scholarly journals Desulfurization of Vulcanized Rubber Particles Using Biological and Couple Microwave-Chemical Methods

2021 ◽  
Vol 9 ◽  
Author(s):  
C. Valdés ◽  
C. Hernández ◽  
R. Morales-Vera ◽  
R. Andler
Keyword(s):  
Morphological Changes ◽  
Chemical System ◽  
Cross Linking ◽  
Chemical Methods ◽  
Vulcanized Rubber ◽  
Rubber Waste ◽  
Rubber Surface ◽  
Rubber Recycling ◽  
First Time ◽  
Energy Disperse Spectroscopy

Currently, recycling or degradation treatments for tires are an enormous challenge. Despite efforts to dispose of or recycle it, rubber waste is increasing year by year worldwide. To create a rubber-recycling system, several researchers have proposed tire desulfurization. In this study, we compare two methods: one biological, using Acidobacillus ferroxidans in shake 250 ml flask experiments, and one chemical using, for the first time, microwaves and an aqueous solution. The results of these methods were analyzed through sulfate quantification, cross-linking differences, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy disperse spectroscopy (SEM-EDS). We observed that the amount of sulfates generated by the chemical system was 22.40 (mg/L)/g of rubber, which was 22-times higher than the biological system, which generated 1.06 (mg/L)/g of rubber. Similarly, after cross-linking studies, a 36% higher decrease after the chemical treatment was observed. When using FTIR analysis, the disappearance of characteristic bands corresponding to functional groups containing sulfur bonds and metal oxides were observed by treating the sample with both desulfurization methods. Morphological changes on the rubber surface structure was also demonstrated by SEM-EDS analysis with the appearance of holes, cracks and changes in the porosity of the material. This work analyzed two different non-aggressive desulfurization approaches that might be used as methods for rubber recycling processes.

scholarly journals Desulfurization of Vulcanized Rubber Particles Using Biological and Chemical Methods

2020 ◽  
Author(s):  
Cristian Valdés ◽  
Camila Hernández ◽  
Rodrigo Morales-Vera ◽  
Rodrigo Andler
Keyword(s):  
Morphological Changes ◽  
Chemical System ◽  
Cross Linking ◽  
Chemical Methods ◽  
Vulcanized Rubber ◽  
Rubber Waste ◽  
Rubber Surface ◽  
Rubber Recycling ◽  
First Time ◽  
Energy Disperse Spectroscopy

Abstract Currently, recycling or degradation treatments for tires are an enormous challenge. Despite efforts to dispose of or recycle it, rubber waste is increasing year by year worldwide. To create a rubber-recycling system, several researchers have proposed tire desulfurization. In this study, we compare two methods: one biological, using Acidobacillus ferroxidans in shake 250 mL flask experiments, and one chemical using, for the first time, microwaves and an aqueous solution. The results of these methods were analyzed through sulfate quantification, cross-linking differences, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy disperse spectroscopy (SEM-EDS). We observed that the amount of sulfates generated by the chemical system was 56 mg / L, which was 10-times higher than the biological system, which generated 5.3 mg / L. Similarly, after cross-linking studies, a 36% higher decrease after the chemical treatment was observed. When using FTIR analysis, the disappearance of characteristic bands corresponding to functional groups containing sulfur bonds was observed by treating the sample with both desulfurization mechanisms. Morphological changes on the rubber surface structure was also demonstrated by SEM-EDS analysis with the appearance of holes, cracks and changes in the porosity of the material. This work analyzed two different non-aggressive desulfurization mechanisms that might be used as sustainable methods for rubber recycling processes.

scholarly journals The Effect of Surfactant-Modified Montmorillonite on the Cross-Linking Efficiency of Polysiloxanes

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2623
Author(s):  
Monika Wójcik-Bania ◽  
Jakub Matusik
Keyword(s):  
Total Pore Volume ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Cross ◽  
Chain Lengths ◽  
First Time ◽  
Substituent Influence ◽  
Benzyl Substituent

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH3)2R’NR]+, where R = C12, C14, C16, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

scholarly journals Identification of pigments in artworks by inverse tangent derivative of spectrum and a new filtering method

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
F. Fazlali ◽  
S. Gorji Kandi
Keyword(s):  
Reflectance Spectrum ◽  
Practical Method ◽  
Chemical Methods ◽  
Munk Function ◽  
Absorption Of Light ◽  
Spectrophotometric Data ◽  
First Time ◽  
Non Destructive ◽  
Derivatives Of

Abstract Employing an economical and non-destructive method for identifying pigments utilized in artworks is a significant aspect for preserving their antiquity value. One of the non-destructive methods for this purpose is spectrophotometry, which is based on the selected absorption of light. Mathematical descriptive methods such as derivatives of the reflectance spectrum, the Kubelka–Munk function and logarithm have been employed for the characterization of the peak features corresponding to the spectrophotometric data. In the present study, the mentioned mathematical descriptive methods were investigated with the aim to characterize the constituents of an Iranian artwork but were not efficient for the samples. Therefore, inverse tangent derivative equation was developed on spectral data for the first time, providing considerable details in the profile of reflectance curves. In the next part, to have a simpler and more practical method it was suggested to use filters made up of pure pigments. By using these filters and placing them on the samples, imaging was done. Then, images of samples with and without filter were evaluated and pure pigments were distinguished. The mentioned methods were also used to identify pigments in a modern Iranian painting specimen. The results confirmed these methods with reliable answers indicating that physical methods (alongside chemical methods) can also be effective in determining the types of pigments.

RUBBER RECYCLING: CHEMISTRY, PROCESSING, AND APPLICATIONS

2012 ◽  
Vol 85 (3) ◽  
pp. 408-449 ◽  
Author(s):  
Marvin Myhre ◽  
Sitisaiyidah Saiwari ◽  
Wilma Dierkes ◽  
Jacques Noordermeer
Keyword(s):  
Process Safety ◽  
Tire Industry ◽  
Ground Rubber ◽  
Rubber Surface ◽  
Rubber Recycling ◽  
Property Loss ◽  
Recycled Rubber ◽  
Cost Factors ◽  
Broad Interest ◽  
Recycled Material

ABSTRACT For both environmental and economic reasons, there is broad interest in recycling rubber and in the continued development of recycling technologies. The use of postindustrial materials is a fairly well-established and documented business. Much effort over the past decade has been put into dealing with of end-of-life tires from landfills and vacant fields. It is only in the last few years that more business opportunities for recycled rubber have come to the forefront. Reclaiming rubber has gained increasing interest, more so in Europe than in North America. In those areas, much work has been done to refine the processes used. The major form of recycled rubber is still ground rubber. This is produced either by cryogenic, ambient, or wet grinding. The material is then used neat with sulfur/curatives, binders, or cements. The binders are normally moisture curable urethanes, liquid polybutadienes, or latex to produce items such as mats, floor tiles, and carpet undercushion. Recycled rubber is still used as tire derived fuel, but less so than 10 years ago. Another outlet is as an additive to asphalt. Recycled rubber can be used in the plastics industry, for which much development is being done. Large particle size ground rubber or chips are used in civil engineering applications, landscaping, or artificial turf. In terms of applications, most use is outside of the conventional rubber industry. Cost factors are still addressed in the tire industry. As of 2012, approximately 8–10% recycled material is used in tires. The biggest obstacles to further adaption are safety factors and property loss. Better methods are needed for treating or modifying the rubber surface and for regenerating the rubber through devulcanization. Devulcanization gives the highest quality recycled material in terms of processing and properties. However, shortcomings to devulcanization are reduced process safety and odorous chemicals that are required at present.

scholarly journals A study on Antioxidant Properties of Different Extracts from Kitaibelia balansae

Proceedings ◽  
2019 ◽  
Vol 40 (1) ◽  
pp. 23
Author(s):  
Zengin ◽  
Aygun ◽  
Aktumsek
Keyword(s):  
Ethyl Acetate ◽  
Human Body ◽  
Antioxidant Properties ◽  
Water Extract ◽  
Antioxidant Ability ◽  
Chemical Methods ◽  
Potential Source ◽  
First Time ◽  
Antioxidant Effects ◽  
Ethyl Acetate Extracts

Nowadays, knowledge of ancient botanical medicinal practices and application of modern phytochemical techniques have provided the excellent tools for the purification and structural elucidation of various phyto-compounds, which, in turn, has given insights into their mode of action on the human body. This study has been designed to investigate for the first time the antioxidant effects of the ethyl acetate, methanolic, and water extracts of Kitaibelia balansae. Different chemical methods were performed and the observed abilities depend on the solvent used. The best antioxidant ability was noted in water extract, followed by methanol and ethyl acetate extracts. The highest level of phenolic was also detected in water extract. The present findings suggest that K. balansae can be considered as a potential source of bioactive compounds for novel phytopharmaceuticals development

Small Molecule Constituents of Periplaneta americana and Their IL-6 Inhibitory Activities

2021 ◽  
Vol 16 (9) ◽  
pp. 1934578X2110331
Author(s):  
Hua-Sheng Zhang ◽  
Yong-Ming Yan ◽  
Dai-Wei Wang ◽  
Qing Lv ◽  
Yong-Xian Cheng ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
High Performance ◽  
Periplaneta Americana ◽  
Ethanol Extract ◽  
Biological Evaluation ◽  
Dependent Manner ◽  
Chemical Methods ◽  
Concentration Dependent Manner ◽  
Inhibitory Activities ◽  
First Time

Two new glycosides, periplanosides A (1) and B (2), 3 compounds reported from a natural source for the first time (3 − 5), and 6 known compounds 6 − 11 were isolated from the ethanol extract of Periplaneta americana (Linnaeus). Their structures, including absolute configurations, were unambiguously identified by comprehensive spectroscopic and chemical methods. Compound 3 is a racemate whose enantiomers were purified by chiral high-performance liquid chromatography . The biological evaluation results showed that compound 7 (0 − 20 μM) did not affect the viability of RAW264.7 cells and could effectively inhibit the production of interleukin-6 stimulated by lipopolysaccharide in a concentration-dependent manner, indicating the potential to develop novel agents against inflammation-related diseases.

Morphological assessment of changes in the cornea of experimental animals after ultraviolet corneal cross-linking

2021 ◽  
pp. 66-69
Author(s):  
A.R. Khalimov ◽  
◽  
E.L. Usubov ◽  
Keyword(s):  
Morphological Changes ◽  
Standard Procedure ◽  
Digital Camera ◽  
Early Postoperative Period ◽  
Cross Linking ◽  
Intact Control ◽  
The Third ◽  
Key Words Cornea ◽  
Hematoxylin Eosin ◽  
Morphological Assessment

Purpose. To investigate the dynamics of morphological changes in the rat cornea after its ultraviolet cross-linking using various photosensitizer solutions. Material and methods. Studies were conducted on 20 rats in three groups. In the first group, 0.1% Riboflavin solution was used for saturation, in the second – 0.1% Riboflavin and 20% dextran; the third – intact (control). A UV cross-linking model (370 nm, 3 mW/cm2, 10 min) with corneal deepithelization with a diameter of 3 mm was used. Histomaterial processing was performed according to the standard procedure on the 3rd, 7th, and 30th days after surgery. Histological sections 1-4 microns thick were prepared on a rotary microtome RM 2145 (Leica Microsystems, Germany), stained with hematoxylin-eosin and using the van Gieson method. Light microscopy was performed using a LEICA DM 2500 microscope with a Leica DFC 450 digital camera (Leica Microsystems, Germany). Results. The main morphological changes in the rat cornea after UV cross-linking with 0.1% Riboflavin solution were associated with loosening of bundles of collagen fibers. This was caused by the development of stroma edema in the early postoperative period (3-7 days), which persisted up to 30 days of the experiment. A morphological feature of the use of Dextralink solution in corneal cross-linking is less pronounced stroma disfoliation, which is associated with the dehydrating effect of dextran. In both groups, a decrease in the density of stroma keratocytes was found. Key words: cornea, ultraviolet corneal cross-linking, corneal morphology.

scholarly journals Stretch-induced Wettability Changes of the Superhydrophobic Microstructured Vulcanized Rubber Surface

2018 ◽  
Vol 61 (6) ◽  
pp. 348-353 ◽  
Author(s):  
Riku TAMURA ◽  
Yuji HIRAI ◽  
Hiroyuki MAYAMA ◽  
Yasutaka MATSUO ◽  
Takahiro OKAMATSU ◽  
...  
Keyword(s):  
Vulcanized Rubber ◽  
Rubber Surface

scholarly journals Whether Keratectasia Area Shown in Corneal Topography Is Appropriate for Evaluating the Effect of Corneal Cross-Linking for Keratoconus: A 12-Month Follow-Up Study

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
Jia Wang ◽  
Zhiwei Li ◽  
Huankai Zhang ◽  
Ning Gao ◽  
Guoying Mu
Keyword(s):  
Endothelial Cell ◽  
Linear Regression ◽  
Early Stage ◽  
Morphological Changes ◽  
Corneal Thickness ◽  
Corneal Topography ◽  
Cross Linking ◽  
Follow Up Study ◽  
Before And After

Purpose. To analyze the keratectasia area (KEA) shown in corneal topography before and after corneal cross-linking (CXL) in patients with progressive keratoconus (KC) and figure out whether KEA is appropriate for evaluating the effect of CXL. Methods. A retrospective analysis was conducted in 34 eyes from 24 progressive KC patients who have underwent CXL from 2015 to 2017. Area with K-value more than 47D shown in the corneal topography was marked and identified as KEA. Keratometry (K1, K2, and Kmax), KEA, thinnest corneal thickness (TCT), and endothelial cell density (ECD) were evaluated preoperatively or at months 3, 6, and 12 postoperatively. The changes of KEA before and after operation were evaluated. The relation of KEA and other parameters, including Kmax and TCT, was analyzed. Results. Linear regression model revealed the KEA, Kmax, K1, and K2 decreased after CXL in model y = 0.9622 -0.02408 x (P<0.05), y = 0.9982 -0.003469 x(P<0.05), y = 0.9977 + -0.001347 x(P<0.05), y = 0.9992 + -0.001779 x(P<0.05) (y represents KEA, Kmax, K1, or K2; x represents time (month)). The KEA is significantly decreased in early stage (before month 3) (P<0.05); however, the Kmax, K1, and K2 have no significant decrease in early stage (P= 0.09, 0.19, 0.32). Conclusions. The KEA is more sensitive than K-value in describing the morphological changes of cornea after CXL, especially in early stage after treatment.

Devulcanization of Automobile Scrap Tyres by a Mechanochemical Process

2005 ◽  
Vol 21 (4) ◽  
pp. 319-331 ◽  
Author(s):  
G.K. Jana ◽  
C.K. Das
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Chemical Process ◽  
Crosslink Density ◽  
Diallyl Disulfide ◽  
Density Data ◽  
Vulcanized Rubber ◽  
Rubber Waste ◽  
Mechanical Shearing ◽  
Vulcanization Process

The de-vulcanization of rubber waste poses a challenging economical, environmental and social problem. We propose a new de-vulcanization process to re-use the rubber waste. It is a mechano-chemical process (MCP), where the waste is de-vulcanized by a combination of mechanical shearing, heat (110 °C) and the use of a de-vulcanizing agent (diallyl disulfide). A new look at the de-vulcanization mechanism and the influence of the de-vulcanizing agent on the mechanical properties of the ultimate re-vulcanized rubber is also presented. One of the most interesting observations is that the retention of tensile strength of the re-vulcanized rubber with respect to the original tyre was 34.9% when de-vulcanized in the absence of diallyl disulfide and 72.4% in its presence. The formation of extra crosslinks in those re-vulcanized rubbers containing disulfide was confirmed from crosslink density data and from TGA results. DMA analysis revealed that the storage modulus also increased for re-vulcanized rubber containing the disulfide.

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