Resin Layer Research Articles

A Study on a New Type of High-Performance Resin-Coated Sand for Petroleum Fracturing Proppants

This study investigates a new type of high-performance coated sand as a petroleum fracturing proppant material. Modified quartz sand was coated with a layer of low-density resin to reduce the overall density of the proppant, thereby improving the suspension of the proppant in the fracturing fluid. Resins play an important role in the preparation of coated sand fracturing proppants. The mechanism of sand formation was studied by examining the phase composition and microstructure of the coated sand proppant. The results demonstrate that when the polyimide resin content is 6% and the curing temperature is 180 °C, the proppant exhibited the best performance with an apparent density of 1.592 g/cm3 and a breakage ratio of only 3.22% under 55.2 MPa. Compared with the widely used epoxy resin-coated support agent and phenolic resin-coated support agent in the early stage, their crushing rate decreased by 5% and their acid solubility decreased by 2%. Hence, this study is worthy of attention.

A novel technique for CAD-CAM assisted digital ocular prosthesis.

There are various techniques available for constructing a custom ocular prosthesis. The present technique report describes a digital workflow for constructing an ocular prosthesis using computed tomography integrated with digital technologies. The outer region of the healthy eyeball was segmented to produce the top surface of the prosthesis, while the contour and bottom surface were segmented from the tissue bed of the anophthalmic socket. The iris position was determined by tracing the optical nerve and confirmed by superimposing the patient's facial scan onto the soft tissue model of the computed tomography. Using these parameters, a standard tessellation language file for the ocular prosthesis was generated and 3D printed. The iris was then printed via UV technology using digital photographs of the patient's contralateral eye; characterization of the sclera and the final layer of clear acrylic resin were done conventionally.

Finite Element Modeling of a Biological Composite Structure Used in Orthodontic Fixed Appliances

AbstractComposite structures currently represent combinations of materials from the most different structures, chemical compositions, or geometric shapes. There is no scientific or technical field in which these materials, due to their special characteristic properties, are not present. Most of the time it is found that they cannot even be replaced. In this sense, the study presented in this work refers to the behavior of a semibiological structure. This structure is found in the field of dentistry when using fixed dental appliances. The composite structure refers to the metal bracket that is fixed by a bonding and a resin layers that are considered as adhesives to the outer surface of the tooth, i.e., to the enamel that is a biological material. In order to make a prediction of the behavior of structure during the mastication process from the point of view of the displacements and the state of tension, study starts from the practical realization of a joint by gluing the bracket on the surface of a devitalized tooth. Based on it, modeling using the finite element method allows the prediction of masticatory forces based on the analysis of stress states and displacements.

An ultrasonic phantom for cortical and cancellous bone

There is interest in developing ultrasonic techniques for diagnosing osteoporosis. Many techniques perform measurements at skeletal sites such as the heel, hip, and spine where the bone tissue consists of a non-porous outer layer of cortical bone that surrounds a porous interior region of cancellous bone. The goal of the present study was to develop an ultrasonic phantom that simulates this tissue configuration. A block of polymer open cell rigid foam (OCRF) was partially embedded in a thin layer of clear epoxy casting resin to create the phantoms. The resulting phantoms were 40mm × 40 mm × 20 mm with one 40 mm × 40 mm face embedded in ∼3mm of resin. Ultrasonic measurements were performed to characterize the speed of sound and attenuation of the resin and the OCRF separately and together, as configured in the phantom. Backscatter measurements were also performed. The resulting specimens can be used to investigate how non-normal incidence of an ultrasonic wave on the bone cortex may produce errors in these measurements.

An investigation to compare the shear strength of the adhesive joint of unidirectional CFRP after KrF excimer laser treatment in normal atmosphere, argon and underwater environments

Unidirectional CFRP was treated by KrF laser in normal atmosphere, argon and underwater environments, before adhesive bonding. KrF laser removed the top resin layer and exposed the carbon fibres. Porosity and holes were generated around exposed carbon fibres after argon environment treatments and flakes-like-surface-structure was generated after underwater treatments with two-step method. KrF laser treatments increased Sq and Sdr values. Sdr was more influential for adhesive joint shear strength. These laser treatments in all environments transformed secondary and tertiary aliphatic amines to primary and secondary aliphatic amines, respectively. SLSS study confirmed that the highest shear strength of 35.78 MPa which was 45% higher than the untreated joint, was achieved after underwater treatment. Normal atmosphere and argon environment treatments resulted in 31.74 and 31.95 MPa, respectively. Adhesive failure which occurred after argon environment treatments, reduced after normal atmosphere treatments. Underwater treatments resulted in cohesive failure and thin layer cohesive failure.

Self-Healing Coatings Consisting of an Outer Electrodeposited Epoxy Resin Layer and an Inner Porous Anodic Oxide Layer with Healing Agents for the Corrosion Protection of Al Alloys

Recently, new surface treatments for the corrosion protection of Al alloys by forming self-healing layers have attracted the attention of many researchers. The authors of this paper have previously developed self-healing polyurethane coatings with micro-capsules containing healing agents and porous anodic oxide films filled with healing agents. In this study, self-healing coatings consisting of an outer electrodeposited epoxy resin layer and an inner porous anodic oxide layer with healing agents were developed for the corrosion protection of Al alloys. The corrosion protection abilities of the self-healing coating were shown in Cu2+/Cl− solutions after damaging with indenters and were affected by freezing treatments and the tip angles of the indenter.

Experimental analysis of the quasi-static penetration test on fiber metal laminated plate reinforced by nano-silica

FMLs are lightweight hybrid materials that possess specific static properties, impact resistance, fracture resistance, and fatigue resistance. These characteristics make FMLs highly desirable for various applications in the transportation industry (Hu et al., 2015 Dec 1) [2].The present study aims to scrutinize the energy absorption and strength characteristics of a kind of Fiber Metal Laminate (FML) reinforced with Nano silica (0, 0.3, 0.6, and 0.9 wt %) that is fabricated from braided fiberglass and carbon fiber sleeve and aluminum 2024-T3. Sleeve-type braided fiberglass, carbon fiber and highly adhesive resin were introduced as interlayers. The arrangement of FMLs layers was in 2 types, first AL/Glass/Glass/Glass/Glass/AL and second AL/Glass/Carbon/Carbon/Glass/AL. The produced FMLs were tested to evaluate the behavior and strength characteristics under quasi-static indention. Quasi-static indentation test performed with spherical head penetrators at a 5 mm/min rate. The experiment continued until the indenter fully penetrated the specimen. These FMLs crushed progressively and are unlikely to fail under catastrophic failure, although specimens with 0.6% Nano silica in glass fiber and specimens with 0.3% in the glass and carbon fiber have better performance. A comparison of the results of glass FMLs with hybrid FMLs shows that Nano silica-reinforced glass fibers have achieved better results than hybrid fiber. To study the structure of amplified FMLs, electron microscopy (SEM) imaging was used which showed that in FMLs with better results, Nano silica was evenly distributed on the layer of epoxy resin. The results also indicate that the mechanical performance of a new FML has a good potential to be applied as a new and efficient energy absorber.

Rapid vat photopolymerization through a superamphiphobic interface

ABSTRACT Vat photopolymerization (VPP) is one of the convenient methods to create high-precision parts; however, due to the significant adhesion between the cured layer of the photopolymer resin and the release film, the currently prevalent VPP equipment is less productive and thus challenging in achieving production on a large scale. To tackle the issues above, a facile method is utilised to produce a transparent film capable of effectively resisting the photopolymer resin. Such film is achieved by incorporating micron-nanometre layered rough features and low surface energy materials onto the surface of quartz glass. It allows innovative applications in speedy VPP processes, achieving a printing speed of up to 323 mm/h in an LCD (Liquid Crystal Display) 3D printer while maintaining sound accuracy, exceptional durability and fair applicability, thanks to the features of the prepared film. The presented approach provides new perspectives into the production and application of VPP technology.

Study on the properties of C-S-H/epoxy nanocomposite structure doped with silica nanoparticles

Nano-SiO2 can promote cement hydration, and it is important to study the effect of nano-doping technology on the microstructure of C-S-H/epoxy resin to improve the performance of epoxy resin cement materials. In this paper, the coupling agent (kh550) molecules were grafted on the surface of nano-SiO2, and the nano-SiO2-modified epoxy resin with different grafting rates was modeled and compounded with C-S-H. The structural properties and interfacial interaction mechanism were discussed utilizing molecular dynamics (MD) simulations. The results show that: nano-SiO2 doping into epoxy resin can increase its atomic surface area, reduce the porosity and thus enhance the stiffness of the composite, and the mechanical properties are best at a surface grafting rate of 15%; with the increase of nano-SiO2 doping and cross-linking degree, the amorphous characteristics of the composite structure are reduced and the crystalline structure of C-S-H in molecular motion is optimized. At the same time, the spacing between the C-S-H layer and epoxy resin layer in the composite structure is reduced, and the interfacial binding energy is increased; due to the improved adsorption performance, the diffusion rate of Ca ions between the C-S-H and epoxy resin layers is enhanced, this phenomenon facilitates the production of hydration products.

Experimental investigation of cutting performance for circular saw blade body modification by resin layers toward green manufacturing

Experimental investigation of cutting performance for circular saw blade body modification by resin layers toward green manufacturing

Digital light processing 3D printing for microfluidic chips with enhanced resolution via dosing- and zoning-controlled vat photopolymerization

Conventional manufacturing techniques to fabricate microfluidic chips, such as soft lithography and hot embossing process, have limitations that include difficulty in preparing multiple-layered structures, cost- and labor-consuming fabrication process, and low productivity. Digital light processing (DLP) technology has recently emerged as a cost-efficient microfabrication approach for the 3D printing of microfluidic chips; however, the fabrication resolution for microchannels is still limited to sub-100 microns at best. Here, we developed an innovative DLP printing strategy for high resolution and scalable microchannel fabrication by dosing- and zoning-controlled vat photopolymerization (DZC-VPP). Specifically, we proposed a modified mathematical model to precisely predict the accumulated UV irradiance for resin photopolymerization, thereby providing guidance for the fabrication of microchannels with enhanced resolution. By fine-tuning the printing parameters, including optical irradiance, exposure time, projection region, and step distance, we can precisely tailor the penetration irradiance stemming from the photopolymerization of the neighboring resin layers, thereby preventing channel blockage due to UV overexposure or compromised bonding stability owing to insufficient resin curing. Remarkably, this strategy can allow the preparation of microchannels with cross-sectional dimensions of 20 μm × 20 μm using a commercial printer with a pixel size of 10 μm × 10 μm; this is significantly higher resolution than previous reports. In addition, this method can enable the scalable and biocompatible fabrication of microfluidic drop-maker units that can be used for cell encapsulation. In general, the current DZC-VPP method can enable major advances in precise and scalable microchannel fabrication and represents a significant step forward for widespread applications of microfluidics-based techniques in biomedical fields.

Ultrasonic evaluation of ply and interleaf layer properties of interleaved composite laminates

An ultrasonic nondestructive evaluation procedure is presented for the ply and interleaf layer properties of carbon/epoxy composite laminates having interleaf resin layers at their interlaminar interfaces. It is shown that the material properties of plies (density, thickness, and transversely isotropic complex elastic moduli) and elastic interleaf layers (density, thickness, Young’s modulus, and Poisson’s ratio) can be identified by best fitting the theoretical energy transmission spectra of longitudinal waves through the laminate immersed in water to those obtained in ultrasonic measurement. It is also demonstrated that compared to the mass-less and null-thickness spring-type interlaminar interface model employed in the previous works, the present finite-thickness interleaf layer model can better reproduce the experimental transmission spectra of a unidirectional interleaved composite laminate containing ultrasonic bandgaps. Furthermore, the property characterization in the case where the plies and interleaf layers are assumed to be elastic and viscoelastic, respectively, is also examined. It is also shown that the ply and interleaf layer properties determined for the unidirectional laminate can be used to reproduce the transmission spectra measured for a quasi-isotropic laminate consisting of the same plies and interleaf layers.

Design of an anticorrosion/bactericidal dual functional organic coating based on the slippery liquid-infused porous surface

In this work, a long-lasting slippery liquid-infused porous surface (SLIPS) was fabricated on an organic coating to achieve both anticorrosion and antibacterial functions. Phenyl-modified etched basalt (PEB) scales were produced to construct micro-nano capillary structures and generate π electrons, which facilitated the retention of lubricant on the surface when assembled onto an epoxy resin layer. Plant oil was selected as a lubricant to introduce numerous –COOH, and was robustly trapped on the surface by π-COOH interactions, which enhanced the durability of the SLIPS coating. Based on the electrochemical tests, the coating displayed superior anticorrosion performance with |Z|0.01Hz values of 1.99 × 1010 Ω·cm2 after 14 days of immersion, which benefited from excellent barrier effect and liquid repellency. The zeta potential result proved that the corrosion resistance of SLIPS coating was further improved by the electrostatic repulsion. In addition, the antibacterial experiment results demonstrated only 0.32% of biofilm coverage and no live bacteria after 3 days of immersion, which implied the dual mechanisms of SLIPS coating in killing bacteria and inhibiting bacterial adhesion. The SLIPS coating with excellent lubricant retention and promising anticorrosion/bactericidal performance possesses tremendous application potential in marine protection.

Investigation of mechanical and viscoelastic properties of Agave cantala fiber-reinforced green composites for structural applications

This study explored using cellulosic plant fibers as composite-reinforcing materials for structural applications. Specifically, a green composite material was created using Agave cantala fiber (ACF) and an epoxy matrix with weight fractions ranging from 30% to 60%. The laminates were fabricated using a compression molding technique, which involved alternating layers of resin and fibers on a flat mold. The fibers were uniformly aligned, and the resin was layered over them. The mold was then covered with polyethylene film to ensure that voids were minimized, and the mold was compressed for 12 h at ambient temperature. Four different samples were created by varying the fiber and resin weight percentages, with ACF30 containing 30% fiber and 70% resin, ACF40 containing 40% fiber and 60% resin, ACF50 containing 50% fiber and 50% resin, and ACF60 containing 60% fiber and 40% resin. The resulting composites were characterized to investigate their mechanical properties and it was found that the 40% ACF laminates had the maximum tensile, flexural, and compressive moduli and strengths. Additionally, viscoelastic characteristics were evaluated, and the 40% ACF composite demonstrated the highest storage and loss moduli. Scanning electron microscopy was also used to interpret the interface between the fibers and the matrix at the fracture surfaces. These findings suggest that cellulosic plant fibers have the potential as reinforcement materials for creating high-performance composites.

Interfaces in reinforced epoxy resins: from molecular scale understanding towards mechanical properties

ContextWe report on atomic level of detail analyses of polymer composite models featuring epoxy resin interfaces to silica, iron oxide, and cellulose layers. Using “reactive” molecular dynamics simulations to explore epoxy network formation, resin hardening is investigated in an unprejudiced manner. This allows the detailed characterization of salt-bridges and hydrogen bonds at the interfaces. Moreover, our sandwich-type composite systems are subjected to tensile testing along the interface normal. To elucidate the role of relaxation processes, we contrast (i) direct dissociation of the epoxy-metal oxide/cellulose contact layer, (ii) constant strain-rate molecular dynamics studies featuring (visco-)elastic deformation and bond rupture of the epoxy resin, and (iii) extrapolated relaxation dynamics mimicking quasi-static conditions. While the fracture mechanism is clearly identified as interface dissociation of the composite constituents, we still find damaging of the nearby polymer phase. The observed plastic deformation and local cavitation are rationalized from the comparably large stress required for the dissociation of salt-bridges, hydrogen bonds, and van der Waals contacts. Indeed, the delamination of the contact layers of epoxy resins with slabs of silica, magnetite, and cellulose call for a maximum stress of 33, 26, and 21 MPa, respectively, as compared to 84 MPa required for bulk epoxy yielding.MethodsMolecular dynamics simulations using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code were augmented by a Monte Carlo–type procedure to probe epoxy bond formation (Macromolecules 53(22): 9698–9705). The underlying interaction models are split into conventional Generalized Amber Force Fields (GAFF) for non-reacting moieties and a recently developed reactive molecular mechanics potential enabling epoxy bond formation and cleavage (ACS Polymers Au 1(3): 165–174).

Effect of build angle, resin layer thickness and viscosity on the surface properties and microbial adhesion of denture bases manufactured using digital light processing

ObjectivesTo investigate differences in the surface properties and microbial adhesion of denture base resins for digital light processing (DLP) with varying resin layer thicknesses (LT), build angles (BA), and resin viscosities. MethodsTwo denture base resins for DLP with different viscosities (high and low) were used to prepare disk specimens applying two manufacturing parameters: 1) LT (50 or 100 μm) and 2) BA (0-, 45-, and 90-degree). Surface roughness and contact angle values were measured on the test surfaces (n=10 per group). Streptococcus oralis and Candida albicans absorbance was measured to assess microorganism attachment (n=6 per group). A three-way analysis of variance (ANOVA) was conducted, considering the main effects and their interactions (viscosity, LT, and BA). Post-hoc multiple pairwise comparisons were performed. All data were analyzed at a level of significance (P) of 0.05. ResultsLT and BA significantly affected the surface roughness and contact angle of the specimens, depending on resin viscosity (P<.001). Absorbance measurement showed no significant interaction between the three factors (P>.05). However, significant interactions were observed between viscosity and BA (P<.05) and between LT and BA (P<.05). ConclusionsRegardless of the viscosity and LT, discs with a 0-degree BA showed the least roughness. High-viscosity specimens fabricated with a 0-degree BA had the lowest contact angle. Regardless of the LT and viscosity, discs with a 0-degree BA showed the lowest S. oralis attachment. Attachment of C. albicans was the least on the disk with 50 μm LT, irrespective of the viscosity. Clinical significanceClinicians should consider the effects of LT and BA on surface roughness, contact angle, and microbial adhesion of DLP-generated dentures, which can differ depending on resin viscosity. A 50 μm LT and 0-degree BA can be used with a high-viscosity resin to fabricate denture bases with less microbial adhesion.

WHY ARE EPOXY-COATED STEEL REBARS PROHIBITED IN BRIDGE STRUCTURES IN SOME REGIONS?

One of the common ways in many countries to protect steel reinforcement from corrosion in reinforced concrete structures is to cover its surface with a thin layer of epoxy resin. However, in practice, in many cases, the anti-corrosion effect of epoxy coating was not significant, and the durability of reinforced con-crete bridge structures was lower than those where steel reinforcement was not coated with epoxy resin. Ex-perts believe that one of the factors that affects the corrosion resistance of steel reinforcement with epoxy coat-ing in reinforced concrete is the presence of mechanical damage in the epoxy coating of the reinforcing rod, through which moisture can penetrate. Therefore, in some countries, instructions have been developed for the prevention of such damage at the stages of applying an epoxy coating to the armature, its storage, transporta-tion, and construction and assembly work in the manufacture of reinforced concrete structures. This article discusses the thermomechanical mechanism of violation of the internal structural integrity of concrete rein-forced with steel rods with an epoxy coating, which is caused by a high value of its coefficient of linear thermal expansion and the epoxy coating itself. Using the methods of the theory of thermoelasticity, a mathematical model of this phenomenon was developed, a system of solving differential equations was formed, and its solu-tion was constructed. It was established that even with relatively minor temperature changes in the concrete environment in the area of its contact with the reinforcement, cracks and damages occur along the entire length of the steel reinforcement. All this contributes to further destructive processes and reducing the durabil-ity of reinforced concrete bridge structures.

Evaluations of atomic-resolution strain fields using molecular dynamics simulations combined with corrected smoothed particle hydrodynamics

Deformation analyses of polymeric materials using molecular dynamics (MD) simulations are very useful in evaluating the physical properties based on the atomic features. Generally, the average responses of a system, such as the stress–strain response, are evaluated, but a molecular chain around a solid should deform in an unusual manner in a composite system, such as a solid/polymer system. This may lead to damage and a microscopic inelastic deformation, ultimately affecting the macroscopic behavior of the material. In this study, we propose a technique for use in evaluating the local pseudo-continuum deformation quantities, such as strain and stretch, during MD simulations by introducing deformation analysis via corrected smoothed particle hydrodynamics in a total Lagrangian formulation. Three different types of systems (uniform deformation of an Au crystal, cured resin sandwiched between silica walls, and cured resin containing a nanofiller) are considered, and the unique local deformations in the composite systems are quantitatively evaluated. In particular, local constitutive behavior can be evaluated using this technique, and in the sandwiched system, a high correlation is observed between the local stiffness inhomogeneity and the cohesive failure point. In the filler-containing system, a highly rigid epoxy resin layer is observed around the filler, and local deformation at the poles of the filler is confirmed owing to elongation. The observed trends are consistent with the experimental results. The insights obtained should contribute to the evaluation and understanding of microscopic deformation and damage, which is the beginning of macroscopic failure in a composite material.

Neutron Reflectometry Analysis of Condensed Water Layer Formation at a Solid Interface of Epoxy Resins Under High Humidity.

Water absorbed by epoxy resins from a humid atmosphere considerably influences their structure and properties. Examining the effects of absorbed water on epoxy resins at their interfaces with solid substrates is crucial because of their adhesive applications in various fields. The spatial distribution of absorbed water in epoxy resin thin films under high humidity was investigated in this study by neutron reflectometry. Water molecules were found to accumulate at the SiO2/epoxy resin interface after exposure at a relative humidity of 85% for 8 h. The formation of an ∼1-nm-thick condensed water layer was observed, and the thickness of this layer varied with curing conditions of epoxy systems. Furthermore, water accumulation at the interface was noted to be affected by high-temperature and high-humidity environments. The formation of the condensed water layer is presumed to be related to the features of the polymer layer near the interface. The construction of the interface layer of epoxy resin would be affected by the interface constraint effect on the cross-linked polymer chain during the curing reaction. This study provides essential information for understanding the factors influencing the accumulation of water at the interface in epoxy resins. In practical applications, the process of improving the construction of epoxy resins near the interface would be a reasonable solution to resist water accumulation in the interface.

Investigating the impact of flowable composite liner on the fracture strength and microleakage of large composite resin restorations of primary anterior teeth.

To investigate the effect of pre-cured and co-cured flowable composite liner on fracture strength and microleakage of primary anterior teeth with extended composite resin restorations. In the current in vitro experimental study, the crowns of 54 extracted primary canine teeth were cut 1mm above the CEJ, and a pulpectomy procedure was performed. The samples were randomly divided into three groups to restore the coronal part up to 4mm above the CEJ. In group 1, the samples were built up with Filtek Z250 packable composite resin. In group 2 (pre-cure), first, 1mm of Filtek Z350 XT flowable liner was applied to the sample, and after curing, the restoration process continued using packable composite resin. In group 3 (co-cure), the flowable composite liner was cured while the first layer of packable composite resin was applied; then, the same restorative procedure similar to the other groups was followed. The samples' cross-sectional area in the fracture strength test was calculated by AutoCAD software. Subsequently, the samples were subjected to a force in a universal testing machine. The samples related to the microleakage experiment were cut vertically, and then, the dye penetration percentage (10% methylene blue) was measured under a stereomicroscope. ANOVA was used to analyze the data. Mean fracture strength in group 2 was significantly higher than in group 1 (P = 0.016). The microleakage mean in group 3 was significantly lower than in groups 1 (P = 0.000) and 2 (P = 0.026). The flowable composite liner and its relevant separate curing increased the fracture strength of composite resin restorations. However, less microleakage was reported in the group where the liner was applied as a co-cure.