Rubber Manufacturing Research Articles

Use of Shore Hardness Tests for In-Process Properties Estimation/Monitoring of Silicone Rubbers

Casting is an important rubber manufacturing process for both production and material developments. A quick and flexible way of testing the constitutive materials properties of rubber products is very important for optimising the processing parameters and quality control. In many cases, standard tests such as tensile or compression tests are time consuming and require a large volume of materials. This work reports some recent work in using a combined numerical and experimental approach to characterise the properties of rubber materials during a casting process. Durometer shore hardness is used to test silicone rubbers (as a model material) with different compositions on different moulding planes and the linear elastic property is estimated from the hardnesses. The predicted properties are systematically compared with the experimental tests on hard and soft silicone rubber samples with different compositions. The work shows that shore hardness can be used as an effective way to monitor the materials properties during amoulding process for process optimisation and quality control.

Carbon footprint reduction: a critical study of rubber production in small and medium scale enterprises in Sri Lanka

In response to the winds of change world over, as a result of rapid advance in science and technology, it has strengthened the Small and Medium Scale Enterprises (SMEs) to exert themselves as engines of their economy in the sphere of production as a whole economy as well as increase of production and competition in the market. This situation is augmented as a result of consumer demand. Its impact is such that we discern a rapid increase of population, urbanization, social mobility and transition with vigorous competition. Looking at opportunities to maximize production to satisfy customer needs, SMEs do not consider the factors that affect environment during manufacturing process, selling and distribution and consumption stages. Considering the magnitude of the excessive toxic effect on the bio-sphere and in order to protect the natural environment for the sustenance and conservation of organisms, it is imperative for all the parties concerned to take up responsibility to include carbon footprint mitigating measures during industrial processes. Available literature revealed that different types of systems have been set up to minimize carbon footprint by the industry at both national and international levels, but still there are issues on identifying carbon footprint usage and emission levels along with implementation systems/methodologies introduced. Researchers identified energy consumption being largely associated at the rubber mill and emissions are extraordinarily connected to productivity of kW/H of energy consumption. In order to carry out research goal barriers in implementing energy-efficient carbon footprint minimization measures, responses to one hundred questionnaires were collected from rubber product manufacturing SMEs registered under the Ministry of Industry and Commerce, Sri Lanka. Twenty five unstructured interviews were conducted with relevant professionals in order to ascertain their opinion. There are vital findings in this research — mainly the correlation of factors affecting relationship on minimizing energy efficient carbon footprint effects which will phase-in obliging emphasis on policy makers to rethink their planning. This was proved by using the fishbone model. Major barriers were identified by using content analysis of respondents. In order to identify the CO2 emission level, the researcher examined the calculation model developed from the results to quantify carbon emission level from the three rubber-band manufacturing factories that were selected as case study domains. Case-studies revealed the overall emissions from the production of rubber band amounting to 1.16, 1.53 and 1.23 ton CO2-eq/ton product respectively. These findings could be directly benefited by any country where rubber production is being put into practice; in order to identify factors that would minimize global warming potentials of rubber manufacturing SMEs, by the application of cleaner manufacturing model to achieve sustainable production.

A constrained maximum likelihood approach to evaluate the impact of dose metric on cancer risk assessment: Application to β-chloroprene

β-Chloroprene (2-chloro-1,3-butadiene, CD) is used in the manufacture of polychloroprene rubber. Chronic inhalation studies have demonstrated that CD is carcinogenic in B6C3F1 mice and Fischer 344 rats. However, epidemiological studies do not provide compelling evidence for an increased risk of mortality from total cancers of the lung. Differences between the responses observed in animals and humans may be related to differences in toxicokinetics, the metabolism and detoxification of potentially active metabolites, as well as species differences in sensitivity. The purpose of this study was to develop and apply a novel method that combines the results from available physiologically based kinetic (PBK) models for chloroprene with a statistical maximum likelihood approach to test commonality of low-dose risk across species. This method allows for the combined evaluation of human and animal cancer study results to evaluate the difference between predicted risks using both external and internal dose metrics. The method applied to mouse and human CD data supports the hypothesis that a PBK-based metric reconciles the differences in mouse and human low-dose risk estimates and further suggests that, after PBK metric exposure adjustment, humans are equally or less sensitive than mice to low levels of CD exposure.

Processability Behaviour of Dual Filler Systems Reinforced Epoxised Natural Rubber

Rheological studies of polymers are of great importance in optimizing the processing conditions and in designing processing equipments like injection molding machines, extruders, and dies required for various products. Melt rheological studies give us valuable viscosity data that will be helpful in optimizing the processing conditions. Parameters like melt viscosity as a function of shear rate or shear stress and temperature have become more and more important. Previous study indicated that the flow behaviour of the compound depends on the filler loading. Lesser elastic torque was found with compound containing lower filler content as compared to higher filler content. In this work, effect of dual filler, based on Carbon Black / Silica filled Epoxidised Natural Rubber (ENR) compound was investigated. A total of 80phr of filler content based on passenger tyre tread formulation was used in the experiment. The compounds were prepared by melt mixing in tangential type of an internal mixer. The rheological and the processability properties of the compounds were determined using three different testing instruments namely Capillary Rheometer, Mooney viscometer and Rubber Process Analyzer (RPA). A variation of shear rates (ranging from low to high) was performed, in order to better reflect the actual processing condition in rubber manufacturing. It was found that ENR mix with ratio silica to carbon black 70:10 exhibited the best flow behaviour and processability properties as compared to control and other mixes.

Electrochemical removal of tetrahydrofuran from industrial wastewaters: anode selection and process scale‐up

AbstractBACKGROUNDIn this work, industrial wastewaters with an average tetrahydrofuran (THF) concentration of 688 ± 140 mg L−1 were treated by electrooxidation. Four anodic materials were tested: RuO2, Pt, PbO2 and boron‐doped diamond (BDD). Bench scale experiments (volume treated 1 L, anode area 140 cm2) and pilot scale tests (volume treated 200 L, anode area 2800 cm2) were performed, and the influence of the applied current density, in the range 300 <japp <1200 A m−2, was assessed.RESULTSBDD was the only anodic material that enabled fast THF degradation and mineralization, using sodium sulfate as electrolyte. Dimensionally stable oxides such as RuO2 with sodium chloride as electrolyte did not achieve mineralization of the organic pollutants. Bench scale experiments allowed the kinetics of THF degradation to be described. The electrooxidation process, under mass transfer control, was enhanced by the contribution of electrogenerated secondary oxidants. The kinetic model and parameters used for the process scale up were fully validated by the excellent matching between the model predictions and the experimental results obtained at pilot scale.CONCLUSIONSThe electrochemical treatment using BDD anodes allows the removal and mineralization of tetrahydrofuran contained in industrial wastewaters generated in rubber manufacturing. Process scale‐up, based on the kinetic model obtained from bench scale data, was successfully achieved. Energy consumption can be optimized by applying current modulation strategies. © 2014 Society of Chemical Industry

Validation of a radial diffusive sampler for measuring occupational exposure to 1,3-butadiene

1,3-Butadiene (BD) is a major industrial chemical used in the manufacture of rubbers and latexes; it is also a ubiquitous environmental pollutant whose major source is traffic. Occupational exposure to (BD) can occur both during its production and during its use as a raw material. The objective of the study was the laboratory and field validation of a new diffusive sampler for BD. The nominal sampling rate of the Radiello® diffusive sampler filled with Carbopack X is 30.5cm3/min, at 0.177mg/m3, 20°C and 50% relative humidity (RH), for an 8-h exposure time. A model can be used for calculating the sampling rate as a function of temperature, time and RH. The concentration does not affect the sampling rate above 30μg/m3. The measurement uncertainty (k=2), calculated both by laboratory data and by field comparison according to International Standard Organization (ISO) 13752, satisfies the EN 482:2006 requirement for measurements between 0.1 and 0.5 times the threshold limit value—time weighted average (TLV–TWA) (uncertainty<50%). For field validation study, 38 workers exposed to BD and 20 administrative employees, as the control group, underwent environmental and biological monitoring. Personal exposure to BD was measured by diffusive samplers (Radiello®) in comparison with active samplers. The BD exposure levels detected for the exposed subjects were low (mean 0.059, range <0.010–1.340mg/m3) but higher than the controls levels, all below 0.010mg/m3. The comparison between diffusive and active (pumped) air sampling showed a good correlation, with no systematic deviation from the ideal values of the intercept and slope of the optimized regression line. The concentrations of two biomarkers were also determined on urine samples, collected at the end of the work-shift: unchanged BD, by GC–MS, and the metabolite dihydroxybutylmercapturic acid (DHBMA), by HPLC–MS/MS. The urinary excretion of the biomarkers was on average higher in the exposed group (urinary BD: mean 8.8, range <1–48.1ng/l; DHBMA: mean 0.232, range 0.016–0.572mg/l) than in controls (urinary BD: mean 6.4, range 2.6–14.5ng/l; DHBMA: mean 0.205, range 0.037–0.602mg/l), but a statistically significant difference was achieved only for unchanged BD and not for DHBMA. In conclusion, the environmental monitoring measured by diffusive samplers (Radiello®) appears to be a reliable method for the assessment of exposure to low levels of airborne BD and a convenient alternative to the conventional active sampling.

Occupational exposures and colorectal cancers: a quantitative overview of epidemiological evidence.

A traditional belief widespread across the biomedical community was that dietary habits and genetic predisposition were the basic factors causing colorectal cancer. In more recent times, however, a growing evidence has shown that other determinants can be very important in increasing (or reducing) incidence of this malignancy. The hypothesis that environmental and occupational risk factors are associated with colorectal cancer is gaining ground, and high risks of colorectal cancer have been reported among workers in some industrial branches. The aim of this study was to investigate the epidemiologic relationship between colorectal cancer and occupational exposures to several industrial activities, by means of a scientific literature review and meta-analysis. This work pointed out increased risks of colorectal cancer for labourers occupied in industries with a wide use of chemical compounds, such as leather (RR = 1.70, 95%CI: 1.24-2.34), basic metals (RR = 1.32, 95%CI: 1.07-1.65), plastic and rubber manufacturing (RR = 1.30, 95%CI: 0.98-1.71 and RR = 1.27, 95%CI: 0.92-1.76, respectively), besides workers in the sector of repair and installation of machinery exposed to asbestos (RR = 1.40, 95%CI: 1.07-1.84). Based on our results, the estimated crude excess risk fraction attributable to occupational exposure ranged from about 11% to about 15%. However, homogeneous pattern of association between colorectal cancer and industrial branches did not emerge from this review.

Bioaccumulation of ZnO-NPs in Earthworm Eisenia fetida (Savigny)

Zinc oxide nanoparticles (ZnO-NPs) are increasingly used in nano fertilizers, sunscreens, biosensors, food additives, pigments, rubber manufacture and electronic materials. With wide application of ZnO-NPs, concern has been raised about its unintentional health hazards and environmental impacts. In the present study, we tested toxicity and uptake of ZnO-NPs as a marker of potential ecological harm. We provided multiple lines of evidence including, percentage of mortality, DNA damage, superoxide dismutase, lignin peroxidase, cellulolytic activity and transmission electron microscopy of coelomic fluid and earthworm tissue to express bioavailability and bioaccumulation of ZnONPs from soil to earthworm. The aggregates of NPs were observed in coelomic fluid and their tissues, away from portal of their entry. The results from response of antioxidant system combined with DNA damage indicated that ZnO-NPs could not induce significant damage to earthworms. The study demonstrated bioavailability of ZnO-NPs was very high throughout the earthworm cross sections in all exposures of NPs particularly at exposure of 10nm sized ZnO-NPs and revealed that intact NPs can be taken up by earthworm from soil and having good potential of bioremediation into non- toxic forms.

Showcasing Istanbul's Jewish Past: The Case of Mayor Synagogue

In the lead up to Istanbul’s year as European Capital of Culture in 2010, a number of preservation initiatives were set in motion to recover the city’s cosmopolitan Ottoman past. Its non-Muslim heritage was remapped through public events and restoration projects. This article focuses on the discourses and practices that surrounded a single building: Haskoy Mayor Synagogue. It traces how this forgotten historical synagogue was rediscovered and turned into a site of memory and negotiation. The building had lost its original function, decayed, and been appropriated for other uses, including metal and rubber manufacturing. The European Capital of Culture program provided funds for the building’s restoration at the request of the local Jewish community. But what brought it into great public attention was the installation of a piece of artwork by a Romanian-American artist, Serge Spitzer. With this attention, Mayor Synagogue was the subject of public debates that negotiated its past and future, and called into question the idea of associating the building only with its Jewish history at the expense of its contemporary use in a gentrifying neighborhood. But there was an unnoticed wider reality: the attempts to rebrand Istanbul by recovering its old multiculturalism was also a way to avoid acknowledging the city’s new multicultural population.

An Existential Study on Structural, Optical and Electronic Properties of ZnO Nanoparticles and Nanorods

Research interest in ZnO nanostructure derives from their excellent luminescent properties and availability of low cost fabricating and processing, which hold promise for the development of electronic and optoelectronic devices. In this work, the synthesis routes for zinc oxide (ZnO) nanoparticles and nanorods, their structural, optical & electronic properties have been established. ZnO has many potential applications like sunscreens,biosensors,food additives,pigments,rubber manufacture optoelectronic, piezoelectric, spintronic devices, field effect transistors(FET)etc.ZnO nanoparticles and nanorods have been received more attention in new age material science. In this paper we discuss ZnO is useful for other semiconductor materials and their properties are different from others.

Plywood with Soy Protein - Acrylate Hybrid Adhesive

This paper is mainly aimed at the problem of low bonding strength of soy bean protein adhesive,poor water resistance,with methyl methacrylate and vinyl acetate composite study made with rubber manufacturing class II plywood,meet the national standard,so as to solve the water resistance of soy protein adhesives and bonding strength of.Experiments that 3.5g soy protein, 5g PVA, 30g MMA, 0.3g APS and 100g water, modified soy protein adhesive bonding strength obtained is excellent, and cost reduction.Preparation of soybean protein-acrylate adhesive solid content,viscosity and strength of plywood detection.

Physicochemical optimization of granular sludge in rubber industrial wastewater

Aerobic granular sludge (AGS) technology is a novel and promising development in the field of biological wastewater treatment where it develops granulated sludge without any additional of supporting carrier material. Self-immobilized granular sludge has high settling velocity and contribute to high efficiency of solid-liquid separation in wastewater. Current problem of rubber manufacturing wastewater are low solid:liquid separation ratio and therefore, this study aims to incorporate aerobic granulation technology into rubber industry treatment in order to improve the problems. Aerobic granules were developed in two identical sequencing batch reactors (SBRs) with different strategies for the enhancement of granulation. The characteristic of the microbial granular sludge was monitored throughout the study period and the results demonstrated good removal of COD and ammonia of 90% and 85%, respectively at the end of the study. Findings of this study show that granular sludge could be developed in rubber industry wastewater and is capable in treating the wastewater.

Genotoxic risk in rubber manufacturing industry: A systematic review

A large body of evidence from epidemiological studies among workers employed in the rubber manufacturing industry has indicated a significant excess cancer risk in a variety of sites. The International Agency for Research on Cancer has recently classified the “Occupational exposures in the rubber-manufacturing industry” as carcinogenic to humans (Group 1). A genotoxic mechanism for the increased cancer risk was suggested on the basis of the evidence from the scientific literature. Exposure assessment studies have shown that workers in the rubber manufacturing industry may be exposed to different airborne carcinogenic and/or genotoxic chemicals, such as certain aromatic amines, polycyclic aromatic hydrocarbons, N-nitrosamines, although the available information does not allow to establish a causal association of cancer or genotoxic risk with particular substances/classes of chemicals or specific jobs. The aim of this paper is to critically evaluate, by conducting a systematic review, the available biomonitoring studies using genotoxicity biomarkers in rubber manufacturing industry. This systematic review suggests that a genotoxic hazard may still be present in certain rubber manufacturing industries. A quantitative risk assessment needs further studies addressing the different, processes and chemicals in the rubber manufacturing industries.

Dynamic mechanical behavior of nickel-based superalloy metal rubber

The work describes the manufacturing and dynamic characterization of nickel wire-based metal rubber (MR) solids. The storage modulus and the loss factor of the nickel MR samples are measured over a frequency range between 0.1Hz and 200Hz, and at different levels of dynamic force and strain using a dynamic mechanical analyzer (DMA) technique. A sensitivity analysis about the effect of different static and dynamic testing parameters is initially carried out to identify suitable testing protocols for this metal porous material. DMA testing is then carried out over three different batches of samples (5 specimens each) with variable relative densities to identify the correlation between storage modulus and loss factors with frequency and dynamic force and strain levels. The results are discussed using a mechanical theoretical model relating the mechanical properties of MR solids to the contact states of the wire composing the microstructure. A comparison with analogous results obtained from cyclic tests at 1Hz from a conventional tensile machine is also performed. The results from this benchmark highlight the necessity to use dynamic-based testing protocols to efficiently implement nickel-based metal rubber for vibration damping and energy absorption designs and applications.

An Application of Lean Supply Chain Management for Cost Reduction in Block Rubber Industry

Application of a lean concept to supply chain management for the block rubber industry is presented. It seeks to reduce the total systemwide cost by reducing wastes throughout the supply chain. Value stream mapping is used to identify non value added activities in the chain. Four major stakeholders are included: rubber grower, minor collector, major collector, and manufacturer. Four study steps are involved: 1) collection of data for a supply chain model constructed; 2) creation of a value stream map and identification of non value added activities; 3) analysis of root causes of non value added activities, or wastes, identified in the first two steps; and 4) proposal of practical guidelines to reduce or eliminate the wastes. Results show that transportation contributes the second highest cost after personnel cost, but is more practical to be trimmed. Hub-spoke concept along with vehicle routing analysis is recommended to be further explored in depth for practical implementation.

A Case of Tracheal Adenoid Cystic Carcinoma in a Worker Exposed to Rubber Fumes

BackgroundPrimary tracheal tumors occur infrequently, accounting for less than 0.1% of all tumors. Adenoid cystic carcinoma (ACC) is the second most common type of malignancy of the trachea after squamous cell carcinoma (SCC). Little has been reported on the risk factors for tracheal ACC. The purpose of this study is to describe a case of tracheal ACC in a patient who had been exposed to rubber fumes, and to review the relationship between tracheal ACC and rubber fumes.Case reportA 48-year-old man who had been experiencing aggravation of dyspnea for several months was diagnosed as having ACC of the trachea on the basis of a pathologic examination of a biopsy specimen obtained via laser microscopy-guided resection. The patient had been exposed to rubber fumes for 10 years at a tire manufacturing factory where he worked until ACC was diagnosed. His job involved preheating and changing rubber molds during the curing process.ConclusionACC of both the trachea and the salivary glands show very similar patterns with regard to histopathology and epidemiology and are therefore assumed to have a common etiology. Rubber manufacturing is an occupational risk factor for the development of salivary gland tumors. Further, rubber fumes have been reported to be mutagenic. The exposure level to rubber fumes during the curing process at the patient’s workplace was estimated to be close to or higher than British Occupational Exposure Limits. Therefore, tracheal ACC in this case might have been influenced by occupational exposure to rubber fumes.

Genetic diversity among progenies of Crambe abyssinica Hochst for seed traits

Crambe is an important biofuel crop and its oil has unique traits such as high erucic acid content which can be used as industrial lubricant, corrosion inhibitor as well as ingredient in synthetic rubber manufacturing. Genetic diversity among 70 progenies of Crambe abyssinica Hochst selected from a population of FMS Brilhante cultivar was quantified by multivariate analysis for traits related to germination, thousand grain weight and oil content. There were significant differences among progenies for all traits studied. Estimation of genetic variance and heritability coefficients showed that the variability found in the progeny is more genetic than environmental which enables genetic gains with selection. Heritability coefficient varied from 68 to 79%, except for oil content and number of dead seedlings. Simple correlation analysis showed that germination and vigor were positively correlated, and thousand grain weight and oil content were not correlated with any of the seed traits. Based on multivariate analysis, the progenies could be grouped into 26 clusters. Clusters 1, 2 and 3 had the highest number of progeny with 7, 8 and 6 lineages, respectively. Clusters 21–26 had higher dissimilarity within the cluster with one in each progeny. The trait that most contributed to the cluster was the germination (36.2%) and less contributed was the number of seedlings killed (1.1%). The progenies indicate genetic diversity for seed traits and the selection of superior progenies is possible considering the studied traits.

Nanosized Zinc Oxide Induces Toxicity in Human Lung Cells

Zinc oxide nanoparticles (ZnO-NPs) are increasingly used in sunscreens, biosensors, food additives, pigments, rubber manufacture, and electronic materials. With the wide application of ZnO-NPs, concern has been raised about its unintentional health and environmental impacts. This study investigates the toxic effects of ZnO-NPs in human lung cells. In order to assess toxicity, human lung epithelial cells (L-132) were exposed to dispersion of 50 nm ZnO-NPs at concentrations of 5, 25, 50, and 100 μg/mL for 24 h. The toxicity was evaluated by observing changes in cell morphology, cell viability, oxidative stress parameters, DNA damage analysis, and gene expression. Exposure to 50 nm ZnO-NPs at concentrations between 5 and 100 μg/mL decreased cell viability in a concentration-dependent manner. Morphological examination revealed cell shrinkage, nuclear condensation, and formation of apoptotic bodies. The oxidative stress parameters revealed significant depletion of GSH level and increase in ROS levels suggesting generation of oxidative stress. ZnO-NPs exposure caused DNA fragmentation demonstrating apoptotic type of cell death. ZnO-NPs increased the expression of metallothionein gene, which is considered as a biomarker in metal-induced toxicity. To summarize, ZnO-NPs cause toxicity in human lung cells possibly through oxidative stress-induced apoptosis.

Drug bioavailability and traditional medicaments of commercially available papaya: A review

Papaya (Carica papaya L.) is regarded as an excellent source of ascorbic acid, a good source of carotene, riboflavin and a fair source of iron, calcium, thiamin, niacin, pantothenic acid, vitamin B-6 and vitamin K. Each and every part of papaya plant from root to shoot is used for medicament purposes. Ripe papaya fruit is used in jam, jelly, marmalade, puree, wine, nectar, juice, frozen slices, mixed beverages, ice-cream, powder, baby food, cooked in pie, pickled, sweet meat, concentrated and candied items. Young leaves are cooked and eaten like spinach, animal feed, tenderize meat, stomach trouble, purgative effects and abortion may result from consumption of the dried papaya leaves. The flowers are sometimes candied and used for making sprays. Papaya seeds are rich source of amino acids; scented oil was extracted, used in treatment of sickle cell disease and poisoning related disorders. Papain is used in food processing to tenderize meat, clarify beer and juice, produce chewing gum, coagulate milk, prepare cereals, and produce pet food, also to treat wool and silk before dying, de-hair hides before tanning, adjunct in rubber manufacturing and proteolytic enzymes (papain and chymopapain). In folk medicine, latex is used on boils, warts, freckles, abortion, expel roundworms, salt making, relieve asthma stomach troubles, purgative for horses, treatment for genito-urinary ailments, tumer destroying, making herbal tea, digestive and aid in chronic indigestion, weight loss, obesity, arteriosclerosis, high blood pressure, blood purifier and weakening of heart etc. It has also several antibiotic, allergic, anti-nutritional and toxic properties. Key words: Pawpaw, drug bioavailability, traditional medicaments, industrial uses, papain, nutritive value.

Compression mechanics of nickel-based superalloy metal rubber

The work describes the manufacturing and testing of metal rubber (MR) samples produced from nickel-based superalloys, and subjected to compression loading in quasi-static regime, three batches of MRs with different relative densities have been fabricated, and their mechanical properties (tangent modulus, loss factor and Poisson's ratio) have been investigated at different maximum strains, and under cyclic loading. The experiments show the significant effect of the MRs' relative density over the global mechanical compression properties, with the tangent modulus increasing and the loss factor from the hysteretic cycles decreasing in samples with higher density. At low strain level, metal rubber appears to behave like a zero Poisson's ratio material. The results show the effectiveness in controlling the mechanical properties of nickel-based metal rubber by careful adjusting of the relative density during manufacturing.