Peel Force Research Articles

A Bio-Based Tackifier Synthesized by Room-Temperature Cationic Copolymerization of Isobutene and β-Pinene

Whereas the cationic homopolymerization of β-pinene and isobutene (IB) have been extensively studied, their copolymerization is still very scarce, and the conditions under which copolymerization can occur are limited to extremely low temperatures. Moreover, the application of the copolymer has not been reported. Here, a series of room-temperature copolymerizations of β-pinene and IB, using group 13 compounds as catalysts, were conducted. The copolymerizations yielded a low molecular weight (Mn ~ 103) and a narrow molecular weight distribution (Mw/Mn < 2.0) copolymer, with a satisfactory yield at various comonomer feeds, and their glass transition temperature was predictable from the comonomer composition. Furthermore, the tackifying property of the obtained copolymer was investigated using a 180° peel adhesion test. A blend polymer of the copolymer and a styrene-isoprene triblock copolymer showed a high peeling force (0.58 ± 0.14 N/10 mm) and a glass transition temperature low enough for its application as a pressure-sensitive adhesive.

Determination traction-separation parameters and its sensitivity analysis of bilinear cohesive zone model through experimental and numerical peeling analysis of electrodes

The optimization of traction-separation parameters within the cohesive zone model (CZM) is crucial for accurately simulating electrode peeling failure in lithium-ion batteries. This study performed 180° peeling tests on NCM electrodes and used Abaqus software alongside the sim-flow optimization tool for simulation analysis, aiming to accurately replicate the failure behavior at the lithium-ion battery electrode interface. Experimental results were used to determine the fracture energy of the electrode interface, while numerical simulations analyzed the peeling performance of the electrode. By fitting the force-displacement curves from both simulation and experiment, the traction-separation parameters within the bilinear CZM were optimized. Additionally, the study analyzed the effects of traction-separation parameters, as well as the modulus and thickness of the current collector, on peeling behavior. The results showed that a significant increase in the interface stiffness and strength increased the steady-state peeling force. Among these, the fracture energy had the most significant influence on the steady-state peeling force. Furthermore, while the modulus and thickness of the current collector affected the maximum peeling force, their effect on the steady-state peeling force was negligible. These findings enhance the accuracy of simulating the failure behavior of the electrode interface.

Ultra-Hydrophobic Gauze Driving Super-Haemostasis.

Controlling bleeding by applying pressing cotton gauze is the most facile treatment in prehospital emergencies. However, the wettable nature of cotton fibers leads to unnecessary blood loss due to excessive blood absorption, inseparable adhesion-induced pain, and pliable to infection. Here, a kind of ultra-hydrophobic haemostatic anti-adhesive gauze whose surface is loaded with polydimethylsiloxane (PDMS) and hydrophobic-modified cellulose nanocrystals (CNCs), achieving a water contact angle of ≈160° is developed. It is demonstrated that the mechanism by which hydrophobic CNCs promote blood clotting is associated with their ability to activate coagulation factors, contributing to fibrin formation, and promoting platelet activation. The blood-restricting effect results from the low surface energy layer formed by PDMS and then the alkyl chains of hydrophobic CNCs are combined. The produced ultra-hydrophobic gauze resists blood flow and diffusion, decreases blood loss, is effortlessly peelable, and minimizes pathogen adhesion. Compared to the commercial cotton gauze, this gauze achieved effective haemostasis and antiadhesion by reducing blood loss by more than 90%, shortening haemostasis time by more than 75%, lowering peeling force by more than 90% and minifying bacterium attachment by more than 95%. This work presents promising applications in terms of prehospital first aid.

Design of chitosan-based drug-loaded laminated materials with superhydrophilic/superhydrophobic properties for simultaneous effective hemostasis and antiadhesion

Hemostatic materials play a crucial role in trauma medicine. However, existing materials have poor hemostatic efficacy and a tendency to adhere to the wound surface, limiting their clinical effectiveness. Herein, a drug-loaded, superhydrophilic/superhydrophobic laminated material (DSLM), consisting of a superhydrophobic inner layer with a micropore array, a superhydrophilic chitosan-based sponge layer loaded with hemostatic/antimicrobial drugs, and a superhydrophobic outer layer, was developed. Furthermore, the DSLM allows unidirectional flow of blood and exudates from the wound bed through the superhydrophobic inner layer while facilitating efficient drug delivery. In addition, it possesses excellent biocompatibility and antiadhesion properties, as confirmed by in vivo and in vitro experiments. Compared with traditional hemostatic materials, the DSLM remarkably increased the survival time by over threefold in the acute femoral transaction wound bleeding model, and simultaneously prevented secondary wound damage by reducing peeling force to one-eighth incomparison to pristine gauze. The DSLM holds promise as a versatile clinical biomaterial for prehospital acute trauma treatment, with its simple structure facilitating manufacturing and expanding applications in biomedicine.

Highly conductive coated wires for interconnection of solar cells with TECC-wire technology

TECC-Wire (thermoplastic and electrically conductive coated wire) represents a promising interconnection technology for temperature sensitive solar cells. TECC-Wire uses round copper wires (160–300 μm) coated with a thermoplastic polymer layer (10–20 μm), filled with electrically conductive particles. This study presents a new wire coating formulation based on a polyamide-type wire enamel (Voltatex® 8609 ECO, melting temperature 180 °C), filled with 12 vol% silver resulting in a conductivity of 480 S/cm. Single half-cut M6 heterojunction (SHJ) solar cells were contacted with the manufactured wires using a laboratory scale stringing machine. Peel tests were performed to characterize the adhesion of the wires to the cell surface, module performance was evaluated using electroluminescence (EL) imaging and current-voltage (IV) measurements, damp heat (DH) tests were used to evaluate the long-term stability of the modules. The wires adhere well to the cells with a peel force of more than 1.5 N/mm, and the highly conductive coating has proven to be robust when contacted with different pressure, which might be beneficial for a reliable high throughput solar module production. The obtained fill factor FF = 81.25 ± 0,12 % is similar to those achieved for solar modules connected via standard soldering techniques IEC standard DH tests confirmed that, the modules exhibiting a power loss of less than 5 % after 1000 h of storage at +85 °C and 85 % relative humidity. These results are very encouraging for further development of the technology towards a low temperature, solder-free, low cost and robust cell interconnection technology.

Enhancing mechanical integrity of vat photopolymerization 3D printed hydroxyapatite scaffolds through overcoming peeling defects

In ceramic vat photopolymerization (VPP) fabrication, directly peeling originally designed scaffolds from the platform is efficient but often introduces defects, compromising the mechanical integrity of hydroxyapatite (HAp) scaffold. The peeling process involves the resistance of the HAp green scaffolds to peeling forces, which is influenced by its modulus and toughness. In this study, the peeling behavior of cubic-pore HAp (CP-HAp) green scaffolds with varying levels of modulus and toughness was investigated. The characterization results show that the HDDA CP-HAp scaffolds with relatively high levels of modulus and toughness could effectively resist the peeling forces and inhibit the occurrence of peeling defects. Stress concentration and inadequate toughness in the HEMA CP-HAp scaffolds lead to the formation of peeling defects. The CTFA and PHEA CP-HAp scaffolds with low modulus exhibit both peeling cracks and numerous pores. The cracks result from stress concentration, while the pores are caused by the coiled and loose molecular chain structure occupying space. Understanding the mechanism of peeling defect initiation in HAp porous scaffolds contributes to improving resistance to such defects and efficiently fabricating high-performance ceramic scaffolds using VPP.

Phosphate Esters: New Coating Materials for a Sustainable Release Paper.

AbstractPaper manufacturers have long used silicone as the coating agent for release liners. However, silicone‐based release paper is very difficult to recycle due to covalent bonds between silicone and fibers. The most suitable solution to overcome this problem is to use alternative coating materials with adequate release properties, provided that they can be easily repulped in typical paper recycling facilities. We proposed a coating agent composed of phosphate esters and dimethylacetamide in order to manufacture a recyclable and efficient release paper. Analyses carried out on coated sheets showed that phosphate esters allowed the formation of a surface with adequate release properties (low peeling force and surface free energy). In addition, the residual adhesion values obtained with phosphate esters confirmed that they are well anchored on the backing paper surface, thus limiting the mass transfer to the adhesive tape.

Evaluation of the influence of the material composition on the peel behavior of adhesive and cohesive peel systems using experimental fracture mechanics methods

AbstractThe study focusses on a low‐density polyethylene/isotactic polybutene‐1 peel system with low‐density polyethylene as matrix and isotactic polybutene‐1 as peel component sealed against itself (cohesive peel system), and on an ethylene vinyl acetate/linear low‐density polyethylene peel system with ethylene vinyl acetate as matrix and linear low‐density polyethylene as peel component sealed against polyethylene terephthalate (adhesive peel system). Due to a new approach to estimate the true fracture surface using 3D reconstruction, it was possible to determine the true adhesive energy release rate, especially for cohesive peel systems. This enables a direct comparison of the fracture mechanics parameters determined from both types of peel systems. The results reveal that the recipe has a distinct influence on the peel behavior. An increasing amount of the used peel component leads in any case to a decrease of the peel force as well as of the energy release rate for both, sealed adhesive and cohesive peel systems. Using application engineering examples generalizable relationships between structure and properties of peel systems could be estimated and the structure sensitivity of the fracture mechanical parameters could be proven.

Efficient and environmentally friendly separation and recycling of cathode materials and current collectors for lithium-ion batteries by fast Joule heating

Spent Li-ion batteries(LIBs) cathodes possess high recycling value. To improve subsequent recovery efficiency and product purity, separating the cathode materials from the aluminum foil is critical. However, traditional separation methods are characterized by high energy consumption, low recycling efficiency, and environmental pollution. This research presents a novel method that involves injecting Joule heat directly into the aluminum foil in the air, resulting in the melting and slight thermal decomposition of the PVDF binder, which reduces its adhesive properties. Owing to the difference in thermal expansion coefficients between the binder and aluminum foil, an instantaneous thermal stress was generated at the interface of the cathode materials and aluminum foil, resulting in a peeling force. This method enabled a rapid and efficient separation of lithium iron phosphate (LFP) and ternary Li-ion (NCM) battery cathode materials. The optimal separation conditions, separation mechanism, and properties of the recovered products were investigated thoroughly using high-speed camera imaging, temperature rise calculations, and microscopic characterization. This chemical-free method avoids the generation of wastewater and gas emissions. Under optimal experimental parameters, the separation efficiency and purity of cathode material reached 99 % and 99.7 %, respectively. Additionally, this method preserves both the structural integrity of the aluminum foil and the crystalline structure of the cathode materials, offering a new pathway for sustainable recycling of end-of-life LIBs.

Assessment of the effect of processing parameters on peel failure of laser-assisted automated fiber placed thermoplastic composites

In this study, thermoplastic composites are fabricated using laser-assisted automated fiber placement, focusing on the influence of compaction force, roller head speed, and temperature. Employing wedge peel testing, digital and electron microscopy, and probabilistic machine learning, the research examines how these parameters affect mechanical performance and failure. Key observations include increased bonding area and peel force with higher processing temperatures, while greater compaction force introduces more variability in bonding and peel strength. Roller head speed shows minimal impact. The study effectively links processing parameters with wedge peel failure, illustrating the complex interactions in composite material behavior.

Silanization as a strategy to design polyurethane-acrylic hybrid pressure-sensitive adhesives

Pressure-sensitive adhesives (PSAs) are a critical class of adhesives used in numerous applications. Acrylic copolymers and polyurethanes are two main categories of polymers that PSAs are made from. However, to take advantage of unique properties of both of them, polyurethane-acrylic hybrid PSAs have been proposed. To date, for synthesis of these hybrid PSAs, there should have been an acrylic comonomer containing a specific functional group to be able to react with the isocyanate group. This research was conducted to eliminate the need for such an acrylic comonomer with a specific functional group through silanization. For this purpose, firstly, a silanized polyurethane (SPU) was synthesized through silanization of a polyol. Subsequently, copolymerization of two acrylic comonomers was performed in the absence or presence of SPU. In the next step, prior to adding the acrylic comonomers to the SPU, silane was added to SPU to enable higher grafting. The PSA containing 0.04 wt % of silane showed a peel force, static shear strength, and tack of 1.6, 1.4, and 2.9 times those of the acrylic PSA on stainless steel, respectively. With this proposed silanization strategy, it is possible to design a wide variety of polyurethane-acrylic hybrid polymers.

Perencanaan Daya Dan Perbedaan Jenis Bantalan (Bearing) Pada Mesin Pengupas Kulit Kacang Tanah Kapasitas 60 Kg/Jam

Appropriate technology is technology that is right on target to be used and developed by the community. The development of technology aims to ease human work. The Indonesian state, with the majority of its population working as farmers, really needs appropriate technological innovation to increase agricultural productivity. In this case, the author highlights the low productivity of peanut farmers in Indonesia. On the other hand, the level of peanut demand is increasing from year to year, but consumer demand cannot be met due to low domestic peanut production. Therefore, this study aims to determine the power and bearing maintenance on peanut shell peeling machines using an electric motor, which uses a Tachometer measuring instrument and is carried out at the Production Laboratory of HKBP Nommensen University Medan located at JL. Sutomo No. 4 Medan. The peanut shell peeling machine is made horizontally with 1 shaft and 40 peeling rods transmitted by a V-belt and pulley using an electric motor that functions to peel peanuts to separate the seeds from the shell. By designing and designing a peanut shell peeling machine, the bearing life used in the peanut peeler machine is 3440.78 and 909.86 hours at a rotation speed of 1382 rpm and 58623.94 and 20877.55 hours at a rotation speed of 795.7 rpm. The faster the engine speed, the enumeration load received by the bearing will be lighter, the slower the engine speed, the heavier the enumeration load received by the bearing. The production capacity that can be produced by this peanut shell peeling machine is 60 kg / hour with a peeling force of 51,012 and AC motor power of 1 Hp with a rotation of 2930 rpm.

Preclinical Assessments of a Novel Peel and Place Extended-Wear Negative-Pressure Wound Therapy Dressing for up to 35 Days in a Porcine Model.

Objective: While the use of negative pressure wound therapy (NPWT) with reticulated open cell foam (ROCF) is well established, the characteristics of ROCF do not allow for extended-wear use. There is the potential for dressing tissue ingrowth if left in place for greater than the recommended 2-3 days. An easy to use, novel peel and place dressing has been designed for extended wear with the wound management advantages of ROCF while alleviating the challenges of tissue ingrowth. Approach: Paraspinal, full-thickness or deep muscle excisional wounds were created in 11 and 2 swine, respectively, dressings applied with continuous negative pressure at -125 mmHg, and dressings changed weekly. Full-thickness excisional wounds were treated for 13 days and deep muscle wounds for 35 days. Wound dimensions were assessed. Granulation tissue thickness and re-epithelialization were measured via digital morphometry. Tissue quality, fibrinous material prevalence, and dressing removal peel force were analyzed. Results: The peel and place dressing substantially reduces dressing tissue ingrowth, is easy to remove with markedly low dressing peel force and promotes more granulation tissue at day 13 than ROCF with an interface layer. The extended-wear peel and place dressing, when applied to deep muscle wounds with weekly dressing changes, was applied for a total of 35 days. Successful wound closure was evident without any negative impact on wound healing. Innovation: This study assessed the wound management capabilities of an extended-wear peel and place NPWT dressing used until wound closure. Conclusion: The peel and place dressing is a suitable extended-wear NPWT dressing.

Directional Adhesion of Monodomain Liquid Crystalline Elastomers.

Pressure-sensitive adhesives (PSAs) are widely employed in consumer goods, health care, and commercial industry. Anisotropic adhesion of PSAs is often desirable to enable high force capacity coupled with facile release and has typically been realized through the introduction of complex surface and/or bulk microstructures while also maintaining high surface conformability. Although effective, microstructure fabrication can add cost and complexity to adhesive fabrication. Here, we explore aligned liquid crystalline elastomers (LCEs) as directional adhesives. Aligned LCEs exhibit direction-dependent stiffness, dissipation, and nonlinear deformation under load. By varying the cross-link content, we study how the bulk mechanical properties of LCEs correlate to their peel strength and peel anisotropy. We demonstrate up to a 9-fold difference in peel force measured when the LCE is peeled parallel vs perpendicular to the alignment axis. Opportunities to spatially localize adhesion are presented in a monolithic LCE patterned with different director orientations.

Enhancing Electrical and Physical Contacts of Copper‐Electroplated Silicon Heterojunction Solar Cells through Chemical Pretreated Seed Layers

Copper electroplating offering the potential to replace low‐temperature sintered silver pastes holds significant promise as a metallization process for silicon heterojunction (SHJ) solar cells (SCs). To unlock the full potential of copper electroplating, it is crucial to enhance the contact properties between the electroplated grids and the indium tin oxide (ITO) films, addressing both contact resistivity and physical adhesion. Herein, a zinc‐assisted Fe2+ system to modify the ITO film is used, leading to the formation of an In/Sn/SnO mixed‐metal transition layer. This transition layer serves as a seed layer for metal electroplating, reducing contact resistivity and enhancing the mechanical connection between the electroplated metals and the ITO films. Following the ITO pretreatment process, the contact resistivity is significantly reduced from 1.4 to 0.2 mΩ cm2, and the peel force value of the pretreated sample reaches 14.2 N mm−1, which is 75.3% higher than that of the untreated sample. The proof‐of‐concept SHJ SC with copper electroplating after ITO pretreatment achieves a remarkable power conversion efficiency of 22.6%. These results clearly demonstrate that ITO pretreatment using the zinc‐assisted Fe2+ system is an effective approach for enhancing contact properties and improving the performance of copper‐electroplated SHJ SCs, showcasing significant potential for industry applications.

Study on Peeling Performance of T-Type Brazing Joints Based on Energy Method

Brazing technology is widely used in modern industrial systems as an important connection method. The brazing joints are the weakest zone in the whole structure and directly determine the working efficiency and life of the entire system. However, the research on the connection mechanism and fracture behavior of brazing joints is still unclear. In this study, the peeling force and displacement curves during the peeling process are tested by using T-type specimens. Based on the cohesive zone model, the peeling energy of each part during the whole peeling process is calculated and analyzed. The results show that the whole peeling process can be divided into three stages, including the initial stage, crack propagation stage, and stable peeling stage. The peeling energy of each stage can be calculated experimentally. The larger the peeling energy, the better the joint performance. Then, a simplified calculation method for peeling energy is developed for T-type joints and is verified as accurate using experimental data. It is also observed that the increase in the base material thickness can effectively improve the peeling performance of the joints. This provides a feasible and effective method for peel strength calculation and evaluation in brazing joints.

Advanced Analysis of the Properties of Solid-Wire Electric Contacts Produced by Ultrasonic Welding and Soldering.

The current article presents an advanced analysis of the properties of solid-wire electric contacts produced with ultrasonic welding and soldering. Soldering is generally used to join thin, solid copper wires to produce electrical contacts in small-volume production, as ultrasonic welding does not provide acceptable peel force and tensile strength due to the deformation and thinning of the wires. In this article, ultrasonic welding of thin, solid copper wires using a ring before and after a thermal shock test is discussed and compared with the standard soldering technique. The thermal shock test was carried out in the temperature range from -30 to 150 °C. Half of the samples, for both the joining techniques and the wires, were subjected to the thermal shock test; the other half were not. Investigations included electrical resistance tests, optical and SEM microscopy, XRD, microhardness measurements, peel tests, tensile tests, and fractographic analysis. The electrical resistance test, microscopy, microhardness measurements, and fracture examinations showed no differences between the thermal shock-exposed and the non-exposed samples with the same joining process. In mechanical tests, the ultrasonic joint demonstrated superior strength compared to the soldered joint.

Analysis of adhesion characteristics of steel back plates and encapsulants for fire-proof BIPV modules

Recently, researchers are actively exploring the use of steel plates as replacements for the backs of building integrated photovoltaic (BIPV) modules to achieve improved workability, reduced weight, and enhanced maintainability. It is crucial to note that the adhesion between steel plates and encapsulants must match the high level observed between conventional backsheets and glass surfaces. In this study, we assessed the adhesion between steel plates and encapsulants and proposed a method to enhance adhesion to the level of existing materials, such as backsheets and glass, by improving the surface of the steel plates and the lamination process. When steel plates were laminated with ethylene vinyl acetate (EVA) encapsulant at 150 °C (as per the preset process), the peel force measured by the 180° peel test was significantly low at 0.045 N/mm. However, it increased nearly 40 times to 1.70 N/mm due to the formation of a structure capable of physical interlocking through surface treatment and an increase in the lamination temperature by 20 °C. Furthermore, we evaluated the adhesion performance of polyolefin elastomer (POE) encapsulant, which demonstrated high adhesion of over 6.0 N/mm, comparable to that between the currently used encapsulants and backsheets. When we examined the surface-treated sample using a confocal microscope and a secondary electron microscope (SEM), the surface-treated sample exhibited a considerably rough surface with a high Rku value of 5 compared to the untreated sample. These modules can maintain high outputs even when exposed to the external environment for extended periods with fire-resistant properties.

Enhancing the crack initiation resistance of hydrogels through crosswise cutting

The achievement of tough adhesion between hydrogels and solid surfaces has significantly expanded the potential applications of hydrogels. This robust adhesion is commonly attained by combining tough hydrogels with strong interfacial bonding and it is reflected in high adhesion toughness. However, the practical use of such strategies is limited since enhanced adhesion diminishes rapidly after cyclic loading. Furthermore, relying solely on adhesion toughness as a measure of adhesion quality may underestimate the adhesive's bearing capacity. To address these issues, here we introduce a macro-structural design strategy called crosswise cutting in hydrogels and propose a new measure of hydrogel adhesion named crack initiation resistance. This strategy can significantly enhance hydrogel adhesion by increasing the peak peel force while constraining the crack initiation length, thus improving the crack initiation resistance. The toughening mechanism behind this strategy is further explored by decomposing the crosswise cutting into longitudinal and transverse cuttings. Through extensive experiments, we demonstrate that longitudinal cutting can increase both the peak peel force and crack initiation length during peeling. Conversely, transverse cutting can constrain the crack initiation length while maintaining a high peak peel force. To quantitatively evaluate the crack initiation resistance of an adhesion system, we define a new parameter, the critical crack initiation energy release rate (Gc*), which considers both the peak peel force and crack initiation length. Theoretical derivations of Gc* for hydrogels with longitudinal and transverse cuttings are provided. By varying cutting types, hydrogel thickness, and cut sizes, the value of Gc* can be significantly increased, with the optimal choice being the crosswise cutting satisfying specific dimensions. The underlying mechanisms pertaining to the increase of Gc* via crosswise cutting are explained by the stress de-concentration effect, and the value of Gc* can be predicted by the macroscopic Lake-Thomas model. It is hoped that this study will draw attention to the assessment of the adhesion quality of hydrogels in practical applications and provide some new insights for the design of future soft adhesives.

Learning the effective adhesive properties of heterogeneous substrates

Adhesion is a fundamental phenomenon that plays a role in many engineering and biological applications. This paper concerns the use of machine learning to characterize the effective adhesive properties when a thin film is peeled from a heterogeneous substrate. There has been recent interest in the use of machine learning in multiscale modeling where macroscale constitutive relations are learnt from data gathered from repeated solution of the microscale problem. We extend this approach to peeling; this is challenging because peeling from heterogeneous substrates is characterized by pinning where the peel front gets stuck at a heterogeneity followed by an abrupt depinning. This results in a heterogeneity dependent critical force and a singular peel force vs. overall peel rate relationship. We propose a neural architecture that is able to accurately predict both the critical peel force and the singular nature of the peel force vs. overall peel rate relationship from the heterogeneous adhesive pattern. Similar issues arise in other free boundary and free discontinuity problems, and the methods we develop are applicable in those contexts.