Standard Rubber Research Articles

CHARACTERISTICS OF RUBBER SHEET WITH RAW MATERIAL OF COMPOSITE MODIFICATIONS - LATEX

Natural starch can be made into modified starch with the desired properties or as needed. Composite of starch and natural rubber for the made of rubber sheets as an alternative to reduce the use of natural rubber in large quantities. The research aimed to study the characteristics of sheets rubber with composite modified starch - latex. The experimental research used non Factorial Completely Randomized Design and each treatments was replicated three times. Single factor of starch and latex modification ratio (Treatment A Starch modification: latex = 1: 1 (500 ml: 500 ml, Treatment B Starch modification:latex = 1:2 (500 ml: 1000 ml and Treatment C Starch modification:latex = 2:1 (1000 ml: 500 ml)). The parameters were plasticity (Po), plasticity resistance index (PRI), mooney viscosity and dirt content. Results showed that the comparison treatment of starch and latex modifications have a influence on the characteristics of sheet rubber meet the quality requirements of Standard Indonesian Rubber (SIR) 20 SNI 06-1903-2000 and standard quality commercial sheets rubber with charactheristics plasticity (Po), plasticity resistance index (PRI), mooney viscosity and dirt content.

The Effect of Pigments on the Flammability Characteristics of a Rubber Compound Based on Methylvinylsiloxane Rubber

When parts manufactured from polymeric materials are used in different sectors of industry, the use of different colours may be required. The use of pigments of different chemical nature and often possessing catalytic activity may lead to a change in fire hazard characteristics. The effect of several inorganic pigments based on carbon black and metal compounds on the flammability characteristics of a rubber compound of grade VR-42 (white-coloured) based on methylvinylsiloxane rubber has been investigated. A comparison with a standard rubber compound containing magnesium hydroxide has been carried out. The considerable influence of the presence of carbon pigment with nanosized particles on improvement in residual burning (smouldering) time by comparison with the base combination has been shown. No statistically significant change in this characteristic has been established for a coloured rubber compound of grade VR-42 by comparison with the base combination when mineral pigments of different colours and based on metal compounds are introduced.

An Investigation of the Effect of Taurit Filling of Rubber Mixes for the Coating of Radial Lorry Tyre Breakers

The results of investigating the effect of the shungite analogue Taurit (grade TSD) on the properties (measured on an RPA 2000 instrument) of a breaker rubber mix and of a rubber compound based on synthetic isoprene rubber SKI-3 are set out. Different methods of introducing Taurit have been tested: 10 parts into the rubber at the stage of its production; 10 parts into the standard rubber mix at the first stage of mixing; 10 parts into the rubber subjected to preliminary mechanical plasticisation in a laboratory internal mixer at a temperature of 100°C. The introduction of Taurit into the rubber in small quantities in order to reduce the proportion of rubber constituent in the rubber mix has also been tested. The test results have been compared with results for standard rubber mixes and rubber compounds. When Taurit is introduced into rubber at the stage of its production, the cohesive strength of the rubber mix and the rate of its vulcanisation and also the dynamic modulus components G′ and G″ are increased. When Taurit is introduced into plasticised rubber, again G′ and G″ are increased, there is an increase in plasticity, and the elastic recovery of the rubber mix is reduced. The breaker rubber compound from this mix has the best adhesion to metal cord and the highest dynamic strength. Data on the Payne effect indicate a better carbon black particle distribution when Taurit is introduced into the rubber at the stage of its production. Reduction in the proportion of rubber constituent in the rubber mix leads to a deterioration in the carbon black particle distribution.

Curing characteristics tensile and physical properties of rice straw filled standard Malaysian rubber

In this research, the effects of Rice Straw (RS) reinforced Standard Malaysian Rubber (SMRL) on curing characteristics, tensile properties and physical properties were investigated. All compounds were prepared using two roll mill at five different RS loading (10, 20, 30, 40, 50 phr). In addition, two different size of RS, fine size (FS) at 300 μm and coarse size (CS) at 10 mm were used. The properties such as cure characteristics, tensile properties and physical properties were determined. Results indicated that the fine size of RS filled SMRL contributed to the better properties such as tensile, hardness and crosslink density compare to coarser size of RS filled SMRL at same loading.

Quantifying the benefit of the Kinetic Crutch Tip.

This research focuses on the difference between the Kinetic Crutch Tip (KCT) and a Standard Rubber Tip. Additionally, the effect of KCT stiffness on the crutch gait cycle and the reaction forces were investigated. This study also examined the maximum backward angle that a crutch is able to move forward without any external forces as well as the ratio of positive to negative horizontal forces were considered. The results were obtained in two ways: one by having subjects walk on the crutches and another to reduce the variability of human walking by measuring the resulting motion only using weights attached to the crutch tip. The results of this measurement indicate an increase in maximum backward angle for Kinetic Crutch Tips. This increase in the rotation angle shows an improvement in forward motion of the crutch.

The Influence of the Concentration of an ‘n-butyllithium–amine-containing Modifier’ Initiating System on the Copolymerisation of 1,3-butadiene and Styrene

The influence of the concentration of an initiating system consisting of n-butyllithium and an amine-containing modifier on the copolymerisation of 1,3-butadiene and styrene in a hexane solvent was studied. The molecular characteristics and the microstructure of specimens of the obtained solution-polymerised styrene butadiene rubber (s-SBR) were determined by gel permeation chromatography on a Breeze liquid chromatograph (Waters) and by IR spectroscopy on a Spectrum GX 100 spectrometer (PerkinElmer) in accordance with ISO 21561/2. It was shown that a reduction in the amount of the initiating system is accompanied with a reduction in the copolymerisation rate and in the monomer conversion, and also with an increase in the average molecular weights of the copolymer. It was established that a reduction in the initiating system concentration in the reaction medium leads to a reduction in the content of 1,2-units in the rubber. A comparative analysis of data for rubber compounds based on the synthesised s-SBR and data for rubber compounds based on standard rubber indicates that their mechanical properties are at the same level. However, the tg δ at 60°C (determined on an RPA 2000 instrument) for rubber compounds based on a trial specimen has a lower value, which will make it possible to produce tyre rubbers providing a lower tyre rolling resistance.

A novel perfused porcine simulator for teaching aortic anastomosis increases resident interest in vascular surgery

ObjectiveThis report describes a novel simulator, euthanized pigs on cardiopulmonary bypass, and validates this simulator with a controlled trial in general surgery residents learning aortic anastomosis. We evaluated this novel simulator with the following hypothesis: our porcine perfused simulator is as good as or better than the standard rubber tubing, low-fidelity models used for vascular anastomotic training. MethodsEuthanized pigs were placed on cardiopulmonary bypass, creating a perfused, ex vivo model on which to perform surgical procedures. The participants in the study were postgraduate year 2, 3, and 4 general surgery residents. Residents were randomized to practice aortic anastomosis in the pig laboratory (PL) simulator or in a dry laboratory. The PL residents and control residents performed a first vascular anastomosis on the rubber tube model. Anastomosis creation was filmed. The anastomosis and video were stored for later grading. Next, all residents underwent an ungraded, one-on-one training session with the attending vascular surgeon. After the training session, all residents completed a second videotaped rubber tubing anastomosis. The grading scales used were validated by other authors: Global Assessment Score, Final Product Score, and Checklist Scoring Instrument. Survey data describing this experience were collected using a 13-question prelaboratory and 16-question postlaboratory questionnaires consisting of yes/no, multiple selection, and 5-point Likert-type scale questions. ResultsAll residents had a statistically significant improvement in time to completion and in the Global Assessment Score with tutored practice. The PL residents showed statistically significant improvement in completion time between the first and second videotaped anastomosis; however, there was no statistically significant improvement in the scoring metrics. The control residents showed statistically significant improvement in all three scoring metrics, but no statistically significant difference was found in completion time. The survey data showed a statistically significant shift in considering vascular surgery as a career after the experience in the PL group (P = .05) compared with the control group, who had no change in interest (P = .91). ConclusionsOur prospective, randomized clinical trial shows that the porcine cardiopulmonary bypass model achieves similar results to a previously validated bench top model while improving general surgery resident interest in vascular surgery as a career.

Study of Properties of Fillers Based on Natural Bentonite and their effect on the Rubber Compounds

The paper deals with the proposal and preparation of the suitable rubber compounds in which materials are based on natural bentonite. It is important to point out that the mentioned materials were used in the function of the fillers. In relation to the prepared rubber compounds, vulcanization and rheological properties were determined (minimum torque - ML, maximum torque - MH, processing safety - tS, optimum vulcanization time - tC(90), rate coefficient of vulcanization - Rv). Prepared vulcanizates were evaluated from the aspect of physical and mechanical properties (tensile strength, elongation, hardness) and heat aging of vulcanizates was also evaluated. These characteristic features were compared with those which are typical for standard rubber compounds used in the rubber industry while standard filler is carbon black of N339 type.

The Effect of New Antiagglomerators of the Quantislip Series for Solution-Polymerised Rubber on the Properties of cis-1,4-polyisoprene

The results of pilot-plant tests of SKI-3 isoprene rubber containing a series of Quantislip™ rubber crumb antiagglomerators (AAs) are presented. Tests were conducted at OAO ‘Sintez Kauchuk’, with the AAs introduced at the degassing stage. The new Quantislip AAs, developed by OOO ‘NPP Kvalitet’, ensure a reduction in calcium and chlorine ions in wastewater and in its alkalinity. An improvement in the elastic strength properties of carbon-black-filled vulcanisates based on cis-1,4-polyisoprene (SKI-3) and containing AAs was shown. For the production of SKI-3 rubber, an optimum AA composition – Quantislip of grade BM-2R – was developed. When BM-2R is used, stearic acid, formed in standard rubber with a calcium stearate suspension as AA, is eliminated. The possible mechanism of improvement in the strength properties of carbon-black-filled vulcanisates based on SKI-3 is discussed. This is possibly due to an improvement in rubber–filler interaction as a result of there no longer being any competition between segments of macromolecules and stearic acid for active centres when carbon black is adsorbed on the surface.

Influence of synthesized nano-ZnO on cure and physico-mechanical properties of SBR/BR blends

This study focuses on the synthesis of zinc oxide (ZnO) nanoparticles by high temperature calcination as well as low-temperature hydrolysis methods and their efficiency as cure activator in styrene-butadiene rubber/polybutadiene rubber blend. The synthesized nano-ZnO samples were characterized by means of X-ray diffraction, BET surface area and transmission electron microscopy. The synthesized nano-ZnO samples had wurtzite structure and average particle size in the ‘nm’ range. ZnO nanoparticles, synthesized on sepiolite template, were of smallest particle size (maximum number of particles in the range of 7–12 nm) and highest surface area (104 m2g−1). Polyethylene glycol (PEG)-6000 coated ZnO nanoparticles had rod-like structure; average diameter of the rods was 50 nm. In the case of PEG-coated ZnO containing compounds, optimum cure time of the blend was decreased by 5 min compared to that of standard rubber grade-ZnO containing compound (used as reference). Optimum cure time was lowered by 7–10 min in the case of synthesized nano-ZnO containing compounds compared to the reference ZnO based compound in presence of conventional filler, carbon black. It was also observed from ICP-OES analysis that the presence of very little amount of magnesium in one of the synthesized ZnO has noticeable impact on cure properties. PEG-coated ZnO increased the tensile strength of gum vulcanizates by 28% compared to the reference ZnO, acting as nanofiller at 3 phr loading. The study of curing behavior in dynamic condition was carried out using DSC. The results differ slightly from static curing except PEG modified nano-ZnO. Use of ZnO nanoparticles could provide faster crosslinking, better reinforcement at lower concentration compared to reference ZnO.

NEW PROCESS DEPROTENISED NATURAL RUBBER (PUREPRENAÔ): RAW RUBBER, PROCESSABILITY AND BASIC PHYSICAL PROPERTIES

Malaysian Rubber Board has developed a new process deprotenised natural rubber (Pureprena™) by treating fresh natural latex with an industrial enzyme which hydrolyses all naturally-occuring proteins in the latex into water-soluble forms. Further research is carried out to determine the processability performance of Pureprena™ by Mooney viscometer, rubber process analyser and capillary rheometer. The Pureprena™ in bale form has low nitrogen, low ash and volatile matter contents as well as being lighter in color compared to commercial Standard Malaysian Rubber. The rheological results indicate that the Pureprena™ has a comparable rheological behavior with synthetic polyisoprene at low shear rate as determined by RPA and capillary rheometer curves. The measurement by viscometer confirms the rheological behavior at low shear rate. However, Pureprena™ has a faster mill breakdown rate compared to synthetic polyisoprene and SMR at 60 C. All rubbers were compounded using the soluble efficient vulcanisation system especially for manufacturing engineering rubber products. It was found that Pureprena™ vulcanisate has comparable tensile strength, modulus, resilience and volume swelling in water compared to synthetic polyisoprene vulcanisate.

The Capital Penetration and Its Impact on Rubber Farmers in Tabir Ilir Jambi Indonesia Based on Sceptic Globalization Theory’s Perspective

This paper is challenging the thesis of sceptic globalization theorists about globalization as a means of capital penetration in the Third World. The propositions are that globalization is a transformation of the control of The Third World natural resources through the role of its agents at the global, national and local, capital penetration creates income inequality for the people in the Third World, and the very significant state role in addressing people problems in globalization. The results of this research support the propositions of sceptic globalization because capital penetration to smallholder rubber in Tabir Ilir conducted through cooperation among rubber importing countries, government and rubber processing factory and rubber local businessmen produce policies on the price of rubber, Standard Indonesian Rubber (SIR), and rubber processing technology. The capital penetration creates income inequality experienced by rubber farmer owner-tapper and rubber farmer-tapper because their rubber products do not meet the SIR, cheaply valued and can not access the rubber factory directly. This condition requires a significant state role in helping the rubber farmers to overcome the problems their facing in globalization.

Prevalence of delayed-type and immediate-type hypersensitivity in healthcare workers with hand eczema.

Occupational contact dermatitis is common in healthcare workers. Although irritant contact dermatitis resulting from wet work is the most frequently reported cause, healthcare workers also constitute high-risk group for the development of allergic contact dermatitis and contact urticaria. To evaluate the prevalence of delayed-type and immediate-type hypersensitivity in 120 healthcare workers with hand eczema. One hundred and twenty healthcare workers from three major hospitals in Denmark with self-reported hand eczema within the last year participated in the study. Patch tests included baseline series plus selected allergens, and prick tests included standard inhalational allergens plus natural rubber latex and chlorhexidine. Levels of IgE specific for latex, chlorhexidine and ethylene oxide were measured. Of the participants, 53% had positive patch test reactions. The most frequent positive patch test reactions were to nickel, thiomersal, fragrances, rubber chemicals, and colophonium. The prevalence of natural rubber latex allergy as diagnosed by prick testing was 2.5%, and chlorhexidine allergy (both contact allergy and IgE-mediated allergy) was found in <1%. Ethylene oxide allergy was not identified in any of the participants. Our results confirm previous reports on contact allergy patterns in healthcare workers. Testing for natural rubber latex allergy is still important, but increased risks of chlorhexidine and ethylene oxide allergy could not be confirmed.

Analysis of Possible Dynamic Vibration Dampers Uses in Tractor Cabins Suspensions

This article is devoted to the research of using dynamic vibration dampers in suspension systems of tractor cabin. The results of research in damping and elastic characteristics of standard rubber vibration dampers are presented. The results of tractors motion modeling with standard dampers in cabin suspensions are described. It is shown that those vibration dampers do not provide good vibroprotection. The possibility of dynamic dampers usage for vibration protection of cabin is analyzed. The analysis of dampers schemes usage is presented. The research of vibration activity at an operator's workplace is made. Thedesign of dynamic damper is also proposed and the results of computational and experimental research of this damper operation are presented. It is shown that dynamic dampers could be successfully used in cabin suspension.

Raw rubber and viscoelastic properties of organoclay filled latex crepe rubber

Organoclay (OC) filled natural rubber (NR) latex crepe was prepared in view of investigating the effect of organoclay on raw rubber properties and viscoelastic properties by incorporating aqueous dispersion of OC clay into NR latex followed by conventional acid coagulation procedure. Raw rubber properties of OC filled fractionated bleached (FB) and unfractionated unbleached (UFUB) crepe rubber were evaluated to characterized the composite samples in comparison to standard crepe rubber whilst process based characterization was carried out with Moony viscosity and Mooney relaxation data. Raw rubber properties have shown that OC acts as a pro-oxidant and as a result, Initial Plasticity (Po) and Plasticity Retention Index (PRI) which measures the thermo-oxidative degradation were negatively affected. Viscoelastic behaviour, as measured with low shear strain rate flow properties, is significantly affected by the addition of OC into the NR latex. Reduction of Mooney viscosity of OC filled crepe rubber has been explained with thermal oxidation as a result of metal impurities in the OC and plasticization caused by the organic modifier of the OC. Mooney stress relaxation has shown that lower clay loading provides a better processability and dispersion of OC within the crepe rubber.

Analysis of damage in commercial natural rubber through NMR spectroscopy

Damage to natural rubber (NR) during processing was investigated through liquid state NMR spectroscopy. Various commercial NR were used in the present study such as Pale Crepe (PC), Rubber Smoked Sheet (RSS3), Technically Specified Sheet (TSS8®), Standard Thai Rubber (STR5L), and Standard Malaysian Rubber (SMR20). As-cast films of the rubbers were prepared by solution casting method and followed by purification by acetone extraction. Chemical structures of the rubbers were elucidated through 1H, 13C-NMR, and DEPT spectroscopy. The 13C-NMR signals at 39.8 and 40.0 ppm were assigned to the trans-1,4-isoprene unit in the trans-trans and cis-trans sequences, respectively, while the signals at 60.8 and 64.5 ppm were assigned to C2 and C3 of an cis epoxy group. The cis epoxy groups were identified for PC, STR5L, RSS3, TSS8®, and SMR20, whereas the trans-1,4-isoprene units from cis-trans isomerization were detected for TSS8® and SMR20. The amount of these groups in TSS8® and SMR20 were higher than those in PC, STR5L, and RSS3. Mechanical properties of TSS8® and SMR20 were found to be inferior to those of PC, STR5L and RSS3. The mechanical properties depended mainly upon the damage of the samples during processing.

Cure Characteristics and Physical Properties of &lt;i&gt;Imperata&lt;/i&gt; &lt;i&gt;cy&lt;/i&gt;&lt;i&gt;lindrica&lt;/i&gt; Activated Carbon Filled SMR L Compounding

The potential of activated carbon as a filler in rubber compound has been reviewed .Cure characteristics and physical properties ofImperataCylindricaactivated carbon filled natural rubber of Standard Malaysian Rubber (SMR L) were studied. SMR L was used as the elastomer and the composition of filler loading were varied from 0-50 parts per hundred rubber (phr). A semi-efficient vulcanization system was used throughout the study. The cure characteristics of the rubber compound was determined by using rheometer. The samples of hardness and resilience were measured by durometer shore A and Wallace Dunlop Tripsometer. Cure characteristics showed that cure time, t90and scorch time,t2increased as increased filler loading which indicate poor interaction between rubber and filler which slow down the vulcanization time. Minimum torque,MLand maximum torque,MHincreased as increased filler loading due to the low processability of the SMR L compounds. Crosslink density and hardness exhibit increment as increased filler loading due to increase rigidity of the SMR L compounds. The resilience will decrease correspondingly as increased in rigidity of the compounds.

Odor Control in the Standard Thai Rubber 20 (STR 20) Industry by Using a Wet Scrubber

This article aims to investigate the potential of using effluent wastewater (called raw wastewater) from wastewater treatment plant as a recirculation liquid in a wet scrubber to remove volatile fatty acid (VFA). This research was conducted in 2 steps. Firstly, surveys and interviews were carried out at STR 20 factory in order to obtain information about STR 20 production and odor control process. Secondly, a study of the potential of using the raw wastewater in a wet scrubber to absorb the VFAs was conducted. The exhausted gas with high VFAs causes malodor in Standard Thai Rubber 20 (STR20) industry. The wet scrubber with counter-current mode runs for 7 operational days. Pall ring is used as packing media without bacterial attachment. The study demonstrates that in these 7 operational days, the raw wastewater has the potential to absorb the VFA. This is indicated by higher VFA concentration 4,372.5 mg/l as acetic acid of a recirculation liquid compared to raw wastewater 75.38 mg/l as acetic acid fed. It increases efficiency of absorbing volatile fatty acid approximately by 24%. VFA concentration in effluent wastewater was found 1,734 mg/L as acetic acid compared to influent wastewater was found 1,395 mg/l as acetic acid fed. In addition, bacterial growth on packing media was observed with volatile solid (VS) and total bacteria count present due to biodegradation of VFA. This information will be useful for further research in the future about biodegradation of VFA by bacterial attachment in packing media.

CHEMICAL DEGRADATION OF POLYURETHANE FOAM WASTE AND ITS CROSSLINKED NATURAL RUBBER

ABSTRACT The objective of this work was to use by-products from the chemical degradation of polyurethane foam waste (w-PUfd) and blend them with an epoxidized natural rubber (ENR), named PENR, for improving the mechanical properties of a Standard Thai rubber 5L (STR 5L). The swelling ratio in toluene of the PENR decreased as a function of w-PUfd content due to an increase in chemical interactions. After blending the PENR with the STR-5L and vulcanizing agents using two-roll mill and then compression molding at 150 °C, the effects of w-PUfd content in PENR on the properties of cured STR-5L were investigated. The cure rate index, tensile strength, and elongation at break of the cured STR-5L were improved after the addition of PENR. The swelling in toluene of cured STR-5L decreased as a function of w-PUfd in PENR. At 100 phr w-PUfd in PENR, the 20:80 PENR:STR-5L provided the highest tensile strength of ~23 MPa. These biodegradable, cured rubbers with w-PUfd content are environmental friendly and cost-effective products.

&lt;i&gt;Calamus deerratus&lt;/i&gt; fibre reinforced natural rubber vulcanizates

This research study investigates the potentials of Calamus deerratus fibre (CDF) as a reinforcing filler in natural rubber, Standard Nigerian Rubber (SNR10) vulcanizates. The Calamus deerratus was cut, dried, pulverized, characterized and incorporated into the natural rubber compounds and the effects on the cure characteristics and physico-mechanical properties of the CDF-reinforced natural rubber vulcanizates were determined. The results of the analyses, in comparison with a standard carbon black, CB(N330)-filled vulcanizates showed that the CDF manifested a reinforcing effect on the SNR10 vulcanizates but inferior to carbon black, N330-filled vulcanizates. The maximum torque, abrasion resistance, modulus, specific gravity and hardness increased while the scorch time, cure time, elongation at break and rebound resilience decreased with increasing filler content. The cure time and scorch time were however higher in CDF-filled SNR10 vulcanizates compared to those filled with carbon black, N330. Tensile strengths of CB(N330)- and CDF- filled vulcanizates increased to optimum levels at 40 phr and 30 phr respectively and decreased with increasing filler content. The results however showed that CDF imparted lower reinforcing potential as shown by the lower tensile strength, abrasion resistance and modulus. The hardness results of the CDF-filled vulcanizates showed slight superiority over that of CB(N330)-filled vulcanizates. Keywords : Natural rubber, Calamus deerratus, fillers, reinforcement and vulcanizates.