Degradation Of Resin Research Articles

Catalytic Activity of Nickel and Iron Sulfides in the Degradation of Resins and Asphaltenes of High-Viscosity Oil in the Presence of Carbonate Rock Under Hydrothermal Conditions

Catalytic Activity of Nickel and Iron Sulfides in the Degradation of Resins and Asphaltenes of High-Viscosity Oil in the Presence of Carbonate Rock Under Hydrothermal Conditions

Accelerated weathering of Compreg with phenol-formaldehyde resin treated top veneers of European white oak (Quercus ssp., L.) and teak (Tectonia grandis, L.F.)

The weather resistance of Compreg surfaces depends on various factors, such as top veneer type, impregnating resin, and protective topcoats. Artificial weathering tests were performed for the first time on material types with oak and teak top veneer surfaces. Both showed strong surface brightening due to resin degradation and subsequent photobleaching of the exposed veneer surface. Directly pressed, phenolic resin-impregnated cellulose paper overlays caused significant surface stabilization.

Catalytic upgrading of heavy oil from the Ashalchinskoye oilfield

The work deals with study the effect of the NiCrWC catalyst on the composition of the products of catalytic cracking of heavy oil at a temperature of 450 °C for 100 minutes is established. The relevance of research aimed at studying the catalytic activity in the processing of heavy oil. It has been installed that the addition of NiCr-WC promotes the retardation of coke and asphaltenes formation and an increase in the destruction of high-molecular components of heavy oil. The use of a catalyst makes it possible to increase the yield of gasoline and diesel fractions by 35.8 wt % compared to the initial oil. Due to the formation of gaseous products, the removal of 2 wt % of sulfur from oil is observed. The data of X-ray phase analysis and scanning electron microscopy show that metal oxides are sulfidized on the surface of nichrome particles to form sulfides of these metals. It was found that NixSy and CrxSy formed on the catalyst surface contribute to an increase in the degradation of oil resins and asphaltenes.

Impact compression behaviors of 3D angle-interlock woven composites under thermo-oxidative ageing

Impact compression behaviors after thermo-oxidative ageing are key to design safety and durability of 3D angle-interlock woven composites (3DAWC). This paper experimentally and numerically presents the impact compression properties and damage morphology of composites before and after ageing, which reveals the effects of thermo-oxidative ageing on impact compression behaviors of 3DAWC. The testing results revealed that the composites impact compression mechanical properties, i.e., maximum stress and modulus, decrease with the increasing ageing time. The impact compression properties degradation of 3DAWC is attributed to the epoxy resin degradation and interface debonding. Moreover, the interfacial debonding hinders the propagation of stress waves. The finite element analysis (FEA) results illustrate the ageing interfacial damage changes the crack propagation path during impact compression. The matrix degradation and interfacial weakening after ageing aggravate the interfacial damage and reduce the stress distribution of aged composites. The failure morphology of aged composites is more serious.

Tensile properties deterioration of BFRP bars in simulated pore solution and real seawater sea sand concrete environment with varying alkalinities

This study investigates the effectiveness of reducing alkalinity on the durability enhancement of basalt fiber reinforced polymer (BFRP) bars to address their durability in the alkaline environment of seawater sea sand concrete (SWSSC). After accelerated aging at different temperatures and durations, the tensile properties of BFRP bars immersed in simulated SWSSC pore solution and embedded in seawater sea sand mortar (SWSSM) with varying alkalinities were evaluated by tensile testing. In addition, scanning electron microscopy, X-ray micro-computed tomography, and low-field nuclear magnetic resonance were used to examine the microstructure of embedded BFRP bars and SWSSMs. The experimental results indicate that reducing the pH of the solution and SWSSM to around 12 or below can significantly mitigate BFRP bar tensile strength loss. The maximum improvement of tensile strength retention for bare and embedded BFRP bars are 43.52% and 40.27%, respectively. Compared to BFRP bars wrapped in normal SWSSM, the degradation of resin, basalt fiber, and fiber-resin interface of embedded BFRP bars in the low-alkalinity SWSSMs is considerably mitigated due to the reduced alkalinity and porosity. According to the Arrhenius prediction, the tensile strength retention of BFRP bars embedded in normal SWSSM will decrease to 70% within 1.70–5.10 years, but it will be more than 85% for those embedded in low-alkalinity SWSSMs. This study indicates that it is an effective way to mitigate the deterioration of BFRP bars by using low-alkalinity SWSSC when BFRP bars are used as reinforcement in marine SWSSC structures.

Induced damage during STEM-EELS analyses on acrylic-based materials for Stereolithography

(Scanning) transmission electron microscopy, (S)TEM, offers a powerful characterization tool based on electron-matter interactions, highly valuable in materials science. However, the possible electron beam induced damage during (S)TEM measurements hinders the analysis of soft materials, such as acrylic resins. Importantly, acrylic resins offer an appealing playground for the development of novel composites with customized properties and convenient processing capabilities for 3D-printing technologies, including Stereolithography (SLA). There are several factors preventing the optimal performance of TEM measurements applied to acrylic resins, among which we focus on the quality of the analyzed specimen (i.e., compromise between thickness and robustness, to achieve electron transparency while keeping the material integrity), particularly challenging when working with soft materials; the electrostatic charging/discharging effects, resulting in sample drift and related noise/artefacts; and the radiolysis and knock-on electron-induced damage, which directly degrade the material under study. We explore and compare different methodologies to obtain resin specimens suitable for (S)TEM analysis, employed for the subsequent study of the electron–beam damage induced during STEM-EELS measurements. Furthermore, we propose likely underlying mechanisms explaining the acrylic resin degradation based on the different EELS monitored signals. On one hand, we assess the evolution of the carbon and oxygen content, as well as the material thinning as a function of the accumulated electron dose. On the other hand, we extract meaningful information from the spectral shape of carbon and oxygen K-edges upon increasing electron doses, unraveling likely degradation pathways. The earned understanding on the electron-beam induced damage and the determination of critical doses provide a useful framework for the implementation of (S)TEM techniques as useful tools to help in the smart engineering of acrylic-based composites for SLA.

Bio-based epoxy vitrimer for recyclable and carbon fiber reinforced materials: Synthesis and structure-property relationship

Recycling or degradation of epoxy resins is difficult because of their covalent cross-linking structures, which causes resource crisis, environmental pollution, and resource waste. To address this challenge, we reported a recyclable and degradable epoxy vitrimer with dynamic ester bonds prepared from tung oil and diglycidyl ether of bisphenol-A via epoxy-acid-anhydride crosslinking system. Owing to the compact rigid six-member ring and the anhydride structure, the epoxy vitrimer shows high thermal stability, and excellent dynamic mechanical, and mechanical properties with tensile strength of 59.21 ± 1.02 MPa and glass transition temperature of 76.73 °C. The vitrimer network can achieve topological rearrangement via dynamic transesterification reactions with the addition of a Zn catalyst. Thus, the contrivable vitrimer exhibits excellent self-healing, shape memory, and physical recycling at elevated temperatures. Moreover, the epoxy vitrimer matrix has high joining strength with carbon fibers and can be used to prepare carbon-fiber-reinforced materials (CFRMs). The carbon fibers can be completely recycled from CFRMs through an ethanol-NaOH mixture solvent. This work can assist in preparation of degradable high-strength CFRMs using a recyclable tung-oil-based vitrimer matrix and provides a strategy for efficient recycling of carbon fibers from CFRMs.

Study on the Effect of Salt Solution on Durability of Basalt-Fiber-Reinforced Polymer Joints in High-Temperature Environment.

Due to the low price and good comprehensive properties, FRP composite material has become a new type of civil application material in recent years. In this paper, Araldite® 2012 adhesive was used to bond basalt-fiber-reinforced polymer (BFRP), and the durability of its bonded joints was investigated. Experiments were carried out at 80 °C/DI water (deionized water), 80 °C/3.5% NaCl solution (3.5% SS), and 80 °C/5.0% NaCl solution (5.0% SS) at 0- (unaged), 10-, 20-, and 30-day aging. The specimen and BFRP in the environment of 80 °C/DI water, 80 °C/3.5% SS, and 80 °C/5.0% SS found salt solution under the condition of all sample water absorption decreases, and the activity of salt solution chemistry was weaker compared with deionized water. The load–displacement curve of the joint failure was obtained through quasi-static tensile experiments, and it was found that the adhesive would undergo a post-curing reaction that had a positive impact on the stiffness of the joint in a high-temperature environment. At the same time, it was found that the joint failure strength decreased less in the salt solution environment, and deionized water was more destructive than the salt solution. Referring to the change in water absorption, it was found that the change in the mechanical properties of the joint was mainly related to the permeation effect of the polymer. The change in the Tg of adhesive was measured by differential scanning calorimetry (DSC). It was found that Tg would decrease after aging, and the change in Tg was mainly related to the mobility of the molecular chain. Thermogravimetric analysis (TGA) was used to analyze the thermal behavior of the epoxy resin and some organic matter, and the main weight loss stage was 340–450 °C, which was the complete degradation of epoxy resin and some organic matter. Macro visual and microscopic scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to analyze the failure section, and it can be concluded that the failure mode of joint tear failure transitioned to cohesion in the late–mixed interface failure, at the visible interface between the fiber and the resin matrix.

Thermal degradation behavior of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide modified epoxy resin with liquid oxygen compatibility

The phosphorus-containing epoxy resin, 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB) modified epoxy resin, has been proved compatible to liquid oxygen, and it is prospective to be used as the matrix in composites for liquid oxygen tanks. It is considered that impact energy would be partially converted into heat and concentrated in small regions to form “hot spots”, which cause the degradation of polymer molecular chains to produce large quantities of free radicals and combustible products, thus initiating sensitive reactions of polymer with liquid oxygen. In the present paper, the temperature of the hot spot was estimated and the thermal degradation behavior of ODOPB modified epoxy resin was investigated simultaneously in gas and solid phases, and then on the base of that, the mechanism of its compatibility with liquid oxygen was proposed. The calculated results showed that the theoretical temperature of hot spots could be instantaneously raised up to 810 K (537 °C) under the impact energy of 98 J, which is sufficient to result in the degradation of epoxy resin. In the investigation of degraded gas products from epoxy resin samples, thermogravimetric-Fourier transform infrared spectroscopy-mass spectrometry (TG-FTIR-MS) results revealed that the incorporation of ODOPB effectively reduced the generation of free radicals and combustible volatiles. On the other hand, in the solid phase, the FTIR results demonstrated that the introduction of ODOPB could endow epoxy resin with preferable char-forming ability, which effectively hindered the diffusion of oxygen, flammable volatiles, and free radicals. The quenching effects of phosphorus-containing radicals and favorable char-forming ability of ODOPB played key roles in the transformation of epoxy resin from sensitive to compatible with liquid oxygen. This work provides a series of experimental evidence for revealing the mechanism of compatibility of ODOPB modified epoxy resin with liquid oxygen, which is important for the development of composites for liquid oxygen tanks.

Low wear braking material with high friction coefficient

The addition of high-hardness friction-increasing fillers causes additional wear and tear, resulting in significant dust and pollutants. In this paper, the role of fluorite, a strategic resource with moderate hardness, in an environmentally friendly friction material with a low wear rate and a high friction coefficient is investigated for the first time. The effects of fluorite on the physical, mechanical, and friction properties of friction composites were explored. It is shown that weak chemisorption between fluorite and phenolic resin improves the binding ability. Meanwhile, fluorite can inhibit the degradation of phenolic resin, improve the thermal stability of friction materials, and effectively reduce the wear rate. This study provides a theoretical guidance for the development of mineral applications in friction materials.

Colorimetric High-Throughput Screening Assay to Engineer Fungal Peroxygenases for the Degradation of Thermoset Composite Epoxy Resins

At present, the end-of-life management of thermoset composite epoxy resins is limited to incineration and landfill storage, highlighting the demand for the development of more sustainable measures. Due to their broad spectrum of C-H oxyfunctionalization reactions, fungal unspecific peroxygenases (UPOs) are becoming important biotechnological tools in organic synthesis while their potential use in biodegradation processes should not be underestimated. Here, we present a colorimetric screening assay aimed at engineering UPOs for the degradation of epoxy resins. We based our study on Hexflow® RTM-6, a commercial epoxy resin used extensively in the aeronautics sector. UPO mutants from the short and long families were initially benchmarked by GC/MS to determine their potential N-dealkylation activity on N,N-bis(2-hydroxypropyl)-p-toluidine (NNBT), the main structural scaffold of Hexflow® RTM-6. A reliable high-throughput colorimetric screening method was developed to quantify the lactaldehyde released by UPO attack on the tertiary amine of NNBT. Based on an evolved UPO from Psathyrella aberdarensis that was expressed by yeast, a small subset of mutant libraries with different mutational loadings was constructed and screened for NNBT N-dealkylation, thereby establishing a directed evolution platform as a vehicle to engineer UPO composite degrading variants.

Preparation of phenol-formaldehyde resin modified with phenol-rich pine needle pyrolysis oil and assessment of bonding strength

ABSTRACT The pine needles bio-oil was partially replaced with phenol-formaldehyde (PF) resin at a rate of up to 40% by weight. The wood adhesive characteristics of a newly produced bio-oil phenol-formaldehyde (BOPF) resin with 10% bio-oil replacements was found to be comparable to those of pure PF resin with similar shear strength. DSC revealed that the curing temperature of 20 wt-% BOPF resin decreased from 95 to 60°C. Thermal degradation of BOPF resins was somewhat lower than that of pure PF resin, according to TGA and DTG data, and was similar in 10 and 20 wt-% BOPF resins. The presence of methylene bridges between phenols shown by FTIR analysis indicated that the wood adhesive had a good quality. According to SEM examination, the 10 and 20% BOPF resins showed a flat microstructure comparable to the pure PF resin.

Influence of curing modes on monomer elution, sorption and solubility of dual-cure resin-cements

ObjectiveTo explore the effect of two curing modes, for dual-cure resin cements, on their monomer elution, water sorption and solubility after 30 d water storage and 30 d dry reconditioning. MethodsEight dual-cure resin-cements were investigated (Bifix SE, Nexus Third Generation, PANAVIA SA, PANAVIA V5, RelyX Ultimate Universal, RelyX Unicem 2, RelyX Universal and SpeedCEM Plus). Six disk-shaped specimens were made per curing mode: light-cure (LC) versus self-cure (SC) to measure amounts of eluted monomers after 30 d of water storage at 37 °C. Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC MS/MS) was performed to identify and quantify three eluted monomers (Bis-GMA, UDMA and TEGDMA). Water sorption/ solubility specimens were prepared according to ISO 4049. Specimens from each curing mode (LC/SC) were immersed separately in distilled water for 30 d and then reconditioned for 30 d; all at 37 °C. Mass change was measured at different time intervals. Data were analyzed via one-way ANOVA, Tukey post-hoc tests and independent sample t-tests (α = 0.05). ResultsAfter 30 d of water storage, the three monomers Bis-GMA, UDMA and TEGDMA were detected in water. All monomers showed a variable extent of elution into water and were significantly higher (p < 0.0001) with SC compared to LC curing modes. BSE had the highest quantity of eluted monomers. After 30 d of water sorption (μg/mm3), all rein-cements showed significantly higher sorption (p < 0.05) of SC compared to LC curing modes except for PV5, RXU and CEM (p > 0.05). After 30 d of water solubility (μg/mm3), all resin-cements showed significantly higher solubility (p < 0.0001) of SC compared to LC curing mode. BSE had the highest water sorption and solubility. The total amounts of eluted monomers correlated positively with solubility: r2 = 0.95 for LC and r2 = 0.93 for SC. SignificanceWhenever light access is possible, light curing remains beneficial to reduce the extent of resin degradation and related properties of dual-cure resin cements. BSE showed statistically the highest extent of eluted monomers, sorption and solubility.

Study on the Morphology Characteristics of Epoxy Resin of Composite Insulator under Acid-heat Condition

Whether epoxy resin is degraded or not in composite insulators is the most direct criterion to distinguish Decay-like fracture from brittle fracture and normally mechanical fracture. During the actual operation of composite insulators, the nitric acid produced by partial discharge and abnormal heating will accelerate the degradation and deterioration of epoxy resin of composite insulators. In this paper, the experimental platform under acid-heat condition is built by using heating furnace, grinding bottle and serpentine condensation tube, and the acid-heat deterioration experiments are carried out under 60 °C (3 mol/L and 5 mol/L) and 80 °C (3 mol/L and 5 mol/L) condition. The macroscopic and microscopic morphologies of epoxy resin after acid-heat deterioration are analyzed, and the morphology changes of epoxy resin under the influence of acid-heat coupling field are studied. Firstly, it is concluded that the epoxy resin changes directly from colorless to light yellow, and then from light yellow to dark yellow under the influence of acid-heat deterioration. In addition, in the early stage of deterioration, the bulge on the surface of epoxy resin decreases gradually. Meanwhile, the maximum height difference and standard deviation of the surface profile of epoxy resin also gradually decreases, and the roughness decreases. In the later stage of deterioration, cracks appear on the surface of epoxy resin and some epoxy resins fall off. At the same time, the maximum height difference and standard deviation of surface profile of epoxy resin increases.

Application of radio analytical tracer technique to study the performance of industrial grade ion exchange resin exposed to UV radiations

Abstract The thermodynamics and kinetics of bromide ion-isotopic exchange reactions performed by using fresh and UV radiation degraded industrial grade anion exchange resin Duolite A-638 resins were studied by application of radio analytical tracer technique. The reaction rate k in min−1 for the fresh resin decreases sharply with decrease in wavelength of UV radiations. Thus for 0.200 M labeled bromide ion solution maintained at a constant temperature of 30.0 °C, the k value for fresh resin (0.367 min−1), decreases to 0.335 min−1 for λ384 UV radiation degraded resin, which further decreases to 0.273 min−1 for λ284 UV radiation degraded resin. Under identical experimental conditions, the thermodynamic parameters like energy of activation (−1.65 kJ/mol), enthalpy of activation (−4.24 kJ/mol), free energy of activation (64.85 kJ/mol), and entropy of activation (−0.229 kJ/K/mol) calculated for the fresh resin increases to −1.61 kJ/mol, −4.19 kJ/mol, 64.92 kJ/mol, and −0.228 kJ/K/mol respectively for λ384 UV radiation degraded resin; which further increases to −1.60 kJ/mol, −4.18 kJ/mol, 65.17 kJ/mol, and −0.228 kJ/K/mol respectively for λ284 UV radiation degraded resin. Increase in thermodynamic parameters calculated here for the fresh and degraded resins suggests that decrease in wavelength of UV radiations has catastrophic effect on the resin making the bromide ion-isotopic exchange reactions thermodynamically less feasible. The impact of UV radiation on resin degradation was supported by their characterization study using Fourier-transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) techniques.

Effect of acid corrosion on properties of composite insulator core rod

In recent years, there have been a number of composite insulator decay-like fracture faults characterized by resin degradation and irregular fracture morphology, which seriously threaten the safety and stability of power system. At present, the research of composite insulator’s decay-like fracture is still in the initial stage at home and abroad, and there is no clear conclusion on the causes of its fracture, influencing factors and other important scientific and technical issues, and there is no unified understanding of the mechanism of decay-like fracture. In view of the above problems, this paper carries out acid corrosion test on core rod samples to explore the corrosion law of nitric acid on core rod and its influence on properties. The results show that acid corrosion is one of the factors causing the degradation of epoxy resin. With the increase of nitric acid concentration and soaking time, the degradation rate of epoxy resin accelerates, and the core rod sample gradually changes from emerald green to yellowish brown, then to light yellow, and finally to white hair like glass fibre. The effect of the sample under the long-time action of low concentration nitric acid is the same as that under the short-time action of high concentration nitric acid. Nitric acid will continuously erode into the core rod, resulting in the decrease of hardness and performance on the core rod surface.

Controlling degradation and recycling of carbon fiber reinforced bismaleimide resin composites via selective cleavage of imide bonds

Carbon fiber reinforced bismaleimide resin (CF/BMI) composites are widely used in aerospace field due to their high thermal stability, chemical resistance and excellent mechanical properties. With the large-scale application of CF/BMI composites, it is inevitable to produce a lot of solid wastes, which have a serious impact on the environment, so people have to recycle waste CF/BMI composites. In view of the physical and chemical properties of BMI resin, we developed a green and friendly chemical recovery method of CF/BMI composites by selectively breaking imide bonds for controlled chemical degradation of BMI resin. In 5 wt% NaOH/H2O reaction system, the controlled chemical degradation of CF/BMI composites can be realized by selective cleavage of imide bonds, and the 4,4′-Diaminodiphenyl methane (DDM) and 2,2′,2″,2‴-((methylenebis(4,1-phenylene))bis(azanetriyl))tetrasuccinic acid (MBTA) can be recovered, and the carbon fiber (CF) can be recycled at the same time. Under the optimal reaction conditions, the yields of DDM and MBTA reached 6.7 wt% and 27.9 wt% at 180 °C for 8 h, respectively. Meanwhile, CF in CF/BMI composites can be completely recovered, and the tensile strength of recovered carbon fiber (rCF) is about 97.6% of that of virgin carbon fiber (vCF). This work provides a very promising strategy for the recycling of CF/BMI composites. The high value-added CF and chemicals (DDM and MBTA) can be recovered by controlled degradation of CF/BMI composites via selective cleavage of imide bonds.

Efficient catalytic degradation of anhydride-cured epoxy resin by amphiphilic molecule catalysts

A novel strategy was proposed for the complete degradation of ACEP by an amphiphilic catalyst in water under mild conditions.

Comparative Evaluation of Microshear Bond Strength of Adhesive Resin Incorporated with Inorganic Nanofillers Cerium Dioxide: An In-vitro Study

Introduction: Dental adhesives are used for a wide range of clinical applications in dentistry. Bonding is required in direct composite resin restorations. In clinical situation, resin to dentin bonds are less resistant than resin to enamel bonds. Because of varying structure and composition of dentin the failure of resin-dentin bonding resulting in staining, caries recurrence microleakage. These set of circumstances can hasten the failure and degradation of resin to dentin bonding hence inorganic fillers can be added to improve the bond strength. Cerium dioxide (CeO2 ) is a rare earth oxide has been increasingly used as a nanotherapeutic material and can be successfully used in adhesive resin to improve the physical properties of adhesive resin. Aim: To evaluate and compare microshear bond strength of adhesive resin after incorporation of inorganic nanofillers cerium dioxide. Materials and Methods: This in-vitro study was conducted in Department of Preventive and Paediatric Dentistry at School of Dental Sciences, Krishna Institute of Medical Sciences, Karad, Maharashtra, India, from February 2022 to April 2022. The unfilled dental adhesive was used as a control (group A) and dental adhesives formulated with nanosized Cerium dioxide (CeO2 ) as the inorganic filler (group B). Total 24 samples were prepared 12 samples each group and adhesives were evaluated for microshear bond strength. Intragroup comparison between experimental and control group was done using Unpaired t-test. Results: The mean microshear bond strength of the adhesive system containing nanosized cerium dioxide at a concentration of 2% was 6.89±2.22 MPa (group B), which was significantly greater than that of the adhesive system without additives (group A) 4.37±1.22 MPa. Conclusion: Microshear bond strength of the dental adhesives with nanosized CeO2 particles, was significantly higher than the unfilled adhesive.

Effect of temperature and water penetration on the interfacial bond between epoxy resin and glass fiber: A molecular dynamics study

According to the hydrothermal working environment, accidents related to composite insulator string rupture are frequently encountered in transmission line, which cause serious hazard to the stability of power system. The interface between epoxy resin matrix and glass fiber fillers is one of the microscopic interfaces in the insulator core rod. The adhesion strength of that interface has important implications for the overall mechanical properties of the core rod. This study aims to analyze the influence of temperature and water intrusion on the interfacial adhesions. By molecular dynamics (MD) simulation, a molecular modelling of epoxy resin / glass fiber interface under water molecular environment was established. The mechanism of deterioration is indicated through the interfacial binding energy, ester number, radial distribution function (RDF) and H-bonds number of the interface model. It was found that when the temperature increased to a certain level, the water molecules were easy to migrate to the interface through the holes in the epoxy resin. When the temperature reaches 373 K, the epoxy resin occurs hydrolysis reaction, which will promote the cracking of epoxy resin. Meanwhile, water molecules migrated to the interface can hinder the formation of hydrogen bonds between epoxy resin and glass fiber. Under the synergistic effect of the above factors, water gradually causes the degradation of epoxy resin / glass fiber interface.