Removal Of Resin Research Articles

Effect of pH Value on Chelating Resin Removal of Heavy Metals in Sewage Using Laser-Induced Breakdown Spectroscopic Detection

Effect of pH Value on Chelating Resin Removal of Heavy Metals in Sewage Using Laser-Induced Breakdown Spectroscopic Detection

Comparison of shear bond strength of rebonded brackets prepared with different methods of resin removal: an in vitro study.

Clinicians and researchers have always made every effort to achieve proper bonding between the surface of the tooth and the rebonded orthodontic brackets in order to prevent the re-fracture failure of orthodontic pressures throughout treatment. The aim of this study was to determine the bond strength of rebonded brackets by four adhesive removal methods.

About Gas Barrier Performance and Recyclability of Waterborne Coatings on Paperboard

For preserving food packed in environmentally friendly and recyclable paperboard packages, it is important to have sufficient gas barrier performance of the paperboard container. Paperboard has poor intrinsic barrier properties and to overcome this deficiency, so a barrier coating is needed that does not hinder the recycling of the paperboard substrate. However, the gas barrier properties and the recyclability of such coatings have been rarely studied. Here, both the gas barrier performance and the removal of an alkali-soluble resin (ASR)-stabilized waterborne barrier coatings from paperboard are investigated. For barriers for gases, such as nitrogen, carbon dioxide, and oxygen, defect-free coatings are needed which is achieved by applying three coating layers. The oxygen transmission rate (OTR) of the three-layered coating on paperboard was 920 cm3/(m2∙day). For water vapor barriers, two coating layers already show a strong improvement, as water follows a different penetration mechanism than the other tested gases. The water vapor transmission rate WVTR of double coated paperboard was 240 g/(m2∙day). Preliminary results show that the coating is removed by immersion of the coated paperboard in an aqueous alkaline solution at room temperature. This causes de-protonation of the carboxylic acids of the ASR and subsequent re-dispersion of the coating in water. Removing double-layer coatings from the paperboard is more challenging, possibly due to the coating/coating interface between the two coating layers and enhanced adhesion between coating and paperboard.

Recording and analysing DNA from osteocytes in resin-embedded bone samples.

We report on a process to record the presence and the location of osteocyte nuclei using two nucleic staining dyes, Diamond™ Nucleic Acids Dye (DD) and DAPI (4',6-diamidino-2-phenylindole). Knowledge of the presence and number of osteocytes is key to any success in subsequent DNA profiling. Osteocytes are most numerous cells and thus the main source of DNA in bone samples, which can be preserved for histological analyses. Archived samples are either fixed in formalin or preserved in ethanol prior to embedding in resin. These resin-embedded samples are potentially used as ante mortem reference samples. Cases of a missing person investigation are one example where this type of preserved reference material may be of value. When resin is required for sample preservation it represents a problem for subsequent DNA profiling, if needed as a reference sample in human identification. It is essential therefore to remove the resin prior to DNA analyses as resin is a known inhibitor of DNA profiling. Current methods of resin removal are lengthy and require toxic chemicals. This report describes a simplified process to remove resin and visualise the location of nucleated osteocytes. Eight sections of bone samples at 5-µm thickness were stained with DD and DAPI. A further three samples were processed using a formalin-fixed method and three additional samples treated following an ethanol-preserved method (11 samples for both the formalin-fixed and 11 for the ethanol-preserved with eight in common). The location and number of nuclei could be recorded clearly due to the fluorescence created by the dye binding to DNA. The number of stained nuclei correlated with the mass of DNA isolated from the sections (r = 0.873, p = 1.21 × 10-10). A significant difference between the degradation indices of two groups (p = 8.505 × 10-5) showed that ethanol preservation is a preferred method to yield DNA of the quality needed for subsequent short tandem repeats (STR) profiling. Ten of the 11 samples isolated using the ethanol-preserved process recorded a complete STR profile (30/30 alleles), whereas eight of the formalin-fixed samples generated full profiles, and only one of the 11 samples amplified less than 23 alleles. Both the ethanol-preserved and formalin-fixed methods are an improvement on current methods by removing the need for strong solutes in resin removal, and the method leads to STR profiles from resin-embedded bone samples within 24h.

Evaluation of Different Adhesive Resin Removal Methods after Debonding Ceramic Orthodontic Molar Tubes: A Scanning Electron Microscope Study.

To evaluate and compare the impacts, bond strength, residual adhesive, and time invested on the enamel surface after debonding of recently introduced ceramic buccal molar tubes with different systems. Ceramic molar tubes were bonded to fifty-four maxillary molar teeth, and a shear bond strength (SBS) test was performed. The adhesive remnant index (ARI) scores were recorded, and the samples were divided into two groups for adhesive removal with low-speed instruments: tungsten carbide bur or diamond-coated micropolisher point. The time to clean the enamel surfaces was also noted down for each tooth. The enamel surfaces were investigated with scanning electron microscope (SEM) after adhesives were cleaned. Shapiro-Wilk's, Kolmogorov-Smirnov's, and Student's independent t tests were used for statistical analysis. The mean SBS value of the tested ceramic molar tubes was 9.78 ± 1.85 MPa, and the majority of the samples were scored as ARI 1 and ARI 2. No statistically significant difference between PoGo micropolisher and TCB was found in terms of time values for surface cleaning. The enamel surface characteristics of TCB for adhesive remnant removal resulted in a better enamel surface than the single-step diamond polisher when the samples were investigated by using SEM. Ceramic molar tubes may be an enamel-safe product for patients seeking for fully aesthetic orthodontic treatment, if used in carefully handled clinical conditions. One-step polishing systems utilised with low-speed instruments could be used confidentially for cleaning the resin remnants on enamel after orthodontic treatment.

A Comparison of Canal Width Changes in Simulated Curved Canals prepared with Profile and Protaper Rotary Systems

With advancement in the endodontic technology there is a quest to introduce root canal instruments showing superior performance by removing minimum amount of sound root dentine and retaining the original shape of the root canal. Objective: To compare the changes in the width of simulated curved canals prepared with ProFile and ProTaper rotary system. Methods: This in-vitro, Quasi Experimental study was carried out in the Dental section of The Aga Khan University Hospital. Pre and post instrumentation photographs (images) of sixty resin blocks prepared with ProFile and ProTaper rotary instruments respectively (with 1:10 magnification) were superimposed using software Adobe Photoshop 6.0. Measurements were done on print out of composite images. Measurements of change in width (resin removed) were recorded along the length of canal at 12 points. Results: Two rotary system showed statistically significant difference in simulated curved canals width after preparation. ProTaper rotary instruments showed more resin removal at the inner walls of the canal at 1, 8-12mm from the apex and more resin removal at outer wall of canal at 9-12 mm from apex. Conclusions: ProFile and ProTaper rotary files showed statistically significant difference in canal width after instrumentation. ProTaper rotary files showed more resin removal in canals towards the inner wall and coronal part of the outer wall.

Thermo-hydrolytic recycling of urea-formaldehyde resin-bonded laminated particleboards

The large global production of particleboards creates an equal quantity of particleboard waste after completion of their service life. Given increasing demand for green products and government environmental policies, it is urgent to develop technologies to recycle these used composite panels into valuable raw materials. This study was conducted to recover particles from waste laminated particleboards using various thermo-hydrolytic treatments. The recovered particles were used as raw materials with different substitutions of fresh particles to manufacture particleboard panels. The performance of the resulting particleboards was evaluated in terms of their mechanical properties and formaldehyde emissions. The nitrogen content of the control and resulting particles were measured to determine the resin removal in recycled particles. The results suggested that different thermo-hydrolytic treatments did not have significant influence on particles size distribution. Approximately 65% of urea-formaldehyde resin was removed from the particleboards treated at 140 °C/20 min. Particles recycled at 140 °C/20 min were comparable to fresh particles in terms of mechanical properties and formaldehyde emissions, and 100% of the recycled particles were used in the manufacture of particleboard without an adverse impact on the board performance.

Three-dimensional assessment of human enamel surfaces after adhesive resin removal using CLSM - an in vitro study

Objective: The aim of this study was to evaluate the effects of three different methods of adhesive resin removal on the enamel structure using a confocal laser scanning microscope (CLSM).

3D Printing of natural sandstone at pore scale and comparative analysis on micro-structure and single/two-phase flow properties

As the first effort in literature, the 3DP sample from the micro-CT image of a natural sandstone in this study achieves the printing resolution of 2 μm. The pore structure of both the 3DP and original sample are analyzed comparatively, as well as the pore size distribution (PSD), porosity, and absolute permeability by DRP simulation. The visualized CO2 displacing oil experiment on the 3DP sample are conducted, and compared with the experimental benchmark data. The results indicate that: 1) The PSNR of the 3DP S1 is in [9.010, 14.983], and its SSIM is in [0.870, 0.925]. Most pore features are printed but some are not in its original size or position. 2) The porosity and permeability of the 3DP sample are 10.01% and 27.81mD, showing a decline of 2.91% and 32.49mD compared to the original sample. 3) Two primary causes for the mismatching of the pore structure are confirmed, including insufficient removal of uncured resin, and shrinkage effect in light curing process. 4) Most contact angles of oil in 3DP sample lie in [0°, 90°], indicating it is oil-wetted. This study provides a new tool for the quantitative characterization and accurate understanding of the mobilization and residual mechanism of the multiphases in porous rock.

Detection and Removal of Tooth-Colored Composite Resin Using the Fluorescence-Aided Identification Technique

The detection and removal of tooth-colored filling materials is a major challenge for every dentist. The Fluorescence-aided Identification Technique (FIT) is a noninvasive tool to facilitate the distinction of composite resin material from sound tooth substance. Compared to conventional illumination, FIT is a very accurate, reliable, and fast diagnostic method. When composite resin is illuminated with a wavelength of approximately 398 ± 5 nm, certain fluorescent components make the composite resin appear brighter than the tooth structure. Any fluorescence-inducing light source with the appropriate wavelength can be used for this method. Optimally, this technique is used without additional natural or artificial lighting. The application of FIT can be used for diagnostic purposes, for example, dental charts, and additionally for the complete and minimally invasive removal of composite resin restorations, bracket debonding, and trauma splint removal. The assessment of volumetric changes after composite removal can be provided by overlapping pre- and postoperative scans and subsequent calculation using suitable software.

Detection and Removal of Tooth-Colored Composite Resin Using the Fluorescence-Aided Identification Technique

Detection and Removal of Tooth-Colored Composite Resin Using the Fluorescence-Aided Identification Technique

Impact damage of composite laminates with high-speed waterjet

Rain erosion may cause substantial damage to aircrafts during supersonic flight. Such event is investigated here via high-speed waterjet impact on composite laminates. An experimental setup is developed to produce waterjets with the speed up to 700m/s and a finite element model of the waterjet-composite impact event is established. The consistency of experiment and simulation results validates the adopted numerical methods. The distribution of the water-hammer pressure is non-uniform and the maximum pressure occurs near the contact periphery when the water is about to eject laterally. After a high-speed (300∼560m/s) waterjet impacts a composite laminate, the impacted surface depression is observed, and the typical surface damage presents a central region with no visible surface damage surrounded by a faded “failure ring” with resin removal, matrix cracking and minor fiber fracture. Delamination occurs at the interfaces of adjacent layers with unequal dimensions and longitudinal matrix cracking appears on the back surface. Both the velocity and the diameter of waterjets are crucial factors on CFRP damage extents. Water-hammer pressure, the stagnation pressure and propagation of stress waves are failure mechanisms for most matrix damage in CFRP impacted by waterjets.

Shaping ability of rotary and reciprocating single-file systems in combination with and without different glide path techniques in simulated curved canals

Background/purposeGlide path management (GPM) is a consequential clinical step that serves to influence predictably successful root canal therapy. However, the effect of GPM on the shaping ability of single-file system remains controversial. This study compared the performance of rotary single-file One Curve (OC) and reciprocating single-file Reciproc Blue (RCB) in combination with/without different glide path techniques: no glide path preparation (NG), PathFile (PF), ProGlider (PG) and WaveOne Gold Glider (WOGG), respectively. Materials and methods80 simulated curved canals (n = 10 canals/per group) were instrumented to an apical size of 0.25 mm using OC and RCB in combination with/without different glide path techniques, respectively. The amount of resin removal, canal transportation, and the degree of canal straightening were measured in Photoshop CS6 software. Statistical analysis of the data was performed by using Kruskal–Wallis test, followed by Dunn's post hoc test with Bonferroni correction (α = 0.05). ResultsPost–glide path analysis found that WOGG and PG produced less canal transportation and curvature straightening than PF (P < 0.05). Post-shaping analysis showed that OC groups removed significantly less resin than RCB groups (P < 0.05). The PG and WOGG subgroups in both OC groups and RCB groups produced less transportation and curvature straightening than NG and PF subgroups (P < 0.05). OC + PG subgroup and OC + WOGG subgroup yielded the least canal transportation and curvature straightening (P < 0.05). ConclusionPG and WOGG can improve the shaping ability of OC and RCB instrument. OC, especially when combined with PG and WOGG, has a less aggressive dentin cutting and more centered preparation than the RCB instrument.

Experimental study on removal of phenol formaldehyde resin coating from the abrasive disc and preparation of abrasive disc for polishing application

In the automotive and aerospace industry, abrasive products lodge the major portion of the machining applications. Among that, the coated abrasive disc is used for a finishing application. Once the disc is fully consumed, the disc is unused and considered waste. The present work focuses on removing phenol-formaldehyde resin coating, and the fiber backing is reused for the same coated abrasive disc production application as flexible fiber backing. A sandblasting technique removes phenol-formaldehyde resin coating and embedded abrasive grains. During the fiber backing recovery process, the experimental parameters such as abrasive pressure, abrasive type, abrasive size, and orientation of the disc are varied to find out the optimal surface roughness value for reusing the produced coated abrasive discs. The results highlight that the recovered backing has an abrasive size of 120 mesh pressure of 0.20 MPa, an abrasive type of garnet, and a standoff distance of 1 mm. Surface features such as surface roughness and micrographs of the eroded surface are analyzed. Finally, the recovered backing was reused in the coated abrasive disc production, and the performance of the recovered disc was compared with the standard discs. The recovered fiber backing disc product was similar to a standard fresh disc.

Process optimization and removal of phenol formaldehyde resin coating using mechanical erosion process

Consumption of coated abrasive discs in various automobile and pipe fitting application is increasing, due to its good surface finish. Coated abrasive disc consists of single layer of abrasive grain bonded to a fibre backing. The major portion of the disc is comprised of fibre backing. But the sustainability of the fibre backing is low and is dumped as waste after usage. The present work deals with the removal of resin coating and recovery of fibre backing from the spent coated abrasive discs using physical separation process such as sand blasting technique. Initially, the recovery experiment was carried out based on L16 orthogonal array. The factors and levels chosen for the experiments were erodent pressure (0.2, 0.4, 0.6 and 0.8 MPa), erodent size (36, 60, 80 and 120 grit), disc orientation (30, 45, 60 and 75°) and number of times flexing (5, 10, 15 and 20). The experimental result shows that erodent size and erodent pressure have a major impact on recovery of the fibre backing. The surface structure of the recovered backing was analysed using scanning electron microscopy and optical microscopy. The recovered backing was very much useful for the coated abrasive industry as the flexible backing and support material for abrasive grain coating.

Influence of resin removal treatments on the surface topography and strength of de-bonded lithium disilicate ceramic.

This study aims to assess the influence of resin removal treatment regimes on the surface topography and compressive strength of de-bonded ceramic surfaces. Sixty-five lithium disilicate ceramic (LDC) discs were prepared, cleaned, and polished with carbide paper. All samples were etched using 9.6% hydrofluoric acid (HFA). Fifteen samples were taken as positive controls; the remaining 50 samples were subjected to the process of silanization. Resin build-up using dual-cure cement was performed incrementally and light cured. Based on different methods of resin cleaning from de-bonded LDC, the samples were divided into five groups, n=10 each: group 1 (no treatment), group 2 (slow-speed diamond bur), group 3 (1 min heat treatment), Group 4 (6 min heat treatment), and group 5 (sandblasting with Al2O3). Following resin removal, LDC samples were tested under compressive failure load in a universal testing machine. Five disc specimens from each group were sputter coated with gold for scanning electron microscopy (SEM). Analysis of variance (ANOVA) and Tukey's post hoc test was used for descriptive statistics. Level of significance was established at p<0.05. The highest compressive strength with significant difference among all experimental groups was found in group 5 (321.54 ± 13.25 MPa) (p<0.05). The lowest compressive strength values, presenting significant difference compared with all other groups, were displayed in group 1 (158.57 ± 5.22 MPa) (p<0.05). Compressive strength among group 2 (231.54 ± 15.55 MPa), group 3 (237.81 ± 10.81 MPa), and group 4 (255.53 ± 8.95 MPa) specimens was statistically comparable (p>0.05). On SEM, heat-treated specimens confirmed coarser granules, with mild porosities and roughening, whereas sandblasted specimens exhibited consistent evenness with moderate porosity and loss of glazed surface. De-bonded LDC surface, treated with heat treatment and sandblasting procedures, exhibited removal of residual resin and significantly high compressive strength compared with non-cleansed ceramic surface.

THE PRODUCTION OF PLASTIC LUBRICANTS BASED ON REGENERATED SYNTHETIC MOTOR OILS USED IN UZBEKISTAN

The purpose of the study is to increase the efficiency of using used engine oils as a dispersion medium for plastic lubricants. It has been established that the removal of resins, carbenes, carbides and asphaltenes from used synthetic motor oils makes it possible to obtain an oil base close to commercial base oils in terms of basic characteristics; refined oils also have a high margin of operational properties. The composition of lubricants for analogues of Lithol-24 and Solidol-Z based on refined used engine oils has been determined. Anticorrosive, adhesive and strength properties of lubricant compositions are considered.

On the potential use of two-photon polymerization to 3D print chromatographic packed bed supports

The continuous quest for chromatographic supports offering kinetic performance properties superior to that of the packed bed of spheres has pushed the field to consider alternative formats such as for example monolithic and pillar array columns. This quest seems bound to culminate in the use of 3D printing technology, as this intrinsically offers the possibility to produce supports with a perfect uniformity and with a size and shape that is fully optimized for the chromatographic separation process. However, to be competitive with the current state-of-the-art, structures with sub-micron feature sizes are required. The present contribution therefore investigates the use of the 3D printing technology with the highest possible resolution available today, i.e., two-photon polymerization (2PP). It is shown that 2PP printing is capable of achieving the required ≤ 1 µm printing resolution. Depending on the laser scan speed, the lower limit through-pore size for a tetrahedral skeleton monolith with a theoretical 80% external porosity was found to be at 800 nm, when printing at a scan speed of 50 mm/s with a laser power of 10%. For a scan speed of 10 mm/s, the minimal through-pore size dropped to 500 nm. However, this very high resolution comes at the cost of excessively long printing times. The total printing time for a column volume equivalent to that of a typical nano-LC column (75 µm i.d. cylindrical tube with length L = 15 cm) has been determined to correspond to 330 and 470 h for the 50 mm/s and the 10 mm/s scan speed respectively. Other issues remaining to be solved are the need to clad the printed skeleton with a suitable mesoporous layer for chromatographic retention and the need to add a top-wall to the printed channels after the removal of the non-polymerized resin. It is therefore concluded that 2PP printing is not ready yet to replace the existing column fabrication methods.

Scanning Electron Microscope Image Analysis of Bonding Surfaces following Removal of Composite Resin Restoration Using Er: YAG Laser: In Vitro Study.

It is impossible to remove tooth-colored restorations by mechanical means without unnecessary damage to the adjacent sound tooth structure. This study is aimed at investigating erbium-doped yttrium aluminum garnet (Er: YAG) laser (Hoya ConBio, VersaWave, CA, USA) in removing composite resin restorations and assessing the change in morphology of bonding surfaces using a scanning electron microscope (EDX, CAMSCANNER, 3200LV, UK). The investigators collected thirty extracted sound human premolar teeth for this investigation, and the conventional design class V cavity was prepared on the buccal surface of each specimen. The specimens were allocated randomly into three groups, according to the procedure used for the ablation of the composite restoration: group A (high-speed diamond fissure bur), group B, and group C (Er: YAG laser) using a different pulse repetition rate of 20 Hz (group B) and 25 Hz (group C). The AutoCAD software program (Autodesk, Inc., 2016) was used to calculate the surface area and the resulting dimensional change of the cavities after restoration removal. The cavities were filled with composite resin and randomly assigned into two groups conforming to the methods applied to eliminate the restoration; diamond turbine fissure bur and laser. In each group, two specimens were selected randomly for scanning electron microscope analysis of bonding surfaces. The least meantime for the composite resin removal was observed in the high-speed diamond bur, significantly less than both Er-YAG laser groups (p < 0.001). However, at a higher pulse repetition rate, time-consuming decreased. The results showed that laser is more conservative in removing composite resin restoration as the change was most remarkable in group A (0.800 mm), then group C (0.466 mm), and the slightest change is in group B (0.372 mm) (p = 0.014). The dentin surface of group A showed a smooth surface with no opened dentinal tubule and intact smear layer. In groups B and C, dentin surfaces were irregular, scaly, or flaky, and dentinal tubules were opened without a smear layer. Therefore, Er: YAG laser is effective for composite resin removal considering the parameters chosen in this study with fewer changes in cavity surface area and better microretentive features.

Requirements for the Chemical Recycling of Fibre Reinforced Polymers

The increasing use of fiber reinforced polymers (FRP) in lightweight construction is presenting new fundamental challenges for the recycling industry. In Germany alone, approx. 225 kt of glass fibre reinforced plastic (GFRP) material was produced in 2019, compared to approx. 141 kt of carbon fibre reinforced plastic (CFRP) worldwide, which has to be recycled even after the end-of-life. Main focus is principally on epoxy resin and carbon fibers (used for example in wind power plants and in electro mobility). Apart from pyrolysis, which currently is the only industrially used process and is mainly applied to carbon fiber reinforced polymers, chemical processes are being researched for the recycling of reinforcing fibres and matrix. The ability to fully recover both fiber and matrix by using solvents at the same time is one of the main advantages of chemical solvent processes. The challenge in chemical recycling is the selectivity of the respective solvents when applied to the variety of material combinations as matrix or fiber reinforcement in composite materials.Aim of this research work is the investigation and definition of requirements for a fiber recovery from the epoxy matrix with subcritical and supercritical water. In the chemical recycling of GFRP and CFRP waste, the epoxy resin is converted into a liquid phase, while the fibers remain as a solid residue. Due to the chemical stability of epoxy resins, their chemical recycling by solvolysis requires high temperatures and high pressures; the process conditions can be defined as subcritical or supercritical depending on the physical state of the solvent during the process. Especially the use of supercritical fluids is considered promising for the recycling of FRP. Supercritical fluids have low viscosity, a high mass transfer behaviour and, most important, a high diffusion coefficient, which leads to a high solvability. The typically used solvents water or alcohols are considered to be environmentally friendly. The results of the research show that the amount of resin remaining decreases with increasing temperature and processing time, while temperature having the greater influence on resin removal.