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In this study, it was aimed to comparatively investigate the grain properties of shoe upper leathers produced for different purposes. Thus, six different types of shoe upper leather (cracked, antique, patent, nappa, nubuck, printed) were provided from three different footwear companies. The tensile strength and elongation at break (TS EN ISO 3376), single and double edge tear strength (TS EN ISO 3377-1, TS EN ISO 3377-2), cracking and bursting resistance (TS 4137 EN ISO 3378, TS EN ISO 3379), flex resistance (TS EN ISO 5402-1) as well as dry and wet rubbing fastness tests (TS EN ISO 11640) were applied to leathers that have similar thicknesses. The results of the study gave information about the physical strength and product performances of different upper leather types. The data were evaluated comparatively and the effects of shoe upper leather types on quality and performance were evaluated. © 2022 Toate drepturile asupra acestei ediţii sunt rezervate editorilor.
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The coronavirus causing the Covid-19 pandemic has been experienced by us since 2020, which has led to an increase in the use of disposable medical masks in Indonesia and even worldwide. Polypropylene is a thermoplastic polymer used as the main ingredient in medical masks that takes more than 25 years to decompose in landfills. This research offers an innovative way to use medical mask waste in high-performance concrete. The resulting medical mask waste is subjected to a sterilization process and cut into fibers to analyze the effect of its addition on the compressive strength and splitting tensile strength of high-performance concrete. The research began with testing the physical and mechanical properties of the materials, designing a concrete mix using the absolute volume method, and taking samples for compression and splitting tests. The variation in the ratio of water-cement and pozzolanic materials w (c+p) is 0.32. As a result, the compressive strength of concrete increased with a fiber size of 5×0.5 cm and 2×0.5 cm. An increase is up to 7 % with an optimum value of 72.37 MPa with a fiber size of 2×0.5 cm and a content of 0.15 %. However, there was a decrease in the compressive strength with a 5×1 cm mask fiber size. The overall split tensile strength value of all variations in waste fiber size and content increased with an optimum value of 7.29 MPa at 0.20 % fiber content with a fiber size of 5×0.5 cm. This indicates that polypropylene fibers from medical mask waste have a positive effect on high-performance concrete, namely improve the properties of concrete with a low tensile strength, which is expected to inhibit the propagation and reduce the size of cracks in reinforced concrete structures © 2023
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The demand for gloves (e.g., disposable gloves, medical gloves) is increasing due to the Coronavirus disease 2019 (COVID-19) pandemic. Stability in the supply chain in the glove industry is important, and thus strategies are used to solve the problem of the shortage of nitrile gloves. The blending of nitrile butadiene rubber (NBR) with polyurethane (PU) and the use of the nanocomposite concept is among the feasible approaches. The present study aims to investigate the effects of nanokaolin (NK) on the tensile and chemical properties of carboxylated nitrile butadiene rubber (NBR)/polyurethane (PU) latex blends. Three different loadings of NK (10, 20, and 30 parts per hundred rubber) were added to the NBR/PU (at a blending ratio of 85/15). The zeta potential showed that all the NBR compounds exhibit good colloidal stability. The incorporation of NK increased the crosslink density and tensile strength of the NBR/PU latex blends. The highest tensile strength was achieved when the NK loading was 20 phr. All the NBR blends and nanocomposites (NBR/PU-based) possess tensile properties that fulfill the requirements for glove application. The chemical resistance of NBR compounds was increased by the incorporation of NK due to the higher crosslink density and barrier properties contributed by the NK. © The Author(s) 2023.
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Accumulation of waste tyres causes an environmental disaster because of the rapid rise in transport vehicle demand resulting from modern developments, Covid-19 and similar pandemics. Thus, recycling waste tyres in the form of aggregates as a sustainable construction material can be a solution to reduce the environmental problems. Current research focuses on the impact resistance and mechanical properties of the crumb rubber self-compacting alkali-activated concrete reinforced with 1% steel fibres (SFs) where fine and coarse crumb rubbers (CR) are partially replaced with 10% and 15% replacement ratios. The compressive, flexural, splitting tensile strengths and modulus of elasticity were investigated;impact resistance was found using a drop hammer impact test. The incorporation of CR reduced the mechanical properties, and the reduction was found more with increased rubber contents, whereas the incorporation of SF compensated for the strength loss. The impact performance was enhanced with the CR and SF incorporations. The 15% CR incorporation improved the impact energy up to three times, whereas both 1% SF and 15% CR incorporations significantly enhanced the impact energy up to 30 times. Similar mechanical strengths were obtained for the different sizes of CR. However, impact performance was significantly influenced by the sizes of CR. © 2022 Informa UK Limited, trading as Taylor & Francis Group.
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Due to the excessive use of disposable face masks during the COVID-19 pandemic, their accumulation has posed a great threat to the environment. In this study, we explored the fate of masks after being disposed in landfill. We simulated the possible process that masks would experience, including the exposure to sunlight before being covered and the contact with landfill leachate. After exposure to UV radiation, all three mask layers exhibited abrasions and fractures on the surface and became unstable with the increased UV radiation duration showed aging process. The alterations in chemical groups of masks as well as the lower mechanical strength of masks after UV weathering were detected to prove the happened aging process. Then it was found that the aging of masks in landfill leachate was further accelerated compared to these processes occurring in deionized water. Furthermore, the carbonyl index and isotacticity of the mask samples after aging for 30 days in leachate were higher than those of pristine materials, especially for those endured longer UV radiation. Similarly, the weight and tensile strength of the aged masks were also found lower than the original samples. Masks were likely to release more microparticles and high concentration of metal elements into leachate than deionized water after UV radiation and aging. After being exposed to UV radiation for 48 h, the concentration of released particles in leachate was 39.45 muL/L after 1 day and then grew to 309.45 muL/L after 30 days of aging. Seven elements (Al, Cr, Cu, Zn, Cd, Sb and Pb) were detected in leachate and the concentration of this metal elements increased with the longer aging time. The findings of this study can advance our understanding of the fate of disposable masks in the landfill and develop the strategy to address this challenge in waste management. Copyright © 2023 Elsevier B.V.
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Global public response to the COVID-19 (SARS-CoV-2) pandemic is highly focused on human health. However, conservationists have cautioned of unprecedented threats to the natural environment from a new type of non-biodegradable microplastic waste resulting from extensive use of disposable medical face masks (DMFMs). Thus, this waste must be recycled in an eco-friendly manner on an urgent basis. In this research, we developed a new environmentally friendly recycling technique using waste DMFMs in sustainable green concrete. More explicitly, a new fiber hybridization approach has been introduced in which two types of fibers namely DMFM fiber and basalt fiber (BF) were incorporated into fiber reinforced recycled aggregate concrete (FRAC). The volume fractions of DMFM fiber were 0%, 0.1%, and 0.2% and the volume fractions of BF were 0%, 0.25%, and 0.5%. In addition, two mineral admixtures (fly ash and ground granulated blast furnace slag) were also used. Test results indicated increase of approximately 12% in compressive strength, 26% in split tensile strength, and 60% in flexural strength of FRAC containing hybrid fibers and mineral admixtures. The density and ultra-sonic pulse velocity (UPV) of DMFM fiber- and BF-modified FRAC ranged from 2406-2433 kg/m3 and 4502-4541 m/s, respectively, which meets structural concrete requirements. The water absorption rate gradually increased with an increase in the volume fractions of fibers but remained within the allowable water absorption limit for construction materials. Lastly, the microstructure investigation indicated excellent concrete quality, improved interfacial transition zones (ITZs), and good compatibility of host concrete matrix with both DMFM fiber and BF that correlates well with the experimental results reported in this study.
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The growing demand for disposable gloves, especially from the healthcare industry amidst the ongoing Covid-19 pandemic and rising awareness about Healthcare-Associated Infections (HAIs). One of the ways to produce disposable gloves is using cast LDPE film machine. The quality of the products depends on material resin used, machine casting film design, part design and the selection of process parameters. However, the part design and casting film design are done at the initial stage of product development, it cannot be change easily. To manufacture a better quality of cast LDPE gloves, the best LDPE casting film parameters have to be identified. This research aims to identify the best LDPE casting film parameters in producing disposable gloves in terms of strong sealed but edges failed defect rate in production line. The three LDPE casting film parameters such as tensile strength, melt flow index (MFI) and load weight of resin were chosen to study their effect on the defect rate. In this research, the Taguchi method is used to optimize the best process parameters. On the other hand, an orthogonal array (OA), signal-to-noise (S/N) ratio, and ANOVA were employed to investigate the strong sealed but edges failed defect rate. According to the results obtained, the tensile strength of 34 MPa, melt flow index of 3 g/10 min and load weight of 2 kg were found to be the best combination of LDPE casting film parameters to fabricate the better performance of LDPE disposable gloves which give the lowest strong sealed but edges failed defect rate with 2%. Based on the statistical ANOVA analysis results, the most significant parameter affecting the strong sealed but edges failed defect rate of LDPE disposable gloves is tensile strength, which is indicated by the percentage contribution of P = 55.56%, followed by melt flow index with 38.89%. The load weight of LDPE resin is the least significant parameter with 5.55%. To conclude, Taguchi and ANOVA method show that tensile strength is the most significant parameter to get the least strong sealed but edges failed defect rate. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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The transmission of pathogens via surfaces poses a major health problem, particularly in hospital environments. Antimicrobial surfaces can interrupt the path of spread, while photocatalytically active titanium dioxide (TiO2) nanoparticles have emerged as an additive for creating antimicrobial materials. Irradiation of such particles with ultraviolet (UV) light leads to the formation of reactive oxygen species that can inactivate bacteria. The aim of this research was to incorporate TiO2 nanoparticles into a cellulose-reinforced melamine-formaldehyde resin (MF) to obtain a photocatalytic antimicrobial thermoset, to be used, for example, for device enclosures or tableware. To this end, composites of MF with 5, 10, 15, and 20 wt% TiO2 were produced by ultrasonication and hot pressing. The incorporation of TiO2 resulted in a small decrease in tensile strength and little to no decrease in Shore D hardness, but a statistically significant decrease in the water contact angle. After 48 h of UV irradiation, a statistically significant decrease in tensile strength for samples with 0 and 10 wt% TiO2 was measured but with no statistically significant differences in Shore D hardness, although a statistically significant increase in surface hydrophilicity was measured. Accelerated methylene blue (MB) degradation was measured during a further 2.5 h of UV irradiation and MB concentrations of 12% or less could be achieved. Samples containing 0, 10, and 20 wt% TiO2 were investigated for long-term UV stability and antimicrobial activity. Fourier-transform infrared spectroscopy revealed no changes in the chemical structure of the polymer, due to the incorporation of TiO2, but changes were detected after 500 h of irradiation, indicating material degradation. Specimens pre-irradiated with UV for 48 h showed a total reduction in Escherichia coli when exposed to UV irradiation.
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Limited studies have been conducted on low-aluminum and rich-iron-calcium fly ash (LARICFA)-based geopolymer concrete with increased strength. This study aims to investigate the mechanical characteristics of LARICFA-based geopolymer concrete, including its compressive strength, split tensile strength, and ultimate moment. The steps of this study include material preparation and testing, concrete mix design and casting, specimen curing and testing, and the analysis of testing results. Furthermore, the specimen tests consist of the bending, compressive, and split tensile strength tests. The results show that the average compressive strength and the ultimate moment of the geopolymer concrete are 38.20 MPa and 22.90 kN·m, respectively, while the average ratio between the split tensile and compressive strengths is around 0.09. Therefore, the fly ash-based geopolymer concrete can be used in structural components.
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With respect to the explosion of single-use plastic packaging consumption during the COVID-19 pandemic, environmentally friendly substitutes are critically needful for sustainable development. Therefore, the present work focuses on the functional properties of bioplastic blends prepared through hot compressing molding of thermoplastic starch (TPS) and spent coffee grounds (SCG) in different ratios (0%–20% SCG) as the potential features of SCG were extensively employed in biocomposites for the first time. The insertion of dark brown SCG into TPS hindered UV transmission by 100% at 320 nm and 99.2% at 400 nm. Moreover, the samples with 15% and 20% SCG induced a surge in radical scavenging activity from 7.95% to over 92% at a concentration of 0.1 g/ml owing to the rich source of antioxidants in SCG. The lignin component and high carbon content also improved the thermal performance of TPS/SCG blends, enhancing thermal stability, delaying onset and maximum degradation temperatures, and achieving the HB rating in the UL-94 test. Compared to a pure TPS matrix, TPS blends incorporating up to 10% SCG exhibited improvement in elastic modulus without deterioration of tensile strength. © 2022 Society of Plastics Engineers.
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Due to the COVID19 pandemic, solutions to automate disinfection using UV-C combined with mobile robots are beginning to be explored. It has been proved that the use of these systems highly reduces the risk of contagion. However, its use in real applications is not being as rapid as it needs to be. One of the main market input barriers is the fear of degrading facilities. For this reason, it is crucial to perform a detailed study on the degradation effect of UV-C light on inert materials. This experimental study proves that, considering exposition times equivalent to several work years in hospital rooms, only the appearance of the material is affected, but not their mechanical functionalities. This relevant result could contribute to accelerate the deployment of these beneficial disinfection technologies. For that purpose, a colorimetry test, tensile strength test, and analysis of the surface microstructure were carried out. The results showed that polymers tend to turn yellow, while fabrics lose intensity depending on the color. Red is hardly affected by UV-C, but blue and green are. Thus, this study contributes to the identification of the best materials and colors to be used in rooms subjected to disinfection processes. In addition, it is shown how the surface microstructure of the materials is altered in most of the materials, but not the tensile strength of the fabrics.
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Background: Nanoparticles such as multi-walled carbon nanotubes present resistance, resilience and biocompatibility with human tissues and could be incorporated into glass ionomer cement materials to improve their characteristics. Therefore, the aim of the present study was to evaluate the effect of multi-walled carbon nanotube (MWCNT) incorporation on different glass ionomer cements’ compressive (σc) and diametral tensile strengths (σt). Methods: Eighty (80) specimens were divided into four groups (N = 20/gr) according to the glass ionomer cement type (conventional and high-viscosity) and the presence or absence of multi-walled carbon nanotubes. Samples were kept in water for 24 h prior to the tests. Data were analyzed using two-way ANOVA and Tukey’s test (p = 0.05). Results: For both σc (p = 0.1739) and σt (p = 0.2183), the glass ionomer cements’ viscosity did not influence the results. The presence of MWCNTs decreased the mean compressive strength values (p = 0.0001) and increased the diametral tensile strength (p = 0.0059). For both conventional and high-viscosity glass ionomer cements, the compressive strength values were higher than the tensile strength data. Conclusions: Regardless of the cement viscosity, the multi-walled carbon nanotube incorporation reduced the compressive strength and increased the tensile strength values.
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Data for interpreting virus inactivation on N95 face filtering respirators (FFRs) by ultraviolet (UV) radiation are important in developing UV strategies for N95 FFR disinfection and reuse for any situation, whether it be everyday practices, contingency planning for expected shortages, or crisis planning for known shortages. Data regarding the integrity, form, fit, and function of N95 FFR materials following UV radiation exposure are equally important. This article provides these data for N95 FFRs following UV-C irradiation (200 nm to 280 nm) in a commercial UV-C enclosure. Viral inactivation was determined by examining the inactivation of OC43, a betacoronavirus, inoculated on N95 FFRs. Different metrological approaches were used to examine irradiated N95 FFRs to determine if there were any discernible physical differences between non-irradiated N95 FFRs and those irradiated using the UV-C enclosure. Material integrity was examined using high-resolution scanning electron microscopy. Form, fit, and function were examined using flow resistance, tensile strength, and particle filtration measurements. A separate examination of filter efficiency, fit, and strap tensile stress measurements was performed by the National Personal Protective Technology Laboratory. Data from these metrological examinations provide evidence that N95 FFR disinfection and reuse using the UV-C enclosure can be effective.
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According to the United Nations, the epidemic has exacerbated poverty and weakened our ability to respond to long-term sustainability challenges. [...]SiC sludge qualifies as a potentially useful ingredient in the production of geopolymers containing metakaolin. [...]the hybrid material passed the burning test and demonstrated outstanding flame-retardant properties. [...]because of its thermal performance, BOFS offers a wide range of potential benefits in pavements, particularly for the purpose of achieving the goal of urban heat island mitigation by radiation cooling.
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Introduction: Here, we discuss a chronic kidney disease (CKD) patient with large pericardial effusion who arrested secondary to tamponade and had an unintentional pericardial decompression secondary to cardio pulmonary resuscitation (CPR) that subsequently saved his life. Methods: PRESENTATION 67 years old male, a case of CKD on maintenance hemodialysis (for last two years) but inadequately dialyzed over last two months after recent covid pneumonia was detected to have large pericardial effusion (red arrows) on echocardiography (Figure 1). He was planned for intensive heparin free dialysis in view of absence of frank clinical and echocardiographic findings of tamponade with close surveillance for pericardial effusion. 60 minutes into hemodialysis, patient developed dyspnea, hypotension, and cardiac arrest. Return of spontaneous circulation was achieved after three cycles of cardiopulmonary resuscitation. Echocardiography (echo) guided pericardiocentesis was planned based on clinical suspicion of tamponade. But, echocardiography revealed only mild pericardial effusion (Figure 1). Chest x ray showed new left pleural effusion. Pleurocentesis revealed hemorrhagic fluid. Subsequently done CT thorax showed multiple rib fractures. Patient was discharged on day eleven in stable condition with repeat chest X ray and echocardiography showing no further collection. Figure1: Panel A ( Pre CPR echo, Large pericardial effusion - red arrows), Panel B (Post CPR echo, minimal pericardial effusion) [Formula presented] Results: DISCUSSION Though cardiac tamponade is largely a clinical diagnosis, various other features like echocardiography aid in its diagnosis. Diagnosis of tamponade in CKD patient with pericardial effusion is difficult because of several reasons. All classical clinical features of tamponade like hypotension or elevated systemic pressures may not be manifested all the time in cases of tamponade. Our patient developed clinical signs of tamponade 60 minutes into dialysis session indicating that precipitation of tamponade was likely due to reduction in preload due to ultrafiltration (UF) during hemodialysis. Though, daily dialysis is the initial preferred treatment of choice for uremic pericardial effusions in CKD patients without clinical or echocardiographic signs of tamponade, there are case reports which support early pericardiocentesis as treatment of choice in all large pericardial effusions in CKD patients on maintenance hemodialysis (MHD). In our case of large pericardial effusion, due to absence of frank clinical/ echocardiographic evidence of tamponade, we were prompted to go for aggressive dialysis treatment plan, but had tamponade during dialysis. CPR can cause inadvertent injury to surrounding structures, ribs, abdominal organs and vascular injury. In our case, CPR associated injury lead to unintentional pericardial decompression probably due to rib injury or due to high force generated during CPR coupled with high pericardial pressures which overcame the tensile strength of pericardium resulting in pericardial decompression. Findings of fractured ribs on CT scan post resuscitation in our case supports that high force and pressure were generated during CPR. Conclusions: This case report supports early pericardiocentesis as treatment of choice for large pericardial effusion in CKD patients on MHD. Also, care should be taken while dialyzing these patient as rapid UF can precipitate tamponade. No conflict of interest
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In the day we fight against Covid-19, the use of disposable masks and isolation clothing is multiplied by 12 compared to the time before the Covid-19 pandemic. Considering that these disposable masks are made of polypropylene (PP), an average of 480 kilotons of PP waste is produced each year, exclusively from masks. After the use of these masks, it is important to collect and re-evaluate them in a controlled manner so as not to pose a risk of contamination and not to threaten the environment. Because of its advantageous properties, PP is used in the production of many parts in the automotive industry. With this study, it is aimed to develop composite materials to be used in car bumper manufacturing by using recycled PP obtained from melt blown PP fabrics (surgical mask fabric). Due to accidents or road conditions, impact damage can occur on the bumpers. Therefore, the impact resistance of the bumpers must be improved. In addition, in case of microscale damage resulting from the impacts received, microcracks may develop and cause material failure below the maximum tensile stress. In summary, effective reinforcements should be used to improve impact strength in composites for use in car bumpers. Accordingly, novel recycled PP (rPP) based composites are manufactured by using elastomer-styrene-ethylene-butylene-styrene (SEBS) and graphene nanoplatelets (GnPs) as compatible reinforcements with rPP. As experimental characterization, three-point bending tests and Charpy impact tests were carried out. Incorporation of GnPs increased the flexural strength and blending with SEBS improved the impact resistance of the developed composites. Certain clusters of the graphene nanoplatelets were observed by means of microscopy. © 2022, The Society for Experimental Mechanics.
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PurposeThis paper aims to investigate effect of infill density, fabricated built orientation and dose of gamma radiation to mechanical tensile and compressive properties of polylactic acid (PLA) part fabricated by fused deposit modelling (FDM) technique for medical applications.Design/methodology/approachPLA specimens for tensile and compressive tests were fabricated using FDM machine. The specimens geometry and test method were referred to ASTM D638 and ASTM D695, respectively. Three orientations under consideration were flat, edge and upright, whereas the infill density ranged from 0 to 100%. The gamma radiation dose used to expose to specimens was 25 kGy. The collected data included stress and strain, which was used to find mechanical properties, i.e. yield strength, ultimate tensile strength (UTS), fracture strength, elongation at yield, elongation at UTS and elongation at break. The t-test was used to access the difference in mechanical properties.FindingsCompressive mechanical properties is greater than tensile mechanical properties. Increasing number of layer parallel to loading direction and infill density, it enhances the material property. Upright presents the lowest mechanical property in tensile test, but greatest in compressive test. Upright orientation should not be used for part subjecting to tensile load. FDM is more proper for part subjecting to compressive load. FDM part requires undergoing gamma ray for sterilisation, the infill density no less than 70 and 60% should be selected for part subjecting to tensile and compressive load, respectively.Originality/valueThis study investigated all mechanical properties in both tension and compression as well as exposure to gamma radiation. The results can be applied in selection of FDM parameters for medical device manufacturing.
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OBJECTIVE: In orthodontic patients using any chemical substances in oral environment could change the elastomeric properties of their appliances. Since the beginning of the SARS-CoV-2 pandemic, efforts have been devoted to explore methods of prevention including the use of antiviral mouthwashes. This study aimed to investigate the effects of Povidone Iodine (PVP-I) and two other disinfecting solutions on the mechanical properties of orthodontic elastomeric ligatures. MATERIALS AND METHODS: In this study, 130 elastomeric ligatures in five groups (three test groups and two control groups) were examined in laboratory conditions for a period of 28 days. In the control group, specimens were kept dry in a dark environment while all other ligatures were stored in artificial saliva. Elastomeric ligatures were immersed into PVP-I solution (1%) Chlorhexidine (0.02%), and hydrogen peroxide (5%) for one minute each day in three time intervals of one day, 7 days and 28 days. Next, the maximum tensile strength of elastomeric ligatures was tested by a universal testing machine (CN 1174, Germany). RESULTS: The results showed that the tensile strength of elastomeric ligatures was significantly decreased in all three test groups after 28 days (p-value<0.05). However, the difference between groups was not statistically significant. Between-subject ANOVA test showed that there were significant correlations between the time of exposure and type of disinfecting solutions. CONCLUSIONS: PVP-I has comparable effects on elastomeric ligatures as artificial saliva, chlorhexidine, and hydrogen peroxide.