Epoxy Blends Research Articles

Biowaste utilisation to fabricate corrosion retarding nanofiller MA/LS (Mango kernel ash/Lauric acid treated SiO2) blended epoxy coating for low alloyed carbon steel in saline medium

In present work, Mango fruit biowaste (collected from local juice shop) was utilised to fabricate MA/LS (Mango kernel ash/Lauric acid treated SiO2) composite by simple sol-gel technique, to fabricate low cost and non-hazardous corrosion retarding nanofiller for epoxy coating. Fabricated composite was added as nanofiller in epoxy to get composite epoxy coating (EP/MA-LS) and then was examined for corrosion resistance by utilising EIS and salt spray analysis. EP/MA-LS has offered excellent Rp value of 2.27 × 108 Ω cm2 as observed from EIS FRA measurement and protection efficiency of 89.32 % (measured from potentiodynamic linear polarisation) even after 51 days of prolong exposure in 3.5 % NaCl. Wettability examination of EP/MA-LS has demonstrated high hydrophobicity with contact angle of 122.3°. Improved thermal stability and better compactness was also observed for EP/MA-LS on examining with TGA and SEM respectively.

Development and analysis of Fe-doped ZnO nanoparticle-infused sisal fiber reinforced hybrid polymer composites for high-performance sound absorption and thermal insulation applications

In the current study, sisal fiber-reinforced hybrid composites have been developed by integrating a bidirectional mat with a blend of epoxy using Fe-doped ZnO (IDZO) nanoparticles at concentrations of 0.2, 0.4, 0.6, and 0.8 wt%. Hand-lay-up approach was used to create the composites. The composites were characterized through a comprehensive analysis of their density, water absorption, elasticity, thermogravimetric analysis, mechanical resistance, thermal conductivity, microhardness, and propagation of sound properties, including sound absorption coefficients and sound transmission class ratings. As filler loading increased, the bio-composite sample’s hardness increased under the density and void volume fraction values, with 0.8 wt% composite sample showing the superior micro-hardness. A positive correlation was observed between the ZnO nanoparticle weight percentage and thermal conductivity, with improve nanoparticle content leading to improved thermal performance. Composites containing 0.4 wt percent nanoparticles showed superior tensile strength (66.8–84.16 MPa), flexural strength (97.69–120.02 MPa) and flexural modulus (3.56–7.68 GPa). It has been observed that the weight percentage of IDZO filler greatly influences the sound absorption efficiency of the current composites. These findings highlight the promising potential of these novel biocomposites in advanced engineering applications, emphasizing their usefulness in demanding environments with biodegradability and high-performance thermal, mechanical, and acoustic properties. Based on the sound transmission class ratings, the sisal fiber biocomposites have been regarded as great adoptions for use as sound-absorbing materials such as wall partitions, doors, enclosures, and structural components, thermal insulation systems, and electrical insulation.

Bio-based liquid crystal epoxy resins: Toughening and strengthening of conventional epoxy resins with strategically extended spacer layers

Liquid crystal epoxy resin, as an ideal toughening agent, combines the features of liquid crystal ordering and network cross-linking, which can effectively optimize the comprehensive performance of blended epoxy resins and achieve an ideal balance of rigidity and toughness. Here we successfully synthesized rigid and flexible bio-based liquid crystal epoxy resin (THBR-EP) by finely tuning the length of alkyl side chains. Using aromatic diamine as curing agent, a homogeneous network without phase separation was constructed by taking advantage of the different activity but good compatibility with ordinary epoxy resins, which significantly improved the toughness of the blended system. Specifically, only a small amount of THBR-EP(2.5 wt%) was required to exhibit a maximum impact strength of 48.8 kJ/m2. Moreover, the increase in system toughness was accompanied by a benign improvement in flexural strength, modulus and thermal stability. The ordered structure of the liquid crystals and their good compatibility with the resin matrix enhanced the ability to inhibit crack extension and energy dissipation. The feasibility to simultaneously achieve effective toughening and other property improvements of common resins broadens the application of resins under various demanding scenarios.

Effect of Temperature and Initiator Concentration on the Curing Reaction of an Epoxy/Amine System

AbstractEpoxy blends of diglycidyl ether of bisphenol A (DGEBA) and 2‐[2‐(dimethylamino) ethoxy] ethanol (DMAEE) were prepared. The effect of DMAEE concentration on the rheological properties of the epoxy blends were investigated through oscillatory rheometry under isothermal conditions. A novel technique was developed to study the rheological behavior of the epoxy blends by using a Rubber Process Analyzer (RPA). The rheological study enabled analyzing the variations in the storage modulus (G’), loss modulus (G’’) and torque during the progress of the curing reaction. Additionally, the theoretical cross‐linking density (νe) and the degree of conversión of the curing reaction (α). The gel time (tgel) was determined at different temperatures, and the activation energy (Ea) was calculated by using Arrhenius‐type equation based on the gel time results. The activation energy values found are 24.79 kJ/mol and 23.01 kJ/mol. The results obtained are consistent with the values described in the literature. It was demonstrated that the proposed methodology is valid and, the use of the tertiary amine DMAEE curing agent for epoxy resins was confirmed.

Study on the nuclear shield behaviors of basalt/carbon fibers reinforced PbO blended epoxy matrix composite – A novel material for thermal insulation applications

This study introduces a novel composite material engineered for thermal insulation, specifically in environments requiring radiation shielding. The composite is composed of basalt and carbon fibers reinforced varying with lead oxide (PbO) nanoparticles for five different composite laminates, all integrated into an epoxy matrix. The research primarily focuses on evaluating the composite's thermal insulation capabilities, gamma-ray attenuation effectiveness, and microstructural characteristics. Mechanical testing reveals that the incorporation of basalt and carbon fibers significantly enhances the composite's tensile strength and modulus. Thermal analysis demonstrates the composite's excellent insulation properties, attributed to the synergistic effects of the fibrous reinforcement and the epoxy matrix, which effectively reduce thermal conductivity. Gamma attenuation tests indicate a substantial improvement in radiation shielding effectiveness with the addition of lead oxide nanoparticles. The composite exhibits improved gamma-ray attenuation compared to conventional materials, due to the high atomic number of lead, which enhances photon absorption and scattering mechanisms.Microstructural analysis provides detailed insights into the composite's structure. Morphological images show a uniform dispersion of PbO nanoparticles and strong adhesion between the fibers and the matrix. Elemental analysis confirms the elemental composition, highlighting the successful integration of PbO nanoparticles, which significantly enhances radiation shielding.

Fabrication of green composite made by Cannabis sativa fiber reinforced granite filler blended epoxy matrix composite – Antimicrobial and structural analysis

The main novelty of this research lies in combining natural fibers and mineral fillers to create a sustainable material with enhanced antimicrobial and structural properties, offering promising applications in various industries requiring eco-friendly and high-performance materials. This study investigates the fabrication and analysis of a green composite made from Cannabis sativa fiber reinforced (CSFR) with granite filler in an epoxy matrix, focusing on antimicrobial properties and structural integrity. Various amounts of granite powder (0, 3, 6, 9, 12, and 15 g) were incorporated into the epoxy matrix. The composite exhibited significant antibacterial activity was observed against E. coli. Mechanical testing revealed that the composite with 12 g of granite powder showed the best performance, with tensile strength improving by 11.4%, flexural strength by 12.3%, impact strength by 29% and hardness is improved by 17.5%. SEM analysis highlighted well-dispersed particulates and strong fiber-matrix bonding at optimal filler levels. TGA showed enhanced thermal stability, with the decomposition onset shifting from 240 °C to 280 °C and weight retention improving 90% at 350 °C. This study underscores the potential of Cannabis sativa fiber reinforced granite filler epoxy matrix composites as sustainable materials with excellent antimicrobial and structural properties for advanced applications.

Investigation of the Thermal and Mechanical Properties of Glass Fiber Reinforced ABS/Epoxy Blended Polymer Composite

This research investigates the formation of polymer blends by blending Epoxy LY556 with Acrylonitrile-Butadiene-Styrene (ABS) at weight percentages ranging from 2 to 10% wt. The thermal properties, morphological characteristics, tensile strength, flexural strength, and interlaminar shear strength (ILSS) characteristics of these composites were examined. The X-ray Diffractometer (XRD) and Fourier Transform Infrared Spectrometer (FTIR) studies confirmed the presence of binary blends. The miscibility of epoxy/ABS blends is shown by the presence of a single melting peak in the Differential Scanning Calorimetry (DSC) analysis. The Thermogravimetric Analysis (TGA) findings indicate that epoxy and ABS blends exhibit greater thermal stability than pure epoxy. The tensile strength increased from 183.6 to 380.6 MPa, flexural strength increased from 165.3 MPa to 335.6 MPa, ILSS increased from 32.4 MPa to 72 MPa for 8% wt. of ABS blending, and the laminates witnessed a decrease in density and hardness values. The Scanning Electron Microscopy (SEM) images demonstrate the commendable blending characteristics and the synergistic impact of the ABS/Epoxy composite, yielding superior outcomes to the pure epoxy material.

Preparation and size control of epoxy resin multilevel structures with SiO2 particles

In the process of preparing porous epoxy materials using reaction-induced phase separation (RIPS), the introduction of an appropriate amount of SiO2 particles enables the control of the phase separation behavior of the system and its ultimate phase structure. This study examined the role of SiO2 particles in the preparation and size control of epoxy resin multilevel structures by analyzing the phase separation and reaction kinetics in an epoxy resin blend system and characterizing the ultimate phase structure. It was found that fumed SiO2 particles (0–3 wt%) added to the DGEBA/DDCM/PEG200 blends resulted in significant interfacial stabilization, delaying phase separation. With an increase in the fumed SiO2 particle content, the phase structure stopped evolving at an earlier stage of phase separation. In addition, the fumed SiO2 particles dispersed in the porogen-enriched phase helped to stabilize the system, i.e., preventing or slowing down the segregation and aggregation of the components in the system, which may inhibit secondary phase separation in the porogen-enriched phase. When 350 nm SiO2 particles were used, an increase in the particle size resulted in a larger phase structure. The SiO2 particles were dispersed within the pore-forming agent phase, increasing the proportion of the pore-forming agent and exerting an occupancy effect, which diminished with decreasing SiO2 particle size and increasing hydrophobicity. Notably, the surface of the epoxy porous material skeleton was decorated with small pits formed by the acid etching of the SiO2 particles, and this multilevel structure contributed to the specific surface area. The multilevel structure can be precisely controlled by adjusting the size, content, and wettability of the SiO2 particles. The results of this study are universal and instructive for the preparation of porous materials using a phase separation method in combination with solid particles.

Hybrid Solid Polymer Electrolytes Based on Epoxy Resins, Ionic Liquid, and Ceramic Nanoparticles for Structural Applications.

Solid polymer electrolytes (SPE) and composite polymer electrolytes (CPE) serve as crucial components in all-solid-state energy storage devices. Structural batteries and supercapacitors present a promising alternative for electric vehicles, integrating structural functionality with energy storage capability. However, despite their potential, these applications are hampered by various challenges, particularly in the realm of developing new solid polymer electrolytes that require more investigation. In this study, novel solid polymer electrolytes and composite polymer electrolytes were synthesized using epoxy resin blends, ionic liquid, lithium salt, and alumina nanoparticles and subsequently characterized. Among the formulations tested, the optimal system, designated as L70P30ILE40Li1MAl2 and containing 40 wt.% of ionic liquid and 5.7 wt.% of lithium salt, exhibited exceptional mechanical properties. It displayed a remarkable storage modulus of 1.2 GPa and reached ionic conductivities of 0.085 mS/cm at 60 °C. Furthermore, a proof-of-concept supercapacitor was fabricated, demonstrating the practical application of the developed electrolyte system.

Green fabrication for ultra-lightweight polyethersulfone/epoxy foam with excellent thermal insulation

High-performance polymers find extensive applications in heat-resisting materials, aerospace, and automobile manufacturing industry. However, due to their challenging processability, achieving low-density high-performance polymer foams for thermal insulation materials remains a big challenge. Furthermore, the preparation of lightweight special engineering plastic foams has garnered substantial attention in current research. Herein, we have developed polyethersulfone (PES)/bisphenol A epoxy resin (EP) blend foams with ultra-low density and good thermal insulation properties using a facile and environmentally friendly supercritical CO2 (ScCO2) foaming approach. The inherent compatibility between PES and EP resin enhanced the free volume of molecular chain in the matrix, subsequently improving the solubility and diffusion rate of carbon dioxide within the PES matrix. Consequently, in contrast to the maximum expansion ratio of 5.5 observed in pure PES, the PES/EP blend foams achieved an expansion ratio of up to 26 times, along with an improvement of the cell structure of PES and increasing cell density from 2.55 × 109 to 2.96 × 1010 cells/cm3. Furthermore, the thermal conductivity of PES-based foams notably decreased from 0.0667 to 0.0348 W/(m·K) with the addition of EP, possibly resulting from the low density (0.05 g/cm3) and high open-cell content (79.9%) of PES/EP blend foam. Our work presents a novel strategy for producing special engineering plastic foams with ultra-low density for thermal insulation, thereby expanding the potential application of special engineering plastic foam in areas such as biological scaffolds, absorbent material applications, and automotive interior industry.

Effect of Block Copolymer Self-Assembly on Phase Separation in Photopolymerizable Epoxy Blends.

Directing self-assembly of photopolymerizable systems is advantageous for controlling polymer nanostructure and material properties, but developing techniques for inducing ordered structure remains challenging. In this work, well-defined diblock or random copolymers were incorporated into cationic photopolymerizable epoxy systems to investigate the impact of copolymer architecture on self-assembly and phase separated nanostructures. Copolymers consisting of poly(hydroxyethyl acrylate)-x-(butyl acrylate) were prepared using photoiniferter polymerization to control functional group placement and molecular weight/polydispersity. Prepolymer configuration and concentration induced distinctly different effects on the resin flow and photopolymerization kinetics. The diblock copolymer self-assembled into nanostructured phases within the resin matrix, whereas the random copolymer formed an isotropic mixture. Rapid photopolymerization and ambient temperature conditions during cure facilitated retention of the self-assembled phases, leading to considerably different composite morphology and thermomechanical behavior. Increased loading of the diblock copolymer induced long-range ordered cocontinuous structures. Even with nearly identical prepolymer composition, controlled nanophase separation resulted in significantly enhanced tensile properties relative to those of the isotropic system. This work demonstrates that controlling phase separation with a block copolymer architecture allows access to nanostructured photopolymers with unique and enhanced properties.

Taking a Tailored Approach to Material Design: A Mechanistic Study of the Selective Localization of Phase-Separated Graphene Microdomains.

To achieve multifunctional properties using nanocomposites, selectively locating nanofillers in specific areas by tailoring a mixture of two immiscible polymers has been widely investigated. Forming a phase-separated structure from entirely miscible molecules is rarely reported, and the related mechanisms to govern the formation of assemblies from molecules have not been fully resolved. In this work, a novel method and the underlying mechanism to fabricate self-assembling, bicontinuous, biphasic structures with localized domains made up of amine-functionalized graphene nanoplatelets are presented, involving the tailoring of compositions in a liquid processable multicomponent epoxy blend. Kinetics studies were carried out to investigate the differences in reactivity of various epoxy-hardener pairs. Molecular dynamics simulations and in situ optical photothermal infrared spectroscopy measurements revealed the trajectories of different components during the early stages of polymerization, supporting the migration (phase behavior) of each component during the curing process. Confirmed by the phase structure and the correlated chemical maps down to the submicrometer level, it is believed that the bicontinuous phase separation is driven by the change of the miscibility between various building blocks forming during polymerization, leading to the formation of nanofiller domains. The proposed morphology evolution mechanism is based on combining solubility parameter calculations with kinetics studies, and preliminary experiments are performed to validate the applicability of the mechanism of selectively locating nanofillers in the phase-separated structure. This provides a simple yet sophisticated engineering model and a roadmap to a mechanism for fabricating phase-separated structures with nanofiller domains in nanocomposite films.

Preparation, Cure, Characterization, and Mechanical Properties of Reactive Flame-Retardant Cyanate Ester/Epoxy Resin Blends and their Carbon Fiber Reinforced Composites

This study explores the formulation space of flame retardant thermoset polymers, specifically involving blends of epoxy and cyanate ester (EP/CE) and a reactive phosphorus-based flame retardant, poly (m-phenylene methylphosphonate) (PMP). Two CE monomers were investigated, each blended with the same epoxy monomer (DGEBA) in a 1:1 wt ratio. The impact of phosphorus concentration on the neat (neat meaning no fibers were present) resin blends was characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The flammability and mechanical characteristics were assessed using micro-combustion calorimetry (MCC) and dynamic mechanical analysis (DMA). Carbon fiber composite panels were successfully fabricated using a wet layup process and autoclave curing with a fiber volume fraction (Vf) of approximately 0.5. DMA testing of the cured composite laminates pinpointed that the average Tg of the EP/CE blend was reduced with PMP addition by up to 39 °C at a phosphorous level of 3 wt%. Cone calorimetry tests confirmed the effectiveness of the flame retardant by reducing the peak Heat Release Rate (HRR) by approximately 27 %. The integration of PMP into EP/CE only marginally reduced the 3-point flexural strength (6–15 %) and modulus (7–13 %) relative to baseline samples.

Improving flame retardancy in BADGE epoxy via novel phosphorus‐functionalized epoxy integration

AbstractA novel epoxy resin, DPHP, was synthesized from diphenolic acid, which contains biobased levulinic acid, with triethylphosphite, to improve the flame retardancy of bisphenol‐A diglycidyl ether (BADGE) epoxy. Curing experiments were conducted using isophorone diamine as a curing agent for BADGE and DPHP mixtures. Variations in cure kinetics, mechanical properties, and flame retardancy were evaluated across different DPHP contents. The introduction of phosphorus functional groups into DPHP affected the polarization of epoxide CO bonds, resulting in reduced apparent activation energy for epoxy curing reactions. However, the higher epoxy equivalent weight of DPHP compared with that of BADGE led to a decrease in the tensile strength and the glass transition temperature of the cured material with increasing DPHP content. A significant increase in char yield for combustion of the epoxy blend was observed, ranging from 8.3% at 0 wt% DPHP to 20.1% at 50 wt% DPHP. Additionally, cone calorimeter measurements showed significant reductions in heat release rate and total heat release, leading to a decrease in fire spread from 1.07 MJm−2 s−1 at 0 wt% DPHP to 0.43 MJm−2 s−1 at 50 wt% DPHP. These results show that the flame retardancy of the cured material improved significantly as the DPHP content increased.

Healing Process Affected by Morphology of PCL/Epoxy Blends

In this study, a blend of epoxy and polycaprolactone (PCL) was prepared to investigate its ‎properties. Different weight percentages of thermoplastic PCL (0.25, 0.5, 1, 2 wt%) were ‎combined with epoxy coatings. The final morphology revealed PCL scattered as spherical ‎particles within the epoxy phase, which was functioning as a continuous matrix. The coating ‎showed toughness and rigidity when it had fully cured. The PCL phase had a special behavior ‎when heated, called "bleeding," in which it filled any open surfaces of its own volition. By ‎using molten PCL to fill in cracks, this property can be used for self-healing applications. The ‎self-healing efficacy of blends with different PCL contents was assessed. The self-healing ‎efficacy of the various mixes was determined by dividing the width of the self-healed crack by ‎the width of the original crack. The results showed that the highest thermal-mending efficiencies, ‎reaching 100%, were achieved with a PCL/epoxy blend containing co-continuous phases, ‎specifically at a 1 wt.% PCL content. Fourier-transform infrared (FTIR) analysis indicated that ‎there was physical interaction between the epoxy and PCL phases, but no chemical bonding ‎occurred between them.‎

Influence of Thiol-Functionalized Polysilsesquioxane/Phosphorus Flame-Retardant Blends on the Flammability and Thermal, Mechanical, and Volatile Organic Compound (VOC) Emission Properties of Epoxy Resins.

In this study, thiol-functionalized ladder-like polysesquioxanes end-capped with methyl and phenyl groups were synthesized via a simple sol-gel method and characterized through gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). Additionally, epoxy blends of different formulations were prepared. Their structural, flame-retardant, thermal, and mechanical properties, as well as volatile organic compound (VOC) emissions, were determined using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), TGA, scanning electron microscopy (SEM), limiting oxygen index (LOI), cone calorimetry, and a VOC analyzer. Compared to epoxy blends with flame retardants containing elemental phosphorus alone, those with flame retardants containing elemental phosphorus combined with silicon and sulfur exhibited superior thermal, flame-retardant, and mechanical properties with low VOC emissions. SEM of the residual char revealed a dense and continuous morphology without holes or cracks. In particular, LOI values for the combustion of methyl and phenyl end-capped polysilsesquioxane mixtures were 32.3 and 33.7, respectively, compared to 28.4% of the LOI value for the blends containing only phosphorus compounds. The silicon-sulfur-phosphorus-containing blends displayed reduced flammability concerning the blends using a flame retardant containing only phosphorus. This reflects the cooperative effects of various flame-retardant moieties.

Experimental investigation on tribo-performance of rice husk nanoparticles blend epoxy composites reinforced by Borassus flabellifer L. fibre using neural network approach

The present study includes the tribo-performance of rice husk nanoparticles (RHN) blend epoxy composites reinforced by Borassus flabellifer leaf fibre (BFLF). RHN obtained from rice husks were blended with epoxy resin to modify them with 0.25, 0.45, and 0.65 wt% (weight percent of composites), respectively, using mechanical stirring and sonication processes. Comprehensive solid particle erosion characterization of modified composites was evaluated. The prepared samples were tested by an air jet type test rig and investigated according to the L16 Taguchi method of the response surface method (RSM) to evaluate the performance of the composites under erosive conditions and factors like impact velocity, filler content, impingement angle, and erodent size. Artificial neural networks (ANN) were used for forecasting of erosion rates under significant control factors at different levels and combinations. The effect of input factors on resistance to erosion was analyzed using an analysis of variance (ANOVA). Erosion loss mechanisms were examined by the microstructure analysis of the worn surfaces. The erosion test outcomes verified that the blend of RHN with epoxy resin improved the resistance to erosion wear of BFLF composites, and their predictive results were consistent with the experimental observations. The analysed composites are to be used with versatile functionality for their intended purpose.

Thermal stability and dynamic mechanical analysis of nano-biofillers blended hybrid composites reinforced by cellulosic Borassus flabellifer L. fiber

The aim of this study is to investigate the dynamic mechanical and thermal stability behavior of rice husk nano-biofillers blend epoxy hybrid composites reinforced by Borassus flabellifer L. leaf fiber. The raw Borassus leaf fibers were treated with 5 wt.% NaOH solution to reduce the disadvantages of hydroxyl bonding. Rice husk nano-fillers (RHNFs) were blended with epoxy resin to modify them with 0.25, 0.45, and 0.65 wt.%, respectively, using sonication and mechanical stirring process. The prepared samples were assessed to evaluate the thermal stability, maximum degradation temperature, storage modulus (E′), loss modulus (E″), damping factor (tan δ) and Cole–Cole plot of the composites. EDX spectroscopy was used to confirm the elemental composition of nano-biofillers. The morphology of RHNFs was analyzed using a scanning electron microscope (SEM). The TG analysis confirmed that the 0.45 wt.% RHNFs blended Borassus leaf fiber (BLF) composites exhibited superior thermal stability (371–384 °C). Derivative thermogravimetry (DTG) analysis exposed that the maximum mass-loss degradation temperature of 0.45 wt.% RHNFs blend composites was 411 °C for the first stage and 678 °C for the second stage, which were more than raw and RHNFs blend (0.25 and 0.65 wt.%) composites. Accordingly, improved E′ (959.16–1637.75 MPa), glass transition temperature (T g) from E″ (90.48–97.69 °C) and, T g from tan δ (103.35–109.67 °C) were derived from the modified composites. Owing to the improved dispersion of the nano-filler, the 0.45 wt.% RHNFs blend composites had a homogeneous polymer system, as verified by the Cole–Cole diagram. The analyzed composites are to be used with versatile functionality for their intended purpose.

Thermal expansion and mechanical properties of urethane-modified epoxy bonded CFRP/steel joints at low and high temperatures for automotive

Long-term reliability is critical in automobiles owing to their frequent exposure to the external environment and lengthy operational durations. Using dissimilar materials as adhesives to reduce the weight of vehicles results in a mismatch of coefficients of thermal expansion (CTE). Difference in CTE causes constant internal stress at the adhesive interface when the temperature changes, leading to delamination of the adhesive at the interfaces, microcrack initiations, and crack propagations. Therefore, a blend of linear urethane prepolymer and epoxy was tested to alleviate stress concentration. Dynamic mechanical analysis (DMA) was performed to determine the modulus according to the urethane content, while tensile strength was measured to evaluate changes in the physical properties. It was observed that increasing the urethane content decreased the modulus but progressively enhanced the tensile strength elongation rate. The lap shear strength specimen was thermally shocked to validate the decrease relative to the initial value based on the cycles. Consequently, combining urethane and epoxy successfully enhanced the elongation and reduced the internal stress caused by temperature changes.

Exploiting the use of deep learning techniques to identify phase separation in self-assembled microstructures with localized graphene domains in epoxy blends

In this study for the first time, convolutional neural networks (CNN) are applied to identify phase-separated microstructures in a novel nano-modified polymer composite. The input data consist of a mixed labelled dataset of homogeneous microstructure and phase-separated microstructure images collected using an optical microscope; the problem is modelled as a binary classification. The initial dataset consisted of microstructural images collected in house from past experiments, expanded in number using the data augmentation method, and upon testing, the model showed an accuracy of 65.4% and a 0.5 F1 score. Additional experiments were performed to generate more ground truth images and the CNN model built on this second data set showed improved accuracy of 80.1% and a 0.9 F1 score; The CNN classifier mimicked the receiver operating characteristic (ROC) curve of perfect classifier. Using the trained model, the phase separated microstructure is distinguished from homogeneous microstructure in a matter of minutes, saving hours of manual screening and cost intensive characterisation.