Excellent Barrier Properties Research Articles

Recent advances in the improvement of protein-based edible films through non-thermal and thermal techniques

A major area of food research focuses on the study of food packaging, which plays a critical role in the containment and protection of foods. In the past, packaging materials have largely consisted of polymers derived from petroleum. However, consumers are more concerned with the environmental and health effects of synthetic polymers. Considering this, protein films may be useful in preserving food freshness due to their ability to insulate light and water. Nevertheless, they are not suitable for use in the food industry because of their limited mechanical strength, tendency to rupture, and poor water resistance. A variety of non-thermal techniques (such as microwave, ultrasound, cold-plasma, irradiation, and high-pressure processing) and thermal methods may be used to overcome this issue by modifying the properties of protein films. The use of these techniques improves protein film properties by reducing particle size, enhancing intermolecular electrostatic repulsion between molecules, and facilitating cross-linking. Further, modified protein films with excellent barrier properties can also be used to reduce food waste and environmental pollution, as well as to improve the quality, safety, and security of food. Thus, this review mainly focuses on the impact of non-thermal and thermal techniques on protein film properties and their applications.

Ultrafast synthesis of novel coal-based graphene and its anticorrosion properties of epoxy/graphene nanocomposite coatings

Graphene has a wide range of applications in anti-corrosion coatings due to its excellent barrier, shielding, and mechanical properties. However, traditional graphene synthesis methods, including the production of graphene oxide (GO) using Homer's method and then its reduction in the form of reduced graphene oxide (rGO) are time-consuming, energy-consuming, and environmentally polluting, which limits their application in anti-corrosion coatings. This study leveraged the capabilities of flash Joule heating (FJH) to synthesize flash coal-based graphene (FCBG) from Taixi anthracite (TA) within 200 ms without pretreatments or chemical reagents. The FJH had the advantages of low energy consumption and being environmentally friendly. Compared with the rGO, the FCBG prepared by FJH was characterized by fewer defects, larger carbon sheets, and a turbostratic structure. Moreover, carbon steel Q235 was used as the substrate to prepare anti-corrosion coatings by mixing FCBG at different flash voltages with epoxy resin (EP). Based on this, the electrochemical performance of different coatings was compared before and after salt spray corrosion. The results demonstrated that the FCBG composite anti-corrosion coating (EP/FCBG190) prepared using EP and FCBG synthesized at 190 V in the FJH, displayed stronger corrosion resistance than the EP and rGO composite coating (EP/rGO). The FJH synthesis process provides a feasible route for improving the synthesis process of the anti-corrosion coatings and the high value-added utilization of coal.

Grafting Polymerization of Long-Chain Hydrophobic Acrylic Monomer onto Lignin and Its Application in Poly(Lactic Acid)-Based Wholly Green UV Barrier Composite Films.

The development of low-cost and high-performance bio-based composites derived from forestry waste lignin and polylactic acid has emerged as a topic of central attention. However, the weak compatibility between lignin and polylactic acid often resulted in high brittleness of the composites. Graft copolymerization is not only the most effective way to modify lignin but also can significantly improve the compatibility of lignin and polylactic acid. In this study, bio-based monomer lauryl methacrylate was grafted onto lignin by feasible radical polymerization to prepare lignin graft copolymers with excellent thermal stability and hydrophobicity, which are expected to improve the compatibility with polylactic acid. Wholly bio-based composites were prepared by compounding this graft copolymer with polylactic acid. The results showed that the crystallization ability of the composite was improved, and the highest crystallinity was increased from 6.42% to 17.46%. With addition of LG-g-PLMA lower than 9%, the thermal stability of the composites was slightly improved. At 5% copolymer addition, the elongation at break and tensile toughness of the composites increased by 42% and 36%, respectively. Observation of the frozen fracture surface of the composite by SEM found that wire drawing and ductile deformation appeared when a small amount of LG-g-PLMA was added. The thus prepared composites also showed excellent UV barrier properties. This approach provides a new idea for the high-value application of lignin.

Bioinspired polyimide film with fire retardant and gas barrier properties by gravity‐induced deposition of montmorillonite

AbstractFlame retardants play a crucial role in improving the flame retardant properties of polymer materials. In recent years, environmental problems caused by flame retardants have attracted widespread attention. It is urgent to use green and effective methods to prepare flame retardant polymers. Bioinspired nanocomposites with layered structures seem to provide effective ideas, but in general, their hydrophilic raw materials limit their applications in certain fields. Here, we prepared biomimetic composites with a layered “brick‐and‐mortar” structure by gravity‐induced deposition using polyimide as the polymer matrix and montmorillonite (MMT) as the filler. The well‐arranged structures of the composite material could isolate oxygen and prevent combustible gases from escaping. The gas barrier performance has been greatly improved, in which the water vapor transmission rate and the oxygen transmission rate decreased by 99.18% and three orders of magnitude, respectively. The flame retardant performance has also been improved, and its limiting oxygen index can reach 67.9%. The polyimide matrix can be converted to water‐insoluble by thermal imidization of water‐soluble poly (amic acid) salt precursors, which endows the composites with low hygroscopicity. The coating containing MMT can protect against polyurethane (PU) foam from fire. During the conical calorimetric test, the coated sample self‐extinguished, and the peak heat release rate, total heat release, and total smoke production are significantly decreased by 53.39%, 40.69%, and 53.03%, respectively. Taking advantage of these properties, this work utilizes a facile method to prepare biomimetic composites with low moisture absorption, excellent gas barrier properties, and flame retardancy, which have great application potential.

Synthesis and characterization of biobased poly(butylene adipate‐co‐furandicarboxylate) with excellent gas barrier properties

AbstractIn this work, we prepared a series of bio‐based poly(butylene adipate‐co‐furandicarboxylate) (PBAF) copolyesters with BF segments ranging from 20 to 80 mol% through a two‐step polycondensation. Then, their thermal, mechanical, gas barrier, and degradable properties were investigated. With the increase of BF content, the glass transition temperatures (Tg) and melting temperatures (Tm) of PBAFs increase constantly. Besides, PBAF copolyesters exhibit excellent mechanical performance with elongation at break in the range of 140% to 870%. The elastic modulus and tensile strength of PBAF60 are 138 and 17 MPa respectively, which are comparable to those of commercial poly(butylene adipate‐co‐terephthalate) (PBAT). Moreover, thanks to the structural characteristics of the furan ring, the barrier performances against CO2, O2, and H2O of PBAFs are 4.6–147.5 folds, 4.0–76.0 folds, and 0.8–8.7 folds of PBAT, respectively. Finally, the degradation tests reveal that the weight losses of PBAFs increase with decreasing BF contents. It is worth emphasizing that although the compost degradation rate of PBAF60 is slightly lower than that of PBAT, it is still a prospective alternative to PBAT due to its improved barrier properties. And it provides a possibility for applications in food packaging, mulch films, and structural elements.

Structure-property correlation of polyvinyl alcohol films fabricated by different processing methods

Polyvinyl alcohol (PVA) films prepared by solution casting method or thermal processing techniques have been widely used in industrial applications. However, the relationship between processing methods and structural properties is still unclear. In this study, three film-forming techniques, namely solution casting, blown film extrusion and extrusion casting, were adopted to prepare PVA films and the influence of processing methods on the structural and physical properties of the films was studied. The results showed that blown film (BF) prepared under biaxial elongational flow had higher crystallinity, larger crystallite size and greater in-plane orientation compared to solution cast film (SCF) and extruded film (ETF). SCF showed the smallest crystallite size, slowest melting temperature, fewer defects, evident skin-core structure and in-plane orientation ascribing to its slow film forming process, stratified solidification and low initial macromolecular concentration. ETF displayed the lowest degree of crystallinity and orientation owing to the fast cooling outside the slit die and the absence of strong flow field. Hence, BF and SCF were endowed with high tensile strength (152.8 and 134.5 MPa), good puncture resistance (245.0 and 245.7 N/mm) and excellent oxygen barrier property (PO2 = 3.07 × 10−19 and 2.33 × 10−18 cm3 cm/(cm2·s·Pa)) while ETF exhibited inferior mechanical properties and oxygen barrier performance. These findings are of significance for building relationships between processing techniques, structural characteristics and practical properties of PVA films and help match appropriate film forming technology to the production of films for different application scenarios.

Designing functionalized graphene-stitched-SiC/fluoropolymer novel composite coating with excellent corrosion resistance and hydrogen diffusion barrier properties

The investigation on ordinary hydrogen barrier composite coatings has been limited in terms of corrosion and high-pressure hydrogen environments, which significantly restricts its practical and industrial applications. Herein, a unique nanohybrid two-dimensional (2D) filler, constituting poly-dopamine (PDA) functionalized graphene (Gr) nanosheets and covalently bridged silicon carbide (SiC) nanoflakes assisted by 3-Isocyanatopropyltrimethoxysilane (IPTMS) via hydrolysis reaction, was innovatively proposed and incorporated into fluoroethylene vinyl ether resin (FEVE) to fabricate final composite coating by spin-coating technique. The hydrogen gas barrier and long-term anti-corrosion performances could be simultaneously enhanced by precisely collaborative effects of interfacial interactions fortification among Gr, SiC, and polymer phase as well as centrifugal force promoted Gr orientation during the spinning process. The optimum sample demonstrated high |Z|0.01Hz values of 3.1 × 1011 Ω cm2 and 3.37 × 1011 Ω cm2 throughout 90 d saltwater immersion and 6-day 1.5 MPa pressurized hydrogen environment exposure respectively. Moreover, its permeability coefficient decreased by 75.66% compared to the pure sample. Other significant properties including 30d constant salt-spray attack tolerance and high adhesion strength of 12.46 MPa were also achieved to meet industrial demands. This work provided paramount inspiration for designing composite coatings for hydrogen transportation pipeline protection and hydrogen energy usage.

Improving properties of Litsea cubeba oil Pickering emulsion-loaded gelatin-based bio-nanocomposite film via optimizing blending ratio: Application for mango preservation

To improve the biological and water-barrier properties of gelatin film, we incorporated the red roselle extract (RRE), ZnO nanoparticles (ZnO), and Litsea cubeba oil Pickering emulsion (LCON) into the GE film. The effect of RRE, ZnO, and LOCN on the properties of GE film was assessed using Box–Behnken response surface design (BBD). The BBD results revealed that these compounds greatly affect the properties of the film, especially the contribution of ZnO/LCON on the mechanical and water barrier properties of the film. The optimal antifungal (80.15%), antibacterial (31.24 mm), antioxidant (73.00%), tensile strength (42.03 MPa), elongation at break (25.50%), water vapor permeability (18.01 g mm·m−2·Kpa−1·h−1), and water contact angle (110.2°) of the film were obtained at 1.10% RRE, 1.51% ZnO and 2.38% LCON. The X-ray diffraction pattern and FTIR spectra results indicated the change of molecular interactions and semi-crystalline structure in the film. The scanning electron microscopy, fluorescence image, and energy dispersive X-ray results revealed that the excellent dispersion of RRE, ZnO, and LCON in the GE matrix led to an even and smooth structure in the film. This structure offers a positive effect on improving the mechanical and barrier properties of the film. The colorful patterns were successfully printed on the film to provide essential product information. Due to its excellent biological, mechanical, and barrier properties, the optimized film was applied for mango preservation. The optimized GE/RRE/ZnO/LCON film significantly controlled the postharvest quality and anthracnose in mango. Thus, the GE/RRE/ZnO/LCON film has great potential for mango preservation in active packaging applications.

Ductile Effect of PGA/PCL Blending Plastics Using a Novel Ionic Chain Extender with Non-Covalent Bonds.

Polyglycolic acid (PGA) is a promising polymer in the packaging field owing to its excellent hydrolysis, heat resistance, and gas barrier properties, but it is limited in application due to its poor toughness. For this reason, a covalently bonded chain extender is introduced to increase compatibility with flexible polymers. However, covalent bonds are unfavorable for application to degradable plastics because of the energy required for reverse reactions. Therefore, we intended to effectively control the ductility of blending plastics by using a novel ionic chain extender with a relatively weaker non-covalent bond than the existing covalent bond. Polycaprolactone (PCL), which has biodegradability and flexibility, was selected as a blending polymer. For comparison, a covalently reactive chain extender (G-CE) and a non-covalently ionic chain extender (D-CE) were synthesized and compounded with blending plastics. Each chain extender improved the compatibility between PGA and PCL, and the ductility of the PGA/PCL blending plastics was more greatly enhanced with non-covalently bonded D-CE than with covalently bonded G-CE. At this time, the ductility of the PGA/PCL(90/10) blending plastic without CE was 7.2%, the ductility of blending plastic with D-CE (10D) was 26.6%, and the ductility of blending plastic with G-CE (10G) was 18.6%. Therefore, it was confirmed that the novel ionic chain extender inducing non-covalent bonds improves the compatibility between PGA and PCL and is more advantageous in enhancing ductility through a reversible reaction.

Polyethylene Terephthalate Composite Films with Enhanced Flame Retardancy and Gas Barrier Properties via Self-Assembly Nanocoating.

The flammability and gas barrier properties are essential for package material. Herein, a highly-oriented self-assembly nanocoating composed of polyvinyl alcohol (PVA) and montmorillonite (MMT) was prepared for endowing polyethylene terephthalate (PET) films with excellent flame retardancy and gas barrier properties. The specific regular nanosheet structure of the PVA/MMT composite nanocoating was confirmed by Fourier transform infrared (FTIR) and X-ray diffraction (XRD). Thermogravimetric analysis (TGA) and the vertical burning test (VBT) suggested that the thermal stability and flame-retardancy of the coated PET films were considerably improved with more pick-up of the resulting nanocoating. When reaching 650 °C, there was still 22.6% char residual left for coated PET film, while only 6% char residual left for pristine PET film. During the vertical burning test, the flame did not spread through the whole PET film with the protection of PVA/MMT nanocoating, and no afterflame was observed. Scanning electron microscopy (SEM) is consistent with vertical burning test, proving that the thermal stability and flame retardancy of coated PET films were considerably enhanced with the increment of PVA/MMT. Thanks to the multi-layer structure, PVA/MMT nanocoating could effectively improve the gas barrier properties of PET films, and the oxygen vapor transmittance rate and water vapor transmittance rate of PET films were more than four hundred times lower and 30% lower than those of neat PET film. Our work demonstrates that bi-functional flame retardant and gas barrier materials could be gained via constructing inorganic/organic highly-oriented self-assembly nanocoating, which is promising in the area of packaging.

Continuously in-situ manufacture of perovskite quantum dots/POE encapsulation adhesive film for silicon solar cell enhancement application

Converting the UV-blue irradiation into longer wavelength can efficiently ameliorate the insufficient solar spectral response and enhance the power conversion efficiency (PCE) of silicon solar cells, whereas there is still no appropriate strategy to make the corresponding luminescence downshifting materials compatible with commercial silicon photovoltaic modules practically. Herein, we first demonstrate an in-situ fabricated CsPbBr3 PQDs/POE encapsulation adhesive film, which can simultaneously achieve continuously large-scale manufacture through melt extrusion and possess well compatibility with the encapsulation technique of silicon photovoltaic modules. According to the separate granulation preparation and technical optimization, the composited adhesive film exhibits an intensive PL emission at 515 nm with a full width at a half-maximum of 20 nm and an ultra high PLQY of 98.2%. Moreover, less than 5% PL intensity decline even after keeping in 50 °C/90 RH aging condition for >2400 h proves its excellent working stability and barrier property. By means of hot pressing operation, the silicon solar cells encapsulated with CsPbBr3 PQDs/POE adhesive film harvest an absolute PCE enhancement of 0.68%. This work provides a way of great potential towards further improving the silicon photovoltaic industry and corresponding optoelectronic applications.

Influence of an innovative, biodegradable active packaging on the quality of sunflower oil and “pesto” sauce during storage

The aim of this research was to produce an innovative, biodegradable multilayer active packaging solution, with excellent oxygen barrier properties, to extend shelf- life of oily foods. In fact, one of the main drawbacks of biodegradable films is the low barrier they offer against external agents that can thus easily accelerate the foods degradation during shelf-life. In this study, a multilayer material obtained by the adhesion of two polylactic acid (PLA) films with cold plasma application, in place of synthetic adhesives, was realized. Moreover, cold plasma treatment was employed to immobilize the oxygen scavenger agent (ascorbic acid), chosen for the activation of the packaging material. Preliminary studies on activated PLA pouches filled with sunflower oil, used as model system, were performed. Model systems were stored at 35 °C to accelerate oil oxidation phenomenon and analysed for PV and colour during 64 days of storage. After that, different samples of “Genovese pesto”, were tested as real food, stored at 25 and 45 °C and analysed for PV, water activity, rheological parameters and microbiological loads during 41 days of storage. Obtained results showed the greater ability of the new active packaging to decrease the oxidation kinetics of “pesto”, mainly when stored at 25 °C. Moreover, all samples packed in the activated biodegradable pouches (both sunflower oils stored at 35 °C and pesto stored at 25 °C) showed better and more stable quality characteristics, in terms of colorimetric, microbiological and textural parameters when compared with the respective control samples. Overall obtained results highlighted the potentiality of the new biodegradable material, activated with the oxygen scavenger, to be applied successfully in food industry, to extend food products shelf-life and/or maintain high quality levels during storage.

Beeswax coating improves the hydrophobicity of sodium alginate/ anthocyanin/ cellulose nanocrystal indicator film

This study investigates the waterproof layer formed by beeswax (BW) to improve the hydrophobicity of sodium alginate/black soybean seed coat anthocyanin/cellulose nanocrystal indicator films. The concentrations of BW and the fabrication method of the waterproof layer, including spraying, coating (CO), and soaking, were optimized. The results showed that the optimal concentration of BW in the waterproof layer was 5% owing to its high water contact angle of 111.5°. Different methods of fabricating waterproof layers with BW led to the formation of particles of different sizes on the microscopic film surface. Hydrophobic films with a waterproof layer of BW-CO had high transmittance and pH sensitivity, ensuring the basic properties of indicator films. Meanwhile, they exhibited excellent water barrier properties based on the water contact angle, water vapor adsorption, water vapor permeability, water content and water solubility. In particular, these films remained highly hydrophobic after 10 days of storage at 100% humidity, with a water contact angle of 108.3°. The findings indicated that hydrophobic sodium alginate/black soybean seed coat anthocyanin/cellulose nanocrystal indicator films were prepared using BW, which improved their potential application in intelligent food packaging.

Coupled thermal stress and moisture absorption in modified a montmorillonite/copolymer nanocomposite: Experimental study

N-Dimethylhexadecyclamine (DMHDA+) montmorillonite (Mt) random copolymer polypropylene (CPP-R) nanocomposites (AmK10CPP-R) are increasingly used in industrial applications such as coating subsea pipelines because they have excellent thermomechanical and barrier properties in front of two coupled properties of moisture adsorption and thermal loading. The coupled properties are experimentally investigated at temperature levels of 298 K and 370 K and water content of 0.0% wt. and 100% wt at 1.0 atm. for three different weight fractions (wt. %) of 0.3%, 3%, and 4% of the nanoparticles. X-Ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), static tensile tests, and dynamic material tensile analysis (DMTA) are conducted on the test samples. XRD pattern of nanofiller shows that using loading content less than 1% wt cannot provide a good basal spacing of nano fillers. The nanocomposite sample with major quantity of clay (4%AmK10CPP-R) presented less clusters of clay dispersed by FE-SEM. DSC indicates that glass transition temperature of 3% AmK10CPP-R is the highest value among all samples and melting temperature of all samples does not change. Moreover, it is observed that the diffusion coefficient of the saturated 4% wt. modified clay random copolymer (4AmAMoisK10CPP-R) is decreased almost 79.4% in comparison with 0.3AmMoisK10CPP-R sample at ambient temperature and atmospheric pressure. Furthermore, thermal analysis shows that temperature and loss of the mass at first stage are the lowest values for 4%AmMoisK10CPP-R. However, thermal stability of the saturated sample is increased in the second stage of TGA/DTG. It is seen that the clay nanoparticle can significantly hinder the degradation of mechanical properties of the nanocomposite even when both temperature and water content increase. Stress-strain curve gives that 3% and 4% wt. modified clay in the polymer matrix can significantly increase the mechanical properties of the polymer. Finally, DMTA determines that the 3%AmAMoisK10CPP-R gives the highest elastic modules. This study finds that mechanical, thermal and rheological properties of the polymer nanocomposite improve and the best compatibilising effect is at a content 3 wt% of the modified clay.

Wet-jet milling exfoliated hexagonal boron nitride as industrial anticorrosive pigment for polymeric coatings

The incorporation of inorganic nanofillers into polymeric matrices represents an effective strategy for the development of smart coatings for corrosion protection of metallic substrates. In this work, wet-jet milling exfoliation was used to massively produce few-layer hexagonal boron nitride (h-BN) flakes as a corrosion-protection pigment in polyisobutylene (PIB)-based composite coatings for marine applications. This approach represents an innovative advance in the application of two-dimensional (2D) material-based composites as corrosion protection systems at the industrial scale. Although rarely used as an organic coating, PIB was selected as a ground-breaking polymeric matrix for our h-BN-based composite coating thanks to its excellent barrier properties. The optimization of the coating indicates that 5 wt.% is the most effective h-BN content, yielding a corrosion rate of the protected structural steel as low as 7.4 × 10−6 mm yr−1. The 2D morphology and hydrophobicity of the h-BN flakes, together with the capability of PIB to act as a physical barrier against corrosive species, are the main reasons behind the excellent anticorrosion performance of our composite coating.

Fabrication and characterization of polyvinyl alcohol/sodium alginate/zein/ chitosan bilayer film for dynamic visualization of pork quality

The development of real-time and convenient meat freshness indication technology is crucial to ensure food safety. A novel antibacterial visualized intelligent film was designed based on polyvinyl alcohol (PA), sodium alginate (SA), zein (ZN), chitosan (CS), alizarin (AL) and vanillin (VA) using layer-by-layer assembly (LBL) method for real-time and in situ monitoring of pork freshness. The fabricated film had various advantageous properties, including an excellent hydrophobicity with a water contact angle (WCA) of 91.59°, improved color stability, excellent water barrier properties and increased mechanical performance (TS = 42.86 MPa). The fabricated film also demonstrated effective antibacterial properties with a bacteriostatic circle diameter of 13.6 mm for Escherichia coli. Moreover, the film can perceive and visualize the antibacterial effect through color changes, enabling dynamic visual monitoring of the antibacterial effect. A good correlation (R2 = 0.9188) between the color changes (ΔE) and total viable count (TVC) of pork was documented. Conclusively, fabricated multifunctional film improves the accuracy and versatility of freshness indication and had great potential for food preservation and freshness monitoring. The outcomes of this research provides a new perspective for the design and development of multifunctional intelligent films.

Preparation of AKD‐coupled mica and research on the modification to poly(butylene adipate‐co‐terephthalate)/poly(propylene carbonate) composite films

AbstractMica is a variety of filler material with excellent barrier properties. In the present study, mica‐AKD was successfully prepared by treating sericite mica surface with alkyl ketene dimer (AKD). The distribution and content of AKD in mica, the mode of its binding with mica and its surface properties were characterized by thermogravimetry, Soxhlet extraction, Fourier infrared analysis, the scanning electron microscope with energy spectrum and contact angle analysis. The results show that AKD was combined with mica through physical adsorption and chemical grafting, with the content of AKD in mica‐AKD exceeding 5 wt%. Due to AKD‐coated mica surface, mica‐AKD showed hydrophobicity. PCM and PCMa films were prepared by blending PBAT and PPC with mica and mica‐AKD, respectively. Given the same content, mica‐AKD has better compatibility with PBAT/PPC matrix, and PCMa films show better mechanical properties, lower water vapor permeability and oxygen permeability, and higher CDTR/OTR ratio, which has a good application prospect in fruit and vegetable preservation materials.

Robust Ionic Cyclic Olefin Polymers with Excellent Transparency, Barrier Properties, and Antibacterial Properties

The development of materials with intrinsic antimicrobial activities has attracted great interest. In this contribution, cyclic olefin polymers (COPs) with excellent mechanical strength and high glass-transition temperature were prepared via ring-opening metathesis polymerization of both a bulky cyclic monomer and a cyclic monomer bearing ionic groups. The ionic COP membranes we obtained showed high antibacterial properties against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus); especially, the sterilization rate of H-Qa on both bacteria was higher than 99%, and it still showed a high bacteriostatic rate after repeated supplementation of new bacteria for 7 days. In addition, high light transmittance (80–90% in vis), excellent thermal stability (Td,95 > 210 °C), and low water vapor/oxygen transmittance also make the COPs promising as a bacteriostatic material with promising application potential in packaging, medical, and other fields.

Diffusion barrier property of Co-W layer compared with Ni layer in fine pitch micro-bumps during high temperature storage

Co-W alloy has the potential to replace Ni barrier layer in Cu/Sn solder joints of advanced electronic packaging due to its excellent electromigration resistance and diffusion barrier property. Nevertheless, little attention has been paid to the fine pitch micro-bumps on the diffusion barrier consumption. In this work, Sn/Co-9at. %W/Cu and Sn/Ni/Cu micro-bumps with a diameter of 12 μm were fabricated by electrodeposition and the consumption of the barrier was investigated during solid stage aging at 150 °C and 200 °C. The consumption of the Co-W barrier was accompanied by the growth of the layered amorphous Co-W-Sn. The depletion of Ni barrier was at least 4 and 2 times faster than the Co-W barrier at 150 °C and 200 °C, respectively. Compared with Sn/Co-W/Cu planar diffusion couple, the consumption rate of Co-W barrier layer in micro-bumps did not increase. A theory of amorphous Co-W-Sn layer without grain boundary and high melting point W reducing the diffusion coefficient was proposed to explain the eliminated scaling effect.

Polystyrene/Polyolefin Elastomer Blends Loaded with Halloysite Nanotubes: Morphological, Mechanical, and Gas Barrier Properties

AbstractHerein, a simple melt‐blending method is utilized to disperse of halloysite nanotubes (HNTs) in polystyrene/polyolefin elastomer (PS/POE) blends. Based on morphological studies, the PS/POE/HNT nanocomposite containing up to 3 phr HNTs shows excellent nanofiller dispersion, while those filled with 5 phr HNTs exhibit nanofiller aggregation. To overcome the nanofiller aggregation issue, the polypropylene‐grafted‐maleic anhydride (PP‐g‐MA) compatibilizer is added to the PS/POE/HNT nanocomposite, which results in improved mechanical properties for the nanocomposite sheets. Furthermore, the addition of compatibilized HNTs to the PS/POE blends leads to decreased O2and N2gas permeabilities. Besides, incorporating POE, HNTs, and PP‐g‐MA leads to a decrease in water vapor transmission of PS. In the end, the experimentally‐determined mechanical properties and gas permeabilities of the nanocomposite sheets are compared to those predicted by prevalent theoretical models, revealing a good agreement between the experimental and theoretical results. Molecular‐dynamics simulations are also carried out to calculate the gas diffusion coefficients in the different sheets to further support the experimental findings in this study. Overall, the PS/POE/HNT/PP‐g‐MA nanocomposite sheets fabricated in this work demonstrate excellent mechanical and gas barrier properties; and hence, can be used as candidate packaging materials. However, the strength of the resulting PS/POE blend may be inferior to that of the virgin PS.