Low-temperature characteristicsof rubbers and performance testsof type 120 emergencyvalve diaphragms

Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.

Natural rubber latex as a potential additive for water-based drilling fluids

The environmental hazards and"carbon footprint"of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and animals.This paper explored for the first time the interaction mechanism between natural rubber latex(NRL)and bentonite suspensions(BTs)through a series of characterization experiments,as well as the potential applications in water-based drilling fluids(WBDF).The gel viscoelasticity experiments showed that NRL could decrease the consistency coefficient(k)and flow index(n)of BTs,and enhance the shear thinning performance of BTs as pseudo-plastic fluids.In addition,0.5 w/v%NRL not only increased the critical yield stress and strengthened the structural strength between the bentonite particles,but also facilitated the compatibility of pressure loss and flow efficiency.The evaluation of colloidal stability and WBDF performance indicated that NRL particles could promote the hydration and charge stability on the surface of BTs particles,and optimize the particle size distribution and flow resistance of WBDF under the"intercalation-exfoliation-encapsulation"synergistic interaction.Moreover,NRL can improve the rheological properties of WBDF at high temperatures(<150.C),and form a dense blocking layer by bridging and sealing the pores and cracks of the filter cake,which ultimately reduces the permeability of the cake and the filtration loss of WBDF.

Multi-omics-driven development of alternative crops for natural rubber production

Natural rubber(NR)is an irreplaceable biopolymer of economic and strategic importance owing to its unique physical and chemical properties.The Parárubber tree(Hevea brasiliensis(Willd.ex A.Juss.)Müll.Arg.)is currently the exclusive commercial source of NR,and it is primarily grown in plantations restricted to the tropical and subtropical areas of Southeast Asia.However,current Parárubber production barely meets the sharply increasing global industrial demand for rubber.Petroleum-based synthetic rubber(SR)has been used to supplement the shortage of NR but its industrial performance is not comparable to that of NR.Thus,there is an urgent need to develop new productive rubber crops with broader environmental adaptability.This review summarizes the current research progress on alternative rubberproducing plants,including horticultural plants(Taraxacum kok-saghyz Rodin and Lactuca L.species),woody plants(Parthenium argentatum A.Gray and Eucommia ulmoides Oliv.),and other plant species with potential for NR production.With an emphasis on the molecular basis of NR biosynthesis revealed by a multi-omics approach,we highlight new integrative strategies and biotechnologies for exploring the mechanism of NR biosynthesis with a broader scope,which may accelerate the breeding and improvement of new rubber crops.

Rheological and Morphological Characterization of Modified Bitumen with Cup Lump Rubber

Pure bitumen is not suitable for heavy traffic loads;hence modifiers are used to improve the bitumen performance.Recently,cup lump rubber(CLR)has become a preferred modifier due to its outstanding performance and less cost.However,little is known about the interactions between CLR and bitumen.Thus,this study investigates the behavior of bitumen with CLR.Four percentages of CLR(2.5%,5.0%,7.5%,and 10.0%by weight of bitumen)were used to modify conventional 60/70 penetration grade bitumen.The modified bitumen was evaluated through different laboratory testing such as dynamic shear rheometer,rotational viscosity,softening point,bending beam rheometer,ductility,and elastic recovery.The testing results show that the addition of CLR increased the bitumen’s rutting resistance by 3 PG grades at high temperatures.At low pavement temperatures,the cup lump rubber modified bitumen(CMB)can withstand up to−34℃.Fourier Transform Infrared(FTIR)analysis shows that the Aromaticity index at 1600 cm^(−1) rose as the CLR percentage increased,indicating the formation of a binder with a compact structure.This is expected to improve the elasticity of bitumen throughπ-πinteractions.Atomic Force Microscopy(AFM)results showed the Catana phase increased in size and quantity at 5.0%and 7.5%CLR content.While contact angle measurement revealed that the binders are hydrophobic and tend to repel the dropped water on the bitumen surface.

Machine Learning Assisted Design of Natural Rubber Composites with Multi⁃Performance Optimization

Multi⁃performance optimization of tread rubber composites is a key issue of great concern in automotive industry.Traditional experimental design approach via“trial and error”or intuition is ineffective due to mutual inhibition among multiple properties.A“Uniform design⁃Machine learning”strategy for performance prediction and multi⁃performance optimization of tread rubber composites was proposed.The wear resistance,rolling resistance,tensile strength and wet skid resistance were simultaneously optimized.A series of feasible optimization designs were screened via statistical analysis and machine learning analysis,and were experimentally prepared.The verification experiments demonstrate that the optimization design via machine learning analysis meets the optimization requirements of all target performance,especially for Akron abrasion and 60℃tanδ(about 21%and 9%lower than the design targets,respectively)due to the inhibition of mechanical degradation and good dispersion of fillers.

Investigation of the Potential of Using Liquid Rubbers in Rubber Industry

Along with the developing technology in the rubber industry, the use of natural and synthetic rubbers as well as liquid rubbers has increased significantly in recent years. The formulation of the tread compound, which directly affects the performance of a tire, is generally produced from natural and synthetic rubbers. Intensive scientific studies have been carried out on liquid rubbers because they reduce the consumption of process oils used in the tire production phase and increase dispersion. In this study, the rheological and physico-mechanical properties of rubbers developed using only liquid rubber (liquid isoprene and liquid SBR) with four different viscosities and without using process oil (Styrene Butadiene Rubber—SBR) were investigated. It has been observed that the rubber blends produced by adding four different liquid rubbers to the same recipe caused changes in rheological and physico-mechanical properties compared to the reference sample. It was observed that the minimum torque/viscosity (ML), maximum torque/viscosity (MH) and curing time (t90) in some of the formulas tested decreased significantly due to the use of liquid rubber.

Evaluation of unconstrained and constrained mathematical functions to model girth growth of rubber trees (Hevea brasiliensis) using young agemeasurements

No attempt has been made to date to model growth in girth of rubber tree （Hevea brasiliansis）. We evaluated the few widely used growth functions to identify the most parsimonious and biologically reasonable model for describing the girth growth of young rubber trees based on an incomplete set of young age measurements. Monthly data for girth of immature trees （age 2 to 12 yearsi from two locations were sub- jected to modelling. Re-parameterized, unconstrained and constrained growth functions,of Richards （RM）, Gompertz （GM） and the monomo- lecular ＇model ^（MM） were fitted to data. Duration of growth was the firsf constraint introduced. In the stagel We attempted a population aver- age （PA） model to capture the trend in growth. The best PA model was fitted as a subject specific （SS） model. We used appropriate error vari- ance-covariance structure to account for correlation due to repeated measurements over time. Unconstrainecl functions underestimated the asymptotic maximum that did not reflective carrying capacity of the locations. Underestimafions were attributed to the partial set＇ of meas- urements made during the early growth phase of the trees. MM proved superior to RM and GM. In the randomcoefficient models, both Gf and Go appeared to be influenced by tree level effects. Inclusion of diagonal definite positive matrix removed the correlation between random effects. The results were similar at both locations. In the overall assessment MM appeared as the candidate model for studying the girth-age relationships in Hevea trees. Based on the fitted model we conclude that, in Hevea trees, growth rate is maintained at maximum value at to, then decreases until the final state at dG/dt 〉 0, resulting in yield curve with no period of accelerating growth. One physiological explanation is that photosynthetic activity in Hevea trees decreases as girth increases and constructive metabolism is larger than destructive metabolism.

Molecular Structures and Mechanical Properties of Microbe Rapid Coagulation Natural Rubber

In this work,molecular structures,dynamic mechanical properties and glass transition temperatures of microbe coagulated natural rubber（NR） samples were analyzed by using pyrolysis gas chromatography-mass spectrometry（py-GC/MS）,rubber process analyzer（RPA） and dynamic mechanical thermal analysis（DMA）.And the cross-linked network structures and mechanical properties of the corresponding NR vulcanizates were further determined by using nuclear magnetic resonance（NMR） crosslink density spectrometer（XLDS-15） and universal testing machines.The results show that NR raw rubber produced by rapidly coagulated with microorganism exhibits a simple molecular structure composition and good dynamic mechanical properties,and the corresponding NR vulcanizates possess the aggregation structure of high cross-linked density,a high glass transition temperature of-61.5 ℃ and high mechanical properties（tensile strength reaches 25.2 MPa）,as compared with that coagulated with acetic acid.

Preparation and Properties of Rare Earth Modified Carbon Black/Natural Rubber Composites

The oxides Eu, Ho, Er and Dy were used to prepare the hydroxides of rare earth modified carbon black. Then natural rubber latex （NRL） was added into the reactor. The system reacted at 85 ℃ with stirring for 1 h to prepare powdered HAF-Ln（OH）3/NR composites. The effects of the kind and content of Ln on the particle size distribution of P [ NR/HAF-Ln （OH）3 ] and mechanical properties of its vulcanizate were studied respectively. It is found that rare earth can help to get the powder of the composite, the product particle with a diameter less than 0.9mm will be get when the composites containing the compound of Ho, Er and Dy with dosage of 1.0, 1.0, O. 5 percent, respectively. The adding of Ln can improve the tensile strength and tear strength of the vulcanizate effectively, what＇s more, Er and Dy can decrease the permanent set of vulcanizate significantly. The SEM studies shows that P[ NR/HAF-Dy （OH）3 ] vulcanizate shows superior mechanical properties that depend primarily on the absence of free carbon black, the fine dispersion of carbon black in the rubber matrix and better polymer-filler interaction.

Preparation of graphene oxide/natural rubber composites by latex co-coagulation: Relationship between microstructure and reinforcement

Graphene oxide(GO)has recently attracted substantial interest as a possible reinforcing agent for next generation rubber composite materials.In this research,GO was incorporated in natural rubber(NR)composites through latex co-coagulation technique.The microstructures of GO/NR composites were characterized through a combination of transmission electron microscope,scanning electron microscope,X-ray diffraction,Fourier transform infrared spectroscopy,and Differential scanning calorimeter.The results showed that highly exfoliated GO sheets were finely dispersed into NR rubber matrix with strong interface interaction between GO and NR.The mechanical properties of the GO/NR composites were further evaluated.The results showed that the tensile strength,tear strength and modulus can be significantly improved at a content of less than 2 phr.Especially,GO exhibited specific reinforce mechanism in NR due to the stress-induced crystallization effects of NR.The stress transfer from the NR to the GO sheets and the hindrance of GO sheets to the stress-induced crystallization of NR were further displayed in stress-strain behavior of GO/NR composites.These enhanced properties were attributed to the high surface area of GO sheets and highly exfoliated microstructures of GO sheets in NR.

Studies on the Morphology of Natural Rubber/Polyacrylate Interpenetrating Polymer Networks

The interpenetrating polymer network(IPN) systems have attracted a lot of attention because of their unique two-phase structure and properties. There have been many publications concerning the IPNs in which poly (isoprene) (PIP) or polyacrylates (PAC) is formed as one of the networks.In the present study, Four serles of natural rubber(NR)/PAC IPNs were prepared and their morphologies were investigated with dynamic mechanics analysis(DMA) and transmission electron microscopy (TEM).

Preparation and Characterization of Natural Rubber/Silica Nanocomposites using Rule of Similarity in Latex

Rule of similarity and latex compounding techniques were combined for the first time to prepare natural rubber/nanosilica （NR/SiO2） nanocomposite with core-shell nanosilica-poly （methyl methacrylate） （SiO2-PMMA） particles and PMMA-modified natural rubber matrix （NR-PMMA）. The micro- structure of SiO2 and nanocomposites with different SiO2 contents was characterized by fourier transform infrared spectroscopy （FTIR）; the morphology of nanocomposites was investigated with scanning electron microscopy （SEM）; the tensile strength was characterized by tensile testing machine and the thermal stability of composites was studied by thermal gravimetric analysis. Results showed that PMMA chains have successfully grafted onto the surface of SiO2, and the core-shell SiO2-PMMA nanoparticles and NR-PMMA latex have been perfectly incorporated. SiO2-PMMA nanoparticles are evenly distributed over the NR matrix with an average size in the range of 60-100 nm at the low content （SiO2≤ 3 wt%）, while aggregations are apparently observed when 5 wt% SiO2 is loaded. In addition, NP/SiO2 composities possess a considerable improvement in ageing resistance compared with the pure NR. The tensile strength of composite increases from 6.99 to 12.72 MPa, reaching the highest value at a 0.5 wt% SiO2 loading, and then the figure decreases gradually because of the aggregation of SiO2 nanoparticles. It is anticipated that the reported process is to provide a simple and economic way for preparing NR composites.

NANOMECHANICAL MAPPING OF CARBON BLACK REINFORCED NATURAL RUBBER BY ATOMIC FORCE MICROSCOPY

Atomic force microscopy （AFM） has the advantage of obtaining mechanical properties as well as topographic information at the same time. By analyzing force-distance curves measured over two-dimensional area using Hertzian contact mechanics, Young＇s modulus mapping was obtained with nanometer-scale resolution. Furthermore, the sample deformation by the force exerted was also estimated from the force-distance curve analyses. We could thus reconstruct a real topographic image by incorporating apparent topographic image with deformation image. We applied this method to carbon black reinforced natural rubber to obtain Young＇s modulus distribution image together with reconstructed real topographic image. Then we were able to recognize three regions; rubber matrix, carbon black （or bound rubber） and intermediate regions. Though the existence of these regions had been investigated by pulsed nuclear magnetic resonance, this paper would be the first to report on the quantitative evaluation of the interfacial region in real space.

Study on Cerium Oxide Modified Natural Rubber

The action of CeO2powders in natural rubber was studied. The effects of particle size, content and surface modification of CeO2powders on the properties of natural rubber was discussed. The results showed that the scorch and curing time of rubber decreased, the physic mechanical properties and aging resistance of natural rubber vulcanizates enhanced after filled with CeO2powders. Especially tear strength and abrasion resistance increased much, and was raised 25% and 20% respectively. The surface of modified CeO2powders had hydrophobic organize layer which could increase interface cohesion with the rubber and dispersity in rubber resulting in exerting reinforcement effect. The modified CeO2powders improve the physic mechanical properties of rubber much compared with the unmodified CeO2powders.

Determination of Natural Rubber Content in Taraxacum Kok-Saghyz by Pyrolysis Gas Chromatography-Mass Spectrometry

Nowadays,natural rubber(NR)is an indispensable material for industrial production and peoples’daily utilization.The root of Taraxacum kok-saghyz(TKS)contains a large amount of NR,which is potentially to be an alternative rubber source of conventional Hevea brasiliensis(HB).In order to find a convenient,fast and green method for qualitative and quantitative analysis of NR in TKS,a pyrolysis gas chromatography-mass spectrometric(Py-GCMS)method was developed accordingly.The results indicated that the main products of TKS rubber after pyrolysis were isoprene and limonene,respectively,and the limit of detection(LOD)of TKS rubber was 2.603 mg/g.The ratios of NR mass fractions in TKSs by Py-GC-MS ranged from 1.20%±0.20%to 8.61%±0.28%.The developed method has been used for determination of actual TKS samples and can be further applied to the field test for rapid breeding and large-scale cultivation of TKS thereof.

Hybrid Composite Based on Natural Rubber Reinforced with Short Fibers of the Triumfetta cordifolia/Saccharum officinarum L.: Performance Evaluation

This article contributes to the development of the new class of fully biodegradable “green” composites by combining fibers (natural/bio) with biodegradable resin. The vegetable fibers (Triumfetta cordifolia and sugarcane bagasse) treated with NaOH and bleached were incorporated into a natural rubber matrix. The influence of the fiber ratio on the physical properties, tensile strength and surface hardness of the hybrid composites was analyzed. The results show that the addition of fibers in the natural rubber matrix increases the water absorption capacity but gradually reduces it with increasing fiber ratio. The hybrid composites of the NRT50-50B proportions show the best tensile strengths at 20 phr and a shore A hardness of 43.7 at 30 phr. The combination of two fibers has improved the physical and mechanical properties of the hybrid composites which can be used in engineering applications.

Preparation of Novel Composite from Natural Rubber, Bagasse and Plaster

The sugar cane bagasse was treated with chemical treatment including sodium hydroxide and silane. The characterization of the modified bagasse was achieved with Fourier transform infrared spectroscopy （FTIR）, and scaning electron microscopy （SEM）. Results showed that the presence Si-CH3 group occurred on bagasse surface after chemical modification. In addition, the roughness of the modified bagasse was higher than that of unmodified bagasse due to chemical modification from sodium hydroxide. Two polymer composite types, namely （1） natural rubber NR/sugar cane bagasse and （2） NR/plaster via two-roll mill method, were prepared. The optimum cure （t90） and torque of the NR/plaster increased with increasing plaster loading in composite. In case of NR/bagasse, the tgo of this sample decreased as a function of sugar cane bagasse while torque of this sample increased with increasing sugar cane bagasse. The modulus of the resulting composite increased with increasing both plaster and sugar cane bagasse, but the tensile strength and elongation at break of the composite decreased as a function of both piaster and sugar cane bagasse in composite.

Strategies for Natural Rubber Production and Development in China

The world's natural rubber output was 12. 31 million t and the consumption reached 12. 17 million t in 2015. China's natural rubber output was 0. 85 million t and the consumption reached 4. 724 million t in 2016. Southeast Asian countries are the main natural rubber producing countries,and ITRC policy affects the natural rubber prices. During 2017-2025,the supply of natural rubber in the world is expected to be abundant to meet downstream demand. Based on natural conditions for rubber planting and production costs,China's rubber production should place emphasis on developing ClassⅠrubber production area,strengthening Class Ⅱ rubber production area and adjusting Class Ⅲ rubber production area. It is recommended to build high-output rubber plantations in Class rubber production area in Xishuangbanna; choose rubber farms with good conditions in Class Ⅱ rubber production area and build high-quality rubber production base as the dedicated production raw material base for aviation rubber; expand the Southeast Asia rubber production belt for development of natural rubber industry.

Modified graphite filled natural rubber composites with good thermal conductivity

The rubber composites with good thermal conductivity contribute to heat dissipation of tires. Graphite filled natural rubber composites were developed in this study to provide good thermal conductivity. Graphite was coated with polyacrylate polymerized by monomers including methyl methacrylate, n-butyl acrylate and acrylic acid. The ratios between a filler and acrylate polymerization emulsion and those between monomers were varied. Eight types of surface modification formulas were experimentally investigated. Modification formula can affect coating results and composite properties greatly. The best coating type was achieved by a ratio of1:1 between methyl methacrylate and n-butyl acrylate. The coating of graphite was thermally stable in a running tire. Filled with modified graphite, the tire thermal conductivity reached up to 0.517–0.569 W·m-1·K-1. In addition, the mechanical performance was improved with increased crosslink density, extended scorch time and short vulcanization time.

Detailed Mechanism and Engineering Applicability of Electrolytic Polymerization Aided by a Magnetic Field in Natural Rubber by Mechanical Approach for Sensing (Part 2): Other and Intrinsic Effects on MCF Rubber Property

The same ordinary electrolytic polymerization of plastic-type polymer solution is applicable to natural rubber, with its C=C bonds, if a magnetic field and a filler are added. With the application of a magnetic field and the magnetic responsive fluid known as magnetic compound fluid (MCF), we have clarified the enhancement of the electrolytic polymerization of NR-latex and the growth of the thickness of vulcanized MCF rubber that results from the addition of a magnetic field. The present new method of MCF rubber vulcanization is effective for use in haptic sensors, which are used widely in various engineering applications. In the previous report, part 1 of this study, we investigated many experimental conditions under mechanical approach for sensing: magnetic field strength;applied voltage;electrodes gap;mass concentration, and the ingredients of the MCF. In the present sequential report, part 2, we investigate many other effects on electrolytic polymerization by the same mechanical approach for sensing as in part 1: the Mullins effect;the Piezo effect;vibration;kind of electrode;atmospheric gas. In particular, we clarify that the voltage generates spontaneously in the MCF rubber and that the MCF rubber becomes a Piezo element. These effects on the electrolytic polymerization as well as the effects of the experimental conditions will be useful in engineering applications. By taking the above-mentioned parameters and effects into account, MCF rubber that is electrolytically polymerized with the aid of a magnetic field, the use of MCF as a filler, and doping, can be useful in haptic sensor applications. In particular, the effectiveness of the Piezo element can be shown.