Resorcinol Formaldehyde Latex Research Articles

A novel one-step eco-friendly dipping system for PA66 fiber/rubber composites with excellent interfacial adhesion and its adhesion mechanism

Fiber-reinforced rubber composites (FRRC) are widely used in tires, hoses, conveyor belts and other fields. Currently, the industry heavily relies on the resorcinol-formaldehyde-latex (RFL) system to enhance interfacial adhesion performance of FRRC; however, both resorcinol (R) and formaldehyde (F) pose significant risks to human health and the environment. Thus, some two-step RF-free dipping systems have been developed to replace RFL system. Nevertheless, these complex two-step systems face challenges during industrialization. In this study, we proposed a novel one-step eco-friendly dipping system (PCGL) for polyamide66 (PA66)fibers. By using the new system, a solid transition bridge between PA66 fiber and rubber matrix can be formed, due to the bonding between PA66 and isocyanate, the interaction among polyacrylic acid resin, isocyanate and epoxy, the catalytic effect of triethanolamine, as well as the co-crosslinking of styrene-butadiene-vinyl-pyridine latex and rubber. The interfacial adhesion performance of PA66 fiber/rubber composites treated by PCGL with optimized ratio of epoxy groups/isocyanate groups can reach more than 90% of RFL level, meeting industry requirements for high interfacial bonding performance, while maintaining strength and safety of composites. The mechanism of largely enhanced interfacial adhesion was revealed through the analysis of modulus transition and co-crosslinking at the composite interface.

Improved adhesion of rubber composites by developing environmentally friendly fiber impregnation coatings with good interfacial modulus transition gradients

Polyester (PET) fibers must undergo impregnation with a resorcinol-formaldehyde-latex (RFL) solution to ensure efficient adhesion with rubber. However, the harmful, carcinogenic resorcinol-formaldehyde (RF) resin in RFL impregnation solution negatively affects human health. In this paper, PET was pretreated with blocked isocyanate and epoxy resins to activate the fibers, and a new environmentally friendly fiber impregnation coating was developed. In the new impregnation coatings, ethylene glycol diglycidyl ether (EGDE) and m-xylylenediamine (MXDA) were applied to replace the resorcinol and formaldehyde. Moreover, glycidyl methacrylate (GMA) containing epoxy groups and double bonds was introduced to enhance interaction with rubber further, and then styrene-butadiene-vinyl-pyridine (VP) latex was mixed. The results show that the peel strength of the impregnated PET/rubber composites with the new impregnation coatings can reach 14.0 N/mm, representing an increase of 30.8 % compared to that of the sample with the pure RFL impregnation coatings, whose peel strength is only 10.7 N/mm. Furthermore, the mechanism for enhancing the interfacial adhesive properties of PET/rubber composites was performed by analyzing the chemical composition and morphological changes of the impregnated PET surface, as well as the change of sulfur content at the interface of the impregnated PET/rubber composites and the transition gradient of interfacial modulus.

The role and mechanism of temporary blocked isocyanate at interface between polyethylene terephthalate high‐strength fibers and activation oil

AbstractIn this paper, activation oil added with temporary blocked isocyanate was chosen to enhance interfacial adhesion in polyethylene terephthalate (PET) high‐strength fibers reinforced rubber via one‐step dipping method, in which the temporary blocked isocyanate could be activated during vulcanization process of rubber. The effect of isocyanate in enhancing adhesion between PET high‐strength fibers and rubber was explored. The amount of residual resorcinol formaldehyde latex on the surface of fibers and H‐extraction force of PET high‐strength fibers reinforced rubber are both obviously increased with 5% activation oil addition especially containing 2% isocyanate. After peeling fibers from composite rubber, the amount of residual rubber on the surface of fibers with activation oil is increased, which is even higher when further adding temporary blocked isocyanate. Based on the results of infrared spectra and nuclear magnetic resonance carbon spectra, the added isocyanate is confirmed to bond with the PET component most likely through reacting with the terminal hydroxyl groups on the surface of PET fibers. This interface reinforcement strategy based on one‐step dipping method will contribute to studies on PET high‐strength fibers reinforced rubber.

Plasma-assisted surface functionalization of UHMWPE fiber for adhesion improvement with rubber matrix

A plasma-assisted surface modification method was introduced to enhance the interfacial adhesion of rubber composites reinforced with ultra-high molecular weight polyethylene (UHMWPE) fibers. First various reactive monomers were grafted onto the fiber surface via a plasma-assisted radical polymerization reaction. Subsequently, the grafted fibers underwent RFL (resorcinol-formaldehyde-latex) dipping process to bolster their interfacial adhesion with rubber. Compared with the original UHMWPE fibers, the modified fiber-reinforced rubber composites showed an increase in H pull-out force by 105.3 %–165.7 N and peel strength by 145.2 % to 10.3 N/mm, reaching the level of general-purpose fabric-core conveyor belt (≥4.5 N/mm). After the modification, the dynamic fatigue life and aging stability of the fiber-reinforced rubber composites were significantly improved, thereby enhancing the service life and safety of the composites. The results show that this method greatly improves the chemical activity, hydrophilicity, and surface roughness of UHMWPE fibers with minimal damage, rendering it a promising choice for industrial applications.

Nylon 66 fibers coated with environmentally friendly dopamine‐modified adhesives and their interfacial adhesion with neoprene rubber

AbstractConsidering the toxicity of traditional resorcinol‐formaldehyde‐latex (RFL) dipping solution used to prepare fiber‐ reinforced rubber composites, a novel eco‐friendly dopamine (DA)‐supported dipping system was developed in this study. Based on the interactions between DA, glycerol triglycidyl ether (GTE), and m‐xylylenediamine (MXDA), the dipping solution successfully coated the surface of the nylon‐66 (PA66), and the resulting GTE/DA/MXDA/latex‐treated PA66 (PA66‐GDML) possessed better thermal stability than untreated PA66. The interfacial adhesion between PA66 and neoprene was significantly improved by using the appropriate interfacial layer and the synergistic effect during co‐vulcanization. The adhesive strength between PA66‐GDML and neoprene was comparable to that obtained in an RFL system, especially when the ratio of GTE/DA/MXDA was 5:1:2.Highlights An eco‐friendly dopamine‐supported dipping system was developed. The dipping solution (GTE/DA/MXDA) could successfully coat nylon 66 fibers. Treated nylon 66 possessed better thermal stability than untreated nylon 66. The adhesive strength was comparable to that obtained in a RFL system. The new dipping system shows great potential to replace RFL system.

Effect of Micromolecules and Macromolecules on the Environmentally Friendly Impregnation Solution for High-Performance Rubber Composites Compared with Traditional RFL Impregnation

In this paper, a novel resorcinol-formaldehyde-free and environmentally friendly adhesives for polyester (PET) fiber impregnation treatment were compounded successfully. First, a network structure was formed by reacting micromolecular and water-soluble glycerol triglycidyl ether (GLTE) and triethylenetetramine (TETA). Then, this was mixed with latex in order to prepare an impregnation solution glycerol triglycidyl ether-triethylenetetramine-butyropyridine latex system (GTL), which can replace the toxic components (resorcinol and formaldehyde) of the resorcinol-formaldehyde-latex (RFL) impregnation system. Similarly, the macromolecular epoxy resin E-51-triethylenetetramine-butyropyridine latex system (ETL) and the traditional RFL impregnation system were also prepared in order to compare with the GTL. Further, the reaction conditions of the impregnation system, the surface chemical composition and interfacial properties were characterized by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and peeling strength, respectively. The results showed that the peeling adhesion performance between the GTL-modified PET fabric and the rubber (38.5% higher than that of the ETL impregnation solution) was comparable to that of the RFL impregnation system because of micromolecular and more active GLTE. This study provides new insights into the interface design of PET/rubber composites and will facilitate the development of PET/rubber composites.

Highly Strong Interface Adhesion of Polyester Fiber Rubber Composite via Fiber Surface Modification by Meta-Cresol/Formaldehyde Latex Dipping Emulsion

As a skeleton material, polyester (PET) fiber can significantly improve the strength and durability of rubber composites, but the interfacial adhesion between polyester fiber and rubber is poor due to the chemical inertia of PET fiber surface. Resorcinol-formaldehyde-latex (RFL) impregnating solution is usually used to treat PET fibers, but RFL contains toxic components such as resorcinol, which is harmful to the human body. A simple and less toxic resin-impregnating system cresol-formaldehyde-latex (CFL) was obtained by alternating resorcinol with low-toxicity cresol and m-cresol formaldehyde resin was synthesized from m-cresol and formaldehyde. CFL (m-cresol formaldehyde resin latex) systems with different C/F mole ratios and CF resin/latex ratios were adopted to modify the surface of PET fibers. The strip peeling adhesive and the H pull-out test results indicated that the PET fiber/rubber adhesion strength increased with the increase in the formaldehyde dosage and the CF resin content, and the peeling force value and the H-pull-out force of treated PET/rubber composites reached 7.3 N/piece and 56.8 N, respectively. The optimal choice of CFL adhesive system was obtained, when the C/F mole ratio was 1/2 and the CF resin/latex weight ratio was 0.23. This environment-friendly CFL dipping emulsion can be used as a new surface modification strategy as it can remarkably enhance the interfacial adhesion of PET/rubber composites.

Nanoscale analysis of the interface of dip layer/rubber in fiber/rubber composites

The reaction mechanism and the interfacial modulus gradient of the interfacial transition layer between the environmentally friendly dipping system (PAL) and the rubber have not been fully studied. In order to better understand the chemical structures and nano-mechanical properties of the interface between the dip layer and the rubber, we used advanced atomic force microscope (AFM) and nanoscale Fourier transform infrared spectroscopy (nano-FTIR) to perform detailed analysis in this article. The characterization of interfacial nano-mechanical properties and chemical structures is very significant for the illustration of interfacial adhesion mechanism. AFM can effectively characterize the detailed interfacial modulus gradient and the thickness of interface, while nano-FTIR can comprehensively measure the interfacial chemical structures and the distribution of chemical bonds. The results suggest that the thickness of the interface between the PAL dip layer and the rubber matrix is 175 nm, and the crosslinking density of the interfacial layer is high, which explains that the failure location of fiber/rubber composites after pull-out tests occurs on the side of the rubber matrix. Similarly, the microstructure of resorcinol-formaldehyde-latex (RFL) system was also characterized, and the preparation of RFL usually requires carcinogenic and toxic substances such as formaldehyde and resorcinol.

A Facile Way to Modify Polyester Fabric to Enhance the Adhesion Behavior to Rubber

Due to the extremely inert surface of polyester (PET) fabric, a toxic and traditional resorcinol-formaldehyde-latex (RFL) dipping solution is always necessary in the rubber composite industry. Unfortunately, other effective methods for fabric surface treatment are in urgent need to improve the poor bonding interface between the fabric and the rubber matrix. In our study, a facile way to modify PET fabric was developed. Specifically, the fabric was treated by an alkaline solution and a coupling agent with magnetic agitation. Afterwards, the treated fabric/rubber composites were prepared through a co-vulcanization process. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and thermogravimetric analysis (TGA) were used to characterize the surface chemical composition of the modified fabrics. The adhesion behavior was analyzed by the peel test. The results showed that the fabric surface was successfully grafted with a coupling agent, and the peel strength reached 9.8 N/mm after KH550 treatment, which was an increase if 32% compared with that of the original fabric/rubber composite. In addition, the vulcanization rate and interfacial fracture mechanism are also researched.

Thermally induced structural changes of resorcinol formaldehyde latex adhesive used in cord-rubber composites

In this study, the accelerated thermal exposure of resorcinol formaldehyde latex (RFL) adhesive used in cord rubber composites was investigated. In particular, the structural changes of the RFL with and without curatives (sulfur, zinc oxide, accelerator and stearic acid) during thermal treatment at 100 °C were identified by a multiscale approach using dynamic mechanical analysis (DMA), atomic force microscopy (AFM), and solid-state nuclear magnetic resonance (ssNMR). The RFL samples with curatives show an approximately four-fold increase in the overall elastic modulus at room temperature during thermal treatment of up to 10 days. At the same time, DMA results indicated an increase of Tg of the latex phase from −39 °C to −3 °C. However, for the RFL samples without curatives, there was no change in the Tg of the latex phase. At the nanoscale, AFM mappings on samples with curatives have also confirmed an increase in the nanoscale modulus in the latex phase (50 ± 10 MPa to 140 ± 20 MPa) and in the RF resin phase (330 ± 100 MPa to 620 ± 200 MPa) for the same thermal treatment duration. Finally, solid-state NMR analysis showed a decrease in the intensity of the vinyl groups (noted at 115 ppm and 145 ppm) in the latex phase indicating the possibility of further sulfur cross-linking during the 10 days of thermal treatment for samples containing curatives. Our studies have highlighted the prominent role of the curatives in the RFL adhesive, as well as its initial structure and evolution during thermal treatment. Accordingly, the RFL structure was drastically modified by the accelerated thermal exposure.

Towards robust synchronous belts: influence of surface characteristics on interfacial adhesion

ABSTRACT The use of carbon fibres is being explored in synchronous belts due to their excellent mechanical properties, chemical and dimensional stability. However, poor adhesion between fibres and the common rubber-fibre adhesive resorcinol-formaldehyde-latex (RFL) compromises load transfer between these constituents. We examined the influence of surface characteristics of commercial glass and carbon fibres, such as fibre surface chemistry, energy and area on carbon fibre-RFL matrix adhesion in model single fibre composites. Fibres with higher surface oxygen content and thus more polar functional groups resulting in a higher surface energy exhibited better adhesion to RFL. Fibre adhesion behaviour to RFL can be ranked using the aspect ratio of the fibre diameter to the critical fragment length as assessed by single fibre fragmentation tests, however, accurate interfacial shear strength values cannot be obtained using the Kelly-Tyson model due to statistical limitations in the treatment of single fibre tensile properties. Our results provide insight into factors affecting fibre-RFL adhesion and identified commercial T700GC-31E carbon fibres as candidates for improved fibre-matrix adhesion for the production of more robust synchronous belts.

Effect of Vulcanization Process Parameters on the Tensile Strength of Carcass of Textile-Rubber Reinforced Conveyor Belts.

Textile-reinforced conveyor belts are most widely used in various industries, including in the mining, construction, and manufacturing industries, to transport materials from one place to another. The conveyor belt’s tensile strength, which primarily relies on the property of the carcass, determines the area of application of the belt. The main aim of the current work was to investigate the influence of vulcanization temperature and duration of the vulcanization process on the tensile properties of the carcass part of the conveyor belt. An extensive experiment was carried out on the tensile properties of woven fabrics that were intended to reinforce conveyor belts by aging the fabrics at the temperature of 140 °C, 160 °C, and 220 °C for six and thirty-five minutes of aging durations. Afterward, the textile-reinforced conveyor belts were produced at vulcanization temperatures of 140 °C, 160 °C, and 220 °C for six and thirty-five minutes of vulcanizing durations. The influence of the vulcanization process parameters on the tensile property of fabrics utilized for the reinforcement of the conveyor belt was analyzed. In addition, the effect of the dipping process of woven fabric in resorcinol–formaldehyde–latex on the tensile property of polyester/polyamide 66 woven fabric (EP fabric) was investigated. The investigation results revealed that the tensile strength of the carcass of the conveyor belt was significantly affected by vulcanization temperature. The conveyor belt vulcanized at 160 °C for 35 min has shown the optimum tensile strength, which is 2.22% and 89.06% higher than the samples vulcanized at 140 °C and 220 °C for 35 min, respectively. Furthermore, the tensile strength and percentage elongation at break of conveyor belts vulcanized at 220 °C were almost destroyed regardless of the vulcanization duration.

Effect Of Liquid Rubbers On The Thermal And Adhesion Properties Of The Tire Skim Compound

Polymeric textile cords, steel cords and steel cables are mainly reinforcing materials that are used in tire production. Polymeric textile cords such as Polyester (PEs), Nylon, Aramid and Rayon are commonly treated with bi-functional resorcinol formaldehyde latex (RFL) to obtain desired adhesion to rubber matrix. PEs cords are known as their poor adhesion to both RFL and rubber compounds due to limited reactivity on the surface and poor reaction extent between methylol and hydroxyl groups of RFL. Increasing carboxyl content on PEs surface or in the rubber compound is one of the best strategies to overcome this adhesion problem. Liquid rubbers, which can co-vulcanize with solid rubbers, are also strong alternatives of process oils with their excellent plasticizing effect without deterioration in mechanical properties of the resulting material. Co-vulcanization also improves the stability of this additive and prevents possible bleeding and migration during service life of the tire. In this study, carboxylated grafted liquid isoprene rubber has been incorporated to rubber compound to improve adhesion in PEs-RFL-Rubber ternary system. Rheological and dynamic-mechanical properties of reactive liquid rubber containing tire rubber compounds have been evaluated extensively, as well as H-adhesion behaviour of PEs cord-rubber composite matrix.

Plasma Enhanced-Chemical Vapor Deposition of 2-Isopropenyl-2-Oxazoline to Promote the Adhesion between a Polyethylene Terephthalate Monofilament and the Rubber in a Tire

A Plasma-Enhanced Chemical Vapor Deposition was chosen in order to deposit an organic thin film on polyethylene terephthalate monofilament to increase its adhesion with the rubber compound in a tire. The aim of the work is to find an alternative “green” method to the classical chemical dipping with Resorcinol Formaldehyde Latex: plasma treatments are environmentally friendly and easy to use. 2-isoprepenyl-2-oxazoline (2-iox) was employed as precursor and the treatments were performed in a vacuum system, both in a continuous regime and a pulsed regime. Initially, the coatings were deposited on polyethylene terephthalate sheets to study the wettability (by the measurement of contact angle) and the thickness (by profilometer) of the plasma polymer. The chemical characterization was investigated by Infrared and X-ray Photoelectron spectroscopies. Finally, the adhesion of the polyethylene terephthalate sheets was measured by Peel Test, using the coating as adhesive and as a pre-dip. The measurement of the peel force made it possible to optimize the plasma parameters that were applied on the monofilament. The adhesion was estimated by the measure of the extraction force and the evaluation of the coverage compared with those of the classical chemical treatment Resorcinol Formaldehyde Latex.

The outstanding interfacial adhesion between acrylo-POSS/natural rubber composites and polyamide-based cords: ‘An environmentally friendly alternative to resorcinol-formaldehyde latex coating’

Resorcinol formaldehyde latex (RFL) dipping system, very effective to enhance adhesion between rubber and cords in the tire industry, has substantial health & environmental (i.e., toxicity) and commercial (i.e., being time-consuming and expensive) negative effects. The present work eliminates these disadvantages, and more importantly reports much better adhesions between natural rubber (NR) and textile cords than RFL itself by proposing Acrylo-polyhedral oligomeric silsesquioxane (A-POSS), a new generation reactive hybrid nanoparticle. The H-adhesion forces between A-POSS/NR and virgin Nylon 6.6 cord highly increased to 123.0 N whereas the same forces between NR and RFL coated Nylon 6.6 was only 95.8 N. A thin layer of NR/A-POSS on the surface of Nylon 6.6 cords in SEM images confirmed a good interfacial H-adhesion between the Nylon 6.6 cord and NR/A-POSS even at the low A-POSS loadings. In addition, higher work of adhesion between NR/A-POSS and virgin Aramid than that of between NR and virgin Aramid was obtained. The strong adhesion between NR and polyamide cords in the presence of A-POSS was revealed by FTIR and NMR analyses. A-POSS/NR provided enhanced thermal stability, crosslinking density, and mechanical properties. Moreover, the tan δ value was reduced by ~9% for NR/A-POSS composites compared to the NR skim composite indicating better dynamic performance for a moving tire. Overall, it was concluded that the use of A-POSS nanoparticles in NR composites can be alternative to RFL dipping method currently being used in the tire industry due to enhanced adhesion between rubber composites and the polyamide cords.

Multiscale characterization of the interfacial region in flexible rubber composites: Initial structure and evolution upon thermal treatment

To investigate the structural changes upon thermal treatment of resorcinol–formaldehyde–latex (RFL) interfacial layer in a rubber-cord flexible composite, a multiscale approach was employed. High-resolution AFM mapping showed a significant increase in the modulus of the (RF) phase from 1.2 GPa to 2.3 GPa and in the latex phase (L) from 0.3 GPa to 0.8 GPa after thermal exposure at 100 °C for 10 days. The increase of the RF and L phase elastic modulus was correlated with the increase of oxygen content in the RFL layer based on SEM-EDX measurements. Furthermore, by combining finite element simulations and AFM modulus profiling, the presence of an interphase region (over 280 nm) between the RFL and the rubber regions was identified and did not deteriorate after the thermal treatment. Peel adhesion testing revealed that the increase of RF and L phase rigidity after thermal treatment was detrimental to the interfacial adhesion of the rubber composite.

Improving adhesion between polyester cord and rubber by using glycidyl‐POSS

AbstractPoly(ethylene terephthalate) (PET) cords are usually coated with epoxy and/or isocyanate solutions (like methylene diphenyl diisocyanate [MDI]) before resorcinol‐formaldehyde‐latex (RFL) to increase the adhesion efficiency of RFL. In this article, the addition of glycidyl polyhedral oligomeric silsesquioxane (GPOSS) as an adhesion promoter to PET cord was investigated for reinforcing PET cord/rubber interfacial adhesion. Therefore, GPOSS treated PET cords (GPOSS + MDI + RFL) were prepared in different process conditions like different GPOSS ratios and oven curing times and then vulcanized with rubber. RFL, GPOSS + RFL, MDI + RFL, and commercial epoxies treated PET cord samples were also prepared for comparison with GPOSS+MDI + RFL treated PET cord. The thermal, mechanical, and morphological properties of the treated PET yarn and their composites with rubber were investigated. It was seen that in the GPOSS coated PET yarns increased the stiffness and no change was observed in the tensile strength of the PET yarns. It was determined that the utilization of GPOSS in the PET cord improved the adhesion of the cord to rubber when compared with other treated PET cords via H‐adhesion and strip peel adhesion tests. Especially, since adhesion values give better results than commercially used epoxies, GPOSS as an adhesion promoter can be recommended in the rubber industry.

Polyester (PET) fabrics coated with environmentally friendly adhesive and its interface structure and adhesive properties with rubber

Due to the chemical inertness of the polyester (PET) fiber surface, it often needs to be immersed in a traditional resorcinol-formaldehyde-latex (RFL) dipping solution before it can be used in rubber composite. However, the RFL dipping system contains toxic components, resorcinol and formaldehyde, and is gradually banned. In this article, a novel resorcinol-formaldehyde-free environmentally friendly adhesion promoter for dipping treatment of PET fiber was synthesized. Specifically, water soluble ethylene glycol diglycidyl ether (EGDE) and diethylenetriamine (DETA) were introduced into the new dipping solution to replace the toxic ingredients of resorcinol and formaldehyde in RFL dipping system. We use polyester fabrics to study the effects of reaction conditions, chemical structures and interfacial adhesion mechanism on the treatment results to achieve the level of conventional RFL treatment. The surface chemical compositions of modified PET fabrics were characterized by attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The results showed that the fabric surface was successfully coated with the dipping layer. In addition, interfacial adhesive properties between modified PET fabrics and rubber were studied. The results showed that the peel adhesive strength between the modified PET fabric and the rubber was 17 N/mm, which was comparable to the RFL dipping system.

Effects of fiber content and resorcinol‐formaldehyde‐latex treatment on composite properties of acrylonitrile‐butadiene rubber reinforced with chopped aramid fibers

AbstractThis paper investigated the effects of the fiber content and the resorcinol‐formaldehyde‐latex (RFL) treatment on characteristics and properties of the aramid fiber (AF)/acrylonitrile‐butadiene rubber (NBR) composites. The relationship between the AF/rubber matrix connection and the mechanical properties/wear resistance of the composites was the main focus. Results showed that the RFL treatment on the AFs significantly increased the elongation at break of the composites via improving the interfacial connection. However, samples with high untreated‐AF content showed the highest tensile strength due to the formation of fiber network during stretching. Moreover, the flexible RFL layer was not conducive to the tear strength of the composites. Furthermore, the addition of the AFs significantly improved the wear resistance of the NBR composites via enhancing the hardness and the tear strength, and the RFL coating was effective in further decreasing the wear rate under low load condition via improving the AF/NBR interaction. Under 20 N load condition, the specific wear rate of the composite with 15‐parts per hundred of rubber (phr)coated AFs was 90% and 40% lower than that of the NBR composites without AF and with 15‐phr untreated AFs, respectively.

Factors influencing resorcinol–formaldehyde–latex‐coated continuous basalt fiber cord/rubber interfacial fatigue behavior: Loading direction and RFL formula

ABSTRACTIn this study, samples were prepared with resorcinol–formaldehyde–latex (RFL)‐coated continuous basalt fiber (CBF) cords and a natural rubber (NR)/styrene–butadiene rubber (SBR) matrix for interfacial fatigue tests under periodic radial loading conducted using a De Mattia Rubber Flexometer. The effects of the RFL formula on the interfacial fatigue behavior, including the fatigue life and the evolution of residual adhesion strength, were the focus of this work. The fatigue behavior was compared with that under axial loading. The results showed that under radial loading, the residual adhesion strength of the samples remained higher than that under axial loading, and the evolution of adhesion was divided into three stages. The adhesion improvement in the second stage was due to further cocrosslinking between the rubber matrix and the latex in the RFL layer, and the duration of the second stage was determined by the amount of reactive latex in the RFL layer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46619.