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The effect of shungite on the structural and viscous-flow properties of compositions based on oligobutadiene was studied. The strength of coagulation structures of ebonite compositions filled with shungite was determined. The critical filling concentration was established and it is 40 wt.% of shungite per 100 wt.% of oligobutadiene. It was shown that increasing the temperature from 200C to 800C leads to a significant reduction in the shear stress required to destroy the structure of the composition. Temperature and shear rate independently affect the structured composition. Thus, it was shown that shungite powder can be used as a filler in liquid ebonite compositions based on oligobutadiene.

For the first time, the effect of γ-radiation (with doses of 5, 10, 15, and 20 Mrad) on the structure and mechanical characteristics of a polymer composite material based on low-molecular-weight rubbers has been studied. It is shown that an increased radiation dose increases its breaking stress and decreases the breaking strain. The fracture energies are calculated from experimental values of the breaking stress and breaking strain. It is shown that the strength (fracture energy) of samples increases with radiation dose. On irradiation with a dose of 20 Mrad, samples acquired the property of ebonite, which was indicated by a sharp decrease in the breaking strain and an increase in the breaking stress. Based on the study of IR spectra of samples, it is assumed that the change in their mechanical characteristics under the influence of γ-radiation is caused by changes in the structure of the material, i.e., destruction of the carbonyl double bond and an increase in the concentration of other chemical bonds.

The effect of gamma-irradiation with doses of 5, 10, 15, and 20 Mrad on the mechanical characteristics of a polymer composite material has been studied. It has been shown that an increase in the radiation dose leads to an increase in the breaking stress and a decrease in the breaking strain. Toughness values have been calculated, from which it follows that the strength of the investigated samples (toughness) increases with increasing radiation dose, reaching a maximum at 20 Mrad. An increase in the test temperature leads to a sharp decrease in the toughness. Irradiation with gamma-rays to a dose of 20 Mrad leads to the material acquiring the properties of ebonite, as indicated by a sharp decrease in the breaking strain and an increase in the breaking stress.

—The problem of determining the complex dielectric constant of materials in the centimeter and millimeter wavelength ranges is solved using the waveguide method with an double-ridged waveguide. The use of a segment of an double-ridged waveguide as the measuring cell made it possible to expand the operating frequency range and increase the measurement accuracy due to localization of the electromagnetic field energy in the space between metal ridges. The electromagnetic fields of hybrid types of waves in the double-ridged waveguide were calculated by the partial region method taking into account the peculiarities of the electromagnetic field on the metal and dielectric ridges. The results of measuring the complex dielectric constant for samples made of ebonite, Teflon, and fiberglass are presented.

The use of link slab as a substitute for expansion joints is one of the innovations that can provide benefits for bridge life, user comfort, and maintenance cost efficiency. Link slab is a slab placed on the upper surface of the adjacent girder end which forms a continuous slab system with the slab deck. In the transition zone, link slab and girder are installed in hard rubber and soft rubber pads at some thick variations in each type of rubber. Moment on the link slab is obtained due to the effect of traffic load according to SNI 1725: 2016 with the condition of the link slab without and with rubber pads. The study of the use of link slab in this paper is carried out in a numerical approach on a finite element software-Abaqus. Link slab is modeled as a 3D solid model in compressive concrete variations. In this study, the addition of hard rubber pads on link slab can reduce the magnitude of moments compared to link slab without rubber pads. This is indicated by the percentage reduction moment between 39,20-83,42% on LS-1, LS-2, and LS-3 hard rubber pads with thichness 10 mm, 20 mm and 30 mm. While on link slab with soft rubber pads is found that moments are greater at the very thick pads This is indicated by the percentage difference in moments between 198,26 – 244,58% on LS-1, LS-2, and LS-3 soft rubber pads with thickness 10 mm, 20 mm and 30 mm. This large difference is due to the effect of moment change from negative moments (initial conditions) to positive moments after the addition of soft rubber pads.

During the last 21 year period from 1996–2016, the total value of imports of rubber and rubber products grew at a rate of 17.66% compared to 14.18% growth rate in the value of exports. As a result of higher growth in imports and lower growth in exports, in the last 10 years, external trade in this segment had shown negative balance of trade consistently. In 2016–2017, the country had a negative balance of trade of US$ 414.76 million dollars. The broad objective of the present study is to identify products groups with comparative advantages in the global market. The study used methods such as Revealed Comparative Advantage, Revealed Symmetric Comparative Advantage and concentration ratio to analyse the comparative advantage of all the 17 rubber and rubber product groups (four digit level) under chapter 40 of the harmonised system nomenclature. Data from world integrated trade solution (WITS) during the period 1996–2016 are used for the analysis. Our results showed that despite a comparative disadvantage of the rubber sector at the aggregate level in the world market, the three product groups, viz, reclaimed rubber (HS 4003), inner tubes, of rubber (HS 4013), and hygienic or pharmaceutical articles (including teats) (HS 4014), exhibited comparative advantage consistently throughout the 21 year period. The two major product groups, viz., new pneumatic tyres of rubber (HS 4011) and other articles of vulcanised rubber other than hard rubber (HS 4016), which accounted for 68.68% of the total value of exports from the sector showed varied trends.

The determination of mechanical properties of materials provides the basis for the fundamental understanding of the behaviour of components that can experience degradation in operation and/or even during storage. A very representative example of this is the thermal aging mechanism that severely affects materials that are ultimately intended to operate in a harsh operating environment as that of a nuclear reactor. Polymers, and especially elastomers, play a key role as part of the many mechanical, electrical and electronic components found in nuclear power generation plants. The degradation of polymeric materials is a frequent phenomenon that is accelerated, in many cases, by arduous operating conditions. Elastomers, especially rubbers - such as acrylonitrile butadiene, NBR - experience degradation that is favoured by contact with oxygen [1]. This type of reaction -which triggers the irreversible damage of the component- is favoured by an increase in the operating temperature. Therefore, it is of interest to analyse how their intrinsic properties influence their thermal aging. One of most usual parts with relevant safety-related function in nuclear equipment is the NBR O-rings or gaskets that are used as mechanical sealing elements, since their safety function is being capable of preventing any leakage (whether internal or external) throughout the useful life of the equipment [2]. The objective of this work is the development of a methodology to determine the useful life -based on the storage temperature- of NBR O-rings using a reliability-based approach that allows to obtain the health condition at different supposed storage scenarios, considering the required in-service performance. For the study, NBR has been selected as a gasket material, since a previous work has shown that acrylonitrile is the best option [3] to withstand moderate levels of radiation thresholds extracted from databases [4-5] as well as its recyclability providing a sustainable life cycle. The evaluated parameter has been the Shore A hardness in accordance with ISO 868 [6] during a period of five years (between 2014 and 2019). Thus, the thermal embrittlement is quantified based on an adaptation of Arrhenius model-based correlation between hardness and temperature and storage time. The study incorporates a comparison between the results obtained for newly manufactured and existing O-rings in the warehouse, considering several statistical scenarios. REFERENCES Azura A., Thomas A (2006): “Effect of heat ageing on crosslinking scission and mechanical properties. elastomer and components. service life prediction–progress and challenges”. In Coveney, V. (Ed.). Elastomer and components: Service life prediction - progress and challenges, 27–38, Cambridge: Woodhead Publishing. Available from: https://www.researchgate.net/publication/281852920_Effect_of_Curing_Systems_on_Thermal_Degradation_Behavior_ofNatural_Rubber_SMR_CV_60 [accessed Sep 08 2020]. EPRI CGI-OR02 (1992): “Commercial grade item evaluation for national O-Rings”. Electrical Power Research Institute, Palo Alto-CA (USA). Rodriguez-Prieto A., Camacho A.M., Sebastian M.A., Yanguas-Gil A. (2019): “Analysis of mechanical and thermal properties of elastomers for manufacturing of components in the nuclear industry”. Procedia Manufacturing 41, 177–184. IAEA-TECDOC-1551 (2007): “Implementation strategies and tools for condition based on maintenance at nuclear power plants”. International Atomic Energy Agency, Vienna, Austria. Van de Voorde M.H., Restat C. (1972): “Selection guide to organic materials for nuclear engineering”. European Organization for Nuclear research, CERN, Geneva, Switzerland. ISO 868 (2003): “Plastics and ebonite — Determination of indentation hardness by means of a durometer (Shore hardness)”. International Standardization Organization (ISO), Geneva, Switzerland.

Ebonite compositions, which are oligo-butadienes-based, are widely used for gumming the chemical equipment and instruments that are operated in aggressive media. For the ebonite compositions with anti-corrosion purposes, of scientific and practical interest was to explore the possibility of using as a filler of chemically resistant polymeric materials, which include the ftorlon powder F-2M. We examined the effect of a ftorlon filler on the rheological properties of ebonite compositions based on 1.2-oligo-butadiene. Results of the study revealed that the compositions on the base of oligo-butadiene, filled with a ftorlon powder, are the weakly structured systems with a pseudo plastic nature of the flow. Fluctuation grids of the compositions filled with ftorlon are easily destroyed under the action of uniform shear and temperature. In order to resolve this issue and to ensure the developed coagulation structure, the compositions need to be introduced with structure-forming additives, in particular aerosil (up to 5 % by weight). We determined the dependence of strength of a vulcanizate on the sulfur content and the duration of vulcanization of coatings, which is important in order to regulate the properties and technological process of obtaining the chemically resistant coatings with improved properties. As a result of vulcanization of the examined compositions, it is possible to receive coatings with high strength (up to 27 MPa at tearing) and adhesion (9.8–10.2 MPa at tearing) without the use of specialized primers and adhesives. We explored the ohmic-capacitive characteristics and demonstrated chemical resistance of the vulcanized coatings in the 20 % solutions of sulfuric and hydrochloric acids.

Reinforcement is a fundamental issue in rubber science and engineering. Traditionally, rubber reinforcement relies on the incorporation of rigid particles into rubber network or creation of the rubber network with dual-crosslink. However, all these methods inevitably sacrifice the unique elasticity of rubber, which is a shackle toward some crucial applications such as energy-saving tires. In this contribution, a novel strategy of rubber-reinforced rubber (3R) with the combination of significant reinforcement and high elasticity is proposed. With experimental/simulating integrated method, a brand-new reinforcing mechanism for rubber is disclosed, called soft matrix-induced large extensionability of hard rubber (“SMILE-HR”). The soft matrix endows the highly-crosslinked rubber particles (HPs) with the capacity of large extensionablity, so the molecular chains in HPs can be highly oriented and thus obtain high strength during stretching, which are primarily responsible for the dramatic reinforcement of 3R. This skillful combination of these two elastic constituents conquers the stubborn contradiction between reinforcement and elasticity, which is very promising for the engineering rubbers served in dynamic environment.

This paper deals with an experimental analysis of hard rubber dynamic tests under finite torsion deformations. The experimental test rig was designed and composed for torsion loading of rubber under defined amplitudes, frequencies and temperatures. The present paper brings an amplitude-temperature analysis of isoprene-butadiene rubber ascertained by the use of the test rig. The mathematical rheological model of rubber was designed for phenomenological description and parametric identification of rubber.

Dampers and shock absorbers consisting of vertical concentric elastic shells are considered. The external and internal shells are made of hard rubber, while the middle shell is made of soft rubber. Independent action of the shells permits optimal loading and energy-efficient operation of the device.

Compound Design * Mixing Technology * Mixing Machinery for the Rubber Industry * Calendering Technology * Extrusion and Extrusion Technology * Vulcanization and Curing Techniques * Computer-Aided Mould Design * Automation and Control in the Rubber Industry * Improving Rubber Testing with Microcomputers * Computer-Integrated Manufacturing (CIM) * Rubber-to-Metal Bonding * Coated Fabrics Computer-Aided Rubber Product Design * Tyre Compound Development * Developments in Tyre Technology * Conveyor Belt Technology * V-Belt and Fan Beft Manufacturing Technology * Hose Technology * Cable Technology * Vibration Isolators and Mounts * Rubber in Automotive Applications * Oil-Resistant Rubber Material for Automotive Hoses * Rubber-Covered Rolls * Footwear Technology * Sealing Technology * Hard Rubber Compounds * Rubber Sports Goods Manufacturing Technology * Latex Products Manufacturing Technology * Foam Products Manufacturing Technology * Pressure Sensitive Adhesive Tape Technology * Just-In-Time and the Rubber Industry * Waste Disposal.

The new technique for measuring the complex permittivity of materials in a wide microwave frequency range has been developed. The double ridged waveguide has been used as a measuring cell. The proposed technique allows to increase the accuracy of measurements by placing the dielectric sample between the ridges of the waveguide, in the place of maximum concentration of electromagnetic energy of the fundamental wave. For the double ridged waveguide with dielectric filling, electrodynamic characteristics have been calculated, such as propagation constants and cutoff frequencies. The structure of the fundamental HE-wave at the operating frequency has been determined and visualized. The measurement results of the complex permittivity of the ebonite sample have been presented.

Sustainable Eucommia ulmoides gum (EUG) was a biomaterial with the molecular structure of trans-1,4-polyisoprene and poor elasticity, and was usually considered as a hard rubber with a limited applications in rubber products. Triazolinedione (TAD)-based Alder-ene reaction was used to modify EUG to precisely tune the mechanical properties and effectively improve the elasticity by reducing crystallinity, introducing urazole groups, and forming hydrogen bonds between EUG molecules. By adjusting TAD feed, the modified EUG could become an excellent tough elastomer with combined high strength, elongation, and toughness; or a unique rubber with superhigh elongation, low Young's modulus, and good elastic recovery rate. Furthermore, the modified EUG displayed enhanced shape memory capability with fast shape recovery speed, high cyclic shape recovery rate after 10-cycle deformations, and large shape memory recoverable deformation. Therefore, these elastomers may have extended applications in tires and smart materials.

Clean floors in dairy housing have a positive impact on claw health, cleanliness of the animals and ammonia-emission reduction. Key indicator of cleaning quality is residual soiling mass, i.e. the manure remaining on the floor after dung removal. The aim of this study was to show the effects of scraping tool, rubber mat type, solid floor type, dung removal frequency and season on residual soiling mass. The comparison two scraping tools and two rubber mat types in winter showed that the rubber mat type (p = 0.001) and the scraping tool (p = 0.001) influenced the residual soiling mass. The cleaning quality was better on the common than on the soft rubber mat and the hard rubber lip left less residual soiling mass versus the metal blade (means: 174 vs. 230 g m−2 on common; 230 vs. 243 g m−2 on soft rubber mat). Further two floor types (with and without 3% slope) and two dung removal frequencies (three and 12 times per day) were investigated in three seasons. The statistical analysis proved the season as significant (p < 0.001). Residual soiling mass in winter was smaller than in warmer seasons regardless of floor type and dung removal frequency. Within the summer dataset the floor type was significant (p = 0.037): the floor without slope showed less residual soiling mass in average 218 resp. 234 g m−2 with three resp. 12 dung removal events per day than the sloped floor with 280 resp. 303 g m−2., Biosystems Engineering, 170, ISSN:1537-5129, ISSN:1537-5110

To improve the properties of hard rubber(Ebonite) from natural rubber, added Nano-Carbon black, where measured the properties of tensile, density, hardness and the properties of the vulcanization of a group of samples with different amount of sulfur from 18-36 pphr and different of carbon black (18-26-30) pphr. The results showed that the best carbon black ratio is 30 pphr, where it gives a balance between tensile properties of hand and toughness and flexibility of on the other hand and reduce brittleness in hard rubber.

In this study, an easy and enjoyable activity to determine the type of electric charge is presented, using a readymade electronic test screw. A four-way usage of the tester is explained with an electroscope. In the activity, ebonite and glass rods are negatively and positively charged by rubbing with paper sheets, respectively.

This dissertation explores the value system held by the author of the Epistle of James. Most likely, this interesting Epistle of a former Galilean peasant is a collection of his sermons or discourses gathered and edited by one of his followers. The Epistle does not relate to any specific problems of concrete communities or persons and, therefore, it may be viewed as an encyclical letter. The author's main tone is: «you must act in this way and only this way». Therefore this document is a type of «halakhah», a literary form used by the sages of Israel before the Common Era. «Halakhah», as well as the Greek literary form paraenesis, does not imply any discussion of the material, but rather calls the readers to submission. The author of this «halakhic» encyclical shifts the attention of his readers from their realities to his idealistic world. He omits many aspects of Second-Temple-Period Jewish life, focusing his attention instead on the rules of spiritual life common for both Judeans and Christians. This focus explains why the Epistle has only two brief and indirect references to Jesus Christ, who as the hero surprisingly does not play a distinctive role. for several reasons the Messiah is replaced by famous characters from the Tanakh (i. e., Abraham, Rahab, Job, and Elijah) as being the best examples for...

Ebonite is an interesting material. It is used as an electrical insulating medium and chemical-resistant material. Vulcanized ebonite is machinable and many engineering products can be made adopting regular engineering practices like turning, grinding, boring, drilling, etc.; however, it cannot be welded for making joints. It looks and feels like a hard plastic. It is called hard rubber because it is a modified version of soft rubber but not having the nature of soft rubber. Soft rubber has a low percentage of sulfur and is elastic, but hard rubber has lost most of its elastic or rubbery properties during conversion to the hard stage. It is a highly vulcanized rubber and has low swelling in a given liquid medium. Ebonites contain more than 30% sulfur combined with the natural rubber molecules. The commercial manufacture of hard rubber products started during the mid-19th century and henceforth ebonite became an important branch of the rubber industry. Though during subsequent years and until today newer types of hard plastics came into existence to replace hard rubber, the hard rubber industry continued to stay in its position of importance by virtue of its unique characteristics, the main one being its chemical resistance and its extensive use in the process industries. The chemical inertness, high strength, and good appearance of ebonite, and its machinability, led to its use in many applications.

A number of ordinary items of everyday use are obtained from complex chemical processes starting from life-saving drugs, capsules and tablets to perfumes, and so on. These are all derived from coal, crude oil, and petroleum gases. From crude oil we get fertilizers, plastics, synthetic rubbers, pesticides, detergents, fabrics, and coatings and paints. From sea water we get vital heavy chemicals like caustic soda, sodium chloride, sodium hydroxide, hydrochloric acid, etc.

We encounter the miracle material rubber everywhere and every day without even realizing it—in cars, toothbrushes, mobile phones, computers, chewing gum, balloons, surgical gloves, bathroom mats, rubber corks, rubber bands, erasers, roads, hospitals, and in aircraft and space craft. When combined with other materials, rubber has an almost infinite number of uses. It is one of the most hardy, robust, and versatile materials in existence. The oldest traces of rubber were found in a fossil estimated to be 55–60 million years old, discovered in 1924 in lignite deposits in Germany. Amazingly, after being treated, the rubber still had its elastic properties!

In this study, a fuzzy artificial intelligence approach is utilized to predict the erosion rate of reinforced ebonite composite materials with carbon fiber owing to the significant accuracy of soft computing techniques. Experimental data were used to predict the erosion rate with respect to the input testing conditions, namely, impact velocity, impingement angle, erodent size, and stand-off distance. The size of the erosive element of randomly shaped sand particles (silicon dioxide) is set between 300 and 600 μm. Other input process parameters, such as the impact velocity between 30 and 50 m/s, the impingement angle between 30° and 90°, and the stand-off distance between 15 and 25 mm, are selected. The consistency between the experimental and fuzzy logic model values, with a 94.45 % accuracy, signifies that the proposed fuzzy logic model is suitable for predicting the erosion rate of reinforced ebonite composite materials. The maximum erosion rate is obtained between a 50° and 60° impingement angle. Morphological images are analyzed by scanning electron microscopy to elucidate the erosion mechanisms.

Based on the formation characteristics of high temperature (above130°C ) and multi-salt, we optimize several blowing agent monomers to compound a new type of foaming agent, and screen out the new foam stabilizer to determine the new ebonite foam drilling fluid system. In the laboratory, we evaluated its resistance to high temperature, salt and oil pollution. And we made a research on its rheological characteristics of the foam and the behavior of high salinity. The experimental result shows that the ebonite foam drilling fluid has much more foam, longer stable time, significant effect of the resistance to high temperature, salt and oil pollution and has good sand-carrying ability, which can effectively prevent the occurrence of loss circulation and meet the requirement of rock carrying and wellbore stabilization.

Tread wear of tyres is one of the serious issues in automobiles. Higher amount of heat is generated due to lesser availability of air in the tread region when the vehicle is travelling at high speeds. The existing M1 vehicle tyre has some specific standards of tread angle. In this paper, flow simulation and drop tests of M1 vehicle tyre are carried out using Solidworks. The objective of the work is to improve the cooling efficiency of tyre for vehicle speeds as 40 kmph, 80 kmph and 120 kmph. Various tread patterns for tyres made with hard rubber, Nylon66 and Nylon6 materials were simulated to predict the temperature distribution. Based on the temperature distribution and drop test results from the simulation, improved designs of M1 vehicle tyre are presented.

The widespread use of polymers for containers led to many premature failures of the thin walls, often caused by poor design such as sharp internal corners and poor moulding practice. Older battery containers were made from ebonite or hard rubber, and needed thick walls, but failed because of the inherent weakness of the material. A new patent led to much thinner walls and polypropylene is widely used for cases. A low density polyethylene bucket fractured when a weld line failed on a lug, injuring the user. Hydrogen explosions in lead–acid batteries are caused by short-circuits within the battery, but can often be detected before failure by swelling of the case sides caused by internal gas pressure. Fractures in truck cases were caused by poor design and moulding. Failures in polycarbonate miners' battery cases were caused by solvent welding and frozen-in strain from cold moulding and were minimized by changing to transparent polymer with quality control using strain birefringence. A new polishing method was developed to section case parts and moulding conditions closely monitored. Internal stress concentration occurred at corners, lowering drop impact strength. A small lithium cell exploded prematurely causing a serious eye injury. Inspection of the remains showed that a critical plastic seal showed brittle cracking across the radius and sub-critical cracking with melting of some corners, implying that the cracks were present before the explosion. A short-circuit likely caused the explosion and the battery cell was faulty. The electrolyte is based on an organic fluid and is highly inflammable.

An endeavor has been made to study and compare the friction coefficient of different polymer and composite materials. Experiments were carried out when stainless steel 304 (SS 304) pin slides on different types of composite and polymer materials such as cloth reinforced ebonite (commercially known as gear fiber), glass fiber reinforced plastic (glass fiber), nylon and polytetrafluoroethylene (PTFE). Experiments were conducted at normal load 5, 7.5, 10 N, sliding velocity 0.5, 0.75, 1 m/s and relative humidity 70%. Variations of friction coefficient with the duration of rubbing at different normal loads and sliding velocities were investigated. Results show that friction coefficient varies with duration of rubbing, normal load and sliding velocity. In general, friction coefficient increases with the increase in normal load and sliding velocity for all the tested materials except nylon. At identical operating conditions, the magnitudes of friction coefficient are different for different polymer and composite materials.

PurposeThe present paper seeks to report the effect of duration of rubbing on friction coefficient for different polymer and composite materials. Variations of friction coefficient and wear rate with the normal load are also investigated experimentally when stainless steel (SS 304) pin slides on different types of materials such as cloth‐reinforced ebonite (commercially known as gear fiber), glass fiber‐reinforced plastic (glass fiber), nylon and polytetrafluoroethylene (PTFE).Design/methodology/approachA pin on disc apparatus is designed and fabricated. During experiment, the rpm of test samples was kept constant and relative humidity was 70 percent.FindingsStudies have shown that the values of friction coefficient depend on applied load and duration of rubbing. It is observed that the values of friction coefficient decrease with the increase of normal load for glass fiber, nylon and PTFE. Different trend is observed for gear fiber, i.e. coefficient of friction increases with the increase of normal load. It is also found that wear rate increases with the increase of normal load for all the materials. The magnitudes of friction coefficient and wear rate are different for different materials.Practical implicationsIt is expected that the applications of these results will contribute to the design of different mechanical components of these materials.Originality/valueWithin the observed range of applied normal load, the relative friction coefficient and wear rate of gear fiber, glass fiber, nylon and PTFE are experimentally investigated.

An unique case of dense fouling by an acidophilic, hard rubber (polymerized rubber) degrading fungus in the acid transfer pipelines of a boron enrichment plant located at Kalpakkam, India is reported. In spite of a highly adverse environment for survival (pH 1.5, no dissolved nutrients), the fungus thrived and clogged the pipeline used for transferring 0.1N hydrochloric acid (HCl). Detailed investigations were carried out to isolate and identify the fungus and examine the nutrient source for such profuse growth inside the system. Microscopic observation showed the presence of a thick filamentous fungal biomass. Molecular characterization by 18S rRNA gene sequencing showed 98% similarity of the isolate with the acidophilic fungus Bispora sp. In laboratory studies the fungus showed luxuriant growth (specific growth rate of 13 mg day⁻¹) when scrapings of the hard rubber were used as the sole source of carbon. Scanning electron microscopy revealed extensive incursion of the fungus into the hard rubber matrix. In the laboratory, fungal growth was completely inhibited by the antifungal agent sodium omadine. The study illustrates an interesting example of biofouling under extreme conditions and demonstrates that organisms can physiologically adapt to grow under unfavourable conditions, provided that a nutrient source is available and competition is low. The use of this fungal strain in biodegradation and in development of environmentally compatible processes for disposal of rubber wastes is envisaged.

The contribution focuses on teaching and innovation for Sustainable development. Teaching the theory on the basis of the practical experiences envisages sustainable development planning as a process of continuous improvement. The article shows an optimization of recycling of concrete from lightweight aggregates containing expanded glass and hard rubber. The purpose of this work was to produce the new combination using rest, construction waste of concrete from lightweight aggregates and hard rubber and new raw components of concrete from lightweight aggregates, as key reactive material.

Numerous gluten preparations were produced by the variation of pressure and temperature. Optimal conditions for the production of gluten films on a laboratory-scale were by suspending of gluten (1 g) in a mixture of ethanol (3 mL), glycerol (0.5 g) and conc. formic acid (10 mL), casting and drying at 40 °C. Small-scale laboratory methods for the production of gluten films by casting and moulding were developed. Film strips obtained were examined by micro-extension tests, which resulted in curves similar to extensigrams for dough and gluten and allowed the determination of the resistance to extension, extensibility and elasticity. The results demonstrated that pressure treatment of gluten in combination with variable cultivars, temperature, process parameters and additives, allow the production of films with a wide range of rheological properties – from soft and smooth to strong and hard rubber like. Finally, it was demonstrated that the addition of fibres to gluten enhanced the stability of films. Thus, high pressure treatment allows a selective modification of gluten as raw material for film production. In comparison with conventional plastic films, gluten films have considerable advantages, because they can be produced from renewable plants and they are readily biodegradable.

PurposeThe purpose of this paper is to present the frictional behaviour of composite materials under external horizontal vibration. Variation of friction coefficient is investigated experimentally when mild steel pin slides on composite materials such as glass fiber reinforced plastic (GFRP) and cloth reinforced ebonite (commercially known as gear fiber).Design/methodology/approachA pin‐on‐disc apparatus having the facility of vibrating the test samples in a horizontal direction is designed and fabricated. Horizontal vibration is created along (longitudinal direction), and perpendicular (transverse direction) to, the sliding direction. The experimental set‐up has the facility to vary the amplitudes and frequencies of vibration while velocity of vibration is kept constant.FindingsThe relative frictional behaviour of these materials and their dimensional analysis are yet to be investigated. Therefore an attempt is made to investigate the relative frictional property of the GFRP and cloth reinforced ebonite (commercially known as gear fiber) and the results of these composite materials are analyzed by dimensional analysis under horizontal vibration.Practical implicationsIt is expected that the applications of these results will contribute to the improvement of different concerned mechanical systems.Originality/valueIt can also be noted that there are no clear correlations between friction‐ and other vibration‐related operating parameters. Considering the above conclusion and lack of correlation, the paper meant to find out a suitable correlation and a way of observing the response of friction force by applying known frequency and amplitude of vibration in a particular direction. It is expected that the application of these results will contribute to the improvement of different concerned mechanical systems.

The effect of ultrasound on convective flow in the melt at pulling of Ga0.03In0.97Sb single crystals has been modeled by the light cut method in an ebonite crucible using transparent liquids (water glycerol solution and acetone). It is established the influence of the temperature gradient in the liquid and crystal rotation affect the convection formation. It is shown that introduction of ultrasound at frequencies of 0.72 and 1.44 MHz in the direction parallel to the crucible axis standing wave channel in the liquid without convective flow. The spherical bottom of the crucible increased of the standing wave channel diameter to 30% in the top part of the liquid volume and change of distance between the antinodes of ultrasonic standing waves. The decrease of the liquid depth does not eliminate ultrasonic standing wave channel.

Adhesion mechanisms and peel strengths of wood/ebonite NR-EPDM laminates were investigated. Three different chemical coupling agents: namely; N-(β aminoethyl)-γ-aminopropyl-triethoxysilane (AAS), 3-methacryloxypropyl trimethoxysilane (ACS), and Bis-(3-triethoxylpropyl) tetrasulfan (Si69) were introduced into the wood/NR composites to enhance an interaction between wood sawdust (SD) particles and NR molecules, and to improve the adhesion strength between the SD/NR and EPDM layers. The quantitative evidences were given to explain the changes in the adhesion or peel strengths of the SD/NR-EPDM laminates through scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDS). The experimental results indicated that the suitable cure time and cure temperature for SD/NR-EPDM melt-laminates were the tc90 of SD/NR composites and 140°C, respectively. The Si69 coupling agent was found to be the most effective coupling agent as compared with AAS and ACS coupling agents. The Si69 of 0.5 wt% was recommended for the optimizations of the tensile modulus of the SD/NR composites and the peel strength of the SD/NR-EPDM laminates. The diffusion level between the SD/NR and EPDM layers could be quantitatively substantiated by determining the sulfur content transfer from the SD/NR layer to the EPDM layer. The diffusion and entanglement of molecular chains from the SD/NR to the EPDM layer initiated the co-crosslinking reaction which played an important role on the changes in the interfacial strength in the SD/NR-EPDM melt-laminates. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Eucommia ulmoides Oliver is a deciduous tree distributed in China, and is the only species in its genus, and the only genus in its family. It grows in temperate zones, and produces long-chain trans-polyisoprene throughout the entire plant. This trans-polyisoprene (TPI) derived from Eucommia is called Eucommia rubber (EU-rubber), and is a hydrocarbon with a carbon molecular weight of a few hundred thousand. EU-rubber is a hard rubber with thermoplasticity, and has properties similar to plastic. In terms of practical use, these plant-derived polymers are attracting attention as an industrial raw material to substitute for petroleum, and demand is expected to grow in the future. Hydrocarbon is also a fuel which has energy with the same value as petroleum.

The simulation of rubber-like materials is usually based on hyperelasticity. If strain-rate dependency has to be considered viscous dampers also have to be taken into account in the rheological model. A disadvantage of such a description is time-consuming parameter identification associated with the damping constants. In this paper, a tabulated formulation is presented which allows the fast generation of input data based on uniaxial static and dynamic tensile tests at different strain rates. Unloading, i.e. forming a hysteresis loop, can also be modeled easily based on a damage formulation. We show the theoretical background and algorithmic setup of our model that has been implemented in the explicit finite element program LS-DYNA [1-3]. Apart from purely numerical examples, the validation of a soft and a hard rubber under loading and subsequent unloading at different strain rates is shown.

Although ebonite has been discovered for a long time, its applications were still limited to some household products. Recently, ebonite rubber has become of interest, especially for structural applications due to its high and adjustable strength and rigidity. The rigidity can be enhanced by several folds by utilizing appropriate curing conditions. In this study, we investigate the effect of curing conditions on the mechanical properties of ebonite at various cure time. Here, the crosslink densities were determined qualitatively both before and after compression cycles to investigate the change in crosslink networks. After the pre-molding stage, the curing process was either continued in the compression mold, in the air-oven, or under nitrogen atmosphere. For the compression-mold and nitrogen-atmosphere curing, crosslink densities and the compressive moduli increased significantly with cure time, whereas, for air-oven curing, only slight increases in the afro-mentioned properties were observed. After completing four compression cycles, the crosslink density and mechanical properties remain high only when curing was done in the compression mold. Therefore, curing under pressure as in the compression mold for a prolonged time could be a mean in boosting the mechanical properties of ebonite.

The authors studied the feasibility of utilizing ebonite as a personal neutron dosemeter in criticality accidents. A disc-shaped ebonite, a hard rubber containing 30wt% sulfur, can be used as a highly effective criticality neutron dosemeter because of a simplicity of measurements of beta activity arising from 32S(n, p)32P reactions. The counting efficiency of beta particles with an end-window GM counter for an ebonite disc in 50mm diameter and 3mm thick was determined by 252Cf neutron irradiation. The neutron spectrum dependency of 32P activity per neutron dose was computed using Monte-Carlo calculations of various neutron spectra that could be encountered in criticality accidents, and the results were tabulated as a set of spectrum correction factors. Performance tests using the SILENE reactor indicated that neutron doses could be evaluated within ±15% with the application of suitable correction factors.