Showing papers on "Natural rubber published in 2015"
TL;DR: In this paper, three groups of singly-sized rubber particle samples (3mm, 0.5mm and 0.3mm) and one sample of continuous size grading (prepared by blending the three singlysized samples to form the same particle distribution curve of sand) were used to replace 20% of the natural fine aggregate by volume.
265 citations
TL;DR: In this paper, a chemically crosslinked epoxidized natural rubber (ENR) was investigated, where disulfide groups were introduced into the rubber using dithiodibutyric acid (DTDB) as a crosslinker.
235 citations
TL;DR: A simple and easy approach to preparing a commercial rubber with self-healing properties offers unique development opportunities in the field of highly engineered materials, such as tires, for which safety, performance, and longer fatigue life are crucial factors.
Abstract: Invented by Charles Goodyear, chemical cross-linking of rubbers by sulfur vulcanization is the only method by which modern automobile tires are manufactured. The formation of these cross-linked network structures leads to highly elastic properties, which substantially reduces the viscous properties of these materials. Here, we describe a simple approach to converting commercially available and widely used bromobutyl rubber (BIIR) into a highly elastic material with extraordinary self-healing properties without using conventional cross-linking or vulcanising agents. Transformation of the bromine functionalities of BIIR into ionic imidazolium bromide groups results in the formation of reversible ionic associates that exhibit physical cross-linking ability. The reversibility of the ionic association facilitates the healing processes by temperature- or stress-induced rearrangements, thereby enabling a fully cut sample to retain its original properties after application of the self-healing process. Other mecha...
224 citations
TL;DR: In this paper, the authors used synchrotron wide-angle X-ray diffraction (WAXD) measurements, and observed that strain-induced crystallization of NR/ZDMA composites had a direct affect on the ultimate mechanical properties.
Abstract: Natural rubber (NR) reinforced by in situ polymerization of zinc dimethacrylate (ZDMA) exhibits excellent mechanical properties. However, the corresponding reinforcement mechanism is still unclear. Using synchrotron wide-angle X-ray diffraction (WAXD) measurements, we observed that strain-induced crystallization of NR/ZDMA composites had a direct affect on the ultimate mechanical properties. An increase in ZDMA fraction resulted in a lower strain at the onset of crystallization. Further analysis revealed that three factors contributed to the reduction in onset strain, including higher whole cross-linking density due to the emergence of ionic cross-linking clusters, strain amplification of nanodispersion of poly-ZDMA (PZDMA), and the confinement effect of the filler network. The results of dynamic Monte Carlo simulation showed that the confinement effect of the filler network on chain segments favored segmental orientation in regions near the polymer–filler interface, thus inducing a decline in onset strain.
210 citations
TL;DR: In this paper, a commercial ethylene-propylene rubber grafted with maleic anhydride has been thermoreversibly cross-linked in two steps using a Diels-Alder coupling reaction.
Abstract: A proof of principle for the use of Diels–Alder chemistry as a thermoreversible cross-linking tool for rubber products is demonstrated. A commercial ethylene-propylene rubber grafted with maleic anhydride has been thermoreversibly cross-linked in two steps. The pending anhydride rings were first modified with furfurylamine to graft furan groups onto the rubber backbone. These pending furans were cross-linked with a bismaleimide via a Diels–Alder coupling reaction. The newly formed Diels–Alder cross-links break at elevated temperatures (>150 °C) and can be re-formed by thermal annealing (50–70 °C). Reversibility of the rubber network was proven with infrared spectroscopy and on the basis of the mechanical properties. Furthermore, reversibility was also shown in a practical way, i.e., by cutting the used material into pieces and pressing them into new samples displaying comparable mechanical properties (impossible for conventionally cross-linked rubbers). The physical properties of the resulting products ar...
203 citations
TL;DR: Significant improvements in the Young's modulus and tensile strength of the nanocomposite were observed because of the reinforcing ability of the nanocellulose in the rubber matrix.
192 citations
TL;DR: In this article, the effect of the rubber content on the compressive and flexural strength, failure mode, modulus of elasticity and toughness of RSRAC was analyzed, and the results indicate that rubber with an optimal rubber content displays good compressive behaviour compared with normal NCA concrete.
162 citations
TL;DR: In this paper, the effect of replacement of fine aggregates by waste rubber fibers on the impact resistance of concrete has been assessed, and the impact tests on concrete have been conducted by three different techniques; drop weight test, flexural loading test and rebound test.
157 citations
TL;DR: In this paper, a DGEBA epoxy resin cured using dicyandiamide hardener, was modified by using two types of CSR nano-particles over a range of volume fractions from 0.% to 38.%.
157 citations
TL;DR: In this article, the authors provided strength and durability test results for rubberized concrete that contains silica fume (microsilica) for road side barriers with the intent to reduce injuries and fatalities during crashes.
151 citations
TL;DR: In this paper, redox-initiated free radical graft copolymerization of microcrystalline cellulose (MCC) and methyl methacrylate (MMA) has been carried out in aqueous media to develop a novel cellulose-based copolymers.
Abstract: In this study, redox-initiated free radical graft copolymerization of microcrystalline cellulose (MCC) and methyl methacrylate (MMA) has been carried out in aqueous media to develop a novel cellulose-based copolymer. Cerium ammonium nitrate was used as the initiator in the presence of nitric acid. Effects of monomer concentration, initiator concentration, polymerization time, and polymerization temperature on the graft parameters of copolymers were studied. The successful grafting copolymerization between MCC and MMA was validated through attenuated total reflection, wide-angle X-ray diffraction, field-emission scanning electron microscopy, and thermal gravimetric analysis. In comparison to native MCC, the resultant copolymers exhibited enhanced thermal stability and better compatibility with natural rubber, suggesting its potential application as reinforcement material in rubber industry. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42666.
TL;DR: In this paper, the epoxidized natural rubber (ENR) as an interfacial modifier was used to improve the mechanical and dynamical mechanical properties of NR/silica composites.
TL;DR: In this paper, waste tyre rubber in the form of crumb rubber was used as a partial replacement for natural fine aggregates in high strength cement concrete and the results showed that the high strength rubberized concrete are highly resistant to the aggressive environments.
TL;DR: In this article, a model material of vulcanized polybutadiene rubber, which is used to simulate the manufacturing process of industrial vulcanised rubber, is presented, and the results of the present preliminary exploration would provide the basis for extending the service life and developing new recycling techniques of the rubber.
TL;DR: In this paper, the physical and chemical changes that occur in the ground tire rubber after different microwave exposure periods were analyzed, and the results showed that the microwave treatment promoted the breaking of sulfur cross-links and consequently increased the rubber fluidity.
Abstract: Microwave devulcanization is known to be a promising and an efficient rubber recycling method which makes possible for the rubber to regain its fluidity, and makes it capable of being remolded and revulcanized. The focus of this work is to understand the physical and chemical changes that occur in the ground tire rubber after different microwave exposure periods. For this purpose chemical, thermal, rheological and morphological analyses were performed on the tire rubber, which contains natural rubber (NR) and styrene-butadiene rubber (SBR) as polymeric material. The results showed that the microwave treatment promoted the breaking of sulfur cross-links and consequently increased the rubber fluidity. However, long periods of exposure led to degradation and modification of some properties. At nanoscale, the deformation of the devulcanized NR domain under stress was observed, and the morphology obtained appears to be a droplet dispersion morphology. The most exposed samples presented only one glass transition temperature, and from this it was concluded that the treatment may have played an important role in the compatibilization of the elastomeric blend. Based on the results, it is required to control the microwave exposure time and polymeric degradation in order to achieve a regenerated rubber with satisfactory properties.
TL;DR: It is proposed that Taraxacum brevicorniculatum rubber transferase activator (TbRTA), a dandelion homologue of the human Nogo-B receptor, is an essential component of the rubbertransferase complex which interacts with rubber CPTs on the surface of rubber particles.
Abstract: High-molecular-mass natural rubber is a valuable plant-derived poly(cis-1,4-isoprene) with many industrial and medical applications. It is synthesized by a rubber cis-prenyltransferase (CPT) complex on the surface of rubber particles in specialized latex-producing cells known as laticifers. Here we show that Taraxacum brevicorniculatum rubber transferase activator (TbRTA), a dandelion homologue of the human Nogo-B receptor, is an essential component of the rubber transferase complex which interacts with rubber CPTs on the surface of rubber particles. The knockdown of TbRTA by RNA interference eliminated rubber biosynthesis, without affecting dolichol accumulation or protein glycosylation in the latex. We also found that TbRTA is localized on the endoplasmic reticulum membrane, supporting the current favoured model of rubber particle biogenesis. We therefore propose that TbRTA acts as a rubber CPT-binding protein that is necessary for the formation of an active rubber transferase complex. Natural rubber is composed of extremely long polymers of isoprene. In dandelion, a potential alternative source of latex for industry, a rubber transferase activator, homologous to the human Nogo-B receptor, is necessary for this synthesis.
TL;DR: Two series of alkylamine-modified (oleylamine and octadecylamine) styrene-butadiene rubber (SBR)/graphene oxide (GO) composites were fabricated through a facile green method involving co-coagulation and in-situ interfacial modification techniques as discussed by the authors.
TL;DR: In this article, the compiled experimental data of slump value, compressive strength, splitting tension strength, flexural strength, static modulus of elasticity and unit weight for eleven different mixtures of rubber lightweight aggregate concretes cured up to 1, 7 and 28 days.
TL;DR: Natural rubber/cellulose nanocrystals (NR/CNCs) form true biocomposites from renewable resources and are demonstrated to show significantly improved thermo-mechanical properties and reduced stress-softening.
Abstract: Natural rubber/cellulose nanocrystals (NR/CNCs) form true biocomposites from renewable resources and are demonstrated to show significantly improved thermo-mechanical properties and reduced stress- ...
TL;DR: In this paper, the effect of using scrap tires in high strength concrete on both the mechanical and dynamic properties was investigated using free vibration tests with impact hammer on simply supported beams and the results gave an insight on the properties of high-strength concrete with scrap tire rubber.
TL;DR: In this paper, a cross-linked natural rubber (NR) continuous phase was found to be a "netlike" continuous phase in the PLA matrix, which explained the surprising shape memory property of PLA/NR TPVs well.
Abstract: Shape memory polymers (SMPs) based on fully biobased poly(lactide) (PLA)/natural rubber (NR) thermoplastic vulcanizates (TPVs) were fabricated via peroxide-induced dynamic vulcanization. Simultaneously, in situ reactive compatibilization was achieved by PLA molecule grafting onto NR chains. Differing from the general concept of spherical rubber particles being formed after dynamic vulcanization, the cross-linked NR was found to be a “netlike” continuous phase in the PLA matrix. This novel structure explained the surprising shape memory property of PLA/NR TPVs well (shape fixities ∼ 100%, shape recoveries > 95%, and fast recovery speed < 15 s at the switching temperature, ∼60 °C): the cross-linked NR continuous phase offers strong resilience and the PLA phase serves as the heat-control switch. We envision that the “green” raw materials and excellent shape memory properties of the dynamically vulcanized PLA/NR SMPs will open up a wide range of potential applications in intelligent medical devices.
TL;DR: In the presence of dicumyl peroxide, biobased thermoplastic vulcanizates (TPVs) composed of poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) were prepared through dynamic vulcanization and the effects of various DCP contents on the impact property were investigated.
Abstract: In the presence of dicumyl peroxide (DCP), biobased thermoplastic vulcanizates (TPVs) composed of poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) were prepared through dynamic vulcanization. Interfacial in situ compatibilization between PLA and ENR phases was confirmed by Fourier transform infrared spectroscopy (FT-IR). A novel “sea–sea” co-continuous phase in the PLA/ENR TPVs was observed through scanning electron microscopy (SEM) and differed from the typical “sea–island” morphology that cross-linked rubber particles dispersed in plastic matrix. A sharp, brittle–ductile transition occurred with 40 wt % of ENR, showing a significantly improved impact strength of 47 kJ/m2, nearly 15 times that of the neat PLA and 2.6 times that of the simple blend with the same PLA/ENR ratio. Gel permeation chromatography (GPC) and dynamic mechanical analysis (DMA) results suggested that a certain amount of DCP was consumed in the PLA phase, causing a slight cross-linking or branching of PLA molecules. the eff...
TL;DR: In this paper, the authors focused on the use of crumb rubber (from end-of-life tires) as elastic aggregates mixed with ballast particles, which could reduce ballast degradation and consumption of natural aggregates.
TL;DR: In this paper, the performance of a two-stage approach of using limestone powder (LP) pre-coated crumb rubber and silica fume (SF) to enhance the rubberized cement mortar was investigated.
TL;DR: Dopamine (DA) was used to simultaneously coat the graphene oxide and partially reduce GO by self-polymerization of DA on GO to obtain dielectric elastomer composites with controllable dielectrics and actuated properties by using a biomimetic method.
Abstract: In this study, we obtained dielectric elastomer composites with controllable dielectric and actuated properties by using a biomimetic method. We used dopamine (DA) to simultaneously coat the graphene oxide (GO) and partially reduce GO by self-polymerization of DA on GO. The poly(dopamine) (PDA) coated GO (GO-PDA) was assembled around rubber latex particles by hydrogen bonding interaction between carboxyl groups of carboxylated nitrile rubber (XNBR) and imino groups or phenolic hydroxyl groups of GO-PDA during latex compounding, forming a segregated GO-PDA network at a low percolation threshold. The results showed that the introduction of PDA on GO prevented the restack of GO in the matrix. The dielectric and actuated properties of the composites depend on the thickness of PDA shell. The dielectric loss and the elastic modulus decrease, and the breakdown strength increases with increasing the thickness of PDA shell. The maximum actuated strain increases from 1.7% for GO/XNBR composite to 4.4% for GO-PDA/XN...
TL;DR: Dynamic measurements demonstrate that rod-like particles induce stronger reinforcement of rubber, increasing with the AR, related to the self-alignment of the anisotropic silica particles in domains able to immobilize rubber.
Abstract: Silica–styrene butadiene rubber (SBR) nanocomposites were prepared by using shape-controlled spherical and rod-like silica nanoparticles (NPs) with different aspect ratios (AR = 1–5), obtained by a sol–gel route assisted by a structure directing agent. The nanocomposites were used as models to study the influence of the particle shape on the formation of nanoscale immobilized rubber at the silica-rubber interface and its effect on the dynamic-mechanical behavior. TEM and AFM tapping mode analyses of nanocomposites demonstrated that the silica particles are surrounded by a rubber layer immobilized at the particle surface. The spherical filler showed small contact zones between neighboring particles in contact with thin rubber layers, while anisotropic particles (AR > 2) formed domains of rods preferentially aligned along the main axis. A detailed analysis of the polymer chain mobility by different time domain nuclear magnetic resonance (TD-NMR) techniques evidenced a population of rigid rubber chains surrounding particles, whose amount increases with the particle anisotropy, even in the absence of significant differences in terms of chemical crosslinking. Dynamic measurements demonstrate that rod-like particles induce stronger reinforcement of rubber, increasing with the AR. This was related to the self-alignment of the anisotropic silica particles in domains able to immobilize rubber.
TL;DR: In this article, a review of wood flour and other lignocellulosic fibres filled rubber composites, including cellulosic rubber composite materials, is presented.
Abstract: The rising concern towards the reduction in the use of petroleum-based, non-renewable resources and the need for more versatile polymer-based composite materials have led to increasing interests on natural polymer composites filled with natural organic fillers, i.e. coming from renewable and biodegradable sources. This paper reviews wood flour and other lignocellulosic fibres filled rubber composites, including cellulosic rubber composites, cellulosic thermoplastic elastomers, nanocellulose based rubber nanocomposites, with the aims at providing the most state of the art information for directing further scientific research, possible commercialization and design of cellulosic rubber composites. It has been found that 1) the surface properties of natural cellulose, hence the compatibility and interface of the natural cellulose and matrix rubber/plastics, are crucial for the successful development of the composites, such, physical and chemical modification and additives have been widely attempted to improve the incompatibility and poor interfacial adhesion between the filler and matrix; 2) the curing characteristics, mechanical properties, thermal stability and morphologies of the composites are complex but closely related to not only the interfacial properties, but also the compositions (e.g. the concentration of cellulosic materials) and other processing parameters; 3) the nature of hydrophilic cellulosic and hydrophobic matrix rubber and/or plastics requires an accurate introduction of coupling agent, one end of its structure shall be compatible to hydrophilic and the other to hydrophobic. The reviews on the main paths and results of study on the advanced nanocellulose reinforced rubber nanocomposites and sandwiches indicate much potentials and needs for further in-depth studies.
TL;DR: In this article, the thermal and acoustical insulation properties of rubberized concrete at high rubber volume fractions were evaluated in terms of density, absorption, compressive strength, impact resistance, ductility and flexural strength.
TL;DR: In this paper, an ultrasonication assisted mixing of aqueous dispersions of multiwalled carbon nanotubes with natural rubber (NR) latex followed by film casting and curing is described.