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Background/Objectives: This study aimed to evaluate a deep learning model for estimating uncorrected refractive error using posterior segment optical coherence tomography (OCT) images. Methods: In this retrospective study, we assigned healthy subjects to development (N= 688 eyes of 344 subjects) and test (N= 248 eyes of 124 subjects) datasets (prospective validation design). We developed and validated OCT-based deep learning models to estimate refractive error. A regression model based on a pretrained ResNet50 architecture was trained using horizontal OCT images to predict the spherical equivalent (SE). The performance of the deep learning model for detecting high myopia was also evaluated. A saliency map was generated using the Grad-CAM technique to visualize the characteristic features. Results: The developed model showed a low mean absolute error for SE prediction (2.66 D) and a significant Pearson correlation coefficient of 0.588 (P< 0.001) in the test dataset validation. To detect high myopia, the model yielded an area under the receiver operating characteristic curve of 0.813 (95% confidence interval [CI], 0.744–0.881) and an accuracy of 71.4% (95% CI, 65.3–76.9%). The inner retinal layers and relatively steepened curvatures were highlighted using a saliency map to detect high myopia. Conclusion: A deep learning algorithm showed that OCT could potentially be used as an imaging modality to estimate refractive error. This method will facilitate the evaluation of refractive error to prevent clinicians from overlooking the risks associated with refractive error during OCT assessment.

Commercial polyblends consist of at least two polymeric components. They allow the combination of favorable properties of known polymers as well as the development of new quality characteristics (ref. 1). [...]

Biogas is an environmentally friendly and sustainable energy resource that can substitute or complement conventional fossil fuels. For practical uses, biogas upgrading, mainly through the effective separation of CO2(0.33 nm) and CH4(0.38 nm), is required to meet the approximately 90–95% purity of CH4, while CO2should be concomitantly purified. In this study, a high CO2perm-selective zeolite membrane was synthesized by heteroepitaxially growing a chabazite (CHA) zeolite seed layer with a synthetic precursor that allowed the formation of all-silica deca-dodecasil 3 rhombohedral (DDR) zeolite (with a pore size of 0.36 × 0.44 nm2). The resulting hydrophobic DDR@CHA hybrid membrane on an asymmetric α-Al2O3tube was thin (ca. 2 μm) and continuous, thus providing both high flux and permselectivity for CO2irrespective of the presence or absence of water vapor (the third largest component in the biogas streams). To the best of our knowledge, the CO2permeance of (2.9 ± 0.3) × 10–7mol m–2s–1Pa–1and CO2/CH4separation factor of ca. 274 ± 73 at a saturated water vapor partial pressure of ca. 12 kPa at 50 °C have the highest CO2/CH4separation performance yet achieved. Furthermore, we explored the membrane module properties of the hybrid membrane in terms of the recovery and purity of both CO2and CH4under dry and wet conditions. Despite the high intrinsic membrane properties of the current hybrid membrane, reflected by the high permeance and SF, the corresponding module properties indicated that high-performance separation of CO2and CH4for the desired biogas upgrading was achieved at a limited processing capacity. This supports the importance of understanding the correlation between the membrane and module properties, as this will provide guidance for the optimal operating conditions.

Waste tires have brought significant problems (refs. 1-3) with the increasing number of automobiles. Therefore, many researchers have studied this field. Three methods of waste tires treatment, including combustion, underground [...]

Inspired by the epidermis–dermis composition of human skin, here we have simply developed a lightweight, robust, flexible, and biocompatible single-electrode triboelectric nanogenerator (S-TENG)-based prototype of bilayer artificial skin, by attaching one induction electrode with unfoamed skin layer of microcellular thermoplastic polyurethane (TPU) foam, which shows high-performance object manipulation [by responding differently toward different objects, viz., aluminum foil, balloon, cotton glove, human finger, glass, rubber glove, artificial leather, polyimide, poly(tetrafluoroethylene) (PTFE), paper, and wood], due to electrification and electrostatic induction during contact with the objects having different chemical functionalities. Comparative foaming behavior of ecofriendly supercritical fluids, viz., CO2over N2under variable temperatures (e.g., 130 and 150 °C) and constant pressure (15 MPa), have been examined here to pursue the soft and flexible triboelectric TPU foam. The foam derived by CO2foaming at 150 °C has been prioritized for development of S-TENG. Foam derived by CO2foaming at 130 °C did not respond as well due to the smaller cell size, higher hardness, and thicker skin. Inflexible N2-derived foam was not considered for S-TENG fabrication. Object manipulation performance has been visualized by principal component analysis (PCA), which shows good discrimination among responses to different objects.

The techno-economic impact of implementing a reconfigurable system in the integrated process was investigated, when L-threonine and L-valine were coproduced with a 5-effect preheater-integrated feed-forward evaporator, followed by single-stage evaporative crystallizers. A superstructure-based modeling and simulation framework was developed to consider all possible multieffect evaporator configurations. Evaporative capacity constrained by solubility limitations and fluid scaling was rigorously examined, providing the knowledge to select the most appropriate configuration and minimize steam consumption without compromising productivity. For L-threonine production, the 4–5–3–2–1 sequence with a preheater showed the highest energy efficiency, with a maximum reduction of 8.4% in steam usage compared to the standard condition. For L-valine production, the 5–4–3–2–1 sequence without a preheater was most energy-efficient, showing a maximum reduction of 7.3% in steam usage compared to the standard condition. These results clearly illustrate the agility of the reconfigurable multieffect evaporation system under various uncertain operational factors.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ajo.2006.01.048 Byline: Seung Jae Lee (a), Jin Kuk Kim (b), Kyung Yul Seo (a), Eung Kweon Kim (a), Hyung Keun Lee (a) Abstract: To compare changes in corneal nerve fibers and keratocyte density by confocal microscopy after laser-assisted in situ keratomileusis (LASIK) and laser epithelial keratomileusis (LASEK). Author Affiliation: (a) Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea. (b) BS Balgensesang Ophthalmology Clinic, Seoul, Korea. Article History: Accepted 12 January 2006 Article Note: (footnote) Supported in part by a grant from the Korea Health 21 R&D project, Ministry of Health and Welfare, Republic of Korea (02-PJ1-PG1-CH02-0003).

The prevalence rate and the incidence rate of hemodialysis and functioning kidney transplant recipients have continuously increased; on the contrary, those of peritoneal dialysis have continuously decreased since 2006. Dialysis patients have been getting older and have been maintained on dialysis longer. Diabetic nephropathy was the leading cause of end stage renal disease. The type of hemodialysis vascular access has been stable during the last 5 years (arteriovenous fistulas 76%, arteriovenous grafts 16%, central venous catheters 8% at 2016). Peritoneal dialysis catheter was mostly inserted surgically (67%), and swan neck straight tip peritoneal dialysis catheter was the most commonly used (48%). Vascular access was managed by radiologists and surgeons, and the management was fragmented among them in the past. However, since the nephrologists became interested in and knowledgeable about the vascular access, they began to play roles in vascular access management. Vascular access has been mostly created by vascular surgeons (≈60%); tunneled central venous hemodialysis catheter insertion and endovascular intervention such as percutaneous transluminal angioplasty (PTA) and thrombectomy have been mostly performed by radiologists (≈70%). Tunneled hemodialysis catheter insertion and endovascular intervention by nephrologists have slowly but consistently increased. Recently, the number of central venous hemodialysis catheter insertion has decreased, and tunneled hemodialysis catheter has been inserted more than non-tunneled hemodialysis catheter, indicating that vascular access has been created timely and the vascular access team has been educated about and following international guidelines.

Chitosan (CS) is an excellent biocompatible natural antibacterial material that has attracted researchers to study its biological applications as artificial tissue scaffolds and wound-healing materials. In this research, CS has been mixed with polyethylene oxide (PEO) and mica at various weight ratios to prepare nanofibers; however, it is found to be a difficult task to prepare the nanofiber using pure CS. The composite in form of nanofibrous mat was prepared with CS/PEO solution and CS/PEO/mica solution using electrospinning. Processing conditions were adjusted to a flow rate of 6 ml/min, with an applied voltage of 27 kV. The distance of capillary tip to target was kept about 10 cm at 25°C with a collector having a speed of 200 rpm. The spinnability of solutions was also evaluated by using both plate and cylinder collectors. The composite mats were analyzed in detail using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis, and X-ray diffractogram (XRD). SEM photomicrograms indicated that the morphology and diameter of the nanofibers were affected by weight ratio of CS/PEO, concentration of mica, and types of collector. Furthermore, mica was incorporated in the CS/PEO matrix to enhance the specific surface area. Molecular interactions between CS/PEO and mica were investigated using FTIR and XRD.

Background Peritoneal dialysis (PD) is characterized by a gain in fat mass. The fat tissue is a complex endocrine organ that releases various adipokines. In this study, we prospectively examined serial changes of fat composition and adipokines in patients undergoing PD.Methods Body composition was assessed by computed tomography (CT). Nutrition status and adipokines (leptin, adiponectin, interleukin [IL]-6, and tumor necrosis factor [TNF]-α) were assessed on the 7th day and 6 months, 12 months, and 24 months after the start of PD.Results Fifty-four patients (28 men), with a mean age of 53.2 ± 13.2 years, were enrolled. Baseline fat mass, especially subcutaneous fat mass, was correlated with baseline leptin (ρ = 0.612), adiponetin (ρ = -0.477), and interleukin-6 (IL-6) (ρ = 0.391). Visceral fat mass was correlated with leptin (ρ = 0.545) and adiponectin (ρ = -0.514). Baseline adiponectin was negatively correlated with baseline leptin (ρ = -0.363). While body weight and leptin increased during the 24 months, serum adiponectin decreased in that period. The changes in visceral and subcutaneous fat mass were greater in the first 12 months and 6 months, respectively. There was no difference in IL-6 and TNF-α. Eight patients died during the follow-up period (mean 47.4 months). Twenty-seven patients continued PD. Increased baseline and serial change of IL-6 level were risk factors for mortality. After adjusting for age, sex, diabetes mellitus (DM), and coronary vascular disease (CVD), the significance of the IL-6 level disappeared.Conclusions Baseline subcutaneous fat in patients starting PD is correlated with baseline adipokine levels rather than visceral fat. The increase in subcutaneous fat was greatest in the first 6 months. While leptin and adiponectin increased and decreased respectively, IL-6 did not change in the first 24 months.

Maintenance of a well-functioning vascular access and minimal needling pain are important goals for achieving adequate dialysis and improving the quality of life in hemodialysis (HD) patients. Far-infrared (FIR) therapy may improve endothelial function and increase access blood flow (Qa) and patency in HD patients. The aim of this study was to evaluate effects of FIR therapy on Qa and patency, and needling pain in HD patients.

A simple combination of solution mixing and melt mixing method for the preparation of fully exfoliated and dispersed graphene nanoplatelet (xGnP) in thermoplastic natural rubber (TPNR) as NBR/PVC (NVC) blend (70:30) has been successfully demonstrated. Two different types of H5−xGnP (~53 layers) and C750−xGnP (~16 layers) were used in this study. The amount of xGnP filled in the nanocomposite has been varied from 0-3 phr. The electrical and mechanical properties of filled TPNR nanocomposites were increased with the increase in both of xGnP types loading. The results suggest that the process provides us a much better dispersion and exfoliation of xGnP into the matrix than direct mixing method. With comparing xGnP types, the number of layer stacked xGnP has significant effect on the tensile strength and electrical conductivity of nanocomposites, the lower the number of layer stacked xGnP, the higher mechanical and electrical properties. The tensile strength of pre−dispersed H5− and C750−xGnP−NR/NVC nanocomposites at 3 phr loading were increased by ~16 % and ~34% respectively compared to conventional direct mixing. While dramatic enhancement of electrical conductivity for the pre−dispersed H5− and C750−xGnP/TPNR nanocomposites has been changed from insulating range to antistatic range.

AbstractThe method of manufacturing nanofibers using the electrospinning technique from trans-polyisoprene (TPI) is presented in this study, possibly for the first time. The process parameters such as solution concentration, applied voltage, distance and feeding rate for electrospinning were investigated and optimized with respect to fiber morphology, as observed from scanning electron microscopy (SEM) photomicrographs. Smooth and uniform nanofibers were found to generate at the optimum conditions with 1% melt concentration, 15 kV of voltage, tip-to-collector distance (TCD) of 15 cm and injection rate 4 ml/h. The physicochemical properties of pure TPI and electrospun TPI fibers were characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) analysis. Both DSC and FTIR characterization results show predominant transformation of TPI crystalline structure from the β form to the α form upon electrospinning.

Background and Aims Peritoneal dialysis (PD) is characterized by a gain in fat mass. Unlike subcutaneous fat, visceral fat is associated with metabolic syndrome and survival. We prospectively examined whether visceral or subcutaneous fat could predict outcome in patients undergoing PD.Methods We studied 117 new patients (57 men) undergoing PD between February 2006 and November 2011. Baseline body composition was measured on computed tomograms. Visceral obesity was defined as a visceral fat area exceeding 100 cm2, and subcutaneous obesity, as a subcutaneous fat area exceeding 130 cm2.Results Among the 117 patients, 37 and 29 were diagnosed with visceral and subcutaneous obesity respectively. Visceral and subcutaneous obesity were both present in 21 patients. In the study population, the 1-year and 5-year survival rates were 94% and 59%. The rates of peritonitis and exit-infection were 0.31 and 0.14 episodes per patient–year. Mortality was greater in patients with visceral obesity than in those without visceral obesity (p= 0.005). Visceral obesity had no influence on peritonitis and exit-infection rates. Subcutaneous obesity was associated neither with survival nor with peritonitis or exit-site infection. In a multivariate Cox regression analysis, visceral obesity was not a risk factor for poor outcome.Conclusions Increased visceral fat at PD initiation is not an independent predictor of poor survival. Any impact of visceral or subcutaneous fat mass on outcomes in patients undergoing PD would be better defined by larger, long-term studies.

Cardiovascular disease is the main cause of mortality in dialysis patients. Carotid intima–media thickness (CIMT) is used as a surrogate marker of early atherosclerosis. Atherosclerosis can cause vascular access failure. The purpose of this study was to define the clinical features of atherosclerosis in hemodialysis patients based on CIMT and to define the relationship between CIMT and access failure.

Various electrospun epoxized natural rubber / poly (vinyl chloride) (ENR/PVC) blend nonwoven membranes were prepared by electrospinning technique. Various concentration of epoxidized natural rubber (ENR) solution in N,N-dimethylformamide (DMF) were directly added to PVC solution for plasticization of the electrospun nanofibrous. Differencial thermal analysis (DTA), thermogravimetry analysis (TGA), fourier transfrom infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) were used to characterize the pristine and plasticized nanofibrous. DTA results indicated that the addition of ENR resulted in the shifting of glass transition temperature (Tg) towards lower temperatures. The blending of PVC with ENR is thermodynamically incompatible.

Nanofibrous membranes based on poly (vinyl chloride) (PVC) were prepared by electrospinning. The morphology of nanofibrous was observed under field emission scanning electron microscope (FE-SEM) and effects of instrument parameters including electric voltage, tip to collector distance, and solution parameters such as PVC concentration and mixed solvent of THF and DMF (50:50) were evaluated. The beads on the fiber were formed with low concentration of PVC. The dielectric constant, thermal properties and crystallinity of the electrospun membranes were characterized by precision LCR meter, and differential thermal analysis (DTA), respectively. It was found that smooth surface of electrospun PVC nanofiber had a high ionic conductivity and their thermal properties were improved comparing with PVC sheet.

Direct access flow measurements are considered the most useful surveillance method for significant stenosis, and ultrasound dilution has become the most popular and validated technique. The goal of this study was to evaluate access flow (Qa) at the time of first cannulation and its relationship to the survival of vascular access in Korean hemodialysis patients.

PP/Ground Rubber Tire (GRT) powder microcellular blend foams were prepared by supercritical carbon dioxide. The effects of blend composition like the content of GRT and maleic anhydride-grafted polypropylene (PP-g-MA) on crystallinity, solubility, diffusivity, morphology and mechanical properties of PP/GRT microcellular composites were studied. The results showed that the PP/GRT composite foams with a unique bimodal (large and small) cellular structure, in which the large-cells embrace a GRT powder. Depending on the composition, generally, the higher content of GRT results in the smaller cell sizes, higher cell densities and relative densities, whereas the 20 wt% GRT composite shows the lowest relative density. The mechanical properties of the microcellular PP/GRT composite foams are directly related to the blend composition and the processing conditions. The PP-g-MA/GRT (50/50) produced microcellular foams with a very fine and uniform cell structure, lower relative densities and improved mechanical properties.

Background Peritoneal dialysis (PD) is characterized by gain in fat mass. Visceral fat mass is associated with metabolic syndrome and atherosclerosis rather than subcutaneous fat mass. In addition, the change in visceral fat mass is a more reliable predictor of survival in PD patients. In this study, we prospectively examined serial changes in fat composition and nutritional status and analyzed factors associated with gain in fat mass in patients undergoing PD.Methods Body composition was assessed by bioelectric impedance analysis (BIA) and computed tomogram (CT). Nutrition status was assessed by Subjective Global Assessment (SGA), protein equivalent of nitrogen appearance (nPNA), serum albumin, C-reactive protein (CRP), and lipid profile. All measurements except BIA were performed on the seventh day and at 6 and 12 months after the start of PD.Results 60 patients (30 men; mean age 55.0 ± 12.5 years) were enrolled. Increase in body weight continued during the 12 months but visceral and subcutaneous fat mass increased during the first 6 months and decreased during the second 6 months. While hematocrit and serum albumin decreased during the first 6 months, they did not change during the second 6 months. Serum creatinine, total cholesterol, and triglyceride increased similarly to the weight pattern. While nPNA decreased during the 12 months, Kt/V, SGA, and CRP did not change. Patients that had more visceral fat mass at the start of PD had less gain of visceral fat mass during the first 6 months (r= –0.821, p= 0.002). Patients that had more subcutaneous fat mass at the start of PD had less gain of subcutaneous fat mass (r= –0.709, p= 0.015). The change in weight was not associated with the change in visceral or subcutaneous fat during the first 6 months.Conclusion Patients starting PD experience weight gain, including visceral and subcutaneous fat, during the first 6 months of PD. Patients with high baseline fat mass had less increase in fat mass than those with low baseline fat mass, regardless of visceral or subcutaneous fat mass.

Importance of the field:Chronic kidney disease (CKD) has become a worldwide public health problem. Renal transplantation is the treatment of choice for end-stage renal disease, but is limited by a small number of organ donors and the immune barrier. To overcome these problems, new therapeutic strategies for tissue repair have recently emerged.Areas covered in this review:We discuss the therapeutic potential of mesenchymal stem cells (MSCs) in kidney injury and examine the latest reports providing evidence supporting MSC efficacy in the treatment of chronic renal failure (CRF).What the reader will gain:MSCs improve histological and functional outcomes in various CRF model systems. Paracrine effects rather than transdifferentiation might result in the prevention of progressive renal failure. In addition, MSCs can reprogram kidney cell differentiation, and modulate neo-kidney transplantation in CRF.Take home message:Although many practical problems remain to be addressed, treatment with MSCs will enter the mainstream of CRF treatment.

PLA biodegradable composites reinforced with various silk fibroin powder contents 0, 1, 3, 5 and 7 wt. were prepared by solution processing technique using CH2Cl2as solvent. After that the composites and virgin PLA were foamed by using supercritical CO2. The influence of silk contents on PLAsilk fibroin powder composite foams were investigated by using SEM, XRD and DSC. Compared with PLA foam, the composite foams exhibited a reduction in cell size and increase in cell density at high silk content. With an increase in saturation temperature and pressure, the cell size was increasing and both the cell density and foam density were decreased simultaneously.

The effect of several network‐forming nanoscale materials such as two different types of graphite and multiwalled carbon nanotube on the property development of thermoplastic elastomer (TPE) gels prepared from microphase‐ ordered poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) triblock copolymer dissolved in paraffin oil was studied. Dynamic rheological measurements of the resultant nanocomposite TPE (NCTPE) gels showed that at temperature between 30 °C to 40 °C below the gel point, the NCTPE gels have dynamic storage modulus greater than loss modulus (G′ and G″), thereby indicating that at ambient temperature a physical network is still present despite the addition of nanoparticles. In general, the nanoparticles lower the gelation temperature. The X‐ray diffraction of NCTPE gels showed that EG2 system exhibited intercalation, those with CNTs exhibited exfoliation and EG1 did not change at all.

Nowadays, waste EPDM (ethylene propylene diene monomer) increasingly has been causing significant environmental problems with increasing numbers of vehicles. From the perspective of the environment and economics, recycling is the best method to treat waste materials. This study investigated waste EPDM/PP (polypropylene) blends with waste EPDM. Waste EPDM powders were treated ultrasonically, which physically modifies the rubber particles to confer good mechanical properties. Also investigated were the relevance of the mass percentage of the dispersed phase, the influence of the geometry and rotation speeds of the screw used in extrusion, and the melting temperature of PP materials on the morphology and mechanical properties of the blend. The purpose of this study was to develop a valuable thermoplastic elastomer from waste EPDM. This study concentrated on determining the optimum conditions for producing a blend by extrusion, including parameters of screw geometry, screw rotational speed, and operating temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2503–2507, 2003

An automated approach from the systematic investigation of interactions between cooling‐tower performance and the cooling‐water network design was developed for retrofit design of cooling‐water systems. Introducing reuse of cooling water between different cooling duties enables cooling systems to be debottlenecked. The series arrangement of heat exchangers, however, results in a pressure drop increase because of the cooling water reuse. An optimization model for cooling‐water networks developed considers pressure‐drop constraints, complexity of networks, and efficient use of the cooling tower. A new node‐superstructure model is suggested to consider the intensive property of pressure and the sequence of connections simultaneously. Physical insights are used to provide a good initialization for the resulting optimization problem. Issues of retrofit analysis are also addressed to give design guidelines for debottlenecking of cooling‐water systems.

Nowadays, with the increase in the number of automobiles, waste EPDM (ethylene propylene diene monomer) is causing a significant environmental problem. From environmental and economical perspectives, recycling is one of the popular methods to solve environmental problems. This study, which involved waste EPDM/PP (polypropylene) blends with the ratio range of 70/30 and 75/25, set out to ascertain the relevance of the mass percentage of the dispersed phase, the influence of the screw geometry, the screw rpm, and the melting temperature of PP materials on the morphology and mechanical properties of the waste rubber blend. The purpose of this study is to develop a high-value thermoplastic elastomer from waste EPDM. This investigation concentrated on determining the optimum conditions for producing a blend by extrusion, relative to screw geometry, screw rational speed, and operating temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2276–2282, 2002

As power lines are built in contaminated environments, the industrial usage of power-line materials requires high reliability. Nonceramic insulators offer better anticontamination performance than that of the traditional ceramic insulators. Among the nonceramic materials, EPDM and silicone rubber provide much better long-term pollution resistance performance than that of any other materials. This study investigated the long-term pollution performance by a corona aging treatment on the surface of the test slabs, which were made of EPDM and silicone rubber. Experimental results showed good hydrophobicity of those materials and their transfer of the contaminant layer deposited on the shed surface of the insulator. The EPDM and silicone rubbers are synthetic polymers of low density and they maintain an outstanding resistance to attack by oxygen and ozone. This study measured the contact angle between water droplets and other materials to determine the hydrophobicity and recovery ability of these synthetic polymers. We also studied surface morphology for a visual confirmation of the migration phenomena. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2251–2257, 2001

Nowadays, waste tires are a significant problem with the increasing in the number of automobiles. Therefore, much research has been performed in this field. From environmental and economical perspectives, recycling is one of the popular methods for the treatment of waste tire. However, it is not easy to melt down and mold scrapped tires into new products because the tire rubber is a crosslinked polymer. Due to such difficulty, the recycled product is not economical. Therefore, the goal of this study is to develop high-value products from waste tires. In this paper, attention has been paid to an economic recycled technology using scrapped waste tires. This technology may be applied to manufacturing the end products such as a rubber block and a ballast mat for high-speed trains. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1573–1577, 2000

The fracture behavior of a crumb rubber-filled elastomer was observed in optical micrographs. It was found that the failure started from the surface of the unfilled samples. The failure, however, started from a cavity around a crumb in the crumb-filled samples. This paper suggests that the failure mechanism in the crumb-filled elastomers (NR, NBR) was based on the microscopic observation of highly strained samples. This paper also considers the failure behavior of two-component systems: NR/NBR, SBR/NR, and NR/SBR. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3137–3144, 1999

The disposal of used car tires has become a major environmental problem, especially in densely populated countries that use motor vehicles as the principle means of transportation. Widespread recycling of waste tires has not taken place because it has not proven to be cost effective. Although there are obvious environmental reasons for recycling waste tires, to date it has not proven to be economically valuable. The aim of this study is to find a more economical way of recycling used car tires. This was done by the “unvulcanization” of vulcanized crumb rubber by two different treatments; chemical treatment with di-(cobenzanidophenyl)disulfide, and microbial treatment with T. peromatabolis. The experimental results indicate that the processing of crumb rubber, as well as the end-product properties, were enhanced by both these treatments, with the microbial treatment being the most effective. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1543–1549, 1999

With recent development of the petrochemical industry, plastic products have made our society more convenient. However, the disposal of these convenience products has become a serious threat to the environment. Therefore, research on recycling plastic wastes is necessary now more than ever. This paper is a basic study of recycling technology for ABS (acryionitile-butadienestyrene) resin. We tried to show the changes in its mechanical, thermal, rheological, and optical properties during the recycling process.

Polymer blends have been drawing attention with the development of the polymer industry. The characteristics of toughened SAN/SBS polymer blends are reported in this study. The effect of the screw configuration on the properties of polymer blends has been investigated. This study also deals with the effect of the operating temperature on the properties of the polymer blend. The microphotographs show SBS (Styrene-Butadiene-Styrene) domains in the SAN (Styrene-Acrylonitrile) matrix. This explains that the well dispersed rubber particles do not always contribute to the good mechanical properties such as impact strength. However, this effect contributed to the fluidity of the molten polymer blends.

Large amounts of butyl rubber (IIR) are used as inner tires for aeroplanes, trucks, cars, two-wheelers etc. However, after long runs when these tires are not serviceable they are discarded. Almost the entire amount of rubber from the worn out tires is discarded, which again need very long time for natural degradation due to crosslinked structure of rubbers and presence of additives. To solve this problem, recycled rubber is used as a partial substitute for new IIR in inner tire compounds. The blends with a certain amount of recycled rubber content show good mechanical properties.