein, for the first time, the development of in situ phosphorus-doped silicon films deposited under ultrahigh-vacuum conditions (~10−9 Torr) using electron-beam evaporation (UHVEE) is reported. This process results in electrically active, fully crystallized, low-stress, smooth, and thick polysilicon films with low thermal budgets. The crystallographic, mechanical, and electrical properties of phosphorus-doped UHVEE polysilicon films are studied. These films are compared with intrinsic and boron-doped UHVEE silicon films. Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used for crystallographic and surface morphological investigations. Wafer curvature, cantilever deflection profile and resonance frequency measurements are employed to study the mechanical properties of the specimens. Moreover, resistivity measurements are conducted to investigate the electrical properties of the films. Highly vertical, high-aspect-ratio micromachining of UHVEE polysilicon has been developed. A comb-drive structure is designed, simulated, fabricated, and characterized as an actuator and inertial sensor comprising 20-μm-thick in situ phosphorus-doped UHVEE films at a temperature less than 500 °C. The results demonstrate for the first time that UHVEE polysilicon uniquely allows the realization of mechanically and electrically functional MEMS devices with low thermal budgets.

A nacre-inspired polymheric multilayer film with high efficiency of low-temperature toughening

Polypropylene (PP) films have been widely used in medical, electronics, and construction fields due to their low cost and excellent comprehensive properties. However, the poor low-temperature toughness of PP films restricts its further applications in extreme cold environments. Here, the nacre-inspired 8-, 32-, 128-, and 512-layer PP/SEBS-based films were constructed via our multilayer blown systems. Compared to the conventional blended films, 128-layer films showed significant improvement under the low-temperature conditions, i.e., 160 %, 150 %, and 136 % in impact toughness, tear toughness, and elongation at break, respectively. The high toughening efficiency of the multilayer films is because of the nacre-inspired multilayer structures, which can develop the multi-stage propagation of the damage behavior such as craze and plastic deformation to dissipate much energy when mechanically broken. Since nacre-inspired PP/SEBS-based multilayer films show high efficiency in low-temperature toughening, this work may provide a possible solution to improving the low-temperature mechanical properties of PP films or even other types of polymeric films.

Component regulation and high-entropy engineering for enhanced antioxidant and high-temperature mechanical properties of protective films

Transition metal nitrides (TMNs) have gained widespread application in protecting structural components due to their high strength and hardness. However, TMNs still have the challenge of structural instability and mechanical deterioration caused by oxidation under harsh high temperature conditions. Herein, we present a strategy combining component regulation with high-entropy engineering to develop an advanced high-temperature Al-containing high-entropy nitrides (HENs) material. To prevent the phase decomposition of AlN within the (NbMoTaWAl)N, theoretical simulations were employed to determine a critical atomic percent of 25.0% Al for maintaining the stability of the high-entropy structure. Ensuing experimental synthesis creates three Nb-Mo-Ta-W-Al-N films with varying Al content: a high-entropy film with 0.0% Al (HEN), a high-entropy film with 21.2% Al (HEN-Al), and an amorphous transition metal nitride film with 30.2% Al (a-TMN-Al), validating key high-entropy engineering benchmarks. It is found that the unique HEN-Al film exhibits excellent oxidation resistance and high-temperature hardness, attributed to the uniform distribution of Al atoms in the robust high-entropy structure, which creates conditions for forming a dense and continuous Al2O3 barrier layer, effectively hindering the diffusion of oxygen into the film interior. This study provides new insights to develop a new generation of high-temperature protective materials.