Pressure-sensitive Adhesive Tape Research Articles

Modified powder suspensions for fingermark detection on adhesive tapes in austere or contested environments

ABSTRACT Pressure-sensitive adhesive tapes may be associated with a wide range of criminal and terrorist activity as physical evidence. In this study, a carbon powder suspension formulation for the detection of latent fingermarks on the adhesive side of tapes was modified by using consumer products as alternative surfactant sources. The modified formulations were used to successfully develop latent fingermarks deposited on transparent adhesive tape. This project ultimately intends to establish the performance windows of the modified techniques to allow evidence-based decision-making during technical exploitation in contested and austere environments.

Wet SPF: A wet powder suspension for the detection of latent fingermarks on the sticky side of adhesive tape for use in Seychelles

WET UCIO is an inexpensive carbon-based powder suspension, reportedly as effective as commercially available formulations for latent fingermark detection on the sticky side of adhesive tapes. However, the surfactant solution used in WET UCIO is not readily accessible outside Europe, limiting its use in Seychelles or other non-European jurisdictions. In this study, the UCIO formulation was modified based on a ‘frugal forensic’ approach, by replacing the surfactant solution with an in-house sodium dodecyl sulfate solution prepared in 5 % aqueous ethanol. A comparative assessment against Wetwop™ using eight different pressure-sensitive adhesive tapes found that the modified formulation was at least as effective as commercial powder suspension. Modifying this technique under the frugal forensic framework has enhanced its accessibility to other jurisdictions and is recommended for validation in Seychelles.

Pressure‐Sensitive Adhesive Tapes with High Peel Strength Derived from Linseed Oil

AbstractThis research attempts to fabricate a novel type of pressure‐sensitive adhesive (PSA) tape utilizing epoxidized linseed oil (ELO) as the primary component in an effort to reduce reliance on petrochemical polymers. This raw material comes from the natural renewable resources, making this tape a more environmentally friendly choice in reducing impact on the environment and alleviating resource pressure. The ester groups on ELO are subjected to hydrolysis in order to yield a combination of epoxy linseed oil fatty acids (ELFAs) containing both epoxy and carboxyl groups. By controlling the temperature and catalyst conditions, the epoxy and carboxyl groups undergo a ring‐opening reaction, resulting in the self‐polymerization of the ELFA mixture and the formation of hydroxy‐functionalized polymers. These polymers are then applied as a coating on kraft paper and subsequently cut to produce PSA tapes. The tapes produced using this method exhibit a peak peel strength of 20.538 N per 25 mm. Moreover, the incorporation of glycerol ester of rosin serves to enhance the peel strength, resulting in a higher value of 21.883 N per 25 mm. The utilization of sealing the cardboard box by the tapes also serves as validation for the immense capabilities of the tapes in practical applications.

Synthesis and Characterization of Pressure-Sensitive Adhesives Based on a Naphthyl Curing Agent.

The incorporation of a naphthyl curing agent (NCA) can enhance the thermal stability of pressure-sensitive adhesives (PSAs). In this study, a PSA matrix was synthesized using a solution polymerization process and consisted of butyl acrylate, acrylic acid, and an ethyl acrylate within an acrylic copolymer. Benzoyl peroxide was used as an initiator during the synthesis. To facilitate the UV curing of the solvent-borne PSAs, glycidyl methacrylate was added to introduce unsaturated carbon double bonds. The resulting UV-curable acrylic PSA tapes exhibited longer holding times at high temperatures (150 °C) compared to uncross-linked PSA tapes, without leaving any residues on the substrate surface. The thermal stability of the PSA was further enhanced by adding more NCA and increasing the UV dosage. This may be attributed to the formation of cross-linking networks within the polymer matrix at higher doses. The researchers successfully balanced the adhesion performance and thermal stability by modifying the amount of NCA and UV radiation, despite the peel strength declining and the holding duration shortening. This research also investigated the effects of cross-linking density on gel content, molecular weight, glass transition temperature, and other properties of the PSAs.

Development of cardanol-derived epoxidized and Si-modified pressure-sensitive adhesives (PSAs)

This research attempts to create a pressure-sensitive adhesive (PSA) from cardanol as an outset material. The two kinds of formulations were established; the first scheme followed the epoxidation of cardanol, dihydroxylation, and PSA development. In the latter system, cardanol was pretreated with dichlorodimethysilane (DCDMS) in the second scheme, continuing the same procedure to obtain PSA resin. The chemical nature and structure confirmation were done using FTIR and NMR spectroscopy, hydroxyl value, epoxy equivalent weight (EEW), etc. To evaluate PSA resin's crystallinity, thermal stability and hydrophilicity the film was separately obtained for both the schemes by curing whereas to obtain PSA tapes the obtained PSA and tackifying resins were applied onto PET sheets. XRD analysis showed a decrease in the degree of crystallinity after incorporating DCDMS. The gel content values decreased, whereas the water absorption values increased, which could be related to the increase in the hydrophilic nature of PSA with an increasing number of tacky sites. TGA and DSC showed the formation of a high amount of char yield (∼31%) and a higher Tg (−37.72 °C) in Si containing film. The probe tack, peel strength, and shear strength values were high for the formulation with equal amounts of PSA and tackifying resin. Finally, the contact angle measurements showed that the hydrophobicity of film was also improved after incorporating DCDMS. The materials resembling PSA tape and including only small amounts of tackifying resins and crosslinkers displayed the ideal characteristics with satisfactory results.

Optical glucose sensor for microfluidic cell culture systems

Glucose is the primary energy source of human cells. Therefore, monitoring glucose inside microphysiological systems (MPS) provides valuable information on the viability and metabolic state of the cultured cells. However, continuous glucose monitoring inside MPS is challenging due to a lack of suitable miniaturized sensors. Here we present an enzymatic, optical glucose sensor element for measurement inside microfluidic systems. The miniaturized glucose sensor (Ø 1 mm) is fabricated together with a reference oxygen sensor onto biocompatible, pressure-sensitive adhesive tape for easy integration inside microfluidic systems. Furthermore, the proposed microfluidic system can be used as plug and play sensor system with existing MPS. It was characterized under cell culture conditions (37 °C and pH 7.4) for five days, exhibiting minor drift (3% day−1). The influence of further cell culture parameters like oxygen concentration, pH, flow rate, and sterilization methods was investigated. The plug-and-play system was used for at-line measurements of glucose levels in (static) cell culture and achieved good agreement with a commercially available glucose sensor. In conclusion, we developed an optical glucose sensor element that can be easily integrated in microfluidic systems and is able to perform stable glucose measurements under cell culture conditions.

Photomelt and photoinduced tacky resins comprising disulfide and photoinitiators as easy-to-release, pressure-sensitive, and separator-free adhesives

Photomelt resins (PMRs) can be liquefied by light exposure, which is promising for applications such as pressure-sensitive adhesives. From the perspectives of environmental friendliness, worker health, and cost, there is a need to develop PMRs that are recyclable and customizable for use with specific substrates, that melt upon exposure to low-energy light, and that use a more economical synthesis method. In this study, we fabricated various PMRs comprising polysulfides cured by isocyanates and commercial photoinitiators via a thiourethane reaction at room temperature. The exchange reactions between the disulfide groups and radicals generated from the photoinitiators alter the mechanical properties of the polymer chains. Upon light exposure, the polymer changes from an elastomer to a pressure-sensitive adhesive, which makes these PMRs promising for use as reworkable and easy-to-release adhesives. Moreover, these PMRs exhibit photoinduced tackiness, which enables the design of separator-free adhesive tape. As separator films are currently used to cover one or both sides of pressure-sensitive adhesive tapes, adhesive films with photoinduced tackiness could significantly reduce the global usage of separator film, thus reducing the environmental impact of these adhesives.

Influences of probe shape and surface roughness on tack properties measured by the probe tack test and characterization of crosslinked polyacrylic pressure‐sensitive adhesives

AbstractFor a probe tack test for a pressure‐sensitive adhesive (PSA) under the conditions of light contact pressure and short contact time, probes with shapes and surface roughnesses suitable to achieve better wettability were investigated. A smooth, polished probe that became slightly convex at its center was found to be superior to flat‐ended. High surface roughness decreased tack. Debonding observations showed that fibrillation started from the probe edge and extended to the center. The fibril grew, without peeling, until the peak of the force–displacement curve was reached. After the peak, the fibril growth and peeling advanced simultaneously. The fibrillation was important to tack development. The test conditions necessary to observe the deformation behavior of PSA tape with sufficient interfacial adhesion were investigated. The system was preheated at 60°C for 1 h after the probe and PSA tape contacted each other, and was then cooled. The PSA performance of crosslinked random copolymers poly(n‐butyl acrylate‐acrylic acid) (A) and poly(2‐ethylhexyl acrylate‐acrylic acid) (B) were compared. A shoulder formed by fibrillation after the peak in the force–displacement curve was observed only for B. Copolymer B exhibited better interfacial adhesion and deformability. The preheating method was found to be useful for characterizing PSAs.

Discharge dynamics from an x-ray generating tribosource

When an adhesive tape is peeled in vacuum, x rays are generated in burst of short duration (order nanosecond) whose origin is not yet fully understood. In this work, we analyze the electrical discharge dynamics occurring when a pressure-sensitive adhesive tape is peeled from its own backing in x-ray emitting conditions. We characterize these dynamics with the time between consecutive discharges and study its statistical properties as a function of both peeling speed and surrounding air pressure. We find that processes whose dynamics are characterized by shorter timescales generate the high energy portion of the x-ray spectrum. Furthermore, the air pressure affects the emission intensity but not the maximum single photon energy attainable. Our results indicate that there exist more complex physical mechanisms at play than previously thought in this system. Understanding the physical processes behind these dynamics may help improve the yield from devices that use this technology for x-ray production.

Influence of Acid-Modified Clinoptilolite on the Self-Adhesive Properties of Silicone Pressure-Sensitive Adhesives.

The preparation of a new "eternally alive adhesive" based on silicone pressure-sensitive adhesives with clinoptilolite is presented. Neat and acid-modified (i.e., treated with sulfuric acid (VI)) clinoptilolite was used. The effect of clinoptilolite acid treatment on the adhesive properties of pressure-sensitive adhesive tapes was tested. The obtained tapes exhibited increased thermal resistance when compared to the reference tapes. Despite introducing the filler, the pressure-sensitive adhesive tapes maintained good functional properties. The new self-adhesive materials show promising implementation potential where increased thermal resistance is required.

Conductive microsphere monolayers enabling highly conductive pressure-sensitive adhesive tapes for electromagnetic interference shielding

Conductive microsphere monolayers enabling highly conductive pressure-sensitive adhesive tapes for electromagnetic interference shielding

Synergistic improvement on both the oil-resistance and heat-resistance performance of a single-component acrylic pressure-sensitive adhesive

Traditional pressure-sensitive adhesive (PSA) materials are prone to failure under oily and high-temperature environments. Herein, a new series of acrylate copolymers, poly(methoxyethyl acrylate - butyl acrylate - ethyl acrylate - acrylic acid - (N-methoxy acrylamide)), were developed as single-component acrylic PSAs. The oil-resistance and heat-resistance of acrylic PSAs were improved remarkably through three strategies: 1) using the polar monomer, methoxyethyl acrylate (MOEA), to replace the commonly used monomer of 2-ethylhexyl acrylate (EHA), as the dominant ingredient in PSA to increase oil-resistance, 2) innovatively introducing N-methoxy acrylamide (NMOAM) as a new internal crosslinking monomer, thereby maintaining the stability of the PSA system at ambient conditions, while crosslinking with acrylic acid (AA) at high temperature curing conditions to obtain a single-component PSA, 3) owing to the synergistic effects of polarity and crosslinking which occurred during curing process, the oil-resistance and heat-resistance of PSAs enhanced greatly. The molecular weight of the acrylate copolymers and viscosity of the copolymer solutions were regulated by using xylene as a co-solvent to balance the adhesive properties of the acrylic PSAs. Effects of MOEA and NMOAM concentration on adhesive properties were investigated in detail. Results showed that the maximum tack of 12 #, shear strength of >168 h, and 180° peel resistance of 23.47 ± 0.07 N/24 mm could be obtained when 60 wt% of MOEA and 3 wt% of NMOAM were used for the PSA preparation. The obtained PSA tapes were able to maintain excellent adhesive properties even in harsh environments, such as high temperature and oily environment. This work demonstrates that how the comprehensive properties of acrylic PSAs can be improved thereby facilitating their application in the automobile industry, including bundling wire harnesses in car engine rooms or mounting attached parts to tanks.

Fabrication and properties of thermally conductive adhesive tapes containing multilayer graphene patterns

In order to overcome the low thermal conductivity of pressure-sensitive adhesives (PSAs), multilayer graphene (MLG) pattern embedded PSA tapes (g-PSAs tapes) were fabricated in this study. First, an acrylic copolymer was synthesized and used as a component of a PSA. The glass transition temperature of the PSA and peel strength of the neat PSA tape were determined as −30 °C and 792 ± 14 gf/25 mm, respectively. Next, g-PSA tapes were fabricated by laminating an uncrosslinked PSA tape onto MLG patterns on a PET film followed by curing. The MLG content of the g-PSA tapes was adjusted with the size of MLG patterns fabricated by using metal masks with various opening sizes. Unlike the neat PSA tape, the peel strength of the g-PSA tapes fluctuated during peeling because of the delamination of the graphene layers. The in-plane thermal conductivity of the stacked g-PSA-2 tape with a graphene content of 21.4 vol% was measured to be 5.51 Wm−1K−1. The mechanical durability of the g-PSA-1 and g-PSA-2 tapes was also measured through a folding test and no delamination of the tapes was observed after 10000 folding cycles.

Generalized characteristics of peel tests independent of peel angle and tape thickness

The peel tests of pressure-sensitive adhesive (PSA) tapes were conducted to clarify the effect of the peel velocity, peel angle, and tape thickness. We focused on the viscoelastic deformation of the PSA layer and its relationship with the adhesion energy. It was found that, at a sufficiently low strain rate of the PSA layer, the adhesion energy has a threshold value of debonding. In addition, the increase of adhesion energy from the threshold value is proportional to the maximum stretch of the PSA layer and follows a power law relationship with the strain rate. The general relationship between the adhesion energy and the strain of PSA layer, independent from the peel angle and tape thickness, was established.

Supramolecular Polymeric Pressure-Sensitive Adhesive That Can Be Directly Operated at Low Temperatures.

Low-temperature adhesion is ubiquitous in daily life and industry. However, most supramolecular adhesives are thermoplastic materials that require heating during the adhesion. Herein, a supramolecular approach is used to construct unique pressure-sensitive adhesives (PSAs) that can be directly operated at low temperatures (-60 °C). Supramolecular polymerization between phytic acid (PA) and water (H) endows poly(PA-H)s with excellent mechanical properties and low temperature adhesion capacity. Poly(PA-H)s can easily be processed into PSA tapes, pastes, and particles. Poly(PA-H)s were directly adhered to various surfaces by pressing at low temperatures (0 to -60 °C). No heating or high-temperature-induced solid-liquid transition was required for the low-temperature adhesion of poly(PA-H)s. With the help of structural water units in supramolecular polymers, poly(PA-H)s showed strong, stable, and organic solvent resistant adhesion performances at low temperatures, with adhesion strength of up to 3.61 MPa at -60 °C.

Influence of Adhesive Tapes as Thermal Interface Materials on the Thermal Load of a Compact Electrical Machine

In this article, a novel form of thermal interface material (TIM), represented by three industrially manufactured pressure-sensitive adhesive (PSA) tapes with electrical insulating properties, is characterized regarding its applicability in an electric motor with air-gap winding. Firstly, the adhesion performances, in terms of the winding process, were investigated experimentally. Here, every TIM shows sufficient shear strength for the wire–TIM joints, as well as peel adhesion to the laminated iron core. Secondly, the thermal–physical properties of the TIMs are inspected experimentally via laser flash analysis (LFA) and differential scanning calorimetry (DSC). For every TIM, the value of the thermal resistance can double if the relatively smooth surface (Ra = 0.2 μm) of the adjacent layers is interchanged with a rougher one (Ra = 2.0–3.7 μm). Additionally, the TIM’s performance at the system level is examined. Therefore, a flat test section, according to the specifications of the original motor, is studied experimentally and numerically utilizing infrared (IR) thermography and the finite element method (FEM). The focus is set on the heat flow and temperature distribution in the test section under varying thermal loads, mass flow, and variety of TIMs.

Three-Dimensional Mass Spectral Imaging of Polymers Via Laser-Assisted Micro-Pyrolysis Program with Flowing Atmospheric-Pressure Afterglow Ambient Mass Spectrometry.

Herein, a novel diode laser-assisted micro-pyrolysis program (LAMP) technique is demonstrated and coupled with flowing atmospheric-pressure afterglow ambient mass spectrometry for instantaneously profiling polymers and polymer additives. Laser power modulation allows thermal separation of additives and different pyrolysis products, as shown through positive- and negative-mode high-resolution mass spectra and Kendrick mass defect plots of homopolymers, copolymers, polymer blends, and complex polymer samples. LAMP allows much faster temperature control through real-time duty cycle changes and gives significantly better spatial confinement compared to typical resistive heating pyrolysis approaches. Finally, MS imaging, with lateral and depth resolution, is demonstrated for a complex polymer pressure-sensitive adhesive tape sample.

Suspended Kirigami Surfaces for Multifoulant Adhesion Reduction

High foulant adhesion remains a critical issue in a wide range of industries, such as ice accretion on aircraft, biofoulants on ships, wax build-up within pipelines, and scale formation in water remediation. Previous anti-fouling surfaces have only shown promise for reducing the adhesion of a single foulant system; a multi-foulant anti-fouling technology remains elusive. Here, we introduce a mechanical metamaterial-based approach to develop anti-fouling surfaces applicable to a wide range of fouling substances. The suspended kirigami inverted nil-adhesion surfaces, or SKINS, show significantly reduced adhesion of ice, different waxes, dried mud, pressure-sensitive adhesive tape, and a marine hard foulant simulant. SKINS mimic the wrinkling of hard films adhered to soft substrates. Foulant adhesion can be minimized by this wrinkling, which may be controlled by tuning the kirigami motif, sheet material, and foulant dimensions. SKINS reduce adhesion mechanically and were found to be independent of surface energy, enabling their fabrication from commonplace hydrophilic polymers like cellulose acetate. Optimized SKINS exhibited extremely low foulant adhesion, for example, ice adhesion strengths less than 5 kPa (a >250-fold reduction from aluminum substates), and were found to maintain their performance on curved surfaces like transmission cables. The low foulant adhesion persisted over 30 repeated foulant deposition and removal cycles, demonstrating the anti-fouling durability of SKINS. Overall, SKINS offers a previously unexplored route to achieving low foulant adhesion that is highly tunable in both geometry and material selection, is applicable to many different fouling substances, and maintains extremely low foulant adhesion even on complex substrates over large fouled interfaces.

A microreactor sealing method using adhesive tape for digital bioassays.

Digital assays using microreactors fabricated on solid substrates are useful for carrying out sensitive assays of infectious diseases and other biological tests. However, sealing of the microchambers using fluid oil is difficult for non-experts, and thus hinders the widespread use of digital microreactor assays. Here, we propose the physical isolation of tiny reactors with adhesive tape (PITAT) using simple, commercially available pressure-sensitive adhesive (PSA) tape as a separator of the microreactors. We confirmed that PSA tape can effectively seal the microreactors and prevent molecules from diffusing out. By testing several types of adhesive tape, we found that rubber-based adhesives are the most suitable for this purpose. In addition, we demonstrated that single-molecule enzyme assays can be successfully performed inside microreactors sealed with PSA tape. The results obtained using PITAT are quantitatively comparable to conventional oil sealing, although it is quick and cost-effective. Finally, we demonstrated that single-particle virus counting of the influenza virus can be achieved using PITAT. Collectively, our results suggest that PITAT may be suitable for use in the design of sensitive tests for infectious diseases at the point of care, where no sophisticated equipment or machines are available.

Debonding of a soft adhesive fibril in contact with an elastomeric pillar.

The debonding criterion of fibrils of soft adhesive materials is a key element regarding the quantitative modelisation of pressure sensitive adhesive tapes' peeling energy. We present in this article an experimental study of the detachment of a commercial acrylic adhesive tape from the top surface of a single micrometric pillar of PDMS elastomer. During an experiment, the pillar and the adhesive, after being put in contact, are separated at a constant displacement rate, resulting in the formation, the elongation and the final detachment of a fibril of adhesive material. A systematic study allows us to uncover power laws for the maximum force and the critical elongation of the fibril at debonding as a function of the diameter of the cylindrical pillar which controls the diameter of the fibril. The scaling law evidenced for the critical elongation appears as a first step toward the understanding of the debonding criterion of fibrils of soft adhesive materials. In addition, viscoelastic digitation at the triple debonding line is observed during detachment for large pillar diameters. The wavelength and penetration length of the fingers that we report appear to be consistent with existing models based on pure elastic mechanical response.