Properties Of Natural Rubber Nanocomposites Research Articles

Impact of graphene nanoplatelet size and hybridisation on the properties of natural rubber nanocomposites

Impact of graphene nanoplatelet size and hybridisation on the properties of natural rubber nanocomposites

Enhancing properties of natural rubber nanocomposites with hybrid fillers and ionic liquid

Enhancing properties of natural rubber nanocomposites with hybrid fillers and ionic liquid

A comparative study on the effect of different fibrous nanofillers on the properties of natural rubber nanocomposites

AbstractThe specific geometry and distinct properties of one‐dimensional nanostructures make them the most ideal candidates as reinforcing elements in composites and the dependence of physical, mechanical, thermal, and wear properties of polymer composites on their dimensionality, nature, and dispersion is interesting. The upsurging demands for high‐performance elastomer composites require the application of such nanomaterials as reinforcing agents. Here, we offer a detailed characterization of some of the novel fibrous nanofillers such as silicon carbide nanofibers, aramid nanofibers, carbon nanotubes, and graphite nanofibers. Morphology, crystallinity, surface chemistry, polarity, and thermal stability of these nanofibers were analyzed using techniques such as electron microscopy, X‐ray diffraction, infrared and Raman spectroscopy, and thermogravimetric analysis. Natural Rubber nanocomposites were developed using these fibrous nanofillers, and their rheometric, mechanical, dynamic mechanical, and thermal properties were studied. ANF‐reinforced compounds gave the highest increment in 300% modulus while the highest tensile strength was obtained by CNT reinforced compounds at 4 phr filler loading. CNT and GNF‐reinforced compounds improved the wear resistance simultaneously by 43% and 33% respectively, while SiC and ANF improved it by 10% and 8% respectively. Lower tan delta and better thermal stability were also recorded. Future exploration may involve the use of these nanofibers in conjunction with carbon black or silica to achieve high‐performance elastomer compounds for real‐life applications.

Synergistic effect between graphene nanoplatelets and carbon black to improve the thermal and mechanical properties of natural rubber nanocomposites

ABSTRACT In this study, we focused on the synergistic effect between carbon black (CB) and graphene nanoplatelets (GNPs) of various aspect ratios and specific surface areas as hybrid fillers in natural rubber (NR) nanocomposites. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM) were carried out to characterize the GNPs properties, while dynamic mechanical analysis (DMA), tensile properties, hardness, thermal conductivity, swelling behavior in toluene and SEM were performed on the NR nanocomposites. The results showed the positive effect of GNPs on the thermal and mechanical properties, which was attributed to the high surface area and aspect ratio of the GNPs playing a vital role in producing a conductive GNPs/CB hybrid fillers’ network. Among the three GNPs investigated, the sample having the highest lateral dimension (25 µm) led to a denser and more thermally conductive network. On the other hand, the GNPs/CB hybrid fillers’ synergy increased with increasing concentration inside the NR nanocomposites up to 5 phr due to their good dispersion as confirmed via SEM.

Influence of nanofiller types on morphology and mechanical properties of natural rubber nanocomposites

Natural rubber (NR) nanocomposite containing different types of filler, i.e., nanoclay (clay) and cellulose nanofiber (CNF) were prepared in this study. The masterbatches of NR with 5 parts per hundred parts of rubber of nanofiller were firstly prepared by using the latex mixing method, followed by compounding on two roll mill and compression molding to obtain NR nanocomposite specimens. The unfilled NR sample was also prepared for comparison. Morphological properties of NR nanocomposites were investigated by using transmission electron microscopy, while the mechanical and dynamic properties were studied by using a universal tensile testing machine and dynamic mechanical analyzer (DMA). It was found that the clay with platelet morphology was uniformLy dispersed, while the long and flexible CNFs were aggregated and poorly dispersed. The greater improvement of modulus at various strains was achieved from CNF filled NR nanocomposites, while the highest tensile strength was obtained from the clay filled nanocomposite. As compared to the clay containing nanocomposite, the addition of CNF markedly decreased the tensile strength and elongation at break of the NR due to poor dispersion of CNF. However, a significant improvement in mechanical properties at low strain was obtained when the CNF was used as filler due to high degree of fiber entanglement, as suggested by DMA observation.

Highly enhanced electrical and mechanical properties of methyl methacrylate modified natural rubber filled with multiwalled carbon nanotubes

Developing conductive networks in a polymer matrix with a low percolation threshold and excellent mechanical properties is desired for soft electronics applications. In this work, natural rubber (NR) functionalized with poly(methyl methacrylate) (PMMA) was prepared for strong interfacial interactions with multiwalled carbon nanotubes (MWCNT), resulting in excellent performance of the natural rubber nanocomposites. The MWCNT and methyl methacrylate functional groups gave good filler dispersion, conductivity and tensile properties. The filler network in the matrix was studied with microscopy and from its non-linear viscoelasticity. The Maier-Göritze approach revealed that MWCNT network formation was favored in the NR functionalized with PMMA, with reduced electrical and mechanical percolation thresholds. The obvious improvement in physical performance of MWCNT/methyl methacrylate functionalized natural rubber nanocomposites was caused by interfacial interactions and reduced filler agglomeration in the NR matrix. The modification of NR with poly(methyl methacrylate) and MWCNT filler was demonstrated as an effective pathway to enhance the mechanical and electrical properties of natural rubber nanocomposites.

Effect of carbon nanotubes decorated with silver nanoparticles as hybrid filler on properties of natural rubber nanocomposites

ABSTRACTDecoration of carbon nanotube (CNT) surfaces with silver nanoparticles (AgNPs) was performed using N,N‐dimethylformamide reducing agent. The CNT‐decorated with AgNP (CNT‐AgNP) was then used to prepare natural rubber (NR) nanocomposites via latex mixing method. Cure characteristics, mechano‐thermal relaxation, electrical conductivity, and thermal properties of the composites were investigated. It was found that the CNT‐AgNP gave cure properties improved over plain NR compounds in terms of scorch time, degree of vulcanization, and activation energy. In addition, temperature scanning stress relaxation measurement revealed stronger network formation after incorporation of AgNP into the NR matrix due to the interaction among CNT and AgNP particles. This also provided high conductivity and low percolation threshold concentration for the CNT‐AgNP filled NR, relative to plain CNT filled NR composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47281.

Effect of novel supported vulcanizing agent on the interfacial interaction and strain-induced crystallization properties of natural rubber nanocomposites

The influence of the novel vulcanizing agent, silica supported sulfur monochloride (silica-s-S), comparing with sulfur on the filler-rubber interfacial interaction, mechanical properties and the strain-induced crystallization behaviors were investigated. Due to the formation of interparticle domain, silica-s-S immobilized more rubber chains approaching its surface as the crosslinking points than sulfur vulcanization system. Furthermore, the tightly immobilized rubber chains on silica-s-S surface bring to the significant enhancement of mechanical properties of NR nanocomposites. Meanwhile, the immobilized rubber chains also induced the formation of highest initial crystallinity index and slower decreasing lateral crystallite size with increasing strain ratio. Silica-s-S with more tightly immobilized rubber chains approaching its surface shown better reinforcing effect and strain-induced crystallization behaviors on rubber than that of sulfur vulcanization system.

Study on the role of crumb rubber on the thermal and mechanical properties of natural rubber nanocomposites

ABSTRACT Crumb rubber represents a series hazardous waste that causes environmental pollution that needs to be treated. Such a problem consumes a high budget in controlling its consequences. The main objective of this study is to get maximum benefit from this waste and use it as a filler in green processing to obtain useful materials such as heat insulators. Thus, the black filler was removed from the natural rubber mixes and crumb rubber from waste in different ratios was used instead to form rubber composite that contains a small amount of organo modified nanoclay to maintain the mechanical properties of the vulcanized rubber composites. A controlling mix containing black carbon filler was used to compare the obtained results from crumb/NR nanocomposites. These mixes were examined by Scanning Electron Microscopy (SEM) and the graphs revealed that at higher ratios of crumb rubber in the mix, crumb forms a dispersible network within the rubber blend matrix which enhances the miscibility between the rubber and all other ingredients. TGA data indicated high thermal stability of all crumb/NR nanocomposites. All results showed that the addition of crumb to natural rubber nanocomposites enhanced the levels of the properties especially for the mix of the ratio 4:6 for crumb:natural rubber. Results of thermal conductivity measurements assured that such mix acts as an insulating material and may be used in constructural applications for shielding purposes.

Effect of expanded organoclay by stearic acid to curing, mechanical and swelling properties of natural rubber nanocomposites

The interlayer basal spacing of organoclay (OC) could be increased with stearic acid (SA) added, thus OC changed into expanded organoclay by SA (OCSA). The effect of various loadings of OCSA on the curing, mechanical and swelling properties of natural rubber (NR) nanocomposites were studied. The natural rubber/expanded organoclay (NR/OCSA) nanocomposites were prepared by melt intercalation using a laboratory open mill. The curing characteristics of NR compounds were determined using a Moving Die Rheometer (MDR). The X-ray Diffraction (XRD), Attenuated Total Reflectance Infrared (ATR-IR) Spectroscopy and Field Emission Scanning Electron Microscopy (FESEM) were used to study the dispersion of OCSA in the NR matrix. The mechanical properties of NR/OCSA nanocomposites such as tensile strength, elongation at break and hardness were determined using ISO standard and swelling of NR/OCSA nanocomposites in toluene were determined using ISO 1817. The results showed that the SA intercalated into the gallery of OC and reacted with the hydroxyl groups in OC. It was indicated with the shifting of the negative peak 1,700 to 1,723 cm-1 in the ATR-IR spectrum and increase the d-spacing of OC. The adding of various loadings of OCSA into NR could increase the torque and accelerate the curing of nanocomposites and it also could increase the mechanical and swelling properties of nanocomposites. The change in modulus at 100% elongation significantly increased with increasing the OCSA load until maximum loading at 10 phr. This trend was same with the hardness and modulus at 300% elongation. Meanwhile, the improvement of tensile strength and elongation at break was higher at 4 phr OCSA compared with the other loading. The increase of mechanical and swelling properties of NR/OCSA nanocomposites was due to intercalation/exfoliation of OCSA in NR matrix. It was revealed by appearing of the out-of-plane Si-O-(Al) stretch with peak value 1080 cm-1 in the ATR-IR spectrum and the peaks of OCSA in the XRD pattern was disappeared until the loading of OCSA 8 phr and the thickness of morphology of OCSA below 100 nm.

Effects of partial replacement of carbon black with nanocrystalline cellulose on properties of natural rubber nanocomposites

Abstract Waste cotton materials were used as source materials to prepare waste cotton nanocrystalline cellulose (WCNC) by optimized acid hydrolysis. The final hydrolysis products had an approximately 30 nm diameter, lengths mainly ranging from 400 nm to 800 nm, and a typical cellulose I crystal structure with a high degree of crystallinity. WCNC was further investigated to partially replace carbon black (CB) in natural rubber (NR) composites via coagulation. NR/CB/WCNC and NR/CB composites were prepared. Through comparisons of the morphology, mechanical properties, dynamic compression fatigue performance, thermal stability and soil biodegradation behaviour of the NR/CB/WCNC and NR/CB composites, WCNC was proven to perform efficiently. WCNC could increase tensile and tear strength as well as reduce heat build-up, and it presented slightly lower thermal stability and superior biodegradability. Moreover, a fine WCNC dispersion was achieved in NR/CB/WCNC. The observed reinforcement effects were evaluated based on the results of rubber processing analysis (RPA), thermogravimetric and scanning electron microscopic analyses of NR/CB/WCNC compared with the NR/CB composites.

Effect of organoclay on the solvent diffusion behavior and mechanical properties of natural rubber nanocomposites

This article aims to investigate the structure–property relationship of organoclay filled natural rubber (NR) nanocomposites. The nanostructure has been investigated by X‐ray diffraction, atomic force microscopy and transmission electron microscopy. The effect of organoclay on the diffusion behavior and mechanical properties of natural rubber has been investigated. The solvent transport properties and the swelling characteristics of the nanocomposites have been studied using toluene and hexane as solvents. It is observed that the nanocomposites exhibit an anomalous trend of transport behavior. The diffusion coefficient and permeability coefficient values are found to be lower for hexane than for toluene. The nanocomposites exhibit improved mechanical properties (tensile strength, tear strength, and modulus) and hardness compared to the unfilled rubber. It is concluded that the dispersion of organoclay has a significant effect on the diffusion and mechanical properties of the nanocomposites. POLYM. COMPOS., 39:3110–3118, 2018. © 2017 Society of Plastics Engineers

Mechanical properties of natural rubber nanocomposites reinforced with high aspect ratio cellulose nanocrystals isolated from soy hulls

Cellulose nanocrystals (CNCs) were isolated from soy hulls by acid sulfuric hydrolysis. The resulting CNCs were characterized using TEM, AFM, WAXS, elemental analysis and TGA. The CNCs have a high crystallinity, specific surface area and aspect ratio. The aspect ratio (around 100) is the largest ever reported in the literature for a plant cellulose source. These CNCs were used as a reinforcing phase to prepare nanocomposite films by casting/evaporation using natural rubber as matrix. The mechanical properties were studied in both the linear and non-linear ranges. The reinforcing effect was higher than the one observed for CNCs extracted from other sources. It may be assigned not only to the high aspect ratio of these CNCs but also to the stiffness of the percolating nanoparticle network formed within the polymer matrix. Moreover, the sedimentation of CNCs during the evaporation step was found to play a crucial role on the mechanical properties.

Effect of the morphology of thermally reduced graphite oxide on the mechanical and electrical properties of natural rubber nanocomposites

Graphene materials often are obtained through thermal reduction of graphite oxide. This is due to the fact that other synthesis methods are more difficult and generally render lower yield. The structure and morphology of these graphene materials could affect their performance in different applications. Herein, thermally reduced graphite oxide (TRGO) was obtained from thermal reduction of graphite oxide prepared by using the methods reported by Brodie and Hummers. The oxidation method greatly affects the structure and morphology of the resulting TRGO. TRGO obtained by the Brodie's method generates a morphology comprised of rather exfoliated galleries while that obtained by the Hummers method presents randomly distributed sheets. The influence of structural differences on the dispersion of TRGOs in natural rubber latex (NR) and on the resulting mechanical and electrical properties of the TRGO/NR nanocomposites is studied. The TRGO prepared by the Brodie's method (TRGO-B) showed a more homogeneous dispersion in the polymer–matrix, rendering enhanced mechanical and electrical properties of their nanocomposites. TRGO-B/NR nanocomposites showed higher electrical conductivity, which is attributed to the formation of an electrically conducting filler network through the polymer–matrix. This is consequence of the morphology presented by TRGO produced by the Brodie's method.

Properties of Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes

In order to achieve improvements in the performance of rubber materials, the development of carbon nanotube (CNT)-reinforced rubber composites was attempted. The CNT/epoxidised natural rubber (ENR) nanocomposite was prepared through latex technology. Physical and mechanical properties of the CNT/ENR nanocomposites were characterized in contrast to the carbon black (CB)/ENR composite. The dispersion of the CNTs in the rubber matrix and interfacial bonding between them were rather good; monitored transmission electron microscopy and scanning electron microscopy. The mechanical properties of the CNT-reinforced ENR showed a considerable increase compared to the neat ENR and traditional CB/ENR composite. The storage modulus of the CNT/ENR nanocomposites greatly exceeds that of neat ENR and CB/ENR composites and a maximum conductivity of about 1 S m-1 can be achieved. The approach presented can be adapted to other CNT/polymer latex systems.

Influence of graphene functionalized with zinc dimethacrylate on the mechanical and thermal properties of natural rubber nanocomposites

An effective approach is developed to synthesize zinc dimethacrylate functionalized graphene (ZDMA‐GE) as reinforcing nanofiller for natural rubber (NR). The morphology and structure of ZDMA‐GE were characterized to confirm the exfoliation and functionalization of GE. The as‐prepared nanocomposites were investigated by transmission electron microscopy, mechanical analysis, crosslinked network analysis, and the analysis of thermal conductivity. The results demonstrated that there is strong interfacial interaction between GE and rubber matrix due to good dispersion and special two‐dimensional structure of GE. The crosslink density of the nanocomposites is greatly improved with the introduction of ZDMA‐GE because of the homopolymerization and graft polymerization of ZDMA. It is also noticed that the tensile strength, tear strength, and modulus at 300% elongation of NR nanocomposites with 15 phr ZDMA‐GE have been improved by 133, 42, and 174%, respectively. The thermal conductivity of nanocomposites with 40 phr ZDMA‐GE is enhanced 1.3 times as that of the pure NR. This remarkable improvement is attributed to the formation of covalent crosslinked network and ionic crosslinked network, good dispersion of GE, and efficient interfacial interaction between GE and NR matrix. This method provides the potential applications of functionalized GE in the polymer composites. POLYM. COMPOS., 36:1775–1785, 2015. © 2014 Society of Plastics Engineers

Tailoring Assembly of Reduced Graphene Oxide Nanosheets to Control Gas Barrier Properties of Natural Rubber Nanocomposites

Self-assembling of reduced graphene oxide platelets, as a tailored interconnected network within a natural rubber matrix, is proposed as a mean for obtaining nanocomposites with improved gas barrier, as compared to neat natural rubber. Interestingly, this nanocomposite structure results to be much more effective than homogeneous dispersion of graphene platelike particles, even at low graphene loadings. Such behavior is interpreted on the grounds of a theoretical model describing permeability of heterogeneous systems specifically accounting for self-segregated graphene morphology.

Effect of carbon nanotubes and graphene nanoplatelets on the dielectric and microwave properties of natural rubber composites

In this study, the effect of carbon nanotubes (CNT) and graphene nanoplatelets (GNP) at various weight ratios between them on the dielectric (dielectric permittivity, dielectric loss angle tangent) and microwave (reflection coefficient, attenuation coefficient, shielding effectiveness) properties of nanocomposites on the basis of natural rubber has been investigated in the wide frequency range (1–12 GHz). Some additional investigations on the morphology and microstructure of the graphene particles and CNT used have been carried out by transmission electron microscopy and selected area electron diffraction. The results achieved reveal how by using the selected combinations between CNT and GNP the microwave and dielectric properties of natural rubber nanocomposites can be tailored depending on the need for real practical application.

Mechanical Properties of Natural Rubber Nanocomposites Filled with Thermally Treated Attapulgite

Natural rubber (NR) nanocomposites were prepared in a double‐roller plasticator mixer with purified attapulgite (PAT) or modified attapulgite, which was treated at 450°C (PAT‐450) and 850°C (PAT‐850) for two hours. The structures of the pristine, purified, and modified attapulgite were characterized by FTIR, TEM, XRD, and BET. The results indicated that the structure of attapulgite changed with the increased temperature. The effects of the PAT treatment and content on the mechanical properties of the NR nanocomposites were also investigated. The results showed that AT increased curing process of natural rubber. A significant improvement in the tensile strength, wearability, and solvent resistance of the nanocomposites was observed with the addition of different types of attapulgite as compared to those of pure NR. Scanning electron microscope images showed that the filler was located at the interface, which induced compatibilization in the immiscible blends. Thermogravimetric analysis revealed a significant improvement in the thermal stability of the NR/PAT nanocomposites.

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.