Properties Of Natural Rubber Nanocomposites Research Articles

The effect of partial replacement of carbon black (CB) with halloysite nanotubes (HNTs) on the properties of CB/HNT-filled natural rubber nanocomposites

The effect of partial replacement of carbon black (CB) with halloysite nanotubes (HNTs) on the properties of natural rubber nanocomposites was investigated. Total hybrid fillers were kept constant at 40 parts per hundred rubber (phr) and were prepared using laboratory two-roll mill. Longer scorch and cure times were observed with the addition of more HNTs. The results also showed a decrement in tensile strength and tensile moduli besides causing an increment in swelling percentage. However, positive results were shown during elongation at break and fatigue life which indicates possible usefulness of HNTs in dynamic application of rubber products. Comparable thermal stability of nanocomposites with variable CB/HNTs ratios was shown in thermogravimetric analysis data.

Influence of the Botanic Origin of Starch Nanocrystals on the Morphological and Mechanical Properties of Natural Rubber Nanocomposites

AbstractThe structural and mechanical properties of natural rubber (NR) nanocomposites filled with starch nanocrystals (SNC) extracted from four different starch sources are investigated. The aim of this work is to explore the influence of botanic sources on final properties of nanocomposites and SNC reinforcing capability. A general trend seems to be that the higher the amylose content of native starch granules used for preparing SNC, the lower the water uptake and reinforcing effect (except for potato starch). It is postulated that SNC prepared from higher amylose content starch might release loosely bonded amylose chains during preparation and/or soaking in water and thus prevent SNC to participate in the formation of a reinforcing network.magnified image

Effect of organoclay on the gas barrier properties of natural rubber nanocomposites

AbstractNatural rubber nanocomposites have been prepared with organically modified montmorillonite clay. The nanocomposites have been characterized by X‐ray diffractometry and transmission electron microscopy. The gas‐barrier properties of the nanocomposites have been studied for three different gases viz., oxygen, nitrogen, and CO2 gases. The natural rubber–organoclay composites exhibit outstanding gas‐barrier properties compared to the neat rubber. Various models have been applied to predict the decrease in permeability in nanocomposites. All other models except Bharadwaj model give low values of calculated aspect ratio. Dynamic mechanical analysis has been carried out to investigate the role of the constrained region on the permeability of the nanocomposites. The permeability decrease of the organoclay nanocomposites is found to have good qualitative correlation with the volume of the constrained region. POLYM. COMPOS.,, 2012. © 2012 Society of Plastics Engineers

Tensile Properties of Natural Rubber Nanocomposites Affected by Crosslink Density

The aim of this study was to investigate the tensile properties of the natural rubber nanocomposites containing surface modified calcium carbonate nanofiller. All nanocomposites were prepared at various nanofiller contents, using a laboratory scale two-roll mill. The results revealed that the ultimate tensile properties altered by changing nanofiller content throughout the elastomeric matrix, which could be ascribed to the particular interactions at the filler/matrix interface. At 10 parts by weight of nanofiller, based on 100 parts by weight of natural rubber, the highest value of tensile properties was achieved as a result of crosslink density being at its highest level, as measured by swelling method.

Effects of partial replacement of silica with surface modified nanocrystalline cellulose on properties of natural rubber nanocomposites

Nanocrystalline cellulose was modified by 3-aminopropyl-triethoxysilane (KH550). The modified nanocrys- talline cellulose (MNCC) was further investigated to partially replace silica in natural rubber (NR) composites via coagula- tion. NR/MNCC/silica and NR/nanocrystalline cellulose (NCC)/silica nanocomposites were prepared. Through the com- parison of vulcanization characteristics, processing properties of compounds and mechanical properties, compression fatigue properties, dynamic mechanical performance of NR/MNCC/silica and NR/NCC/silica nanocomposites, MNCC was proved to be more efficient than NCC. MNCC could activate the vulcanization process, suppress Payne effect, increase 300% modulus, tear strength and hardness, and reduce the heat build-up and compression set. Moreover, fine MNCC dis- persion and strong interfacial interaction were achieved in NR/MNCC/silica nanocomposites. The observed reinforcement effects were evaluated based on the results of apparent crosslinking density (Vr), thermo-gravimetric (TG) and scanning electron microscopic (SEM) analyses of NR/MNCC/silica in comparison with NR/NCC/silica nanocomposites.

Effect of phenol functionalization of carbon nanotubes on properties of natural rubber nanocomposites

AbstractThis paper reports the results of studies on the effect of phenol functionalization of carbon nanotubes (CNTs) on the mechanical and dynamic mechanical properties of natural rubber (NR) composites. Fourier transform infrared spectrometry (FTIR) indicates characteristic peaks for ether and aromatic rings in the case of phenol functionalized CNT. Although differential scanning calorimetric (DSC) studies show no changes in the glass‐rubber transition temperature (Tg) of NR in the nanocomposites due to surface modification of CNT, dynamic mechanical studies show marginal shifting of Tg to higher temperature, the effect being pronounced in the case of functionalized CNT. Stress‐strain plots suggest an optimum loading of 5 phr CNT in NR formulations and the phenolic functionalization of CNT does not affect significantly the stress‐strain properties of the NR nanocomposites. The storage moduli register an increase in the presence of CNT and this increase is greater in the case of functionalized CNT. Loss tangent showed a decrease in the presence of CNT, and the effect is more pronounced in the case of phenol functionalized CNT. Transmission electron microscopy (TEM) reveals that phenol functionalization causes improvement in dispersion of CNT in NR matrix. This is corroborated by the increase in electrical resistivity in the case of phenol functionalized CNT/NR composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Effect of nanosized mesoporous MCM-41 (with template) material on properties of natural rubber nanocomposites

Mesoporous mobil composition of matter 41 (MCM-41) (with template) was used directly as a new filler for naural rubber (NR). Inside the pore chanels, and on the outer surface of the MCM-41 particle, were cationic surfactant CTAB and Pluronic F127 (molecular weight = 11 500) mixture. Results showed that the tensile properties and the thermal stability of NR/mesoporous MCM-41 (with template) nanocomposite were improved at low filler loading as compared with those of NR compound. Scanning electron microscopy observations revealed that enhancement of the interface was obtained by adding MCM-41 (with template).

Mechanical properties of natural rubber nanocomposites reinforced with cellulosic nanoparticles obtained from combined mechanical shearing, and enzymatic and acid hydrolysis of sisal fibers

In a previous work (Siqueira et al. 2010b) the preparation of cellulosic nanoparticles from sisal fibers using different processing routes, viz. a combination of mechanical shearing, acid and enzymatic hydrolysis was reported. It was shown that the pre-enzymatic hydrolysis treatment of bleached sisal pulp helps the preparation of well individualized rod-like nanocrystals. An amorphous polymer (natural rubber—NR) was chosen as model matrix to investigate the effect of these nanoparticles on the thermo-mechanical properties of nanocomposites. Both tensile tests and dynamic mechanical analyses showed improved stiffness for all nanocomposites. The enzymatic treatment allowed production of a huge range of cellulosic nanoparticles which provided completely different mechanical properties to NR matrix.

Effects of Surfactant Content and Clay Content on Properties of NR Nanocomposites

Montmorillonite (MMT) was modified by octadecylamine (ODA) surfactant. The surfactant contents were varied, i.e. 0.5, 1.0 and 2.0 times the cation exchange capacity (CEC) of the MMT. XRD and FTIR spectra of the organoclay revealed that ODA molecules intercalated into MMT layers. The MMT-ODA was melt-mixed with natural rubber (NR) using a two roll mill. Effects of surfactant content and organoclay content on cure characteristics, mechanical properties, and morphologies of NR nanocomposites were investigated. Morphologies of the NR nanocomposites, with increasing surfactant content, revealed the exfoliated structure and the good dispersion of the organoclay in the NR matrix. These caused the enhancement of mechanical properties of the NR nanocomposites. With increasing the MMT-ODA2 content up to 5 phr, scorch time and cure time of the NR nanocomposites decreased while their tensile strength increased.

Influence of Different Nanofillers and their Dispersion Methods on the Properties of Natural Rubber Nanocomposites

Abstract The effects of varying morphological and chemical constitution of nanofillers and various dispersion methods on natural rubber nanocomposites prepared by conventional processing techniques were determined by incorporating various nanofillers like montmorillonite, sepiolite (SP), hectorite, carbon nanofiber (F) and expanded graphite. When compared with the gum, SP filled (4 phr) nanocomposite exhibited an increment of 26% in the modulus and F (6phr) increased the tear strength by 18%, over the gum. Nanofiller dispersion was enhanced by various compatibilization and dispersion techniques which helped SP introduce 56 and F 113% increment in the modulus of the nanocomposites, over the gum rubber vulcanizate. It also rendered 28% improvement in the tear strength of F filled system. Deeper insights into the material properties were obtained through dynamic mechanical and swelling studies. Property-morphology correlation of the hybrids was performed through X-ray Diffraction, Atomic Force Microscopy and Transmission Electron Microscopy. Surface energy (SE) studies exhibited that the higher surface energy of SP (38 mJ/m2) and F (44 mJ/m2) than the rubber (35 mJ/m2) ensured necessary wetting and hence was responsible for improvement of the properties. Using SE, cleavage energy and work of adhesion data, a new mechanism based on adsorption followed by shear of polymer-bound nanofillers was suggested.

The Comparison of Organoclay with Respect to Silica on Properties of Natural Rubber Nanocomposites

Effects of organoclay loading (organophilic modified montmorillonite with octadecylamine) in comparison to silica loading on the curing characteristics, tensile properties, thermal stability, and morphology of natural rubber (NR) nanocomposites were studied. Organoclay loading from 2 to 10 phr and silica with 10 and 30 phr loading were used as fillers in this study. The NR/organoclay nanocomposites were compounded using two roll mills and cured at 150°C. The results indicate that the tensile strength and tensile modulus reach maximum at 8 phr of organoclay but elongation at break and thermal stability increase with increasing organoclay loading. Tensile strength, tensile modulus, and elongation at break increase with increasing amount of silica from 10 to 30 phr. Overall results show that organoclay filled NR nanocomposites exhibit shorter processing time and higher tensile properties than silica filled NR nanocomposites. The enhanced properties are due to the homogenous dispersion of individual silicate layers in NR matrix, which is evidenced from the X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) results.

Preparation and properties of natural rubber nanocomposites with solid‐state organomodified montmorillonite

AbstractA novel organomodified montmorillonite prepared by solid‐state method and its nanocomposites with natural rubber were studied. The nanocomposites were prepared by traditional rubber mixing and vulcanizing process. The properties of solid‐state organomodified montmorillonite were investigated by Fourier‐transform infrared spectroscopy (FITR) and thermogravimetric analysis (TGA). The dispersion of the layered silicate in rubber matrix was characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the nanocomposites consisting of solid‐state organomodified montmorillonite and natural rubber are obtained. The solid‐state organomodified montmorillonite can not only accelerate the curing process, but also improve the mechanical and aging resistance properties of NR. The properties improvement caused by the fillers are attributed to partial intercalation of the organophilic clay by NR macromolecules. In addition, the dynamic mechanical analysis (DMA) results showed a decrease of tanδmax and increase of Tg when the organoclay is added to the rubber matrix, which is due to the confinement of the macromolecular segments into the organoclay nanolayers and the strong interaction between the filler and rubber matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Combined Effect of Nano-clay and Nano-carbon Black on Properties of NR Nanocomposites

Natural rubber (NR)/clay/carbon black nanocomposites, filled with 10 phr, 20 phr, and 30 phr of filler (in total) were obtained by adding carbon black (N330) on a two-roll mill to NR/clay nano-compounds prepared by the emulsion compounding method. X-ray diffraction patterns and transmission electron microscope photographs of the nanocomposites showed that both fillers were dispersed randomly in the NR matrix at nano-scale and that the space between the clay layers was filled with carbon black particles. At the same total filler loadings, the mechanical properties of the naocomposites filled with both clay and carbon black, such as moduli at 100% and 300% elongation, tensile strength and tear strength, were greatly improved compared with those of either NR/clay nanocomposites or NR/carbon black nanocomposites. This indicates that the samples with both fillers possessed excellent mechanical properties. It was found that the NR/clay/carbon black nanocomposites retained advantages from both fillers, for example, the processability and dynamic properties were close to those of NR/carbon black nanocomposites, and the gas barrier properties were almost as good as those of NR/clay nanocomposites.