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Acrylic pressure sensitive adhesives (PSAs) are used in the production of flexible displays. Acrylic PSAs must have high flexibility and recovery to meet the industry demands for flexible displays. For these reasons, acrylic PSAs were designed to determine the effects of molecular weight and cross-linking on acrylic PSAs. Stress relaxation and creep tests were measured with dynamic mechanical analysis to identify the flexibility and recovery of the acrylic PSAs. The molecular weight and glass transition temperature of the PSAs were measured by gel permeation chromatography and differential scanning calorimetry. A texture analyzer was used to measure the adhesion performance of the acrylic PSAs. With increasing molecular weight, the adhesion performance increased, especially from 86 to 108 K molecular weight PSAs. This is due to the entanglement of the polymer chains. The stress and recovery of cross-linked acrylic PSAs was much higher than that of neat acrylic PSAs. This result is attributed to in...

Four types of flexible polyester are synthesized between urethane polyol of polycarbonatediol (PCDL)-isocyanate and carboxylic-terminated polyester pre-polymer. Urethane polyol of PCDL-isocyanate is synthesized between isocyanates such as IPDI and H12MDI and PCDL which has long alkyl chain. Carboxylic-terminated polyester pre-polymers are synthesized using 1,4-CHDA, Ph-An, NPG, 1,6-HD, and 1,4-CHD. The synthesized flexible polyester is measured using GPC and 1H NMR. From the 1H NMR spectra, urethane polyol of PCDL-isocyanate has been introduced to the polymer chain of synthesized resin. Those resins are formulated and characterized using DMA and tensile strength, and to control formability and anti-corrosion property. Results showed that storage modulus decreased, and the glass transition temperature shifted to a lower temperature with increasing contents of the urethane polyol of PCDL-isocyanate. So, it provides lower stiffness and higher flexibility to the polyester coatings. CU-IPDI-2 had highe...

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.

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 95%. The refractive indices of the a...

Current issues of energy and environment prompt us to replace fossil-based resources with renewable and sustainable ones. In this regard, carbohydrate biomass photosynthesized from atmospheric carbon dioxide attracts much attention due to its abundance and availability. Recently, furanic compounds that can be derived from carbohydrate biomass are highlighted as promising substitutes for aromatic compounds that are totally dependent on petroleum reforming processes. In this article, we report on several carbohydrate biomass-based furanic compounds as alternatives to petroleum-based adhesives. Furanic compounds bearing epoxide end group(s) were synthesized from renewable and sustainable carbohydrate biomass-based compounds (>70% yields). Another bis-epoxy furanic compound with a mimetic structure of bisphenol A (BPA) was also synthesized from xylose-derived 2-furan carboxylic acid and acetone (39% overall yield). In particular, epoxy groups were efficiently introduced to the hydroxymethyl functionality atta...

To improve the thermal stability of general acrylic pressure-sensitive adhesives (PSAs), polydimethylsiloxane (PDMS) was used and UV curing was employed. Silicone urethane methacrylate (SiUMA) was synthesized and introduced into acrylic PSAs for a semi-interpenetrating polymer network structure. The structure of the SiUMA was investigated through C NMR, H NMR, and FT-IR. The kinetics and behaviors of SiUMA (S1) were found by adding photoinitiators (PI) of 0.5, 1.0, 5.0, and 10 phr in a binder, which were examined using the photo-DSC (pDSC). After setting PI as 5.0 phr in a binder and UV intensity as 1000 mJ/cm2, the SiUMA, which was prepared by a radical polymerization, was added to acrylic PSA to 20, 40, 60, and 80% composition, and its kinetics and behaviors were analyzed by pDSC. Finally, the peel strength was checked to evaluate adhesion performance of the acrylic PSAs. The reaction rate was increased with increasing amounts of S1 and PI. Peel strength was dropped sharply with increasing crosslinking ...

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 improvem...

In the present study, randomly aligned jute fiber/poly(lactic acid) (PLA) and two-directionally aligned jute fabric/PLA green composites with jute (50% by weight) treated with electron beam at different dosages (0, 5, 10, 30, 50, and 100 kGy) were fabricated by compression molding technique and the effect of electron beam treatment on their thermal properties was investigated in terms of thermal expansion, thermal stability, dynamic mechanical thermal property, and heat deflection temperature (HDT). The dynamic storage modulus and HDT of neat PLA were significantly increased by incorporating jute fibers or fabrics into PLA, whereas the coefficient of thermal expansion (CTE) and the damping property were decreased, reflecting the enhancement in the interfacial adhesion between the jute and the PLA by electron beam treatment with an optimal dosage of 10 kGy and the reinforcing effect by jute. The result exhibited that the thermal stability, storage modulus, and HDT of jute/PLA green composites were highest ...

Acrylic pressure-sensitive adhesives (PSAs) need to show proper adhesion and improved wettability on the silicon wafer as the wafer becomes thinner. The acrylic copolymers were synthesized by solution radical polymerization of 2-ethylhexyl acrylate, ethyl acrylate, and acrylic acid with AIBN as an initiator. Adhesion performance and wettability of acrylic PSAs were studied depending on the content of lauryl side chains and the degree of crosslinking. The introduction of lauryl side chain was characterized by Fourier transform infrared spectroscopy. The adhesion performance of acrylic PSAs having lauryl side chain was investigated using contact angle, wettability, probe tack, peel strength, and cohesiveness tests. The wettability of acrylic PSAs was improved significantly with increasing the content of lauryl side chain.

An eco-friendly poly (vinyl acetate) emulsion adhesive was synthesized without phthalate. Four types of eco-friendly plasticizers for use in these adhesives were selected to confirm their primary properties by injecting the eco-friendly plasticizer without any prior change to its processing or cost. The four types of eco-friendly plasticizers used were dibutyl phthalate DBP-based product, dialkyl ester, acetyl tributyl citrate, and pentandiol-di-isobutyrate. Their properties were determined by comparison with the existing (DBP)-based product. As a result, an emulsion adhesive was produced without addition of phthalate or need for additional additives, resulting in a significant decrease in cost. However, the low temperature characteristics of the eco-friendly plasticizers were slightly inferior to those of DBP. These adhesives containing eco-friendly plasticizer were studied and their characteristics for adhesion strength, water resistance, ability for low temperature film formation, excellent storage sta...

This study investigated the effect on the curing behavior, activation energy (E a) of the curing reaction, crystalline structure, crosslinking, and free formaldehyde content of the addition of the following scavengers in urea-formaldehyde (UF) resins: medium density fiber board flour, rice husk flour, silica powder, and tannin powder. The scavenger content was 3 and 7 wt% of the UF resin solid content. The curing behavior of UF resins was monitored by differential scanning calorimetry, thermogravimetric analysis, and X-ray crystallography. The curing E a was correlated to the free formaldehyde content of the scavenger containing UF resins. The thermal stability of the UF resins increased but the curing E a decreased with increasing scavenger content. After curing, the crystallinity of the UF resins decreased in the presence of scavengers. The unreacted free formaldehyde content was reduced in the tannin powder containing UF resins. The degree of crosslinking affects the formaldehyde emission from wood pan...

As Si-wafers, as used in the electronic industry, become thinner and thinner, it is important to investigate the conditions which are suitable for easily peelable acrylic dicing tapes. In the ‘pick-up’ process, the adhesion strength decreased after UV irradiation as a result of polymer network formation. In this study, interpenetrating polymer network (IPN) structured acrylic pressure sensitive adhesives (PSAs) were investigated with two different types of UV irradiation — a steady UV irradiation and a pulsed UV irradiation of 100 mJ/cm2. The PSAs binder contained 2-ethylhexyl acrylate (2-EHA), acrylic acid (AA) and 3-methacryloxypropyl trimethoxysilane (3-MPTS). The hexafunctional monomer, dipentaerythritol hexacrylate (DPHA) and 3-methacryloxypropyl trimethoxysilane (3-MPTS) were used as diluent monomers. The adhesion performance as related to the peel strength and the tack properties on the Si-wafer substrates, was examined with increasing UV dose. The effect of UV-curing on the behavior and v...

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.

UV-curable acrylic pressure-sensitive adhesives (acrylic PSAs) have many applications in industry. As the Si-wafers become thinner, the acrylic PSAs for MCP need to show proper adhesion and leave little residue on the Si-wafer after UV irradiation when released from the dicing tapes. Strong adhesion is required in the dicing process to hold the Si-wafer before UV irradiation. On the other hand, weak adhesion strength is required after UV irradiation to prevent damage to the Si-wafers during the pick-up process. This study employed semi-interpenetrating polymer network-structured dicing of acrylic PSAs in the Si-wafer manufacture process. The binder PSAs contained 2-ethylhexyl acrylate (2-EHA) and acrylic acid (AA). The adhesion performance of the peel strength on a Si-wafer was examined as a function of the UV dose. The results showed that the abovementioned two requirements were achieved using semi-IPN dicing acrylic PSAs using a hexafunctional acrylate monomer and a UV-curing system. FE-SEM and XPS reve...

The front and back layers of plywood formwork consist of veneers made of Oceania timber (Shorea spp.). As the demand for Oceania timber has increased worldwide, it has become difficult to find good front and back layers for plywood. This study, therefore, has investigated plywood made with water-based phenolformaldehyde (PF) resin impregnated linerboards of different basis weights and pulp types. Manufactured plywood with water-based PF resin impregnated linerboards made of Korean recycled linerboard pulp layers, which were pressed at 140° C and 10 kg/cm2 for 3 min, had the highest internal bond strength. Furthermore, the internal bond strength of plywood with K2 linerboard was highest among all those tested. Based on the results of heat and cold cycle tests, alkali tests, abrasion tests, and boiling water tests, three types of linerboards: K2, KAC and KLB were found to be suitable for plywood formwork.

This article reports on the curing behavior and adhesion performance of ultraviolet (UV)-curable, polystyrene–polyisoprene–polystyrene (SIS)-based pressure-sensitive adhesives (PSAs) blended with di- or tri-functional monomers and a photoinitiator. The curing reaction was achieved by direct excitation of PSAs by irradiation with a 100 W high-pressure mercury lamp at different UV doses. The curing behavior of the PSAs was studied by gel fraction determination, rigid-body pendulum type physical properties test (RPT) and Fourier transform-infrared–attenuated total reflection (FT-IR–ATR) spectroscopy. The adhesion performance was determined by probe tack, peel strength and shear adhesion failure temperature (SAFT) measurements. The reaction rate and extent of UV curing reaction were found to be strongly dependent on the curing rate for the following five multifunctional monomers studied: three di-functional monomers, ethylene/glycol dimethacrylate (EGDMA), triethylene glycol dimethacrylate (TEGDMA) and poly(e...

A novel kind of bisphenol-type epoxy resin with a vinyl side-chain was developed and its miscibility behavior with liquid nitrile-butadiene rubber (NBR) was investigated. The diglycidyl ether of bisphenol propylene (DGEBP) was prepared by the condensation of phenol with acrolein in the presence of an acid catalyst and the subsequent epoxidization with epichlorohydrin (ECH). The structures of the bisphenol and corresponding epoxy resin were characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectral analyses and the epoxy value was determined to be 0.34 mol/100 g by titration. The mixture of DGEBP with the liquid NBR containing diglycidyl ether of bisphenol acetone (DGEBA) was prepared and cured with diaminodiphenylmethane (DDM). The miscibility and morphology of the mixture system were studied by dynamic mechanical thermal analysis (DMTA) and transmission electron microscopy (TEM), respectively. The cured mixture of DGEBP/NBR/DDM exhibited good miscibility and, therefore, no separation, a...

In this study we investigated the effects of using four additives, wheat flour (WF), tannin, rice husk (RH) and charcoal, to melamine-formaldehyde (MF) resin for decorative veneer and base plywood in engineered flooring in order to reduce the formaldehyde emission levels and improve the adhesion properties. We determined the effects of variations in hot-press time, temperature and pressure on the bonding strength and formaldehyde emission. Blends of various MF resin/additive compositions were prepared. To determine and compare the effects of the additives, seven MF resin blends were prepared with the four different additives: four with a wt ratio of 8:2 (MF/WF, MF/tannin, MF/RH and MF/charcoal), and three in the wt ratio of 8:1:1 (MF/WF/tannin, MF/WF/RH and MF/WF/charcoal). The desiccator and perforator methods were used to determine the level of formaldehyde emission. The formaldehyde emission level decreased with all additives, except for RH. At a charcoal addition of only 20%, the formaldehyde emission...

Hot-melt pressure-sensitive adhesives (HMPSAs) usually contain styrene-isoprenestyrene (SIS) or styrene-butadiene-styrene (SBS) block copolymers, tackifier, plasticizer and other additives. However, these PSAs cannot be used in high-temperature applications or where solvent and chemical resistance properties are required. We, therefore, developed UV-cross-linkable HMPSAs by the thiol-ene reaction with the aim to increase adhesion properties at elevated temperature. For effective UV cross-linking, the selection of photoinitiator and photo-cross-linker is very important for thermal stability and fast curing. Adhesion properties, such as probe tack, peel strength and shear adhesion failure temperature (SAFT), were evaluated to measure PSA performance as a function of photoinitiator type.

This article reports on the curing performance of UV-curable acrylic binders prepared with trifunctional monomers and a photoinitiator. The curing reaction was achieved by direct excitation of pressure-sensitive adhesives (PSAs) by irradiation with a 100-W high-pressure mercury lamp with different UV doses. The curing performance of PSAs was studied by photo-differential scanning calorimetry (photo-DSC), gel-fraction determination and Fourier transform infrared–attenuated total reflection (FTIR–ATR) spectroscopy. The reaction rate and extent of UV curing were found to be strongly dependent on the curing rates of the trifunctional monomers, trimethylolpropane triacrylate (TMPTA) and trimethylolpropane ethoxylated (6) triacrylate (TMPEOTA), which have different molecular weights. Exothermic areas increased with increasing acrylic acid concentration. Moreover, gel fractions sharply increased after UV irradiation and then remained constant with prolonged UV exposure. TMPTA blends had higher gel fractions than...

Two types of wax were added to a ethylene vinyl acetate (EVA) copolymer/aromatic hydrocarbon resin (tackifier) blend in the molten state and the miscibility, viscoelastic and adhesion properties of ternary blends as hot-melt adhesives (HMAs) were investigated. Miscibility and viscoelastic properties were studied using differential scanning calorimetry (DSC), Brookfield viscometry and dynamic mechanical thermal analysis (DMTA), and their adhesion strength was determined in terms of single lap shear strength. DSC thermograms of both types of waxes showed their melting peaks in a similar region to that of EVA/tackfier blend. It was difficult to evaluate the miscibility of ternary blends using DSC because the melting peaks of the waxes overlapped with those of the EVA/tackifier blend, although the glass transition temperature (T g) of the ternary blend systems slightly increased with increasing wax concentration. However, their storage modulus (E′) increased slightly and loss tangent (tan δ) showed different ...

The initial tack and viscoelastic properties of blends of melamine–formaldehyde (MF) resin and poly(vinyl acetate) (PVAc) emulsion on decorative veneer and plywood surfaces were investigated using a texture analyzer and dynamic mechanical thermal analysis (DMTA) at room temperature with respect to the 'open time', the time delay between applying an adhesive to a surface and contacting that surface with the other material. We determined and compared the effects of PVAc content, at 0, 30, 50, 70 and 100 wt%, in blends with MF resin. As PVAc is curable at room temperature, PVAc markedly affected the initial tack, as well as DMTA results. The degree of 'tack' was determined quantitatively based on the probe tack data. As the adhesion in an engineered flooring should be achieved in 2–3 min, the acceptable tack range is between 100 and 200 g. From the DMTA results, i.e., the tan δ max values, the maximum loss modulus (E&Prime) and the rigidity (ΔE) of MF/PVAc blends at room temperature, it was found that tan δ ...

UV-crosslinkable acrylic pressure sensitive adhesives (PSAs) were synthesized by copolymerization of 2-ethylhexyl acrylate (2-EHA), vinyl acetate (VAc), acrylic acid (AA), 2-hydroxyethyl methacrylate (2-HEMA) and 4-acryloyloxydiethoxy-4′-chlorobenzophenone (unsaturated photoinitiator), with varying contents of 2-HEMA and photoinitiator, by solution polymerization. The UV-crosslinking behavior of the PSAs was studied by ATR–FT-IR spectroscopy, and PSA performance was characterized by probe tack, peel resistance and shear adhesion failure temperature (SAFT). As 2-HEMA acts as a good hydrogen donor to benzophenone, the efficiency of the photo-reaction was enhanced; thus with increasing contents of 2-HEMA and photoinitiator in the PSAs the incorporation of benzophenone groups in the PSAs, even at low UV doses, was quite fast. In addition, as the crosslinking reaction proceeds via photo-reaction mainly between 2-HEMA and photoinitiator, the probe tack and peel resistance of the PSAs having high concentrations ...

UV-curable solvent-free pressure sensitive adhesives (PSAs) are gaining importance in the area of adhesives because of increasing environmental concerns and the goal to reduce volatile organic compounds (VOCs) in work areas and consumption places. These PSAs have advantages such as low emission of VOCs, a solvent-free process, a fast producton rate at ambient temperature and only a modest requirement for operating space. In this study, UV-curable PSAs were investigated by measuring their adhesion performance in terms of probe tack, peel strength, shear adhesion failure temperature (SAFT) and holding power. PSAs were synthesized from 2-ethylhexyl acrylate (2-EHA), acrylic acid (AA) and vinyl acetate (VAc), using variations in AA concentration to control the glass transition temperature (T g) of the prepared PSAs. In addition, two types of trifunctional monomers, trimethylolpropane triacrylate (TMPTA) and trimethylolpropane ethoxylated (6) triacrylate (TMPEOTA), which have different chain lengths, were used...

The objective of this research was to investigate the miscibility behavior of melamine-formaldehyde (MF) resin and poly(vinyl acetate) (PVAc) blends for their use as adhesives for bonding fancy veneer and plywood in engineered flooring, by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). Blends of various compositions of MF resin/PVAc were prepared. To determine and compare the effect of PVAc content, blends with PVAc to MF resin weight ratios of 0, 30, 50, 70 and 100% were prepared. These blends displayed a single cure temperature over the entire range of compositions indicating that this blend system was miscible in the amorphous phase due to the formation of hydrogen bonding between the amine groups of the MF resin and the carbonyl groups of PVAc.

To improve the peel strength between a pressure-sensitive adhesive (PSA) and its substrate, grafting of acrylic acid (AA) onto the surface of poly(ethylene terephthalate) (PET) film was carried out. After AA was coated onto the surface of PET films using a spin coater, the coated PET films were irradiated by UV. To investigate the surface chemistry and topography of the PET-g-AA films, the grafted surface of the PET films was characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM). From these investigations, the effects of grafting of AA at the surface of PET by UV irradiation were discussed. In addition, to determine the effect of grafting on the adhesion between PSA polymer and PET-g-AA films, peel strength was measured after the PSA/PET-g-AA system was cured at various temperatures. As the esterification between PSA polymer and PET-g-AA films occurred in the interfacial region, the peel strength of the PSA/PET-g-AA system generally increased with ...

A volatile organic compound (VOC) analyzer is a portable device to measure the four main aromatic hydrocarbon gases: toluene, ethylbenzene, xylene and styrene. With the VOC analyzer, a semiconductor gas sensor eliminates the need for the carrier gas which is required for conventional gas chromatography. In addition, since the semiconductor gas sensor is supersensitive to gas components, it is not necessary to use a conventional gas concentrator or other complicated equipment. Compared with other measurement methods, the VOC analyzer is useful for measuring toluene, ethylbenzene, xylene and styrene in new buildings because of its ease in obtaining field results and repeating the test. For easy, fast and economic testing of total (TVOC) emission from adhesives used for building materials, we developed a test method using the VOC analyzer and compared its measurement of VOC emissions from building materials such as adhesives, paints and wood-based panels with that of the 20-l chamber method, which is the sta...

The objective of this research was to investigate the activation energy and viscoelastic properties of urea-formaldehyde (UF) resin, melamine-formaldehyde (MF) resin and UF-MF resin mixtures by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The purpose of adding MF resin to the UF resin was to reduce the formaldehyde emission. As the MF resin content was increased in the UF-MF resin mixture, the formaldehyde emission decreased. The storage modulus (E′), loss modulus (E″) and loss factor (tan δ) of each resin were measured by DMTA. With increasing temperature, as the resin cured, the storage modulus (E′) increased in all resin systems. The storage modulus (E′) increased both as a function of increasing temperature and with increasing MF content. The activation energies (E a) of the curing reactions of the UF and MF resins alone, as well as the mixed resins, on different substrates, were calculated on the basis of the variation of the temperature of the maximum of ea...

SIS (styrene-isoprene-styrene)-based pressure sensitive adhesives (PSAs) were prepared by melt- or solution-blending. In the coating process, two methods were used: solution coating and melt coating. The performances of the PSAs were found to be different, depending on which of these two blending or coating methods was used. In this study, we investigated the relationship between the viscoelastic properties and the performances of the SIS-based PSAs using different blending and coating methods. Three methods were used: (1) melt-blending and melt-coating, (2) melt-blending and solution-coating and (3) solution-blending and solution-coating. PSAs applied using melt-blending/melt-coating (M—M) have higher peel strength and probe tack than PSAs applied using melt-blending/solution-coating (M—S) and solution blending/solution coating (S—S). However, PSAs applied using M—M blends have lower holding power and SAFT (Shear adhesion failure temperature) than PSAs applied using M—S and S—S blends. The viscoelastic p...

We have shown that the addition of small amounts of carbon black can drastically reduce the interfacial fracture toughness between polymers. This is interpreted as being due to strong interactions ...

This study investigated the curing behavior and viscoelastic properties of two types of tannin-based adhesives, wattle and pine, with three hardeners: paraformaldehyde, hexamethylenetetramine and TN (tris(hydroxylmethyl)nitromethane), by FT-IR-ATR spectroscopy and dynamic mechanical thermal analysis (DMTA). Using FT-IR-ATR spectroscopy, the chemical structures of tannin-based adhesives were determined and the degrees of curing as a function of temperature and time were compared with the conversion degrees of the hydroxyl groups. Paraformaldehyde was shown to be more reactive with wattle tannin than the other hardeners, while hexamethylenetetramine was the most reactive with the pine tannin. As the quantity of hardener was increased, the conversion degree also increased. The storage modulus (E′), loss modulus (E′′) and loss factor (tan δ) of each adhesive system were obtained by DMTA. With increasing temperature, as the tannin-based adhesives hardened, the storage modulus (E′) increased in all adhesive sys...

A series of ethylene vinyl acetate (EVA) copolymers were blended with aromatic hydrocarbon resins in the molten state in various ratios and possible relations between viscoelastic and adhesion properties as hot-melt adhesives (HMAs) were investigated. When the softening point of aromatic hydrocarbon resin was high and the concentration of aromatic hydrocarbon resin was low, the tan δ peak height decreased and broadened. This result corresponds to the miscibility of the blend. The single lap shear strength increased with increasing softening point of the aromatic hydrocarbon resin and it reached a maximum value with increasing temperature. A large scatter was observed in lap shear strength values, which were higher at higher test rates and lower temperatures, and under these conditions interfacial failure occurred.

This study investigated the physical and mechanical properties of particleboards made using two types of tannin-based adhesives, wattle and pine, with three hardeners, paraformaldehyde, hexamethylenetetramine (hexamine) and TN (tris(hydroxyl)nitromethane), by measuring the physical (thickness swelling, linear expansion and water absorption) and mechanical properties (bending strength and internal bond strength). The performance of the particleboards made using tannin-based adhesives was influenced by physical conditions such as press time and temperature as well as by chemical conditions, such as the chemical structure of the tannin and the hardener. Wattle tannin-based adhesive being a thermoset, the wattle tannin-based particleboards were more influenced by physical conditions, while the pine tannin-based particleboards were influenced by the chemical structure of the pine tannin nuclei, which include phloroglucinolic A-rings. The reactivity of the hardener toward the tannin was in the order: paraformal...