Rubber Products Research Articles

Влияние браслетной пружины на контактную нагрузку в соединении «Вал-манжета»

Reinforced rubber seals are used in bearing assemblies. Their reliable operation is ensured by pressing the working edge of the seal to the shaft. The contact load in the connection is affected by the force generated by the band spring. The presented method is used to determine the specific contact load of the working edge of the seal on the shaft offered by the bracelet spring, depending on the parameters of the seals and springs. To check the adequacy of the methodology, the authors studied a batch of reinforced seals 1.1‑45×65‑1 GOST 8752‑79 in the amount of 25 pcs. Theoretical calculations of the contact force from the action of the spring were 2.64 to 3.804 N, specific contact loads – 0.098 to 0.153 N/mm, and according to experimental data – 2.75 to 3.50 N and 0.102 to 0.141 N/mm, respectively. High convergence confirms the correctness of the presented calculated dependencies. It has been established that the parameters of the seals have a large spread, which hampers accurate calculation of the specific load in the “shaft-seal” connection. To increase the accuracy of readings, it is necessary to reduce the tolerances on the dimensions of rubber products.

BİST İMALAT ALT SEKTÖRLERİNİN KÂRLILIK PERFORMANSLARININ FARKLI ÇOK KRİTERLİ KARAR VERME YÖNTEMLERİ İLE ANALİZİ

The objective of the study is analyzing the profitability performances of the BIST manufacturing sub-sectors for the period 2019-2021 using different multi-criteria decision-making methods. Six profitability criteria consisting of financial ratios are determined, and the profitability performances of seven sub-sectors are examined. The weights of the evaluation criteria are calculated with CRITIC and Entropy methods, and rankings are obtained using VIKOR and TOPSIS methods. Also, to convert negative values to positive in the decision matrices z-score calculation method is applied. The results reveal that the Chemicals, Petroleum Rubber and Plastic Products sub-sector ranks the first, while the Food, Beverage and Tobacco sub-sector ranks the last in terms of profitability performance in the analyzes made using four different integrated methods. In addition, it is concluded that the ranking results of the analyzes using four different methods are similar to each other. Also, profitability performance rankings of manufacturing sub-sectors are compared with their index price performances with Spearman’s rank correlation. The results show that there is no significant relationship between the index price and profitability performance rankings of the manufacturing sub-sectors for the years 2019, 2020 and 2021.

Financial Performance Analysis with the Entropy-Based TOPSIS in the Impact of the COVID-19 Pandemic: An Application on BIST

Bu çalışmanın amacı, Borsa İstanbul’da işlem gören Kimya, İlaç, Petrol, Lastik ve Plastik Ürünler sektörüne dahil işletmelerin, COVID-19 pandemisi öncesi ve pandemi süreci finansal performanslarının Entropi tabanlı TOPSIS ile değerlendirilmesidir. Sektörün pandemi ile birlikte rekor satış rakamlarına ulaşması ve tedarik zincirine bağlı olarak ciddi oranda artan riskler, çalışmanın motivasyonunu oluşturmaktadır. Araştırma kapsamına 32 adet işletme dahil edilmiş; 2018, 2019 ve 2020 yılları tarih aralığı olarak belirlenmiş ve işletmelerin finansal performansları “cari rasyo, asit-test rasyosu, nakit rasyosu, stok devir hızı, alacak devir hızı, aktif devir hızı, borçlanma rasyosu, satış karlılığı, özsermaye karlılığı ve aktif karlılığı” ile hesaplanmıştır. Analiz sonucunda 2018, 2019 ve 2020 yıllarında en önemli rasyo ve en başarılı işletme sırasıyla; nakit rasyosu-SODSN, alacak devir hızı-BAGFS ve alacak devir hızı-BAGFS şeklinde gerçekleşmiştir.

Inventory Management Practices and Organizational Productivity in Nigerian Manufacturing Firms

This study examined the relationship between inventory management practices and productivity of selected manufacturing firms in Nigeria. The inventory management practices examined include inventory record accuracy, lean inventory system, buffer stock management and Information and Communication Technology. In addition, organizational productivity was measured along two dimensions namely: organizational effectiveness and organizational efficiency. A survey research design was adopted for the study. The population of the study comprises employees in the following departments – commercial, finance, production, distribution and inventory – of five selected manufacturing companies in Benin City. A sample size of two hundred and sixteen (216) employees from Seven-Up Bottling Company Ltd, Global Horn Industry PVC Ceiling Limited, Integrated Rubber product Nigeria Plc., Livestock Feeds Plc and Nigeria German Chemicals in Nigeria were selected for the study. The instrument for data collection was a questionnaire. Data collected from the questionnaire were analysed using frequency distribution, mean, correlation and regression. All analyses were done using the Statistical Package for the Social Sciences (SPSS) software. The findings of the study revealed that inventory record accuracy, lean inventory system and information technology have a positive and significant effect on organizational productivity in Nigeria while buffer stock management was found to be insignificant. The study recommends the need for manufacturing firms to improve their inventory record accuracy by using system-based inventory management practices to enhance organisational performance.

Storage Life Prediction of Rubber Products Based on Step Stress Accelerated Aging and Intelligent Algorithm.

Compared with the constant stress accelerated aging test, the step stress accelerated aging test reduces the accelerated aging test time by increasing the aging temperature step by step to obtain the aging failure life of rubber in a shorter time, but its data processing method is not mature enough. In this paper, a simplified step is proposed to process the step stress accelerated aging data. The identification of the acceleration factor is transformed into an optimization problem to avoid the error accumulation problem caused by fitting the data at each temperature. Considering the non-Arrhenius phenomenon in the rubber aging process, a modified Arrhenius equation was used to extrapolate the acceleration factor at low temperatures to calculate the prediction curves for the degradation of polyurethane rubber properties at low temperatures. The life prediction results of the constant stress accelerated aging test and step stress accelerated aging test were compared, and the dispersion coefficient between the two results was between 0.9 and 1. The results obtained by the two methods were in good agreement, which proved the correctness and feasibility of the method used in this paper.

Developing a prototype of fire detection and automatic extinguisher mobile robot based on convolutional neural network

The object of research is a prototype of fire detection and automatic extinguisher mobile robot based on convolutional neural network. Within the recent few decades, fires are considered as one of the most serious disaster that occurs in many places around the world. The severity of fire incidents causes damages to buildings, infrastructures and properties. Resulting losses of human’s life and costs them a lot of losses. Thus, fire poses a great threat to us significantly; it is extremely dangerous for fire fighters. Fires can be resulted by materials such as rubber and chemical products. Other sources of fire are the short circuits on electrical devices and faults in power circuits. Additionally, overheating and overloading problems can be the cause of fire incidents. All these reasons lead to bad consequences when there is no immediate response to such problems. The advent of computer vision technology has played such a significant role for human life. Artificial intelligence field has improved the efficiency and behaviors of robotics beyond expectations. The interference of artificial intelligence made robotics act intelligently. For this reason, in this paper we presented a mobile robot based on deep learning to detect the fire source and determines its coordinate position then automatically moves toward the target and extinguish fire. Deep learning algorithms are the efficient ones for object detection applications. CNN model is one of the most common deep learning algorithms which have been used in the study for the fire detection. Due to the insufficient amount of datasets and large efforts required to build model from scratch. MobileNet V2 is one of the CNN models that support transfer learning technique. After training the model and testing it on 20 % of the used datasets the classification accuracy achieved up to 98.01 %. The motion repeatability of the robot has been implemented and tested resulting mean error 0.648 cm.

ORGANIZATIONAL CITIZENSHIP BEHAVIOR (OCB), KESELAMATAN DAN KESEHATAN KERJA (K3) SERTA PENGARUHNYA TERHADAP KINERJA KARYAWAN PT. AIR MURING BENGKULU UTARA

One of the mainstay commodities in Bengkulu Province is rubber plantation products. PT Air Muring Bengkulu Utara is a company engaged in rubber plantations and rubber processing in the form of crumb rubber with Ribbed Smoke Sheet (RSS) quality. This study aims to see the effect of the observed variables, namely Organizational Citizenship Behavior (X1) and Occupational Safety and Health (X2) on Employee Performance (Y) and test the hypotheses that have been formulated. This study uses quantitative data derived from distributing questionnaires to respondents and then processed in statistical analysis. The results of the analysis show that (1) Organizational Citizenship Behavior (X1) Occupational Safety and Health (X2) has a positive effect on Employee Performance (Y). (2) Occupational Safety and Health variables make a greater contribution than Organizational Citizenship Behavior to Employee Performance of PT Air Muring Bengkulu Utara. The implementation of this study shows that companies supported by employees who have good Organizational Citizenship Behavior, Occupational Safety and Health can develop their business

Influence of aviation hydraulic oil swelling on the mechanical properties of HNBR/EPDM vulcanizates reinforced by carbon black

AbstractThe study on swelling behaviors of rubber products in liquid media is of great value for life prediction and practical application guidance. In this work, changes in the mechanical properties of hydrogenated nitrile rubber/ethylene propylene diene monomer (HNBR/EPDM) blends caused by swelling in aviation hydraulic oil YH‐15 were studied. Effects of two kinds of carbon black, N220, and N990, on the tensile properties of HNBR/EPDM blends at both unswollen and swollen states were investigated. The results turned out that N220 exhibited better reinforcing effects than N990 on HNBR/EPDM blends. The tensile properties of unfilled and filled HNBR/EPDM blends decreased rapidly at first and then tended to stabilize with the extension of swelling time in YH‐15, while the modulus at 100% declined firstly and then increased. After swelling for 72 h, the tensile strength of HNBR/EPDM blends filled with N220 decreased by more than 35%, and by comparison, it decreased by about 20% for the N990‐filled HNBR/EPDM blends. The cross‐sections of the tensile samples after swelling changed greatly compared with the unswollen samples. In addition, the effect of swelling on the hardness of the HNBR/EPDM blends was not obvious.

COMPLEMENTARITY OF BILATERAL TRADE RELATIONS BETWEEN POLAND AND UKRAINE

Poland and Ukraine and to substantiate on its basis the priority areas of further mutually beneficial cooperation built on the principles of complementarity and strategic partnership. The authors of the article applied a comprehensive approach to the analysis of bilateral trade relations between Poland and Ukraine, in particular, the Trade Complementarity Index (CI) and the Revealed Comparative Advantage Index (RCA) were used in the analysis. The statistical data of the State Statistics Service (Ukraine), WTO, Ministerstwo rozwoju i tekhnologii (Poland) and Główny Urząd Statystyczny (Poland) were the sources for the calculations. The trends in the development of bilateral trade relations between Poland and Ukraine were analyzed on the basis of statistical information. The main prerequisites that form the basis of mutually beneficial Polish-Ukrainian economic cooperation have been identified. It is proposed to use a complex methodical approach in the process of analyzing the complementarity of bilateral relations, in particular through the use of the complementarity index and the index of revealed comparative advantages. The dynamics and product structure of export-import trade between Poland and Ukraine are analyzed. The main differences between the structure of Polish imports to Ukraine and Ukrainian exports to Poland have been revealed. A conclusion was made about the high level of optimality and balance of bilateral relations, the existence of mutual dependence both in terms of imports and exports. The conducted analysis proved the fact that trade between Poland and Ukraine is symmetrical and equal, which makes trade relations mutually attractive. Indicators of revealed comparative advantages within the framework of bilateral cooperationbetween Poland and Ukraine were calculated. Calculations showed that Ukraine has the highest comparative advantages in foreign trade in such goods as ferrous metals, ores, slag and ashes, fats and oils of vegetable or animal origin, furniture, wood and wood products, edible fruits and nuts. Instead, Poland achieves the highest level of comparative advantages in the supply to the Ukrainian market of ground transport means (except railways), plastics and polymer materials, nuclear reactors, boilers and machines, fertilizers, mineral fuels, products of oil distillation, printing products, rubber and rubber products, electric machines and equipment. The economic, organizational and institutional components of the perspectivemodel and priorities for the development of bilateral Polish-Ukrainian trade relations in the conditions of сurrent global challenges are substantiated. The most important strategic priorities for the development of foreign trade relations between Poland and Ukraine in the near future are proposed, namely: creation of a system for monitoring the complementarity of bilateral foreign trade relations between Poland and Ukraine; implementation and comprehensive support of interstate agreements on the development of mutually beneficial trade in complementary goods, including on a barter basis; supporting the development of complementary exports and imports in the sectors of small and medium-sized business, smallscale production, in particular on the basis of production cooperation; support of complementary foreign trade relations not only at the level of industries, but also of individual regions of Poland and Ukraine, in particular within the framework of cross-border cooperation; further improvement of the system of consulting support for exporters in Poland and Ukraine, assistance in entering foreign markets and in the process of searching foreign partners. It was concluded that the development of complementary trade relations should be transformed into joint projects of Polish-Ukrainian production cooperation with the aim of joint production and supply of competitive products and services to the domestic and global markets.

High-value recycling of waste tire rubber powder by wet mixing method

Producing waste rubber into powder and adding it to rubber products as filler is one of the most direct and valuable methods to recover waste rubber. However, weak interface adhesion between waste rubber powder and rubber matrix severely damages the properties of rubber composites. To solve this problem, we propose a method of filling waterjet-produced rubber powder (WPRP) in natural rubber (NR) matrix via a wet mixing process. The characterizations of WPRP, the wet mixing mechanism participated by WPRP, and the properties of the wet-mixing rubber composites are carefully investigated. The surface of WPRP is irregular and contains some hydroxyl groups generated by the cavitation effect of waterjet, which endows the WPRP surface with certain hydrophilicity. The hydrophilic groups enable the stable suspension and uniform distribution of WPRP in latex. The active and irregular surface accelerates the flocculation during high-speed shear mixing, promotes the entanglement of NR molecular chains with WPRP, and forms a network between WPRP and NR matrix, which improves the dispersion of carbon black. When adding 5 parts per hundred rubber (phr) of WPRP, the tensile strength and elongation at break of the rubber composites are 27.8 MPa and 614.1%, respectively, which are even better than those of pure NR. When adding 10 phr of WPRP, the tensile strength and elongation at break of the rubber composite maintain 97.6% and 96.2% of that without WPRPs, respectively. Additionally, the addition of WPRP can reduce the rolling resistance of the rubber composites. This method will allow more waste rubbers to be incorporated into high-value rubber products, thereby relieving environmental pressure and realizing the recycling of rubber materials.

Effects of antimicrobial agents on the processing and performance properties of rubber material formulations with no cytotoxicity

AbstractThe present work aims to develop antimicrobial rubber for safe industrial toys. For this purpose, natural rubber (NR) and synthetic rubber as styrene butadiene rubber (SBR) and ethylene propylene diene monomer (EPDM) were examined. Rubber and their ingredients as well as antimicrobial agents (doxycycline and cephalexin) were mixed in a rubber mixer. The rheological properties of compounded rubber were studied, and the curing time was determined. Mechanical properties and cytotoxicity were evaluated at optimally cured rubber compounds. Scanning electron micrographs of vulcanizates showed good dispersion of ingredients throughout the investigated matrices. Rheology study for the investigated vulcanizates in presence of tested antimicrobial species exhibited no significant change in their flow behaviors. It is significant to remember that the desired physical characteristics of rubber products, including their chemical and mechanical characteristics (elongation at break and tensile strength) enhanced when doxycycline and cephalexin are present, depending on their nature and concentration. Similar results were obtained for both the SBR and EPDM rubber vulcanizates. The cytotoxicity of the prepared vulcanizates towards human normal retina cell line (RPI‐1) indicated good safety of these rubber products. Furthermore, developed rubber vulcanizates showed good antimicrobial efficacy towards the test bacteria and fungi strains.”

Characterization of the Commercial Rubber Band as a Shape Memory Smart Material by Swelling Process with Fused Stearic Acid

This study attempted to focus the light on the characterization possibility of the vulcanized, chlorinated, natural rubber products (as the commercial rubber band used in this study) as a shape memory smart material in the case of impregnating it with fused stearic acid by swelling mechanism. Where in this study, the ability of the commercial rubber band on fixing the stretching strain chosen in this study which is of 70% after removing the applied load off the rubber band, was measured after impregnating it with stearic acid (SA) material of weight ratio (30.4%) and swelling time=2hr. At the same time, measuring the ability of that rubber band on rid of this mechanical deformation once it is thermally stimulated and returning to its original shape (before the deformation) by subjugating it to the hot classical shape memory cycle (based on normal cooling at room temperature) with its two stages represented by the shape memory effect (SME) property activation and deactivation stages. Also, the techniques of differential scanning calorimetry (DSC) and x-ray diffraction (XRD) were used to know the agreement between these tests and the SME property test results (thermomechanical cycle test). Through the practical results of all the tests depending on the diagnosis, it was shown that the direct responsibility for the characterization of the commercial rubber band as a shape memory smart material is the stearic acid (SA) material, which acted as a lock in the rubber band structure that can be opened and closed with a temperature change within the melting range of (SA).

EC fines styrene buyers

The European Commission has fined the chemical companies Sunpor, Synbra, Synthomer, Synthos, and Trinseo a total of $162 million for participating in a cartel to depress the price of styrene, a raw material they buy, on the European market. Ineos also participated in the cartel but avoided a fine by blowing the whistle on the illegal activity. The commission began its investigation in September 2017. It found that the companies had been operating as a cartel between May 1, 2012, and June 30, 2018. “The six buyers of styrene exchanged sensitive commercial information and coordinated their negotiation strategy,” the commission states in a press release. Such practices are banned in the European Union because they distort the competitive process. Styrene is an intermediate for plastics, rubber, and other products. The fines were $17.7 million for Synbra, $32.7 million for Sunpor, $33.5 million for Synthos, $33.7 million for Trinseo, and $44.4

Results of derivatographic and ir-spectroscopic investigations of wear-out rubber of car tires after pyrolysis processing

The paper presents the results of a study of the physicochemical characteristics of a carbon-containing material obtained by pyrolysis of worn tires. The temperature balance in the pyrolysis of car tires in the range of 50-1100 °C was determined by derivatographic analysis. It is proposed to develop composite elastomeric materials based on rubber of grades SKI-3 and SKMS-30, which are filled with carbon-containing material after pyrolysis. A relationship between structural characteristics, the nature of the surface of a carbon-containing material, and rubber macromolecules has been found. The use of the solid phase of pyrolysis as a filler of a carbon-containing material, which can be used in the production of rubber, has been studied.

Digital manufacturing process quickly produces liquid silicone rubber parts

To support manufacturers, Trelleborg Sealing Solutions has developed and is offering a fast and flexible digital manufacturing process for product development and small-batch production of liquid silicone rubber (LSR) parts. This article briefly looks at what is involved.

Influence of platinum on ablation behavior of silicone rubber

The influence of platinum on silicone rubber ablation was studied by muffle furnace,X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The addition of platinum promoted ceramic formation, causing the silicone compound to burn into a hard ceramic, significantly increasing the residual weight. The XRD showed that the crystallization peak was weakened and the crystal structure was disrupted. The XPS revealed a decrease in the calcium content in the residue.Overall,the addition of platinum allowed the decomposition products of silicone rubber to participate in the ceramic process and form a hard solid.

ВИКОРИСТАННЯ ГУМОВОЇ КРИХТИ ДЛЯ МОДИФІКАЦІЇ БІТУМУ

The main reason for the destruction of road wear layers is the loss of structural connections in the material of asphalt concrete layers, which is largely due to the low quality of bitumen. In order to improve the properties of binding materials, composite binders based on bitumen and modifiers are used in foreign and domestic practice for the installation and repair of road surfaces. One of the ways to improve the properties of asphalt concrete is the use of modifiers based on rubber crumb obtained from car tires that have lost consumer properties, as well as other rubber products. The problem of using tires is also of great environmental importance. Used products accumulate in places of operation (car parks, airfields, industrial enterprises, etc.). In addition, tires have a high fire hazard, and products of uncontrolled combustion have an almost irreversible impact on the environment. The paper presents a domestic and foreign analysis of the use of rubber crumb to modify bitumen in order to improve the physical and mechanical indicators of road wear. Asphalt concrete coating on transport facilities, which includes bitumen, is subject to significant influence of adverse factors (precipitation, change in environmental temperature, load from motor vehicles, etc.), which reduce its durability. Modification of road bitumen is one of the promising ways of increasing the durability of asphalt concrete pavement on artificial structures. Since the rubber crumb has an organic affinity with the components of bitumen and the physical and mechanical interaction gives a homogeneous material with significantly different characteristics from the original material.

Indonesia’s Natural Rubber Productivity and Technically Specified Natural Rubber 20 Export: The Effect of El Nino Southern Oscillation

El Nino Southern Oscillation (ENSO) causes rainfall anomalies, which may disrupt Indonesia’s natural rubber production by interfering with the trees’ growth and affecting the export volume. This study analyzed the effect of ENSO dynamics on the monthly productivity of natural rubber and Technically Specified Natural Rubber (TSNR) 20 export. Monthly data from January 2006 to December 2019 were collected from the Statistics Indonesia, International Trade Centre (ITC), World Bank, Bank Indonesia, and National Ocean and Atmospheric Administration (NOAA). Descriptive statistics unveiled that strong La Nina increased the average of monthly productivity by 3.37% to 9.68%, while strong El Nino tended to decrease productivity by 1.30% to 9.27%. Moreover, the Vector Error Correction Model (VECM) demonstrated the negative effect of ENSO on Indonesia’s natural rubber export, both in the short and long term.

Self‐healing natural rubber based on dynamic disulphide exchange towards fatigue lifetime extension

AbstractDynamic disulphide exchange mechanism was introduced to promote self‐healing characteristics to natural rubber compound and the corresponding healing mechanism and mechanical properties are presented. The formation of reversible dynamic disulphide bonds within rubber molecular chains was evidenced via FTIR and the total crosslink density of dynamic disulphide crosslinks was quantitatively measured by equilibrium swelling test. Scanning Electron Microscopy (SEM) results revealed that the healed area of the fractured surface adhered well with minor scar on the contact surface, suggesting that intermolecular diffusion occur at the fracture surface. It was also found that the tensile strength and tear strength of the broken samples able to recover 91% and 103%, respectively, under thermal healing at 150°C for 10 min. The fatigue lifespan of the materials increased 154.9% compared with the conventional rubber. The successful fabrication of self‐healing natural rubber through dynamically reversible disulphide exchange mechanism would be expected to open up new opportunities for development of sustainable rubber products.

Capacitive Interdigitated Electrodes Sensor for the Field Device to Measure Moisture Content in the Nitrile Gloves Manufacturing Industry

This paper investigates the impedance spectroscopy technique in determining moisture content in Nitrile gloves. Interdigitated electrode was designed and fabricated, then evaluated on LCR Impedance meter subjected to frequency range of 100Hz, 120Hz, 1kHz, 10kHz, 20kHz and 100kHz. Samples of Nitrile gloves were compounded and prepared for different moisture content level and regression analysis was performed to evaluate the relationships between capacitance and moisture content of the glove samples. Experimental results indicated that the capacitance value is a strong function of moisture content in gloves and also that the capacitance of moisture content in Nitrile gloves decreased with increasing drying time over the measured frequency range whilst statistical analysis results have confirmed that the 1kHz, 10kHz and 20kHz signal frequencies have highest reliable prediction of the nitrile gloves’ moisture content with high R2 value of 0.96, 0.97 and 0.97, respectively. The ability to determine average moisture content of Nitrile gloves via a non-destructive and online method, utilizing a low-cost instrument, will be of considerable use in the glove industry. This method could also be extended to other types of gloves and rubber products.