Degradation Of Resin Research Articles

Controlled Degradation of Commercial Resin and Its Application to Melt Blowing Process

Controlled Degradation of Commercial Resin and Its Application to Melt Blowing Process

Degradation Behavior of Biobased Epoxy Resins in Mild Acidic Media

The accelerated hydrolytic degradation of biobased epoxy resins, prepared through anhydride curing of epoxidized vanillic acid (EVA, a product of lignin depolymerization) and epoxidized soybean oil...

A comparison of spent resin degradation by Fenton and O3-Fenton process

The treatment of spent resin generated by nuclear power plants using Fenton and O3-Fenton process as an alternative to the present cementation method is an attractive solution. A comparison among O3-Fenton and Fenton process for spent resin degradation were performed in this investigation. The different effects of reaction temperature and ozone concentration was compared between Fenton and O3-Fenton process. In addition the resulted COD removal ratio, residue weight, iron ions concentration change, resin dissolution, degradation intermediates and final products were also compared in these two processes. The results showed that the addition of O3 to Fenton process can improve the degradation ratio of spent resin. With an O3 concentration of 161.3 mg/L, the resin degradation ratio reached 97.1%. The residue COD of O3-Fenton process was 60.0% lower than Fenton process. With O3 addition, the dissolution rate of spent resin was reduced and the mineralization rate of dissolved organics increased by 19.3%. The residual organic matters in the final solution included mainly oxalic acid. The degradation of spent resin after dissolution conformed to the first-order kinetic equation in both Fenton and O3-Fenton process. O3-Fenton process could get better results and save processing costs.

Impact of dietary acids on the surface roughness and morphology of composite resins.

This in vitro study was performed to evaluate the surface roughness (Ra) and morphology by scanning electron microscopy (SEM) of composite resins that had been stored in acidic solutions typical of those present in the diet. Three composite resins (4 Seasons, Z250, and P90) were selected and divided into three groups (n = 7) according to the solutions tested: G1: distilled water; G2, Coca-cola, and G3: orange juice. The Ra test was repeated after immersion periods of 15, 90, and 180 days. The mean Ra values were subjected to LS means analysis and the Tukey-Kramer (P < 0.05). One test specimen of each composite resin was selected for SEM analysis after each period. The Ra data indicated that P90 had the lowest Ra values. 4 Seasons and Z250 had statistically similar roughness values for all the solutions and evaluation periods. With the exception of 180-day immersion in Coca-cola, 4 Seasons showed significantly higher values than Z250. SEM analysis showed that P90 was the composite resin most resistant to the actions of all acid solutions for the periods analyzed. Interaction between components of the solutions and the active components of other dietary items, as well as oral hygiene, may affect the chemical degradation of composite resins.

Nanoscale Fe0/Cu0 bimetallic catalysts for Fenton-like oxidation of the mixture of nuclear-grade cationic and anionic exchange resins

Spent resins generated from the nuclear industrial processes are still difficult to be treated and disposed. Fenton-like processes have great application potential in the treatment of spent resins, but the Fenton reaction mechanisms and resin degradation pathways remain challenging. In this study, nanoscale Fe0/Cu0 bimetallic catalysts were prepared and characterized for the Fenton-like degradation of the mixture of cationic and anionic resins. High catalytic property of Fe0/Cu0 bimetallic nanoparticles activated by H2O2 was evaluated, according to the effects of various nanoparticles, temperature, catalyst amount, H2O2 concentration and the mixing ratio of cationic and anionic resins. Combined the shape and color changes of mixed resins with the experimental and calculated characterization results, different degradation difficulty of cationic and anionic resins and their degradation mechanisms were studied. According to the density functional theory calculations of the optimized resin molecules with the Fe0/Cu0 catalyst, the mechanisms of Fenton-like reactions and the degradation of mixed resins through the synergistic effect of Fe and Cu species were proposed. The comprehensive Fenton-like reactions and degradation mechanisms provide new insights to advance the treatment of spent resins and organic polymers by Fenton-like processes.

A Study of the Interactions between Phenolic Resin and Metal Sulphides and Their Contribution to PAD Performance and Wear

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;In order to keep the coefficient of friction stable, some additives such as metal sulphides, are included in the brake pads formulation. Previous work from RIMSA has shown that oxidation temperature range of the metal sulphides can be one of the key properties to explain their contribution to the performance and wear of a PAD. This new work is a step forward in the interpretation of the mechanism of sulphides as chemically active additives in the brake pads. Phenolic resin is the matrix of the brake pads and starts to decompose around 300 °C in presence of oxygen and temperature.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;In order to establish a connection on between sulphide oxidation and phenolic resin degradation, several studies based on heat treatment of blends of different metal sulphides (Iron sulphide, Tin sulphide and Composite sulphide) with phenolic resin have been done. Then the material evolution was studied with techniques such as TGA-DSC, XRD, IR and SEM-EDS.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;The results obtained confirm that there is an interaction between metal sulphides and resin, and the oxidation mechanism of both materials seems to be modified when they were blended. Studying PAD surface cross section after SAE J2522 and J2707, this work then introduces several SEM - EDS evidences that this mechanism can be found in the brake pads, and the results appoint that oxygen is present several tens of microns beneath the PAD surface during braking. This research will contribute to understanding the tribochemistry of the metal sulphides and phenolic resin that take place during braking and so the pad behaviour.&lt;/div&gt;&lt;/div&gt;

Synthesis of a comb-like silicone-epoxy co-polymer with high thermal stability and mechanical properties for ablative materials

A comb-like silicone-epoxy co-polymer was prepared by synergizing o-allylphenol modified (UC-233) and methoxy-terminated methylphenyl silicone intermediate (PMPS-S). The SEM and DMA revealed that the comb-like silicone-epoxy co-polymer showed better compatibility owing to the pre-chemical grafting reaction. Additionally, TGA revealed that the carbon residue of the comb-like silicone-epoxy co-polymer reached 45.06% at 800 °C in N2, the thermal stability of the comb-like silicone-epoxy co-polymer was improved and maintained the excellent mechanical properties of epoxy resin. Furthermore, TGA-FTIR shows the thermal degradation process that methoxy-terminated methylphenyl silicone intermediate (PMPS-S) and phenyl hydrogen-containing silicone oil (UC-233) could inhibit the degradation of epoxy resin. Therefore, it is believed that comb-like silicone-epoxy co-polymer, with mechanical properties, thermal stability and high thermal residual weight and will have application potential in ablative materials.

Human neutrophils compromise the restoration-tooth interface

Neutrophils, cells of the innate immune system, enter the mouth and release factors that are hypothesized to contribute to the degradation of tooth dentin, methacrylate resin composites, and adhesives at the restoration-tooth-dentin interface. The objectives were to characterize neutrophils’ degradation towards resin composite, self-etch (SE) and total-etch (TE) adhesives, SE and TE resin-dentin interfaces and to identify proteins that could contribute to the degradation process. Neutrophils’ degradation of cured resin composite, and SE and TE adhesives, was quantified by measuring the specific resin degradation by-product, bishydroxy-propoxy-phenyl-propane (bisHPPP), released after 30 days incubation of the materials with the cells. Neutrophils’ degradative effect on resin-dentin interfaces was examined by recording the interfacial fracture toughness (FT), and surface analysis of the fracture mode following incubation of SE and TE miniature short-rod (mini-SR) specimens with the cells. Neutrophils increased degradation of polymerized resin composite, and TE adhesive, but not SE adhesive over 30 days (p < 0.05). Incubation of SE and TE resin-dentin interfaces with neutrophils led to a reduction in FT over time (p < 0.05). The effect was more pronounced for TE interfaces. Neutrophils also affected the fracture mode of SE and TE resin-dentin interfaces. Several proteins that could contribute to the degradative activity of neutrophils, including Neutrophil collagenase (MMP-8), Matrix metalloproteinase- 9 (MMP-9), Cathepsin G, Neutrophil- gelatinase associated lipocalin (NGAL) and Myeloperoxidase, were isolated. The ability of neutrophils to degrade resin, tooth dentin, and reduce the bond strength of resin-dentin interfaces suggest neutrophils’ potential role in primary and recurrent caries and dental restoration failure.

Carbon particulate and controlled-hydrolysis assisted extrusion foaming of semi-crystalline polyethylene terephthalate for the enhanced thermal insulation property

This work presents a facile method to produce low-density PET foams using pristine semi-crystalline resin by moisture-induced controlled-hydrolysis in a tight processing window (moisture content ∼ 0.12 wt.%). We investigated the effect of moisture and moisture containing activated carbon (AC) on the foam expansion ratio, cell morphology, and PET resin degradation and crystallization properties. Controlled-hydrolysis increased the melt-flow rate of PET resin (intrinsic viscosity: 0.52 to 0.54 dL/g) without losing crystallinity, and thus the PET foams possess better tensile properties (∼2 MPa stress and ∼100% strain) and higher thermal stability (&gt;200°C) than chemically modified PET foams. The foam density could be made as low as ∼ 0.15 g/cm3 using a lab scale twin-screw extruder. A strand array die was also designed to produce plate-shaped foam samples. AC allowed easier control of the moisture content and delayed resin degradation in extrusion. Both AC and micrographite (mGr) could stabilize the PET foam morphology in extrusion and serve as good infrared attenuation agents (IAAs) in a simulated housing thermal insulation experiment.

Formation Mechanism of Bleaching Damage for a Biopolymer: Differences between Sodium Hypochlorite and Hydrogen Peroxide Bleaching Methods for Shellac.

Bleached shellac, a widely used material in food processing and products, was deeply affected in terms of structures and properties by the bleaching method. In the present study, a marked difference was observed between the damage performances of sodium hypochlorite-bleached shellac (SHBS) and hydrogen peroxide-bleached shellac (HPBS). The main bleaching damage reactions of sodium hypochlorite were the addition of double bonds to generate chlorine and the oxidation of hydroxyl to form aldehydes or ketones. In the case of hydrogen peroxide, degradation of shellac resin was caused by the hydrolysis of ester bonds and the oxidation of hydroxyl groups to form aldehydes and ketones, as well as carboxylic acids with deep oxidation. Based on the structural characterization of shellac resin, the bleaching damages were affected by the bleaching agent via the oxidizable groups, such as the unsaturated double bonds, hydroxyl and aldehyde groups in cyclic terpenes, and fatty acid chains. The differences could be attributed to the action of sodium hypochlorite on the hydroxyl group of aldehyde or ketone. Conversely, hydrogen peroxide bleaching oxidized the hydroxyl group and aldehyde group to carboxylic acid and initiated the hydrolysis reaction of the ester bond of the shellac resin, leading to the degradation of the resin. Thus, understanding the mechanism underlying the bleaching damage could provide a scientific basis for the subsequent targeted regulation of bleaching damage.

Effect of polydopamine incorporated dentin adhesives on bond durability

Inspired by mussel-adhesion phenomenon in wet environment, polydopamine (PDA) was tried in recent research reports to improve the dentin adhesive interface with better strength and durability. The aim of this study was to comparatively evaluate the effect of PDA incorporated dentin adhesive systems and conventional adhesive systems on degree of conversion (DC), resin dentin bond strength (SBS), durability and MMP inhibition activity. In this study, PDA was incorporated in total-etch adhesive system (TE) and self-etch adhesive systems (SE) and degree of conversion (DC%) was evaluated using Fourier transform infrared spectroscopy. Dentin slabs obtained from 160 non-carious human premolars were divided into the following: Group 1, TE; Group 2, PDA incorporated TE adhesive (TEP); Group 3, SE; Group 4, PDA incorporated SE adhesive (SEP) and bonding procedures were performed. Samples were stored for either 24 h or 6 months, after which shear bond strength and resin dentin interface was evaluated using universal testing machine and confocal laser scanning microscopy (CLSM), respectively. The zymographic assay was performed on protein extracts obtained from dentin powder treated with each of the adhesives or with or without PDA followed by functional activity assay for MMP-2 and -9. Statistical analysis was done with two-way analysis of variance and Student t-test at significance level as p < 0.05. There was statistically no significant difference in the DC% between PDA incorporated adhesives and control. No significant reduction in SBS was observed in TEP and SEP in pre- and post-aging while CLSM showed better penetration depth of resin and lesser degradation of hybrid layer on aging. Significantly lesser MMP activity was seen in PDA incorporated adhesives qualitatively and quantitatively on zymographic and functional MMP activity assay respectively. HIGHLIGHTS Catechol moieties present in polydopamine provide anti-collagenolytic activity, MMP inhibitory activity and enhances wet adhesion. Polydopamine incorporated dentin bonding systems attempts to provide stable resin dentin bond with increased bond durability. It can inhibit both proteolytic and hydrolytic breakdown of resin–dentin bond degradation.

Fire behaviour of hybrid filament-wound single and adhesively bonded composites tubes under static pressure

The present work aims to experimentally investigate the fire behaviour of water-filled E glass reinforced thermoset resin hybrid filament-wound composites tubes under static pressure. Heretofore, fire endurance tests have been conducted on single and adhesively bonded tubes manufactured by CTRA Company. Furthermore, internal pressure tests until failure have been performed on the burnt single and burnt joined tubes in order to quantify their abilities to contain the fluid after being exposed to heat flux. A comparison between the pressure behaviour of exposed to fire (burnt) and non-exposed tubes (single and joined) was also inspected. The identification of the fire-induced damage mechanisms of the tubes was performed through optical microscopy, Scanning Electron Microscopy (SEM) and X-ray tomographic observations. Finally, the thermal analysis was carried-out on burnt specimens in order to better understand the multiphysical phenomenon taking place during the fire endurance tests. The experimental results have revealed that the combustion process of both single and joined tubes was described in four steps namely tube heating, resin degradation, ignition and flame decay. Moreover, it was found that no leakage was witnessed on the tubes (single and joined) outer surfaces during the fire endurance tests. The comparison between the pressure behaviour of the burnt single tube and the burnt joined one has proved that the single tube is much resistant under internal pressure loading than the burnt joined tube. Finally, the fire-induced damage included matrix cracking and delamination between the tube plies which was noticed from microscopic observations.

Transformation of Organic Matter of Domanik Rock from the Romashkino Oilfield in Sub- and Supercritical Water

The transformation of the organic matter (OM) of low-permeable carbon-rich domanik rock of the Romashkino oilfield in sub- and supercritical water (SCW) at temperatures of 320, 374, and 420°C and pressures of 17, 24.6, and 24.4 MPa in a neutral medium has been studied. The original rock with a TOC content of 7% has a high oil generation potential and a low productivity index. The productivity index increases with an increase in the severity of the thermal treatment of the rock, which is due to intense kerogen degradation resulting in the formation of free hydrocarbons that are easy to recover from the rock. In rock extracts, in comparison with the original rock, the amount of saturated and aromatic hydrocarbons increases by more than two times and that of resin–asphaltene substances decreases. Distinctive features of the yields and compositions of rock extracts depending on the temperature of the experiments have been revealed. The highest yield of the extract was observed in the experiment with subcritical water at 320°C and associated with the degradation of resins and more complete extraction of asphaltenes and high-molecular-weight n-alkanes from the rock. Treatment in SCW at 374 and 420°C leads to intensive degradation of the kerogen structure involving the detachment of aliphatic chains from large fragments of kerogen and asphaltene macromolecules to form lower n-alkanes and carbon-rich substances, such as carbenes and carboids. The structure of asphaltenes becomes more condensed and oxidized in the SCW medium at 420°С, leading to a decrease in their paramagnetic properties. Using the EPR technique, the features of hyperfine splitting of the vanadyl complex line on 14N nitrogen nuclei have been revealed in the spectrum of asphaltenes of the SCW experiment at 420°С, indicating specific changes in their structure.

The Influences of Moisture on the Mechanical, Morphological and Thermogravimetric Properties of Mineral Wool Made from Basalt Glass Fibers.

Mineral wool made from basalt fibers is frequently used as an insulating material in construction systems. In this study, both unused mineral wool and wool obtained from the softened roofing area were comprehensively analyzed in a laboratory using different characterization techniques. Firstly, the initial water content and compressive strength at 10% deformation were determined. Secondly, microstructure and surface chemical composition were analyzed by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDX). To study heterogeneities near the fiber surface and to examine cross-sectional composition, a scanning transmission electron microscope (STEM) was used. Finally, to verify possible reasons for resin degradation, thermogravimetric analysis and differential scanning colometry (TGA-DSC) were simultaneously carried out. The results show that natural aging under high humidity and thermal fluctuations greatly affected the surface morphology and chemical composition of the fibrous composite. Phenol-formaldehyde and other hydrophobic compounds that protect fibers against moisture and give compressive resistance were found to be degraded.

Evaluation of the anticorrosive behavior of epoxy-Nb2O5 paint in high temperatures submitted to the environment with sulfuric acid

The aim of the present work is to evaluate the corrosion resistance of epoxy-Nb2O5 paint in acid atmosphere and high temperatures. For comparison, samples of SAE1020 carbon steel were coated with an epoxy-Nb2O5 paint and an epoxy commercial paint. The samples were partially immersed for 720 h and 1440 h in 40% (v/v) H2SO4 solution at temperatures of 25°C, 60°C, and 80°C. The degradation analysis, mechanical characterization, and electrochemical measurements of the samples were carried out after immersion period. The coatings were characterized by scanning electron microscopy. Electrochemical impedance spectroscopy was used to evaluate the electrochemical behavior. Results showed the epoxy-Nb2O5 paint was less blistering, cracked, flaked, and rusted than the commercial epoxy paint samples. However, it was important to note that the increase in temperature led to the degradation of epoxy-Nb2O5 paint. The addition of temperature was probably responsible for the degradation of epoxy resin over the immersion time.

Decomposition of spent radioactive ion‐exchange resin using photo‐Fenton process

AbstractBACKGROUNDThe treatment of spent radioactive ion‐exchange resin is of great importance in reducing total waste volume and minimizing potential environmental hazards. In this study, a comparative investigation of resin decomposition by the Fenton and photo‐Fenton process was performed to address these concerns.RESULTSThe effect of UV energy density and irradiation time on residue chemical oxygen demand (COD) was investigated. With a UV energy density of 6.1 J cm−2 and irradiation time of 120 min, the COD removal ratio reached 97.3%. Under optimized conditions, the residue COD obtained via photo‐Fenton was 47.3% lower than that via Fenton. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and ion chromatography (IC) were used to characterize the resin beads and intermediates. Four types of small molecular organic acids were monitored during the reaction. The degradation process of two stages was proposed, involving resin dissolution and mineralization.CONCLUSIONPhoto‐Fenton showed better performance for IRN 77 resin degradation compared to the Fenton process. Both the UV energy density and irradiation time showed significant effects on resin degradation. UV irradiation enhanced the mineralization stage during resin degradation. Oxalic acids showed the highest concentration in all main intermediates. © 2020 Society of Chemical Industry

Influence of different structures of palm oil-based polyol on the mechanical and thermal properties of hybrid resin from polyurethane-/polysiloxane-modified epoxy

Hybrid resin from polyurethane-/polysiloxane-modified epoxy (PPME) has been synthesized by using palm oil-based polyol as the polyurethane component. The palm oil-based polyol used are glycerol monooleate, polyethylene glycol monooleate, 1,4-butanediol monooleate and 1,4-butanediol,9-hydroxy-10-methoxy-monostearate. These polyols have a different chemical structure with each other. Here, we studied the influence of palm oil-based polyol structure on the mechanical and thermal properties of hybrid resin from PPME. Characterization of palm oil-based polyols structure was conducted by analysis FTIR and NMR. The qualitative analysis of palm oil-based polyols was carried out by determining acid value, ester value, iod value and hydroxyl value. The mechanical properties showed that PPME hybrid resin from 1,4-butanediol,9-hydroxy-10-methoxy-monostearate has the highest mechanical properties, while the thermal properties of hybrid resin showed that there is no significant influence of the polyols structure, but all of the PPME hybrid resins have higher thermal properties than unmodified epoxy. Nevertheless, the thermal degradation of PPME hybrid resin from 1,4-butanediol,9-hydroxy-10-methoxy-monostearate at 400–450 °C has the highest residual weight. It means that it shows the highest thermal stability.

Ageing of Dental Composites Based on Methacrylate Resins-A Critical Review of the Causes and Method of Assessment.

The paper reviews the environmental factors affecting ageing processes, and the degradation of resins, filler, and the filler-matrix interface. It discusses the current methods of testing materials in vitro. A review of literature was conducted with the main sources being PubMed. ScienceDirect, Mendeley, and Google Scholar were used as other resources. Studies were selected based on relevance, with a preference given to recent research. The ageing process is an inherent element of the use of resin composites in the oral environment, which is very complex and changes dynamically. The hydrolysis of dental resins is accelerated by some substances (enzymes, acids). Bonds formed between coupling agent and inorganic filler are prone to hydrolysis. Methods for prediction of long-term behaviour are not included in composite standards. Given the very complex chemical composition of the oral environment, ageing tests based on water can only provide a limited view of the clinical performance of biomaterial. Systems that can reproduce dynamic changes in stress (thermal cycling, fatigue tests) are better able to mimic clinical conditions and could be extremely valuable in predicting dental composite clinical performance. It is essential to identify procedure to determine the ageing process of dental materials.

Examining the early stages of thermal oxidative degradation in epoxy-amine resins

Epoxy-amine resins continue to find widespread use as the binders in protective and decorative organic coatings, as the matrix in composite materials, and as adhesives. In service, exposure to the environment ultimately results in oxidative deterioration of these materials, limiting the performance lifetime. Defining this auto-oxidation process is therefore a key challenge in developing more durable high-performance materials. In this study, we investigate oxidative degradation of a model resin based on diglycidyl ether of bisphenol-A (DGEBA) and an aliphatic amine hardener, triethylenetetraamine (TETA). Using infrared spectroscopy, we find that prior to the expected detection of formate groups (corresponding to the well-known radical oxidation mechanism of DGEBA), a band at 1658 cm−1 forms, associated with amine cross-linker oxidation. Infrared microspectroscopy, in-situ heated ATR-infrared, Raman spectroscopy and AFM-IR techniques are thus employed to investigate the early stages of resin oxidation and demonstrate strong parallels between the initial stages of cured resin degradation and the auto-oxidation of TETA cross-linker molecules.

New methodical approaches for the investigation of weathered epoxy resins used for corrosion protection of steel constructions

Epoxy resin coatings applied to steel constructions for corrosion protection purposes are often exposed to UV-irradiation and weathering during the construction process. Chemical alteration of the hardened coating might lead to i) the release of potentially harmful substances into the environment and ii) delamination of the polyurethane top layer. However, chemical processes and mechanisms occurring on the surfaces of exposed epoxy resin coatings are not fully understood yet. Herein, we present an innovative approach combining time-of-flight secondary ion mass spectrometry (ToF-SIMS) with inductively coupled plasma mass spectrometry (ICP-MS) and liquid chromatography mass spectrometry (LC-MS) enabling the elucidation of underlying chemical processes and the identification of released organic and inorganic photolytic products. IR-spectroscopy and experiments targeting the acidity/pH-value changes on top of weathered surfaces complement our investigations. It was confirmed that UV-A irradiation leads to photooxidative degradation of the epoxy resin and that inorganic photolytic products are exposed on the weathered surfaces. Polar moieties (hydroxyls, carbonyls, carboxyls, amines) and released metalloids form a hydrophilic surface layer, which hinders adhesion and eventually prevents profound chemical linkage of the polyurethane top layer. Thus, an early delamination of the top layer might occur very likely.