Search Results (9)

Multilayer packaging materials are extensively used in food packaging, particularly for powdered products. In alignment with sustainable development goals, packaging design should aim to minimize material usage while maintaining the protective properties necessary to preserve food quality and safety, thereby reducing environmental impact. A key strategy is to simplify multilayer structures to enhance recyclability. This study aims to evaluate the potential of sustainable alternative packaging materials with reduced metal and plastic content and improved recyclability for pudding powder packaging, as substitutes for conventional films. Four packaging structures were tested: a conventional three-layer laminate (polyethylene terephthalate (PET)/aluminum foil (Al-foil)/low-density polyethylene (LDPE)), two two-layer structures (AlO_x-coated PET/LDPE and Al-coated PET/LDPE), and a monolayer metallized biaxially oriented polypropylene (MetBOPP). Samples were stored under accelerated conditions (38 °C and 90% relative humidity) for 180 days, and changes in moisture content, water activity, caking degree, glass transition temperature, color, and sensory attributes were monitored. The experimental data were examined for their agreement with various sorption models by creating adsorption isotherms. The acceptable storage period was estimated using the constants calculated from these models. Statistically significant differences (p < 0.05) were observed among the packaging types, primarily associated with their water vapor permeability, affecting moisture content, water activity, caking degree, and color stability. In terms of moisture content, water activity, and caking degree, the conventional PET/Al-foil/LDPE (Polyethylene terephthalate/Aluminum foil/Low density polyethylene) structure demonstrated the best performance, followed by PET.AlO_x/LDPE (AlO_x-coated Polyethylene terephthalate/Low density polyethylene), MPET/LDPE (Metallized polyethylene terephthalate/Low density polyethylene), and MBOPP (Metallized biaxially oriented polypropylene), respectively. The sensory analysis scores followed the same ranking; however, all samples maintained scores above the threshold value of 3 throughout the storage period, indicating that they remained acceptable. Caking degree increased moderately (from 0.61% to 0.89%) and was negatively correlated with appearance scores (R² = −0.89, p < 0.01). Despite slight darkening (Browning Index increased from 18.16 to 20.37), sensory scores for appearance, odor, and taste remained above the acceptable threshold (score > 3.0). Based on the WVTR values of the packaging materials and the application of the GAB model, the estimated shelf lives were 800.32 days for PET/Al-foil/LDPE, 577.92 days for PET.AlO_x/LDPE, 407.58 days for MPET/LDPE, and 229.26 days for MBOPP. In conclusion, the longest shelf life was achieved with PET/Al-foil/LDPE, and it was observed that as the WVTR of the packaging materials increased, the shelf life of the cocoa-based pudding powder decreased; PET.AlO_x/LDPE and MPET/LDPE could be considered for medium-term storage (up to about 1–1.5 years), while MBOPP appeared suitable only for shorter durations (6–8 months). Full article

We have demonstrated the fabrication of laminate composites with functional features to demonstrate energy storage capabilities. The present study investigates the surface modification of carbon fibers by coating dual materials of reduced graphene oxide (rGO) and cellulose-based activated carbon to enhance their energy storage capacitance for the development of structural supercapacitors. The dual coating on carbon fibers enabled a near 210-fold improvement in surface area, surpassing that of pristine carbon fibers. This formed a highly porous graphene network with activated carbon, resulting in a well-connected fiber–graphene-activated carbon network on carbon fibers. The electrochemical supercapacitor, fabricated from surface-functionalized carbon fibers, provides the best performance, with a specific capacitance of 172 F g⁻¹ in an aqueous electrolyte. Furthermore, the symmetrical structural supercapacitor (SSSC) device delivered a specific capacitance of 227 mF g⁻¹ across a wide potential window of 6 V. The electrochemical stability of the SSSC device was validated by a high capacitance retention of 97.3% over 10,000 cycles. Additionally, the study showcased the practical application of this technology by successfully illuminating an LED using the proof-of-concept SSSC device with G-aC/CF electrodes. Overall, the findings of this study highlight the potential of carbon fiber composites as a promising hybrid material, offering both structural integrity and a functional performance suitable for aerospace and automobile applications. Full article

Drilling-induced damage in fiber-reinforced polymer composite materials was measured excavating four laminates, basalt (B₁₄), glass (G₁₄) and their two sandwich type hybrids (B₄G₆B₄, G₄B₆G₄), with 6 mm twist drills at 1520 revolutions per minute and 0.10 mm rev⁻¹ under dry running with an uncoated high-speed steel (HSS-R), grind-coated high-speed steel (HSS-G) or physical vapor deposition-coated (high-speed steel coated with Titanium Nitride (TiN) and Titanium Aluminum Nitride (TiAlN)) drill bits. The hybrid sheets were deliberately incorporated to clarify how alternating basalt–glass architectures redistribute interlaminar stresses during drilling, while the hard, low-friction TiN and TiAlN ceramic coatings enhance cutting performance by forming a heat-resistant tribological barrier that lowers tool–workpiece adhesion, reduces interface temperature, and thereby suppresses thrust-induced delamination. Replacement of an uncoated, grind-coated, high-speed-steel drill (HSS-G) with the latter coats lowered the mechanical and thermal loads substantially: mean thrust fell from 79–94 N to 24–30 N, and peak workpiece temperatures from 112 °C to 74 °C. Accordingly, entry/exit oversize fell from 2.5–4.7% to under 0.6% and, from the surface, the SEM image displayed clean fiber severance rather than pull-out and matrix smear. By analysis of variance (ANOVA), 92.7% of the variance of thrust and 86.6% of that of temperature could be accounted for by the drill-bit factor, thus confirming that the coatings overwhelm the laminate structure and hybrid stacking simply redistribute, but cannot overcome, the former influence. Regression models and an artificial neural network optimized via meta-heuristic optimization foretold thrust, temperature and delamination with an R² value of 0.94 or higher, providing an instant-screening device with which to explore industrial application. The work reveals TiAlN- and TiN-coated drills as financially competitive alternatives with which to achieve ±1% dimensional accuracy and minimum subsurface damage during multi-material composite machining. Full article

Lateral flow tests (LFTs) had a pivotal role in combating the spread of the SARS-CoV-2 virus throughout the COVID-19 pandemic thanks to their affordability and ease of use. Most of LFT devices were based on nitrocellulose membrane strips whose industrial upscaling to billions of devices has already been extensively demonstrated. Nevertheless, the assay option in an LFT format is largely restricted to qualitative detection of the target antigens. In this research, we surveyed the potential of UV nanoimprint lithography (UV-NIL) and extrusion coating (EC) for the high-throughput production of disposable capillary-driven, foil-based tests that allow multistep assays to be implemented for quantitative readout to address the inherent lack of on-demand fluid control and sensitivity of paper-based devices. Both manufacturing technologies operate on the principle of imprinting that enables high-volume, continuous structuring of microfluidic patterns in a roll-to-roll (R2R) production scheme. To demonstrate the feasibility of R2R-fabricated foil chips in a point-of-care biosensing application, we adapted a commercial chemiluminescence multiplex test for COVID-19 antibody detection originally developed for a capillary-driven microfluidic chip manufactured with injection molding (IM). In an effort to build a complete ecosystem for the R2R manufacturing of foil chips, we also recruited additional processes to streamline chip production: R2R biofunctionalization and R2R lamination. Compared to conventional fabrication techniques for microfluidic devices, the R2R techniques highlighted in this work offer unparalleled advantages concerning improved scalability, dexterity of seamless handling, and significant cost reduction. Our preliminary evaluation indicated that the foil chips exhibited comparable performance characteristics to the original IM-fabricated devices. This early success in assay translation highlights the promise of implementing biochemical assays on R2R-manufactured foil chips. Most importantly, it underscores the potential utilization of UV-NIL and EC as an alternative to conventional technologies for the future development in vitro diagnostics (IVD) in response to emerging point-of-care testing demands. Full article

This study investigates the properties of various adhesives and assesses the effects of the coating and drying conditions of aluminum surface treatment agents on adhesion strength and chemical resistance. The adhesion between aluminum and the polymer film is improved through the application of a surface treatment agent to the aluminum surface. This study examines the initial adhesive strength of a manufactured pouch film with respect to the drying temperature and time and evaluates its adhesive strength in the presence of moisture. The results indicate that the residual moisture on the aluminum surface weakens the adhesive strength and significantly affects electrolyte resistance. A noticeable reduction in strength was observed after water spraying, when the drying temperature and time were relatively low during the initial strength measurement. Among the adhesives used for aluminum and CPP lamination, olefin adhesives exhibit less susceptibility to electrolyte effects and have higher adhesive strengths compared to urethane and ester adhesives. Leveraging these characteristics, flexible pouch cells were manufactured and their stability was evaluated. The results confirm that the flexible cells demonstrate excellent stability, exhibiting potential for application in wearable devices. Full article

Oxygen scavengers are used to reduce the oxygen permeation of packaging (active barrier) and to absorb oxygen from its direct environment, e.g., a headspace of packaged food. Few oxygen scavenger coatings have been developed. Therefore, in this study, a novel oxygen scavenger coating has been developed. It is based on inorganic–organic polymers (ORMOCER^®). The oxygen absorption reaction is activated by UV light. The scavenger was synthesized, coated on aluminum foil, subsequently dried and afterwards laminated with a polyethylene sealing layer. UV light activates the oxygen scavenging reaction. The oxygen absorption capacity, measured at 23 °C and 0% r.h., was 242 ± 8 mg oxygen/g scavenger coating. When the oxygen scavenger coating layer was laminated by using a two-component polyurethane laminating adhesive, the absorption capacity was hardly reduced, with a measured absorption capacity of 223 ± 18 mg oxygen/g scavenger coating. In an experimental packaging sample with the oxygen scavenger coating with a thickness (dry) of 3 µm and 18 µm, near-zero mbar oxygen partial pressure was reached by the non-laminated oxygen scavenger coatings within two days, and within about 20 days when laminated with a polyurethane laminating adhesive and a PE-layer on the oxygen scavenger layer. The oxygen partial pressure was kept near zero mbar for 500 days, whereas in the experimental packaging without oxygen scavenger, the oxygen partial pressure increased to 110 mbar during this time. The developed oxygen scavenger based on inorganic–organic polymers can be applied as wet chemical coating on various surfaces with standard application procedures. Application scenarios are oxygen-sensitive goods such as food, pharmaceutical products and cosmetics. Full article

This study examined the water repellency (WR), waterproof, and water vapor permeability (WVP) characteristics of twelve types of laminated and coated woven fabrics for outdoor clothing. These characteristics were compared with the fabric structural parameters, such as cover factor, thickness, and weight, and surface modification (finishing) factors, such as coating, laminating, and Teflon treatments. In addition, an eco-friendly process for surface modification was proposed followed by a summary. Superior waterproof-breathable characteristics with 100% water-repellency were achieved in specimen 3 in group A by treatment with a hydrophilic laminated finish using nylon woven fabric with a cover factor between 0.7 and 0.9 in a 2.5-layered fabric, which was the best specimen with waterproof-breathable characteristics. A high WVP in the coated and laminated fabrics was observed in the fabrics with a low weave density coefficient (WDC) and low thickness per unit weight of the fabric, whereas superior water repellency and waterproof characteristics were observed in the high-cover-factor (WDC) fabric with appropriate fabric thickness. The determination coefficient (R²) from regression analysis between the WVP and fabric structural parameters indicated a higher contribution of the fabric structural parameters than surface modification factors, such as coating and laminating to the WVP in the coated and laminated fabrics. Furthermore, the cover factor was the most important factor influencing the WVP of the waterproof-breathable fabrics. Of twelve coated and laminated fabrics, the laminated nylon and nylon/cotton composite fabrics showed superior WVP with high WR and waterproof characteristics. Accordingly, based on the WR, waterproof, and WVP characteristics of the coated and laminated breathable fabrics, the laminating method, as an eco-friendly process, is recommended to obtain better waterproof-breathable fabrics. Full article

This study examined the effects of the fiber materials, fabric structural parameters, and surface modification method on the moisture vapor resistance of coated and laminated fabrics according to the measuring method in comparison with evaporative wet heat transfer method. The moisture vapor resistance (R_ef) of the coated and laminated fabrics measured using evaporative wet heat transfer method was much more precise than water vapor transmission rate (WVTR) and water vapor permeability (WVP) measured using American Society for Testing and Materials (ASTM) and Japanese Industrial Standard (JIS) methods. The correlation coefficient between R_ef and WVTR in the laminated and coated polyethylene terephthalate (PET) fabric specimens was the highest, i.e., −0.833, and −0.715, in coated fabric specimens. Hence, selecting an appropriate measuring method according to the fabric materials and surface modification method is very critical. According to curvilinear regression analysis, the influential factor affecting breathability of the PET fabric specimens measured using evaporative wet heat transfer method was fabric weight (R² = 0.847) and fabric thickness (R² = 0.872) in the laminated fabric specimens. Meanwhile, as per multiple linear regression, the most influential fabric structural parameters affecting the breathability of laminated fabric specimens measured using evaporative wet heat transfer method were the fabric density, weight/thickness, and weight followed by the fabric thickness (R² = 0.943). These results would be valid for laminated breathable fabrics with characteristics within the range of this study and are of practical use for engineering laminated fabrics with high breathability. Full article

Graphene as an interphase not only improves the mechanical performance of fiber reinforced polymer composites but also induces functional properties like electrical conductivity, thus providing the possibility of strain monitoring in real time. At this aim, graphene oxide (GO) was electrophoretically deposited at different applied potentials on glass fibers to create a uniform coating and was subsequently chemically reduced to obtain a conductive layer of reduced graphene oxide (rGO). After the optimization of the deposition process, composite laminates were prepared by hand lay-up with an epoxy resin, followed by curing in vacuum bag. The deposited rGO interphase improved the dynamic moduli (storage and loss modulus), the flexural strength (+23%), and interlaminar shear strength (ILSS) (+29%) of the composites. Moreover, laminates reinforced with rGO-coated glass fibers showed an electrical resistivity in the order of ~10¹ Ω·m, with a negative temperature coefficient. The piezoresistivity of the composites was monitored under flexural loading under isothermal conditions, and strain/damage monitoring was evaluated at different temperatures through the change of the electrical resistance with the applied strain. Full article