Film Shrinkage Research Articles

Interaction mechanism and factors influencing dynamics of rock-heavy oil-chemical agent interface

The interactions among the rock, oil, and chemical agent are critical for oil recovery. However, the mechanisms underlying this synergistic effect remain unclear. Therefore, this study used custom-made experimental methods to analyze these interactions and behavior of heavy oil on rock surfaces and elucidate the micro-interaction mechanism of the liquid–solid interface. Oil adhesion, flow, and deformation were studied via experiments on oil spreading, oil film emulsification, oil film shrinkage, and oil droplet peeling and deformation. Moreover, the contributions of oil diffusion on rock surface and flow through porous media to oil spread dynamics were detailed for the first time. The influence of the oil flow in porous media on oil recovery and the influencing factors were also studied. Furthermore, the effects of the rock–oil–water interface on the emulsification, shrinkage, and peeling of oil film were studied via chemical agent–oil film interactions. The main mechanisms underlying the effects of chemical agents on heavy oil flow were elucidated. Finally, the morphologies of the oil droplets under weak buoyancy were studied. The degree of deformation of oil droplets was evaluated to analyze the effect of chemical agents on the oil–water interface and factors influencing this process. Therefore, this study offers insights into the oil recovery process by analyzing heavy oil flow through porous media and the effects of chemical agents on rock surfaces and oil–water interfaces and lays the groundwork for chemical agent optimization to enhance oil recovery.

An Analysis of Changes in the Harmfulness of the Bottle Packaging Process Depending on the Type of Heat-Shrinkable Film.

This article shows an analysis of selected stages of a machine's life cycle environmental impact in the specific case of machines that package bottles in thermo-shrinkable film. As part of this analysis, laboratory tests were carried out to compare the performance properties of polyethylene films (with and without recycled material). Then, a life cycle assessment (LCA) was carried out within the specified system boundaries using the SimaPro program. Using the ReCiPe 2016 method, differences in the impact of the mass bottle packaging process on the categories human health, ecosystems and resources were determined depending on the shrink film used in the process. These tests showed that the tested batch of film with the addition of recyclates has similar functional properties to traditional ones and can therefore be used in the mass packaging process. The environmental analysis showed that changing the type of film to film with the addition of recyclates results in an almost 70% reduction in the potential negative impact of the process in terms of damage to health and ecosystems, and by 85% in terms of resources.

Breakdown and interface dynamics of pulsed discharge plasma across air-water interface: From single to repetitive stimulation

Pulsed discharge in the vicinity of a multi-phase interface, where a discontinuity of physical properties exists, can be a joint problem of both electro- and thermo-physics. This study shows a comprehensive analysis of electric breakdown across an air-water interface and its successive multi-physical effects. The scenario is constructed via a pair of pin electrodes positioned on both sides of the interface, and the transient discharge is analyzed using high-speed backlight photography synchronized with electrical and optical diagnostics. It is observed that the corona/streamer develops from either side of the pin electrode. Electrostatic instability causes the interface to fluctuate and a water column to form above the interface. By increasing the applied voltage, discharge evolves from “dielectric barrier” mode (pin to interface) to “through breakdown” mode (pin to pin). Once the conductive channel bridges two electrodes, electric power of ∼40 kW peak and deposited energy of 100 mJ will be injected into the channel and promote the “streamer-spark” transition, resulting in a crown-like splash (100 m s-1) near the interface and cavity formation. As the quenching of diffused plasmas, the over-expanded splash (5 mm in diameter) would be re-compressed by the ambient air. Particularly, the shrinkage of the thin water film of the splash can reach a 20 mm jet near the axis and develop Rayleigh-Taylor instability, along with the formation of micro-jets eruption during the convergent collision. More sophisticated interactions will appear at higher repetitive frequency (>100 Hz), where the perturbation caused by one pulse will influence the next, namely the “memory” effect. Furthermore, periodic loading on the interface effectively changes the cavity characteristics, showing an attractive prospect in fluid control applications.

Environmental Analysis of the Impact of Changing Shrink Film in the Mass Bottle Packaging Process

The aim of this study was to assess the environmental impact of using recycled polyethylene film for shrink-wrapping bottles. For this aim, film properties were tested and the harmfulness of the packaging process was simulated for film made from virgin and recycled material. For the recycled film, the results showed an increase of 14.7% in impact resistance, a change from −21.6 to +94.3% in tear resistance, and a decrease of up to 45.4% in tensile strength in dependence on the test direction. Using differential scanning calorimetry (DSC), the changes in the properties of the two types of film with temperature changes were evaluated. DSC analysis showed that recycled film has a 1.94 °C lower glass transition temperature and a 1.85 °C lower melting point in comparison to polyethylene film. This can reduce the temperature of the packaging process and lead to energy savings. A study conducted with SimaPro 9.3 software showed that a change in films made of virgin raw material to recycled films reduces the negative impact on the environment from 68.5 to 11.5%. The change also reduces resource consumption by about 80 percent. The results of conducted tests and simulations showed that using recycled film for bottle packaging allows reducing the negative environmental impact of examined process, especially in terms of resource consumption and energy savings.

Drying Behavior Analysis of the Coating Layer of Metal Powder Paste Based on Film Shrinkage

Drying Behavior Analysis of the Coating Layer of Metal Powder Paste Based on Film Shrinkage

Cyclic pressing as a viable approach for dewatering and controlling shrinkage of micro-nanofabricated cellulose films

Cellulose films, predominantly consisting of micro-nanocelluloses, are a new type of product with interesting properties for functional packaging applications. However, the potentially scalable production methodology has not yet been elucidated. Poor dewatering and high web shrinkage are issues that need solutions beyond what is available in conventional paper production. This research investigates a cyclic pressing method that shows potential in cellulose film consolidation. Cyclic pressing allows the MNFC films to be dewatered to about 90% solids while yielding a smooth, flat product. The results show no inherent physical limits for mechanical dewatering these high swelling webs, even at very high solids. Cyclic pressing allows controlled restraint during consolidation, which could be adjusted in an industrial setup to produce even films with desirable product characteristics.

Controlled shrinkage of cellulose nanofibril films to enhance mechanical and barrier properties

Standalone cellulose nanofibril (CNF) films have a natural tendency to shrink upon drying from wet conditions due to capillary drying stresses. This shrinkage happens in both the radial direction, and the vertical direction. In this study, we prepared two types of CNF films- one in a restrained condition that did not allow shrinkage in the radial direction but enabled it in the vertical direction and another with 11 % radial shrinkage but limited vertical shrinkage. The radial shrinkage led to a more porous structure than the vertical shrinkage, which brought about poorer oxygen/moisture barrier performance. However, the density and oxygen permeability of the films converged to a similar value upon a simple thermocompression process. Radial shrinkage resulted in 140 % and 90 % higher strain at break and toughness in films with a significant sacrifice in strength and modulus. Scanning electron microscopy revealed that radial shrinkage formed wavy layers in the core structure leaving more free space, whereas vertical shrinkage formed flatter layers. Radial shrinkage is likely to produce a thicker individual layer in the core structure of CNF films than vertical shrinkage. The insight from this study will help tune the mechanical and barrier performance of CNF films and their composites.

Rapid-Response Water-Shrink Films with High Output Work Density Based on Polyethylene Oxide and α-Cyclodextrin for Autonomous Wound Closure.

Conventional wound closure methods, including sutures and tissue adhesives, present significant challenges for self-care treatment, particularly in the context of bleeding wounds. Existing stimuli-responsive contractile materials designed for autonomous wound closure frequently lack sufficient output work density to generate the force needed to bring the wound edges into proximity or necessitate stimuli that are not compatible with the human body. Here, semi-transparent, flexible, and water-responsive shrinkable films, composed of poly(ethylene oxide) and α-cyclodextrin, are reported. These films exhibit remarkable stability under ambient conditions and demonstrate significant contraction (≈50%) within 6 s upon exposure to water, generating substantial contractile stress (up to 6MPa) and output work density (≈1028kJ m-3), which is 100 times larger than that of conventional hydrogel and 25 times larger than that of skeletal muscles. Remarkably, upon hydration, these films are capable of lifting objects 10000 times their own weight. Leveraging this technology, water-shrink tapes, which, upon contact with water, effectively constrict human skin and autonomously close bleeding wounds in animal models within 10 seconds, are developed further. This work offers a novel approach to skin wound management, showing significant potential for emergency and self-care scenarios.

Interfacial Dehydration Strategy for Chitosan Film Shape Morphing and Its Application.

Shape morphing of biopolymer materials, such as chitosan (CS) films, has great potential for applications in many fields. Traditionally, their responsive behavior has been induced by the differential water swelling through the preparation of multicomponent composites or cross-linking as deformation is not controllable in the absence of these processes. Here, we report an interfacial dehydration strategy to trigger the shape morphing of the monocomponent CS film without cross-linking. The release of water molecules is achieved by spraying the surface with a NaOH solution or organic solvents, which results in the interfacial shrinkage and deformation of the entire film. On the basis of this strategy, a range of CS actuators were developed, such as soft grippers, joint actuators, and a light switch. Combined with the geometry effect, edited deformation was also achieved from the planar CS film. This shape-morphing strategy is expected to enable the application of more biopolymers in a wide range of fields.

Evolution of asphalt performance under the coupled aging of ultraviolet, high temperature and water

During the service of asphalt pavement, it is affected by natural environmental factors for a long time, and the pavement performance declined. In order to simulate the cumulative effects of multiple aging components, the indoor "ultraviolet radiation, high temperature and water" multi-factor cyclic coupling aging test was designed. The properties of asphalt during cyclic coupled aging were measured by conventional physical properties tests, photoelectric colorimetric tests, and Fourier Transform Infrared Spectroscopy test. Then the surface morphology of asphalt was observed by camera and optical microscope. After asphalt aged, a large number of oxidation functional groups were formed, causing asphalt to become hard and brittle, adhesion to diminish, and surface roughness to increase. Ultraviolet light and high temperatures led to the exudation and dissolution of the liquid constituents within the asphalt, which were subsequently washed away by water. The thermal stress induced the shrinkage and wrinkle of the asphalt film, resulting in the formation of cracks. Under high temperatures, a limited number of cracks could potentially self-repair during the early stages of aging. Nevertheless, as the aging process progressed, the self-healing capacity of the asphalt diminished, leading to the widening and deepening of cracks. Concurrently, water infiltrated along the cracks into the inner layers of the asphalt, exacerbating the degradation of its properties.

Evaluation of the effect of the incorporation of poly(lactic acid) and maleic anhydride in the thermoshrinkage of films from thermoplastic starch

AbstractStudies on the property of shape memory in thermoplastic starch (TPS) have shown good results, making such starch a suitable candidate for use in shrink packaging. It is however necessary to evaluate blending it with other bioplastics that would improve its properties while maintaining heat shrinkage. This article thus shows the evaluation of the incorporation of different concentrations of polylactic acid (PLA) and maleic anhydride (MA) as coupling agent and their effect on shrinkage and the changes in structure of the films obtained by blown film extrusion. In most of the blends, the incorporation of PLA and MA was found to favor film shrinkage, obtaining values of up to 55% due to the fact that the interaction between TPS and PLA increased with the incorporation of MA. This was corroborated by the % of MA grafted, thermogravimetric analysis (TGA), rheological and structural tests. This allowed generating a greater molecular orientation of the films, thereby obtaining greater shrinkage. It was determined that the incorporation of PLA and % MA grafted generated good shrinkage results due to the physical and chemical crosslinking achieved in the processing of the blends in the presence of MA, enhancing their application as packaging.

Synthesis and characterization of organosilicon functionalized water-based polyvinylidene chloride emulsion with core-shell structure

The outstanding barrier performance of polyvinylidene chloride (PVDC) has attracted widespread attention. In this work, a series of organosilicon functionalized water-based PVDC emulsions with core-shell structure are synthesized by seed emulsion polymerization using vinylidene chloride (VDC), methyl acrylate (MA), isooctyl acrylate (EHA) as core and vinylidene chloride (VDC), methyl acrylate (MA) as shell. Vinyl-terminated polydimethylsiloxanes (VT-PDMS) are introduced into the core-shell as modifier. The properties of PVDC emulsions and films modified with VT-PDMS are investigated. On the one hand, when VT-PDMS is properly incorporated into the core-shell particles, the Si-O bonds in VT-PDMS are dissociated, which further forms a cross-networking structure, thereby enhances the adhesion of PVDC film to the substrate. The barrier performance of the film is also improved by a small amount of cross network structure. On the other hand, the addition of VT-PDMS leads to the phenomenon of thin film shrinkage, which further enhances the barrier performance of PVDC. All results indicate that the best comprehensive performance is achieved when the VT-PDMS content in the PVDC core is 2 wt%, the adhesion can be increased to 0.527 MPa, the oxygen transmittance is 5.68 cc/m2·24 hr, and the actual time of water barrier after coating starch-based tableware is over 12 hours. This provides an effective line of thinking for the further application of PVDC barrier film in the field of environmental protection food packaging.

Evaluation of the risk of occupational exposure to antineoplastic drugs in healthcare sector: part II - the application of the FMECA method to compare manual vs automated preparation.

Healthcare workers handling antineoplastic drugs (ADs) in preparation units run the risk of occupational exposure to contaminated surfaces and associated mutagenic, teratogenic, and oncogenic effects of those drugs. To minimise this risk, automated compounding systems, mainly robots, have been replacing manual preparation of intravenous drugs for the last 20 years now, and their number is on the rise. To evaluate contamination risk and the quality of the working environment for healthcare workers preparing ADs, we applied the Failure Mode Effects and Criticality Analysis (FMECA) method to compare the acceptable risk level (ARL), based on the risk priority number (RPN) calculated from five identified failure modes, with the measured risk level (MRL). The model has shown higher risk of exposure with powdered ADs and containers not protected by external plastic shrink film, but we found no clear difference in contamination risk between manual and automated preparation. This approach could be useful to assess and prevent the risk of occupational exposure for healthcare workers coming from residual cytotoxic contamination both for current handling procedures and the newly designed ones. At the same time, contamination monitoring data can be used to keep track of the quality of working conditions by comparing the observed risk profiles with the proposed ARL. Our study has shown that automated preparation may have an upper hand in terms of safety but still leaves room for improvement, at least in our four hospitals.

Characterization of Shrink Film Properties for Rapid Microfluidics Lab-on-Chip Fabrication.

Shrink film is a thin sheet of polystyrene plastic that shrinks to 25-40% of its original size when heated. This study investigated the shrinkage factor of the film at different temperatures and baking times to determine the optimal fabrication recipe for shrink film microfluidic device production. Additionally, this study characterized the properties of shrink film, including minimum possible feature size and cross-section geometries, using manual engraving and the CAMEO 4 automated cutting machine. The optimal shrinkage factor ranged from 1.7 to 2.9 at 150 °C and a baking time of 4 min, producing the ideal size for microfluidic device fabrication. The X- and Y-axes shrank ~2.5 times, while Z-axis thickened by a factor of ~5.8 times. This study achieved a minimum feature size of 200 microns, limited by the collapsing of channel sidewalls when shrunk, leading to blockages in the microchannel. These findings demonstrate the feasibility and versatility of using shrink film as a cost-effective and efficient material for the rapid fabrication of microfluidic devices. The potential applications of this material in various fields such as the medical and biomedical industries, bacteria and algae culture and enumeration are noteworthy.

Assessing the Sustainable Potential of Corrugated Board-Based Bundle Packaging of PET Bottles: A Life Cycle Perspective—A Case Study

Large amounts of PET bottles are used worldwide as primary packaging for numerous liquids, including water and soft drinks. In many cases, between two and eight of such bottles are bundled for transport and sales using plastic collation shrink film. This study evaluates paper-based alternatives for plastic bundling material using a life cycle assessment (LCA) of four different types of bundle packaging: LDPE shrink film, recycled Low-Density Polyethylene (rLDPE) shrink film, Ecogrip (existing paper-based bundle packaging) and Ecobundle (new paper-based bundle packaging). The study focuses on the case of bundling six bottles of 1.5 L of sparkling water. The most environmentally friendly option is identified, taking into consideration the material usage, effects on human health and effects on the biosphere. It is concluded that the new corrugated board-based bundling method (Ecobundle) is very promising. Further optimization of the design, minimization of material, improved choice of materials and improved design of the production machinery may result in a corrugated board performing even better than rLDPE shrink film in terms of the global warming potential.

Sustainable fabrication of chitosan membranes with optimized performance for ultrafiltration

A key to the sustainable development of membrane technology is the green fabrication of biopolymer membranes, whose filtration performance is comparable to that made from petroleum-based polymers. In this study, chitosan membranes were fabricated via wet precipitation of the alkaline dope; both the composition and temperature of the coagulation bath were regulated to optimize the filtration performance for ultrafiltration. It is revealed by comparing the morphological characterization with the filtration-performance evaluation that the use of pure ethanol as the coagulant at a subzero temperature would be in favor of the formation of a laminated substructure, which can enhance the water permeance not at the cost of decreasing the rejection of micron-sized particles and macromolecules. Optical coherence tomography (OCT) was employed to in-situ characterize the film formation in an effort to understand how the variation in coagulating conditions could change the geometrical and topological characteristics of the resulting membrane. The OCT-based characterization highlights the key role of the Liesegang phenomenon in forming the hierarchical substructures, while resolving the synergistic effects emanating from the ethanol-induced film shrinkage and the structural preservation in the subzero environment.

Solidification dynamics of polymer membrane by solvent extraction: Spontaneous stratification

Nonsolvent-induced phase separation is widely used to create polymer membranes, but its demixing process is generally understood by liquid-liquid separation. In this work, the solidification dynamics of polymer solutions for membrane formation are explored through dissipative particle dynamics simulations. The shrinkage of the symmetric film of polymer solution is monitored, and the evolutions of the concentration profiles of polymer, solvent, and nonsolvent are analyzed. Additionally, the evolution of the degree of crystallinity (local alignment) and the morphology of the developing membrane are also studied. Three regions can be identified: (i) interfacial region, (ii) dense layer, and (iii) middle region. The demixing process associated with liquid-solid separation is found to be caused by the extraction of solvent and concentration of polymers rather than nonsolvent-induced separation. Our results provide valuable insights into directional solidification and spontaneous stratification of the membrane, driven by solvent loss and oversaturation (beyond the maximum solubility of polymer).

Theoretical study on the wetting rate in wet channel of dew-point evaporative cooler based on Marangoni effect

Dew-point evaporative cooler is widely concerned as a fresh air precooling system, for its high efficiency, energy saving and environmental protection. A mathematical model for a plate-type counter flow dew-point evaporative cooler is developed in the paper, in which the film shrinkage induced by the Marangoni effect is taken in account. The results show that the model based on Marangoni effect has a higher accuracy compared to the model with wetting rate σ = 100%, in which the Average Relative Deviation from the experiment decreases by 15.8%. The wettability distribution characteristics are investigated. Along the air flow, the transverse contraction distance of film is varied, which mostly depends on the evaporation process. The higher inlet air temperature, the lower inlet air humidity, the higher velocity of inlet air, the larger channel gap, and the higher ratio of working air to inlet air would cause the higher Marangoni number and lower wetting rate. Further, a constant value of wetting rate 96.2% is recommended to simplify the calculation, while the Average Relative Deviation of the simulated results compared to the actual process is only 0.47%.

Stretchable and Flexible Micro-Nano Substrates for SERS Detection of Organic Dyes.

Surface-enhanced Raman spectroscopy (SERS) is a precise and noninvasive analytical technique to identify vibrational fingerprints of trace analytes with sensitivity down to the single-molecule level. However, substrates can influence this capability, and current SERS techniques lack uniform, reproducible, and stable substrates to control plasma hot spots over a wide spectral range. Herein, we demonstrate a flexible SERS substrate via longitudinal stretching of a polydimethylsiloxane (PDMS) film. This substrate, after stretching and shrinking, exhibits an irregular wrinkled structure with abundant gaps and grooves that function as hot spots, thereby improving the hydrophobic properties of the material. To investigate the enhancement effect of Raman signals, silver nanoparticles (AgNPs) were mixed with Rhodamine 6G (R6G) solution, and the obtained blend was dropped onto the PDMS film to form a coffee ring pattern. According to the results, the hydrophobicity of the substrate increases with the degree of PDMS stretching, achieving the optimal level at 150% stretching. Moreover, the increase in hydrophobicity makes the measured molecules more aggregated, which enhances the Raman signal. The stretching and shrinkage of the PDMS film lead to a much higher density of nanogaps among nanoparticles and nanogrooves, which serve as multiple hot spots. Being highly localized regions of intense local fields, these hot spots make a significant contribution to SERS performance, improving the sensitivity and reproducibility of the method. In particular, the relative standard deviation (RSD) was found to be 2.5544%, and the detection limit was 1 × 10-7 M. Therefore, SERS using stretchable and flexible micro-nano substrates is a promising way for detecting dyes in wastewater.

Effects of drying rate and slurry microstructure on the formation process of LiB cathode and electrochemical properties

The drying process of electrode slurry for LiB should be crucial to obtain higher electrochemical performance, but it has been a black box. Furthermore, the lack of sufficient information on slurry microstructure complicates solving this issue. In this study, the cathode slurries having different internal structures are prepared and characterized by rheological properties. The drying process of the coating layer is evaluated in terms of film shrinkage. When the coarse particles of active material and the network structure of acetylene-black particles are uniformly mixed, a low drying rate results in extensive particle segregation and poor cycle performance. On the other hand, it is found that insufficient dispersion of active materials causes poor rate performance. Under the optimal drying condition, the slurry microstructure is found not to affect battery performance. However, the optimization of drying conditions requires consideration of material mobility during drying.