Shear Adhesion Failure Temperature Research Articles

Designing the regularity of biodegradable copolyester for sustainable hot-melt adhesives: Adhesion, removability, and biodegradability

Recent research has increased in eco-friendly hot-melt adhesives as alternatives to conventional commercial hot-melt adhesives. However, there have been limitations in terms of removability and biodegradability. This study addresses these issues by designing a novel molecular structure for a single polymer, resulting in a sustainable hot-melt adhesive that offers strong adhesion, clear removability, and high biodegradability without additional additives. By varying the ratio of alcohol monomers 1,4-butanediol (BD) and ethylene glycol (EG) during polymerization, we synthesized poly(butylene adipate-co-butylene terephthalate-co-ethylene adipate-co-ethylene terephthalate) (PBEAT) with four block segments. We increased the open time by reducing the regularity of the molecular structure, controlling crystallization behavior, and inhibiting polymer chain packing. This improvement in wettability with the adherend allowed us to achieve a lap shear adhesion strength of 3.18 MPa. Additionally, we proposed a debonding mechanism based on the correlation between the crystallization temperature (Tc) block copolymer's and shear adhesion failure temperature (SAFT), demonstrating the removability of the prepared hot-melt adhesive. Finally, analyses of hydrolysis, enzymatic degradation, and biodegradation in compost confirmed that reduced crystallinity enhances biodegradability. PBE30AT, exhibiting the strongest adhesion strength, achieves complete degradation in compost within 20 days, faster than neat poly(butylene adipate-co-terephthalate) (PBAT). This research offers a novel and practical approach to enhancing the potential and expandability of sustainable adhesives by tailoring the molecular structure of the polymer.

Enhanced Heat Resistance of Acrylic Pressure-Sensitive Adhesive by Incorporating Silicone Blocks Using Silicone-Based Macro-Azo-Initiator

To improve the heat resistance of acrylic-based pressure-sensitive adhesive (PSA), silicone-block-containing acrylic PSAs (SPSAs) were synthesized using a polydimethylsiloxane (PDMS)-based macro-azo-initiator (MAI). To evaluate the heat resistance of the PSA films, the probe tack and 90° peel strength were measured at different temperatures. The acrylic PSA showed that its tack curves changed from balanced debonding at 25 °C to cohesive debonding at 50 °C and exhibited a sharp decrease. However, in the case of SPSA containing 20 wt% MAI (MAI20), the balanced debonding was maintained at 75 °C, and its tack value hardly changed with temperature. As the MAI content increased, the peel strength at 25 °C decreased due to the microphase separation between PDMS- and acryl-blocks in SPSA, but the shear adhesion failure temperature (SAFT) increased almost linearly from 41.3 to 122.8 °C. Unlike stainless steel substrate, SPSA showed improved peel strength on a polypropylene substrate due to its low surface energy caused by PDMS block. Owing to the addition of 20 wt% silicone-urethane dimethacrylate oligomer and 200 mJ/cm2 UV irradiation dose, MAI20 showed significantly increased 90° peel strength at 25 °C (548.3 vs. 322.4 gf/25 mm for pristine MAI20). Its heat resistance under shear stress assessed by shear adhesion failure test (SAFT) exhibited raising in failure temperature to 177.3 °C when compared to non-irradiated sample.

High holding power of acrylic emulsion PSA with sorbitan nonionic surfactants and cross-linker

Since traditional nonyl phenyl type nonionic surfactants have been known as destructive to the ecosystem, sorbitan nonionic surfactants (Tween 20, 40, 60 and 80) were used to make acrylic emulsion type pressure sensitive adhesives (PSA), and the type of effects they have on the adhesive properties were investigated. Also, their adhesive properties were compared with those synthesized using traditional nonyl phenyl nonionic surfactant (NP 40). As a result, PSA made using Tween60 showed higher initial tack and peel strength and a much higher holding power than those properties made using NP 40 at room temperature. PSA made by Tween 60, and cross-linked by DGEBA (Bisphenol A diglycidyl ether) and phenyl aziridine, exhibited over 12 h of holding power at 150 °C, and showed a holding state up to 180 °C during a SAFT test (Shear Adhesion Failure Temperature).

Incorporation of flame retardancy in bio‐resourced mannitol based curing agent for clear pressure‐sensitive adhesive

Recently, the flame retardancy of the pressure‐sensitive adhesive acquired a large amount of research interest because of their ability to cease the effect of fire on products, which are widely used for high‐temperature applications. The current study comprises the addition of the phosphorus modified mannitol (PMM) in a clear acrylic pressure‐sensitive adhesive (CPSAs). Mannitol indulges the replacement of the petroleum‐based crosslinking agent used for CPSAs, and phosphorus modification imparts the inherent flame retardancy. The process includes two parts, the first part comprises the conversion of D‐mannitol into 2,4:3,5‐di‐O‐methyl‐D‐mannitol followed by the modification through phosphorus oxychloride (POCl3) and the second part includes the addition of the PMM in CPSAs. The qualitative analysis of the formed compound was done with Fourier transform infrared spectroscopy (FT‐IR), and nuclear magnetic resonance spectroscopy (NMR). To understand the dependency of the PMM dose on adhesive performance, glass transition temperature (Tg) was measured through dynamic mechanical thermal analysis (DMTA). The performance of adhesive was evaluated by determining optical and adhesion properties such as refractive index, impact resistance, peel strength, the probe tack, and the shear adhesion failure temperature. Thermogravimetric analysis (TGA) was used to understand the thermal degradation of the adhesive. Successively, it was observed that the Tg and other properties are the functions of PMM concentration. Adhesive shows the excellent flame retardancy with maximum limiting oxygen index (LOI) value of 48 and a self‐extinguishing behavior, as confirmed by the UL‐94 test. The extinguishing of the fire occurs with the formation of the 0.9 to 6 mm char with a closed cell‐like structure confirmed through SEM.Highlights Research involves the preparation of phosphorus modified curing agents of bio‐based resources and understand in the application in the clear pressure‐sensitive adhesive. A bio‐based curing agent has synergic behavior of flame retardancy. The use of a bio‐based curing agent imparts thermal stability in the adhesive. The presence of phosphorus in the structure allows the formation of intumescent char.

Adhesion performance and optical properties of optically pressure-sensitive adhesives including an isosorbide

Isosorbide is newly used as a cross-linking agent to replace petroleum-based cross-linking agents for optically clear pressure-sensitive adhesives (PSAs). To control and determine the optimal concentration of isosorbide, the relationship between the glass transition temperature (Tg), referring to the viscoelastic characteristics of the organic polymeric materials as a key factor not only to synthesize the binders and but also to utilize the final products, and the concentration of isosorbide were investigated by measuring the optical properties, the adhesion performance via the peel strength, the probe tack, and the shear adhesion failure temperature. Consequently, it was found that the relationship provided by the linear plots between Tg and the other properties was strongly affected by the concentration of isosorbide due to the cross-linking density.

Enhanced Mechanical and Adhesion Properties in Sustainable Triblock Copolymers via Non-covalent Interactions

ABA triblock copolymers are used as thermoplastic elastomers (TPEs) for a wide variety of applications. Herein, we describe incorporation of sugar-based glassy components to create sustainable triblock copolymers as alternatives for commodity TPEs. Poly(glucose-6-acrylate-1,2,3,4-tetraacetate) [PGATA] and poly(acetylated acrylic isosorbide) [PAAI] end blocks were chain-extended from a poly(n-butyl acrylate) [PnBA] midblock. PAAI–PnBA–PAAI exhibited excellent adhesion properties: peel = 8.74 N cm–1, loop tack = 2.96 N cm–2, no shear failure up to 100 h, and shear adhesion failure temperature (SAFT) = 60 °C. Although similar peel adhesion and higher loop tack were observed for PGATA–PnBA–PGATA, the shear strength and SAFT were moderate (18 h and 42 °C, respectively). PAAI–PnBA–PAAI are tough elastomers and demonstrated high stress and elongation at break (σ = 6.5 MPa and e = 620%, respectively) while the GATA-based analogue exhibited weaker tensile properties (σ = 0.8 MPa and e = 476%). To address this, the...

Preparation and characterization of acrylic pressure-sensitive adhesives based on UV and heat curing systems

UV curable acrylic oligomers were prepared for a dual-crosslinking system applicable to general thermosetting acrylic pressure-sensitive adhesives (PSAs). UV-curable oligomers were synthesized using isophorone diisocyanate (IPDI), acrylate monomers, and propylene imine (PI). Acrylate monomers were added at a constant rate to one isocyanate group of IPDI for selective binding, and a polymerization inhibitor was added to prevent polymerization. Also, binding sites bound to the adhesive backbone were generated by adding PI at a constant rate after solvent addition. The synthesized UV oligomers were confirmed by ATR-FTIR spectroscopy. In addition, dual-curable PSA tapes were prepared by simply blending UV curable oligomers and thermosetting acrylic PSAs at room temperature, and their mechanical properties (gel fraction, ball tack, 180° peel strength, and shear adhesion failure temperature (SAFT)) were evaluated based on the volume of UV curable oligomers.

Improving the properties of water-borne pressure sensitive adhesives by using non-migratory surfactants

The adhesive performance of high solids content water-borne acrylic pressure sensitive adhesives synthesized using polymerizable surfactants (Latemul®PD-104 and Sipomer®Pam-200) or a polymerizable stabilizer (Sipomer®Cops-1) has been studied. The use of a high pH during the polymerization process has a deleterious effect on the final adhesive properties because gel polymer is not formed. Interestingly, at low pH it is found that the surfactant concentration used during the polymerization process has also an effect on the polymer microstructure; the higher the surfactant concentration, the higher the final gel content of the latex. When polymerizable surfactants or a stabilizer are used the peel strength of the final films is considerably improved due to the surfactant incorporation into the polymer backbone and hence reduced surfactant migration to the air-film interface. Work of adhesion and shear adhesion failure temperature (SAFT) are not noticeably affected by surfactant migration but their performance is affected by the surfactant employed.

Temporary Bonding and Debonding 공정용 UV 경화형 접착 소재의 코팅 두께에 따른 물성 및 경화거동

UV curable adhesives with different acrylic functionalities were synthesized for temporary bonding and debonding process in 3D multi-chip packaging process. The aim is to study various factors which have an influence on UV curing. The properties and curing behaviors were investigated by gel fraction, peel strength, probe tack, and shear adhesion failure temperature. The results show that the properties and curing behaviors are dependent on not only acrylic functionalities of binders but also UV doses and coating thickness.

High performance pressure sensitive adhesives by miniemulsion photopolymerization in a continuous tubular reactor

High solids content PU/(meth)acrylics latexes for application as pressure sensitive adhesives (PSAs) were successfully synthesized by miniemulsion photopolymerization in a continuous tubular reactor at room temperature. It was shown that the process is very flexible and the polymer microstructure can be widely changed by simply controlling the radical initiation using different photoinitiator types and concentrations and varying the incident light irradiance. PSAs presenting a whole spectrum adhesive properties were obtained, some of them having the desired and unusual combination of high work of adhesion and maximum shear adhesion failure temperature (SAFT > 210 °C). The adhesive properties were analyzed in terms of the molecular weight distribution of the whole sample measured by asymmetric flow field flow fractionation.

Hot-Melt Pressure-Sensitive Adhesives Containing High Biomass Contents

A hot-melt pressure-sensitive adhesive (PSA) was generated containing a high content of renewable biomass. The polymer is based on a commercial hot-melt acrylic formulation containing primarily 2-ethylhexyl acrylate (EHA). The new polymer is synthesized with a majority of the EHA replaced with a macromonomer (MM) prepared with l-lactide and e-caprolactone via catalyzed bulk ring-opening polymerization using N-hydroxyethyl acrylamide as the initiator. Incorporation of the MM into the polymers was confirmed via proton NMR. The properties and adhesive performance of the new polymer were compared with those of its 100% acrylic commercial version. When synthesized using the same approach, the biomass-containing PSA had a lower molecular weight, higher glass transition temperature, and lower melt viscosity. Introduction of MM had little impact on the tack force, shear time, and shear adhesion failure temperature, and the peel strength increased substantially. It is expected that these hybrid materials can be op...

High-Performance Adhesives Resulting from Spontaneous Formation of Nanogels within Miniemulsion Particles

Molecular structure plays a crucial role in determining the final properties of pressure-sensitive adhesives. Here, we demonstrate that the molecular structure of polyurethane/(meth)acrylic hybrids synthesized by miniemulsion photopolymerization changes during storage of the dispersion at room temperature because of the spontaneous formation of nanogels by the assembly of polymer chains within the polymer particles. Analysis of the nanogel structure by asymmetric-flow field-flow fractionation allows identification of the molecular structure that provides the unusual combination of high tack adhesion and excellent shear resistance at high temperature [maximum value of the shear-adhesion failure temperature (SAFT) test, >210 °C].

Optical properties and adhesion performance of acrylic PSAs; influence of functionalized monomer and curing agent

Acrylic pressure–sensitive adhesives (PSAs) were synthesized by solution polymerization using zirconium carboxyethyl acrylate (ZrCEA) with methyl aziridine derivatives (MAZ) as a curing agent. The acrylic PSAs were characterized by Fourier transform-infrared spectroscopy and gel contents. The viscoelastic properties of the acrylic PSAs were determined using an advanced rheometric expansion system. The adhesion performance of the acrylic PSAs was determined by measuring the probe tack, peel strength, shear adhesion failure temperature, and holding power. The optical properties of the acrylic PSAs were evaluated by the transmittance and refractive index. The results show that the adhesion performance and optical properties of the acrylic PSAs are influenced by the ZrCEA and MAZ content.

Fabrication of optically clear acrylic pressure–sensitive adhesive by photo-polymerization: UV-curing behavior, adhesion performance, and optical properties

Acrylic pressure–sensitive adhesives (PSAs) with 2-phenoxy ethyl acrylate (PEA) were polymerized using UV-curing technology. This study examined the effects of PEA content and UV dose. The photo-polymerization behavior of the pre-polymer was examined by viscosity measurements, real-time Fourier transform infrared spectroscopy, and photo-differential scanning calorimetry. The curing behaviors of the acrylic PSAs were investigated by shrinkage test, a modular advanced rheometer system, and gel content. differential scanning calorimetry and Advanced Rheometric Expansion System were used to characterize the acrylic PSAs. Adhesion performances were measured by probe tack, peel strength, and shear adhesion failure temperature. The optical properties of acrylic PSAs were examined by UV–visible spectroscopy and prism coupler. The PEA content had a larger effect on improving the optical properties, than did the UV dose. The transmittances of the acrylic PSAs with <75% PEA were >95%. The refractive indices of the acrylic PSAs increased with increasing PEA content, due to its high refractive index, >1.5, which affected the overall refractive indices, particularly in the visible region.

Adhesion performance of PSA–clay nano-composites by the in-situ polymerization and mechanical blending

The synthesis and characterization of acrylic polymer/Na-montmorillonite (Na-MMT) clay nano-composites pressure sensitive adhesives (PSA) are researched. The PSA/clay nano-composites were synthesized by in-situ emulsion polymerization and mechanical blending. And then, different amounts of nanoclay were dispersed in 2-ethylhexyl acrylate (2-EHA)/n-butyl acrylate (BA)/methyl methacylate (MMA)/acrylic acid (AA) monomer mixture, which was synthesized using in-situ emulsion polymerization technique. Morphological observation was carried out using X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). Viscoelastic properties of PSA/clay nano-composites were analyzed using advanced rheometric expansion system (ARES). The adhesion performances of synthesized PSA/clay nano-composites were determined by measurements of peel strength, probe tack and shear adhesion failure temperature.

Optical properties and adhesion performance of optically clear acrylic pressure sensitive adhesives using chelate metal acetylacetonate

Optically clear acrylic pressure-sensitive adhesives (PSAs) with different co-monomers were synthesized. This study employed metal chelate aluminum acetylacetonate and zirconium acetylacetonate as curing agents. The optical properties of the acrylic PSAs were examined by UV–visible spectroscopy and a prism coupler. In addition, the adhesion performance was obtained by assessing the peel strength, the tack, and the shear adhesion failure temperature. The decrease in the adhesion performance may be related to a higher crosslinking density, which also resulted in a higher gel content.

Synthesis and characterization of thermally stable acrylic PSA using silicone urethane methacrylate with a semi-IPN structure

To improve the thermal properties of acrylic PSA, silicone urethane methacrylate (SiUMA) is applied to acrylic PSA using a semi-interpenetrating polymer network (IPN) structure. Acrylic PSA was prepared by free radical polymerization and SiUMA was synthesized by additional polymerization via urethane linkage. By preparing synthetic SiUMA formed in a semi-IPN structure in acrylic PSA, the thermal stability can be verified with the shear adhesion failure temperature using 1 kg plumb weight. Normally, acrylic PSA can easily be cleared from the substrate at less than 50° C; but when using SiUMA at 10%, it can be resistant up to 100 C. When measuring the photo-DSC value, a 5.0 phr photoinitiator and UV intensity of 1000 mJ/cm2 can be used to complete the curing reaction. Two types of chain polymers – short and long chain polymers – were synthesized, and the structure was confirmed through FT-IR and gel permeation chromatography. By measuring the Thermogravimetric analyses, the cross-linking effect and improvement of the thermal resistance can be checked using silicone materials. With advanced rheometric expansion system, the thermal property changes and viscoelastic changes were detected. In this study, the mobility of silicone is detected while moving onto an air interface. The result of this study can provide information with which to improve the thermal stability when using SiUMA with a semi-IPN structure and acrylic PSA.

Optical properties and UV-curing behaviors of optically clear PSA-TiO2 nano-composites

Optically clear PSAs-TiO2 nano-composites were investigated for the purpose of display. TiO2 nano-particles can be directly incorporated into the polymer matrix to form high refractive index PSAs-nanocomposites films. Moreover, this study also employed semi-interpenetrated structured polymer network through the process of UV-curing with high refractive trifunctional acrylic monomer. The optical properties of PSAs-TiO2 nano-composites were examined by using UV-visible spectroscopy and a prism coupler. Viscoelastic properties were obtained by ARES and adhesion performance was measured by the peel strength, probe tack and shear adhesion failure temperature. Furthermore, curing behaviors of the PSAs-TiO2 nano-composites were investigated by using FTIR-ATR and gel content.

Morphology and properties of waterborne adhesives made from hybrid polyacrylic/montmorillonite clay colloidal dispersions showing improved tack and shear resistance

The morphology and adhesive properties of waterborne films from n-butyl acrylate/methyl methacrylate/montmorillonite clay hybrid polymer latexes which were synthesized by miniemulsion polymerization in the presence of a reactive organoclay ((2-methacryloylethyl) hexadecyldimethylammonium modified montmorillonite, CMA16) were investigated. It was found by cryo-TEM analysis that the hybrid dispersions were a mixture of colloidal particles composed of a small fraction of free montmorillonite clay platelets, polymer latex particles, polymer particles to which one or more clay platelets where adhered onto its surface and a fraction of colloidal material consisted of a clay platelet with a polymer lob adhered to either side, in other words hybrid particles with a dumbbell-like morphology. The films made from these waterborne hybrid dispersions presented a homogeneous dispersion of the clay platelets and exfoliated morphology. The shear adhesion failure temperature (SAFT) and shear resistance of the hybrid latex films synthesized with CMA16 were better than those prepared with a commercial clay (Cloisite 30B), but presented a liquid-like probe-tack performance. When allyl methacrylate (AMA) was added in the formulation, SAFT and shear resistance improved, but the film had a very low energy of adhesion due to the excessively crosslinked matrix. In order to reduce crosslink density and thus improve the adhesion energy, small amounts of chain transfer agent, in this case n-dodecyl mercaptan (n-DDM), were used in the miniemulsion polymerization process. Adhesive films made from these waterborne hybrid dispersions showed excellent SAFT and shear resistance, and good energy of adhesion.

Adhesion Performance and Thermal Stability of Fluorinated PSAs as a Crosslinking System

The use of pressure sensitive adhesives (PSAs) is becoming increasingly popular in many industrial fields. In the automobile industry the main reasons for using PSAs are that they reduce the overall weight of the vehicles and because they are easy to use. However, in the case of acrylic PSAs, the non-crosslinked linear chains results in low thermal stability. In this study, a fluorinated acrylic pressure sensitive adhesive was synthesized under UV irradiation and crosslinking was applied to the linear chain of acrylic PSAs to improve the thermal stability. The adhesion performance was evaluated by analyzing the peel strength, probe tack and shear adhesion failure temperature (SAFT) as a function of the type of crosslinking system. In particular, the peel strength and probe tack were measured at 25, 50 and 80°C. The viscoelastic properties, which were measured using an advanced rheometric expansion system (ARES), revealed a proper balance between the thermal stability and adhesion performance.