Thermal Stability Of Films Research Articles

Influence of Substrate Polarity on Thermal Stability, Grain Growth and Atomic Interface Structure of Au Thin Films on ZnO Surfaces

Influence of Substrate Polarity on Thermal Stability, Grain Growth and Atomic Interface Structure of Au Thin Films on ZnO Surfaces

Effect of Morphology and Concentration of CeO2 Nanoceria on the Thermal Stability of Polyvinyl Alcohol Films

Objective: To determine the thermal stability of polyvinyl alcohol films under different concentrations of CeO2 nanoceria. Method: Cerium Oxide doped polyvinyl alcohol (PVA) nano-composites were synthesized by the traditional solution casting method for various concentrations of nano CeO2 by solution combustion method. The thermal properties of prepared PVA-2.5 wt% CeO2, PVA-7.5 wt% CeO2 , PVA-12.5 wt% CeO2, and PVA-25 wt% CeO2 composite films were elucidated by using techniques such as Differential Scanning Calorimetry, Thermogravimetry analysis and Differential Thermal analysis. Findings: The glass transition temperature of the pure PVA is found to be 114°C, whereas it varies between 110°C-120°C for composite films. The melting temperature of the composite films is the same as that of pure PVA except in the case of 7.5wt% CeO2 and 25wt% CeO2 composites. The reduced melting point of these composites elicits a decrease in crystallinity. A 12.5 wt % and 25 wt% CeO2-PVA nano-composite films exhibit an increase in the final degradation temperature, a high specific heat capacity, low mass loss, and a larger residual weight, indicating their potential applicability in thermal coating and thermal sensing applications. Polyvinyl alcohol (PVA) films are being used routinely as a dielectric layer for electrical applications due to the good physiochemical and dialectic properties of the material. An incorporation of CeO2 nanoceria improves not only the thermal but also the mechanical properties of PVA and extends its application for electrical and optical operation. Here in the present study, different concentrations of CeO2 were incorporated with the PVA and analysed for the thermal properties. The study showed that 12.5 wt % and 25 wt% CeO2-PVA nano-composite enhanced PVA film thermal stability. Keywords: PVA-CeO2 Nanocomposites; Differential Scanning Calorimetry; Thermogravimetry Analysis and Differential Thermal Analysis; Physical properties and thermal properties

Preparation of pectin/carboxymethyl cellulose composite films via high-pressure processing and enhancement of antimicrobial packaging

This study investigated the impact of high-pressure processing (HPP) treatment on the structure and physicochemical properties of pectin (PEC)/carboxymethyl cellulose (CMC) composite films, along with the development of new active films incorporating emodin as an antibacterial agent. The results showed that 500 MPa/20 min HPP treatment significantly improved the tensile strength (from 45.91 ± 4.63 MPa to 52.24 ± 4.87 MPa) and elongation at the break (from 5.00 ± 1.44 % to 11.72 ± 2.97 %) of the films. It also improved the film's thermal stability and had no significant effect on its thermal degradability. Moreover, emodin was incorporated into the PEC/CMC film-forming solution and subjected to 500 MPa/20 min HPP treatment to investigate the structure, functional properties, optical properties, and antibacterial activity of the film. The emodin caused the film structural alteration, but significantly improved the water vapor barrier properties. It also reduced the film brightness and light transmission. The antibacterial assessment demonstrated that the film's antibacterial activity was correlated positively with increasing emodin content, and the number of viable cells of Staphylococcus aureus decreased by 1.29 log10 CFU/mL, 1.70 log10 CFU/mL, and 1.80 log10 CFU/mL with different levels of EM antimicrobial films after 12 h.

Green synthesized CeO2 nanoparticles-based chitosan/PVA composite films: Enhanced antimicrobial activities and mechanical properties for edible berry tomato preservation.

The current study is intended to enhance unique bioactive and eco-friendly composite films following a simple solvent-casting approach by incorporating cerium oxide nanoparticles (CeO2 NPs) with a chitosan (CS)/polyvinyl alcohol (PVA) matrix. Antimicrobial activity, preservation impact, mechanisms for the edible berry tomatoes and physicochemical properties of the produced films were tested. FTIR, SEM-EDX, XRD, UV–vis spectroscopy and contact angle were used to characterize the films. Incorporated (3.0 wt%) CeO2 NPs practically developed composite film's thermal stability, structural, mechanical, bioactive, antioxidant, barrier and wettability properties. The tomatoes' look, weight loss and stiffness were better preserved after 25 days of storage at room temperature (25 ± 5 °C) when 3.0 wt% CeO2 NPs films were used instead of the original CS/PVA film. CS and CeO2 NPs have unique physiochemical and antibacterial properties. Food packaging extensively investigates the modified films as antimicrobials and preservatives to increase the shelf life of packaged foods, owing to their ability to inhibit gram-positive bacteria (Bacillus cereus and Staphylococcus aureus), gram-negative bacteria (Klebsiella pneumoniae and Pseudomonas aeruginosa), and filamentous fungi (Bipolaris sorokiniana, Fusarium op., and Alternaria sp.). Our findings indicated that the CeO2/CS/PVA composite films could be used as effective wrapping materials for food preservation.

Thermal stability of gold films on titanium-adhered silicon substrate

In this study, thermally induced changes in the surface of a thin gold film deposited on Si(100) with a 5 nm thick titanium adhesion layer were investigated. The analysis involved X-ray photoelectron spectroscopy, low-energy electron diffraction, and scanning tunnelling microscopy. The sample was subjected to stepwise annealing under ultra-high vacuum conditions at temperatures ranging from 430 to 1330 K. Low-temperature annealing up to 450 K did not alter the morphology but improved the cleanliness of the gold film surface. Annealing between 530 and 930 K resulted in the disintegration of the gold film, along with mixing and interaction between the sample components. Annealing the sample at 980 K led to the emergence of a gold silicide surface on Si(100) exhibiting the (5 × 3.2)R5.7° reconstruction.

Impact of agar–glycerol ratios on the physicochemical properties of biodegradable seaweed films: A compositional study

To develop technology more applicable to industrial settings, this study aimed to produce agar-based bioplastic films using extrusion followed by hot compression. The research examined various amounts of glycerol incorporation as the plasticizer, which also facilitated the flowability of the extrusion process. These variations included agar–glycerol ratios of 75:25, 70:30, 65:35, 60:40, and 55:45 (% w/w). Moreover, the films underwent thorough testing to assess their physical, mechanical, chemical, water sensitivity, surface imaging, and biodegradability properties. The results showed that increasing the amount of glycerol in the agar film matrix generally made the films more sensitive to water, resulting in greater hydrophilicity. This change was primarily owing to the increased presence of hydroxyl groups. It also affected other characteristics, such as enhancing the film's stretchability and thermal stability. Furthermore, a decrease in film density was observed, leading to reduced tensile strength and barrier properties. Moreover, the higher glycerol content improved its surface wettability and the higher agar content accelerated the film's biodegradability rate. Microstructural examination using scanning electron microscopy and chemical analysis (FTIR) revealed a homogeneous mixture of agar and glycerol produced through the extrusion process. These findings demonstrate the potential of extrusion techniques for the large-scale production of agar-based bioplastics.

Biodegradable active composite film based on pea protein isolate, sage seed gum, and cumin essential oil: Fabrication and characterization

The present study perused the physicochemical, mechanical, thermal, barrier, and optical properties of pea protein isolate (PPI)-Sage seed gum (SG) (3:1, 1:1, and 1:3) composite films incorporated with cuminum essential oil (CEO, 0, 1, and 2 %). Results indicated that the thickness, contact angle (CA), yellowness index (a*), total color differences (∆E), and opacity (OP) significantly enhanced with increasing PPI portion and CEO concentration (p < 0.05), as well as heterogeneous and inconsistent structure were increased in film surface due to protein agglomeration and oil droplets. However, the moisture content (MC), water solubility (WS), and swelling ratio (SR) decreased. Results also indicated that the antioxidant property significantly increased (P < 0.05) following the increase in CEO concentration. The highest tensile strength (TS) and elastic modulus (EM) and the least elongation at break (EAB) in PPI 3-SG 1–0 % were estimated. The potential antimicrobial property of CEO containing film was confirmed, and the maximum inhibition zone for E.coli, S.aureus, C.albicans, and A.niger were measured in film containing 2 % CEO. The barrier properties of the film against water and oxygen (WVP, OXP) diminished with increases the SG ratios, due to the hydrophilic nature of SG. The FTIR analysis identified the functional groups in film components and the interaction between film components. The DSC thermogram indicated the thermal stability of films and the highest decomposition temperature in PPI 3-SG 1–2 % film. XRD revealed a semi-crystalline structure of biopolymer active films. With the increase of SG portion and CEO concentration, the crystallinity of the films was enhanced. Results also indicated that prepared films were more than 90 % biodegradable.

Exploring the Feasibility of Polysaccharide-Based Mulch Films with Controlled Ammonium and Phosphate Ions Release for Sustainable Agriculture.

Bio-based polymers are a promising material with which to tackle the use of disposable and non-degradable plastics in agriculture, such as mulching films. However, their poor mechanical properties and the high cost of biomaterials have hindered their widespread application. Hence, in this study, we improved polysaccharide-based films and enriched them with plant nutrients to make them suitable for mulching and fertilizing. Films were produced combining sodium carboxymethyl cellulose (CMC), chitosan (CS), and sodium alginate (SA) at different weight ratios with glycerol and CaCl2 as a plasticizer and crosslinker, respectively, and enriched with ammonium phosphate monobasic (NH4H2PO4). A polysaccharide weight ratio of 1:1 generated a film with a more crosslinked structure and a lower expanded network than that featuring the 17:3 ratio, whereas CaCl2 increased the films' water resistance, thermal stability, and strength characteristics, slowing the release rates of NH4+ and PO43-. Thus, composition and crosslinking proved crucial to obtaining promising films for soil mulching.

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.

Thermal stability prediction of copolymerized polyimides via an interpretable transfer learning model

To address the issues with molecular representation of copolymerized polyimides (PIs) and the mini dataset of PI powders. We constructed an interpretable machine learning (ML) model for PI films using the weighted-additive Morgan Fingerprints with Frequency descriptors and developed an interpretable transfer learning model for PI powders. To enhance Thermal Stability (Temperature at 5% weight loss) of PI films and powders, it is recommended to add conjugated functional groups to diamines, control phenyl ring side chains, and reduce pyridine and hydroxyl groups; select copolyimides (co-PIs); ensure that anhydride is directly connected to the benzene ring in dianhydrides, avoiding aliphatic cycles. It is noteworthy that the close alignment between experimental results and model predictions serves to confirm the model is a reliable prediction tool. It is hoped that this polymer informatics approach will provide further implementation for practical applications of other functional materials.

Nelumbo nucifera flower extract incorporated alginate/polyvinyl alcohol films as a sustainable pH indicator for active food packaging applications

In recent years, there has been a growing demand for environmentally friendly smart packaging materials. Therefore, in this study, we developed an eco-friendly pH-sensitive indicator film through the solvent casting process, incorporating alginate, polyvinyl alcohol, garlic, and Nelumbo nucifera flower extract. The effect of extract on the chemical and physical properties of the film were extensively studied using various characterization techniques. XRD and FTIR reveal the strong interaction between the polymers and the extract. The incorporation of the extract influenced various parameters such as swelling behavior, water solubility, and moisture content, while also improving the film's thermal stability, biodegradability, as well as its antioxidant and antimicrobial properties. Interestingly, the film exhibited a color change in response to pH change. During shrimp storage, the film showed a visible transition from purple to green, indicating shrimp spoilage. Additionally, the film's ability to detect freshness was confirmed by measuring total volatile basic nitrogen (TVBN). These findings suggest that the PVA/alginate/garlic/Nelumbo nucifera film shows promise as an intelligent packaging material for real-time food monitoring applications.

Fabricating active Egg Albumin/Sodium Alginate/Sodium Lignosulfonate Nanoparticles film with significantly improved multifunctional characteristics for food packing

In food packaging, sodium lignosulfonate nanoparticles (SLS NPs) showed significant antibacterial properties, antioxidant and UV barrier activities. Herein, the SLS NPs were synthesized via a sustainable green method and were added into egg albumin/sodium alginate mixture (EA/SA) to fabricate a safe, edible EA/SA/SNPs food packaging. A composite film EA/SA/SNP was examined microstructurally and physicochemically. The mechanical characteristics, UV protection, water resistance, and the composite film's thermal stability were all enhanced by the inclusion of SLS NPs, and water vapor permeability reduced by 44 %. This composite film exhibited robust antioxidative properties with DPPH and ABTS free radical scavenging rates reaching 76.84 % and 92.56 %, and effective antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with antibacterial rates reaching 98.25 % and 97.13 % for the positively charged nanoparticles interacting with the cell membrane. Freshness tests showed that the EA/SA/SNPs packaging film could delay the quality deterioration of fresh tomatoes. This composite film can slow down spoilage bacteria proliferation and prolongs food's preservation period by eight days at ambient temperature.

Enhanced carbohydrate-based plastic performance by incorporating cerium-based metal-organic framework for food packaging application

The development of biodegradable active packaging films with hydrophobic characteristics is vital for extending the shelf life of food and reducing the reliance on petroleum-based plastics. In this study, novel hydrophobic cerium-based metal-organic framework (Ce-MOF) nanoparticles were successfully synthesized. The Ce-MOF nanoparticles were then incorporated into the cassava starch matrix at varying concentrations (0.5 %, 1.5 %, 3 %, and 4 % w/w of total solid) to fabricate cassava-based active packaging films via the solution casting technique. The influence of Ce-MOF on the morphology, thermal attributes, and physicochemical properties of the cassava film was subsequently determined through further analyses. Biomedical analysis including antioxidant activity and the cellular morphology evaluation in the presence of the films was also conducted. The results demonstrated that the consistent dispersion of Ce-MOF nanofillers within the cassava matrix led to a significant enhancement in the film's crystallinity, thermal stability, antioxidant activity, biocompatibility, and hydrophobicity. The introduction of Ce-MOF also contributed to the film's reduced water solubility. Considering these outcomes, the developed cassava/Ce-MOF films undoubtedly have significant potential for active food packaging applications.

Effect of annealing in air on the properties of carbon-rich amorphous silicon carbide films

Thermal stability of thin carbon-rich Si carbide films was studied. Air anneals at the temperatures up to 700 °C were used to model the operation thermal conditions of the films in photoelectronic devices such as solar cells covered by Si carbide antireflection coatings. Si carbide films with different carbon-to-silicon ratios were studied. Annealing in air was shown to lead to consecutive film oxidation and transformation from Si carbides to oxidized Si carbide composites. The oxidized composites demonstrated the changes in thickness, element composition and optical properties as compared to the non-annealed films. At this, the films with higher Si content showed better stability of the optical properties at increased temperatures. During annealing, the increase of the film thickness by Si oxide formation competed with the thickness decrease by formation and evaporation of carbon oxide.

A degradable multi-functional packaging based on chitosan/silk fibroin via incorporating cellulose nanocrystals-stabilized cinnamon essential oil pickering emulsion

In this study, cellulose nanocrystals (CNC) exhibited a higher aspect ratio derived from Rosa roxburghii pomace (RRP), enabling them to effectively carry more charge and consequently form a Pickering emulsion (PE) of cinnamon essential oil (CEO) with enhanced stability. This mixture was then incorporated into a chitosan/silk fibroin (CS/SF) matrix to create an activated food packaging film successfully. Additionally, the cinnamon essential oil - Pickering emulsion (CEO-PE) prepared in this study exhibited superior compatibility with the film substrate. Scanning electron microscopy (SEM) results showed that the Pickering emulsion was uniformly distributed in the CS/SF matrix and formed microstructure-sized holes in the film. The FT-IR results revealed the formation of robust hydrogen bonds between the film components, indicating successful encapsulation of the CEO within the film. Furthermore, the incorporation of CEO-PE enhanced the film's mechanical and thermal stability, reduced the water vapor transmission rate, improved the film's DPPH radical scavenging and bacterial inhibition abilities, and imparted slow-release properties. Moreover, the prepared CS/SF/PE films had good degradation ability, which were basically decomposed by microorganisms within 14 d. And a life cycle assessment revealed that the CS/SF/PE film production reduces fossil resource consumption by more than 68% and global warming by more than 34% compared to film sourced from petroleum. In summary, this research demonstrated that CNC obtained from RRP can be successfully prepared as CEO-PE and combined with CS/SF matrix to prepare active food packaging film, which was promising films for extending the shelf life of fresh fruits.

Exceptional Thermal Stability and Properties of Amorphous High-Entropy SiNbTaTiZr Thin Films

Exceptional Thermal Stability and Properties of Amorphous High-Entropy SiNbTaTiZr Thin Films

Silicone-geranium essential oil blend for long-term antifouling coatings

This study explores the potential of geranium essential oil as a natural solution for combating marine biofouling, addressing the environmental concerns associated with commercial antifouling coatings. Compounds with bactericidal activities were identified by 13Carbon nuclear magnetic resonance (13C NMR). Thermogravimetric analysis (TGA) revealed minimal impact on film thermal stability, maintaining suitability for antifouling applications. The addition of essential oil induced changes in the morphology of the film and Fourier transform infrared spectroscopy (FTIR) analysis indicated that oil remained within the film. Optical microscopy showed an increase in coating porosity after immersion in a marine environment. A total of 18 bacterial colonies were isolated, with Psychrobacter adeliensis and Shewanella algidipiscicola being the predominant biofilm-forming species. The geranium essential oil-based coating demonstrated the ability to reduce the formation of Psychrobacter adeliensis biofilms and effectively inhibit macrofouling adhesion for a duration of 11 months.

Effect of Si content on the thermal stability and oxidation resistance of arc-deposited TiAlSiN films with cubic structure

Recently, TiAlSiN thin films have attracted increasing research interest due to their potential to have simultaneously enhanced hardness, thermal stability, and oxidation resistance compared with Si-free TiAlN films. Previous studies have revealed that a relatively low Si content (2.1–6.0 at.% Si) is essential for the phase stability and hardness of TiAlSiN thin films. Despite the optimum Si content for the hardness of TiAlSiN thin films being proposed, a systematical study concerning the optimum Si content for tailored phase stability, thermal stability, and oxidation resistance of TiAlSiN thin films is still missing. Here, we arc-deposited Ti1-x-zAlxSizN thin films (x = ~0.45, 0.01 ≤ z ≤ 0.08), and investigated the dependence of their structure, mechanical properties, thermal stability, and oxidation resistance on Si content. XRD analysis reveals the transformation from single-phase cubic structure for z ≤ 0.06 to a cubic-wurtzite dual-phase structure for z = 0.08. Increasing the Si content of cubic-structured Ti1-x-zAlxSizN thin films conduces a continuous increase of hardness (H) from 29.3 ± 0.5 GPa for z = 0.01 up to 37.3 ± 0.7 GPa for z = 0.06, whereas the w-AlN formation leads to a drop of H to 32.8 ± 0.6 GPa for z = 0.08. Furthermore, enhancing the Si content from z = 0.01 to z = 0.06 continuously improves film thermal stability, where the Ti0.48Al0.46Si0.06N film presents the highest hardness values within the whole studied temperature range (as-deposited, 800–1200 °C). All Ti1-x-zAlxSizN films undergo age-hardening, with peak H of 33.3 ± 1.0 GPa at 1000 °C for z = 0.01, 35.0 ± 0.6 GPa at 1100 °C for z = 0.02, 35.4 ± 0.5 GPa at 1100 °C for z = 0.03, 40.2 ± 0.7 GPa at 1200 °C for z = 0.06, and 37.8 ± 0.6 GPa at 1100 °C for z = 0.08. Additionally, the oxidation resistance of Ti1-x-zAlxSizN films at 800–1000 °C is improved with increasing Si content, due to the suppressed transformation of anatase-to-rutile TiO2 and the promoted formation of a top dense oxide scale. After oxidation at 900 °C for 15 h, the Ti0.54Al0.45Si0.01N film has been completely oxidized, whereas Ti0.53Al0.45Si0.02N, Ti0.51Al0.46Si0.03N, Ti0.48Al0.46Si0.06N and Ti0.45Al0.47Si0.08N films exhibit oxide scales of ~1.7, ~1.4, ~1.2 and ~0.9 μm, respectively. Overall, we propose z = 0.06 as the optimum Si content for the over-rounded performance of Ti1-x-zAlxSizN thin films.

Preparation, formation mechanism, and performance of nitrocellulose aqueous coating based on the anti-solvent method

The organic solvent-based nitrocellulose (NC) coatings exhibit a high volatile solvent content, leading to significant environmental pollution. Whereas, existing waterborne NC-based coating have demonstrated poor water resistance and complex application methods. Therefore, this study aims to develop a green and highly water-resistant waterborne NC-based coating system utilizing a simple anti-solvent method with two environmentally friendly plasticizers, namely acetyl tributyl citrate (ATBC) and triethyl citrate (TEC), as film-forming additives. The dynamic light scattering (DLS) studies revealed that the particle size of NC-based nanoparticles increased with an increase in ATBC content, while it remained relatively constant with an increase in TEC content. Moreover, the particle size results demonstrated that the storage stability of aqueous dispersions containing NC/ATBC (NA) was superior to those containing NC/TEC (NT). Additionally, the physicochemical properties of aqueous dispersions-based films (Ndis), including film formation, hygroscopicity, water resistance, transparency, thermal stability, and mechanical properties were evaluated using solvent-based films (Nsol) as control samples. The results demonstrated that the Ndis films exhibited a dense and uniform structure, with physical and chemical properties that were essentially comparable to those of Nsol films. However, the mechanical properties of Ndis films were somewhat influenced by the nanoparticle size, leading to reduced mechanical performance when the particle size of nanoparticles in the aqueous dispersion was excessively large. The equilibrium moisture content for NA and NT films were reduced to 1.119% and 1.872%, respectively, at a relative humidity of 95%, in comparison to pure NC films (3.975%). Simultaneously, water contact angle measurements indicated an increase from 77° for pure NC film to 89° for NA film and 82° for NT film. All films exhibited superior transparency characteristics. Overall, NA films display excellent water resistance and transparency as well as good mechanical properties.

Preparation, physicochemical properties, antioxidant, and antibacterial activities of quaternized hawthorn pectin films incorporated with thyme essential oil

To investigate the impacts of thyme essential oil (TEO) on the structural, physical, antioxidative, and antibacterial properties of quaternized pectin film (QHP), the 0.5%, 1.0%, and 1.5% TEO were incorporated to prepare quaternized pectin and TEO composites films. Scanning electron microscopy (SEM) pictures of the apparent morphology revealed that TEO had good compatibility with quaternized pectin. With TEO combined, the thickness and opacity of films increased, while the water content and swelling degree decreased. TEO has a plasticizing effect on films and improve the elongation at the break of films. However, hydrophobic TEO did not improve the hydrophobicity and water vapor barrier performance of films. The complex of TEO had slight influence upon the thermal stability of films. The composite films exhibited higher UV shielding, antioxidative, and antibacterial performance. Thus, the complex films have potential application value in active food packaging materials.