Rubber-based Adhesives Research Articles

Promoting Adhesion of Natural Rubber/Styrene-Butadiene Rubber to Brass Using Vietnamese Natural Rubber-Based Adhesives

Abstract This study aimed to enhance the adhesion between brass and NR/SBR rubber sheets using solvent-based adhesives derived from Vietnamese natural rubber. The effects of silane coupling agents and iron nanoparticles on adhesion were investigated. (3-Aminopropyl) Triethoxysilane (APTES) and iron nanoparticles are incorporated into the adhesives at varying concentrations to enhance adhesion levels. The characteristics of the adhesive, such as viscosity, peel-off tensile strength, and the surface morphology of the adhesive bond failure, have been studied and evaluated. The research results demonstrated that as the APTES content added to the adhesives increases gradually, the peel strength between the NR/SBR and brass significantly improves. The highest peel strength value achieved was 5.27 N/mm at 25 phr APTES, representing a 974% increase compared to the sample without silane. The continued addition of iron nanoparticles to the adhesive further improves the peel tensile strength, reaching a maximum value of 5.93 N/mm at a nanoparticle content of 5 phr. This information will be crucial for developing practical applications for this type of adhesive.

Application of Organo-Modified Silica Nanoparticles to Improve the Load-Bearing Capacity of Bonded Joints of Dissimilar Steel Substrates

The paper deals with the joining of dissimilar steels by adhesive bonding. The base materials for the experimental work were deep-drawn low-carbon steel DC04, and hot-dip galvanized HSLA steel HX340LAD+Z. Adhesive bonding was performed using rubber-based and epoxy-based adhesives. The research aimed to verify the importance of surface preparation of steel substrates using a formulation with organically modified silica nanoparticles and epoxy organic functional groups, where one end of the functional group can be incorporated into the organic binder of the coating material and the other end can be firmly bonded to substances of an inorganic nature (metals). Since the binder base of adhesives is very similar to that of coatings, verifying the performance of this surface preparation when interacting with the adhesive is necessary. The load-bearing tensile shear capacity of single-lapped joints and the resistance of the joints against corrosion-induced disbanding in a climate chamber were tested. The energy dissipated by the joints up to fracture was calculated from the load-displacement curves. Bonded joints with organosilane were compared with joints without surface preparation and joints prepared by chroman-free zirconate passivation treatment. Exposure of the joints in the climatic chamber did not cause a relevant reduction in the characteristics of the joints. Organosilicate formulation was proved effective when bonding ungalvanized steels with a rubber-based structural adhesive, where it improves the bond quality between the adhesive and the substrate.

Evaluation of in vivo bond strength and skin irritation test for new skin adhesive

ObjectivesThis study developed a new skin-deproteinized natural rubber latex (DNRL) silicone adhesive for adhering to silicone prostheses and compared the properties with a commercial Daro-Hydrobond adhesive. Materials and methodsThe new DNRL skin adhesive formulation was made from non-vulcanized natural rubber-based adhesives consisting of DNRL, 20% polyvinyl alcohol, cumarone resin, 2% methylcellulose, and Wingstay L. The peel bond strength of the adhesives was tested using a 90-degree peel test. Biocompatibility was accessed using in vitro keratinocyte cell viability. Animals (rabbits) and humans were tested for skin irritation tests. Results were analyzed using SPSS Version 24 and compared between the two adhesives. ResultsThe peel bond strength of the new DNRL skin adhesive was 103.61 ± 23.18 N/m whereas that of the Daro-hydrobond adhesive was 131.52 ± 21.72 N/m. There was no significant difference (p>0.05) between the peel bond strengths of the two test adhesives. Cell proliferation under the DNRL skin adhesive-soaked medium showed higher cell viability than the positive control (p<0.05). The DNRL skin adhesive produced moderate erythema and edema on rabbit skins, however, the skin lesions recovered within 14 days. Two volunteers showed mild irritation at the first hour of the contact which was reduced within an hour without any therapy. The patient satisfaction with the DNRL skin adhesive ranged from slightly satisfied to completely satisfied. ConclusionThe new DNRL skin adhesive showed comparable peel bond strength and patient satisfaction to those of commercial adhesives. The adhesive was biocompatible and can be used carefully.

Characterisation and adhesion properties of UV-cured natural rubber-based adhesives

The adhesion properties of rubber adhesives based on SMR-L, ENR-25 and ENR-50 elastomers cured by ultraviolet (UV) light radiation were examined. Various parameters were studied, namely the effects of UV radiation dosages and coating thickness on adhesion properties such as tackiness, peel strength, and shear resistance. Prior to curing, the viscosity of uncured adhesives was analysed in order to understand the effect of adding benzoyl peroxide cross-linker. The reduction of double bonds due to UV-curing was confirmed by FTIR analysis. These adhesives were properly cured after 15 passes (repetitive irradiation on moving conveyor belt) inside UV-curing machine, as proven by both pendulum hardness and gel content tests. Results indicated that for all rubber-based adhesives, 120 μm coated samples showed higher peel strengths than their 60 μm counterparts. ENR-25 based adhesives showed better peel strength as compared to the others, while SMR-L based adhesives possessed higher tackiness and shear resistance than those of ENR-25 and ENR-50 based adhesives.

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.

Novel Deproteinized Natural Rubber Latex Adhesive Used in Extraoral Maxillofacial Prostheses

This study aimed to develop an adhesive for silicone maxillofacial prostheses and compared the properties with the Daro adhesive hydrobond (Factor II, Inc, Lakeside, AZ, USA). Two adhesives were developed from non-vulcanized natural rubber-based adhesives (Adhesive A) and deproteinized natural rubber latex (DNRL) products (Adhesive B) and stored at 4 °C. The Control group was the commercial Daro adhesive hydrobond (Factor II, Inc, Lakeside, AZ, USA). The physical properties (appearance, viscosity, spreadability, color, and pH) of the adhesives were measured and every week for 12 weeks after storing at 4 °C. The adhesives were characterized under scanning electron microscopy. Mechanical testing done were peel bond strength and biocompatibility testing was done using MTT assay. Physical, surface, and mechanical properties were compared with the commercial adhesive. Data analysis was done using SPSS version 24. Both adhesives were physically and chemically stable at temperature 4 °C and had suitable peel bond strength adhesives as the commercial adhesive. Hence, the adhesives can be used to adhere to the maxillofacial silicone prostheses.

Improved adhesion properties of natural rubber-based pressure-sensitive adhesives by incorporating particulate fillers

A new concept of producing natural rubber (NR) based pressure-sensitive adhesive (PSA) using solid particles relatively at a low-cost as tack enhancer has been proposed. The effect of tack enhancer (i.e., xyloglucan (XG), rice flour (RF), calcium carbonate (CaCO3), and silica (SiO2)) on the adhesion properties of the PSA was investigated. Moreover, stress relaxation, tan δ, initial plasticity (Po), and molecular weight of NR which relates to the adhesion properties were also determined. The study found that XG, RF, and SiO2 can be used as tack enhancers for NR-based PSA. The obtained PSA from those tack enhancers can adhere and peel off on a polypropylene (PP) substrate without any adhesive residue. An increase in the adhesion properties of NR-based PSA can be explained by the effect of fillers on the viscoelastic properties and molecular weight of the PSA. Stress relaxation and molecular weight of the NR-based PSA were significantly found to be decreased, while the tan δ was increased by the addition of particulate tack enhancers compared to the masticated neat NR. NR-based PSA with the highest peel strength (2.11 × 102 N/m) was successfully developed by using XG (40 phr). The NR-based PSA with XG was also showed the ability to resist the unfavorable aged hardening of the NR-based PSA in 180 days.

Natural rubber-based solution adhesives: effect of carbon black on the adhesive properties

In the retreading industry, generally two types of adhesives say a solid adhesive (bonding gum) and a solution adhesive (black vulcanising cement) are mainly used. In this study, the performance of natural rubber (NR)-based solution adhesive for the rubber to rubber bonding was examined. The effect of different grades of carbon black (CB) say ISAF (N220), HAF (N330) and GPF (N660) as a reinforcing filler in adhesive was evaluated. The loading used was different for the three grades of CB to achieve the required level of hardness for the adhesive. A blend of natural rubber and butadiene rubber (BR) was used as the adherend substrate. The vulcanisation characteristics, mechanical properties, swelling measurements and adhesion strength of different CB-filled NR-based solution adhesive were studied. All the three grades of CB-filled NR-based adhesives showed an increase in the rheometer torque and crosslink density compared to unfilled NR-based adhesive. The incorporation of CB improved the mechanical properties, adhesion strength and thermal stability of NR-based adhesives. CB-filled NR adhesives showed lower solvent uptake compared to unfilled ones. The measured properties of all the three grades of CB-filled NR-based solution adhesives were found to be comparable at the fixed hardness level.

Analysis of the effect of molecular weight and testing rate on shear strength of epoxidized natural rubber-based adhesives with a statistical model

Abstract The effect of the molecular weight and testing rate on shear strength of epoxidized natural rubber (ENR 25)-based adhesives with statistical model was investigated using gum rosin as the tackifying resin. Toluene and polyethylene terephthalate (PET) were used as the solvent and substrate, respectively, throughout the study. A SHEEN hand coater was used to coat the adhesive on the substrate at a coating thickness of 120 μm. All the adhesion properties were determined by a Lloyd Adhesion Tester operating at different rates of testing. Result shows that shear strength increases up to an optimum molecular weight of 6.5×104 ENR 25. Shear strength increases with coating thickness, an observation that is ascribed to the increasing amount of adhesive present in the coating layer, which enhances the shear resistance of the adhesive. It also increases with increase in rate of testing, a phenomenon that is associated with the viscoelastic response of the adhesive.

ECO-Adhesive from Modified Natural Rubber for Wood Applications

Both commercial entities and the government have expressed interest in safe and environ-mentally friendly adhesives, ECO-adhesives, containing no volatile harmful or toxic chemicals. In the wood industries, currently common adhesives such as urea formaldehyde (UF), phenol formaldehyde (PF) release formaldehyde vapors that are a human health concern, with unpleasant odor. We examined the potential of modified natural rubber latexes (MNRL) for use as ECO-adhesives. Three latex types were used, namely epoxidized natural rubber (ENR), liquid natural rubber (LNR), and NR/PMMA blend. The MNRL was characterized by FT-IR, NMR, and GPC. The proportion of tackifying agent to the dry weight of latex was varied in the range 0 to 60 phr. It was found that the MNRL uniformly mixed in the latex form. All MNRL adhesives would have passed the Thai standard for rubber-based adhesives, based on their: total solids content (TSC), pH, viscosity, shear strength, and emissions of formaldehyde. Up to 30% fraction of tackifying agent, tack and shear strength increased with its content. Compared to a commercial UF adhesive, the MNRL had lower emissions of formaldehyde vapors, lower shear strength, but higher TSC, and higher viscosity. In summary, for select wood applications with moderate bond shear demands, these new rubber based adhesives could provide a health conscious and non-toxic alternative, with the further advantage of low odor.

Effect of zinc oxide concentration and testing rate on shear properties of Standard Malaysian Rubber (SMR) L-based pressure-sensitive adhesives

The effect of zinc oxide and testing rate on shear strength of natural rubber-based pressure-sensitive adhesives was studied using coumarone-indene resin and toluene as the tackifier resin and solvent, respectively. The range of zinc oxide concentration varied from 0 to 60 parts per hundred parts (phr) of rubber, whereas the testing rate was from 10 to 50 cm/min. Viscosity and shear strength of adhesive were determined using a Brookfield viscometer and a Lloyd Adhesion Tester, respectively. Results show that the viscosity of adhesive increases gradually with the increase in zinc oxide concentration. For a fixed coating thickness, shear strength increases with zinc oxide loading up to 20 phr, after which it drops with further addition of zinc oxide, an observation that is attributed to varying degree of cohesive strength of adhesive. Shear strength increases with coating thickness and testing rate, suggesting that the shear strength is both thickness- and rate-dependent.

Material Properties and Influence of Molecular Weight and Testing Rate on Adhesion Properties of Epoxidized Natural Rubber-Based Adhesives

The effect of molecular weight and testing rate on peel and shear strength of epoxidized natural rubber (ENR-50)-based adhesive was investigated using petro resin as the tackifier. Toluene and polyethylene terephthalate were used as the solvent and substrate respectively. Peel and shear strength were determined by a Llyod Adhesion Tester operating at different rates of testing. Result shows that peel strength and shear strength increases up to an optimum molecular weight of 4.2 × 104 g/mol of ENR-50. This observation is attributed to the combined effects of wettability and mechanical strength of rubber for peel strength. For shear strength, it is ascribed to the optimum cohesive and adhesive strength. Both peel strength and shear strength increases with increasing rate of testing, an observation which is associated to the viscoeslastic response of the adhesive. Thermal study, SEM and FTIR study confirms the miscibility of tackifier with ENR-50.

Effect of silica on viscosity, tack, and shear strength of epoxidized natural rubber‐based pressure‐sensitive adhesives in the presence of coumarone‐indene resin

AbstractThe viscosity, loop tack, and shear strength of silica‐filled epoxidized natural rubber (ENR 25 and ENR 50 grade) adhesive were investigated using coumarone‐indene as the tackifying resin. Silica loading was varied from 10–50 parts per hundred parts of rubber (phr), whereas the coumarone‐indene concentration was fixed at 40 phr. Toluene was used as the solvent throughout the study. Polyethylene terephthalate substrate was coated at various adhesive coating thicknesses, i.e., 30, 60, 90, and 120 μm using a SHEEN Hand Coater. Viscosity of the adhesive was determined by a HAAKE Rotary Viscometer whereas loop tack and shear strength were measured by a Llyod Adhesion Tester operating at 30 cm/min. Result shows that viscosity of the adhesive increases gradually with increase of silica loading due to the concentration effect of the filler. Both loop tack and shear strength show maximum value at 40 phr silica for ENR 25. However, the respective values for ENR 50 are 20 and 40 phr of filler. This observation is attributed to the maximum wettability and compatibility of adhesive on the substrate at the respective silica loadings. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Solvent Gels for Removing Aged Pressure-Sensitive Tape from Paper

The removal of pressure-sensitive tapes from paper, particularly aged rubber-based adhesives, is optimized with a poultice that consists of a solvent gel prepared with cetyl-hydroxyethylcellulose (PolySurf 67™ CS). The application necessitates interleaving with lens tissue or a TST (polyester) non-woven fabric. The application of the solvent gel allows more economical treatments of paper objects disfigured by aged tape adhesive. The article presents a case study involving the successful removal of a rubber-based discoloured adhesive from architectural drawings on tracing paper belonging to the Hessisches Landesmuseum, Darmstadt.

Hierarchical cluster analysis as a tool for preliminary discrimination of ATR-FT-IR spectra of OPP acrylic and rubber-based adhesives

It is difficult to discriminate colorless and transparent oriented poly(propylene) (OPP) packaging tapes by the physical measurements of the backings. They are normally discriminated by the analysis of the adhesives. In the present study acrylic and rubber-based adhesives of colorless and transparent OPP packaging tapes were analyzed by attenuated total reflection (ATR) FT-IR. The performance of hierarchical cluster analysis (HCA) as a tool for discriminating ATR-FT-IR spectra was studied. The spectra were collected over the range from 4000 to 650 cm −1 and the spectral resolution was 4 cm −1; the number of the data per spectrum was ca. 1700. The spectrum data was analyzed by a built-in function, “agnes”, in R language. The HCA classification of the raw spectra of acrylic adhesives was almost consistent with the visual classification. HCA excluded the importance of the characteristic absorption peak in discriminating spectra. The classification of the spectra of rubber-based adhesives by HCA and the visual classification were same. HCA can reduce the forensic examiner's workload to classify the adhesives.

Singlet Oxygen Generation and Adhesive Loss in Rubber-based Adhesives using Metallic Nitride Fullerene Sensitizers

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Analysis of rosin and modified rosin esters in adhesives by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS)

The optimum method for analyzing glyceryl rosinate by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was studied. The performances of dithranol, anthracene, and 2,5-dihydroxybenzoic acid, pyrene, trans, trans-1,4-diphenyl-1,3-butadiene, 9-nitroanthracene, indole-3-acrylic acid and retinoic acid as a matrix agent, and those of sodium trifluoroacetate (NaTFA) and silver trifluoroacetate (AgTFA) as a cationization agent were measured. Dithranol showed higher signal to noise ratio and lower base-line, and AgTFA showed better performance than NaTFA. In this study, however, NaTFA was chosen since the ester peaks with high signal to noise ratios were observed, and the spectra of sodium-cationized molecules are simpler than those of silver-cationized molecules. Rosin esters and modified rosin esters in 22 rubber-based pressure sensitive adhesives and a paper-cement were analyzed. Glyceryl rosinate, glyceryl disproportionated rosinate, pentaerythrityl rosinate and pentaerythrityl hydrogenated rosinate were easily detected despite the fact that rubber-based adhesives are complex mixtures of elastomers, tackifiers, antioxidants and other additives. The detection limit of this method was studied and 2% of glyceryl rosinate in a rubber-based pressure sensitive adhesive was detected. It has been proved that MALDI-TOF-MS is a useful analytical method to analyze rosin and modified rosin esters in adhesives.

Nano- and bulk-tack adhesive properties of stimuli-responsive, fullerene–polymer blends, containing polystyrene-block-polybutadiene-block-polystyrene and polystyrene-block-polyisoprene-block-polystyrene rubber-based adhesives

Nano-tack (measured using AFM) and bulk-tack adhesive forces of blends of C60 and either polystyrene-block-polybutadiene-block-polystyrene (SBS) or polystyrene-block-polyisoprene-block-polystyrene (SIS) triblock copolymer pressure sensitive adhesives were measured after exposure to white light irradiation. The nano-tack adhesive forces in C60–SIS/SBS were found to decrease with increasing C60 concentration and exposure time, approaching the value for 100% polystyrene, providing an indication that significant surface hardening and crosslinking of the soft isoprene and butadiene phases occurs in the presence of C60. Films produced during the study were smooth, having low RMS surface roughness, and showed nanoscale phase separation between the soft (diene) and hard (styrene) segments. This phase separation disappeared after addition of C60 sensitizer and white light irradiation. Bulk adhesive measurements (tack and peel strength) showed a similar trend with C60 concentration and exposure time, and in irradiated systems containing as little as 0.2wt% C60, a significant decrease in adhesion was observed. Estimated Tg (measured using DMA, shear mode) of the soft-block shifts to higher temperatures (increasing by 30–40°C), and high gel fractions were obtained, indicating the presence of chemically crosslinked networks.

Effect of phenolic resin structure on the bonding properties of nitrile rubber-based adhesives

Three phenolic resins were used to study the effect of resin structure and its percentage content on the bonding properties of nitrile rubber-based adhesives. The phenolic resins studied are derived from phenol, resorcinol and para-t-butyl phenol, and are of novalac type. These resins were characterized by infra-red and thermal studies. Several formulations were prepared by varying the phenolic resin/nitrile rubber ratio and these formulations were tested for viscosity and bonding properties. At a given resin-to-rubber ratio, the viscosity for resorcinol-formaldehyde resin was higher than phenol-formaldehyde resin followed by para-t-butyl phenol-formaldehyde resin. The peel strength of nitrile rubber-based adhesive prepared from resorcinol-formaldehyde resin was higher than adhesives that from para-t-butyl phenol-formaldehyde resin followed by phenol-formaldehyde resin. The lap shear strength of nitrile rubber-based adhesive containing para-t-butyl phenol-formaldehyde resin was higher than of adhesives containing the other two resins. The trend observed in peel strength could be explained on the basis of hydrogen bonding between hydroxyl groups of phenolic resin (adhesive) and hydroxyl groups of the starch-coated canvas cloth (adherend), whereas the trend observed in lap shear strength could be explained on the basis of extent of linearity in the resin structure.

Carbon Black Reinforcement in Natural Rubber-Based Adhesives and Sealants

Carbon Black Reinforcement in Natural Rubber-Based Adhesives and Sealants