Rubber-filler Interaction Research Articles

The Effect of Rubber-Metal Interactions on the Mechanical, Magneto-Mechanical, and Electrical Properties of Iron, Aluminum, and Hybrid Filler-Based Styrene-Butadiene Rubber Composites.

Multifunctional stretchable rubber composites are gaining attention due to their unique electrical, mechanical, and magnetic properties. However, their high production costs pose economic challenges. This study explores the use of cost-effective metal powders-iron, aluminum, and their 1:1 (vol/vol) hybrid filler-in styrene-butadiene rubber composites, varying from 10 to 20 vol%. The effects of these metal particles on the mechanical, electrical, morphological, and swelling properties were investigated. Metal particles generally act as non-reinforcing fillers but can significantly enhance the mechanical modulus, electrical, and magnetic properties based on the filler structure and the filler-rubber interactions. Iron-based composites exhibit significant electrical conductivity and excellent magnetic properties. Aluminum enhances the modulus, while the combination yields average mechanical properties with added magnetic characteristics. Iron demonstrates higher reactivity with sulfur-based crosslinking ingredients, adversely affecting the rubber matrix's crosslinks, as shown by swelling tests. This reactivity is attributed to iron's transition metal characteristics. At 20 vol%, iron-filled composites display the highest magnetic anisotropic effect on toughness (~25%) under a magnetic field by permanent magnets and excellent electrical conductivity (1.5 × 10-2 S/m). While iron significantly boosts the electrical and magnetic properties, higher filler amounts degrade the mechanical properties. These composites are currently suitable for electrical and smart mechanical applications, but incorporating reinforcing fillers could enhance their robustness for broader applications.

From Nanoscale to Macroscale Characterization of Sulfur-Modified Oxidized Carbon Nanotubes in Styrene Butadiene Rubber Compounds.

The homogeneous dispersion of carbon nanotubes (CNTs) in a rubber matrix is a key factor limiting their amazing potential. CNTs tend to agglomerate into bundles due to van der Waals interactions. To overcome this limitation, CNTs have been surface-modified with oxygen-bearing groups and sulfur. Using atomic force microscopy (AFM) techniques, a deep nanoscale characterization of the morphology, the degree of dispersion of the CNTs in the styrene butadiene rubber (SBR) matrix, and the thickness of the interfacial layer was carried out in this study. In this context, the results from nanoscale characterization showed that the thermal oxidation-sulfur treatment leads to a composite with better dispersion in the matrix, as well as a thicker interfacial layer, indicating a stronger filler-rubber interaction. The second part of this work focused on the macroscale results, such as the Payne effect, vulcanization curves, and mechanical properties. The Payne effect, vulcanization curves, and mechanical properties confirmed the lower reinforcing effect observed in the case of the chemical oxidation treatment because, on the one hand, this composite showed the highest agglomeration of CNTs after the acid treatment. On the other hand, the presence of acid residues provoked the absorption of basic accelerators on the surface of the CNTs.

Effects of Nanofillers and Synergistic Action of Carbon Black/Nanoclay Hybrid Fillers in Chlorobutyl Rubber

Nanocomposites based on chlorobutyl rubber (CIIR) have been made using a variety of nanofillers such as carbon black (CB), nanoclay (NC), graphene oxide (GO), and carbon black/nanoclay hybrid filler systems. The hybrid combinations of CB/nanoclay are being employed in the research to examine the additive impacts on the final characteristics of nanocomposites. Atomic force microscopy (AFM), together with resistivity values and mechanical property measurements, have been used to characterise the structural composition of CIIR-based nanocomposites. AFM results indicate that the addition of nanoclay into CIIR increased the surface roughness of the material, which made the material more adhesive. The study found a significant decrease in resistivity in CIIR–nanoclay-based composites and hybrid compositions with nanoclay and CB. The higher resistivity in CB composites, compared to CB/nanoclay, suggests that nanoclay enhances the conductive network of carbon black. However, GO-incorporated composites failed to create conductive networks, which this may have been due to the agglomeration. The study also found that the modulus values at 100%, 200%, and 300% elongation are the highest for clay and CB/clay systems. The findings show that nanocomposites, particularly clay and clay/CB hybrid nanocomposites, may produce polymer nanocomposites with high electrical conductivity. Mechanical properties correlated well with the reinforcement provided by nanoclay. Hybrid nanocomposites with clay/CB had increased mechanical properties because of their enhanced compatibility and higher filler–rubber interaction. Nano-dispersed clay helps prevent fracture growth and enhances mechanical properties even more so than CB.

Rubber/clay nanocomposites prepared by compounding clay gel with hydrophilically treated styrene-butadiene rubber

In this work, high-performance rubber/clay nanocomposites (NCs) were prepared by hydrophilic modification of styrene-butadiene rubber (SBR) in conjunction with gel compounding method. The hydrophilicity of SBR matrix increased by 76 % with the addition of hexadecyltrimethylammonium chloride (CTAC), which significantly enhanced the clay-rubber compatibility and processing efficiency. The vulcanization rate of the SBR/clay NC was increased by adding CTAC. The addition of CTAC greatly improved the clay dispersion and the rubber-filler interactions. With increasing the clay loading, the SBR/CTAC/clay NCs showed a gradual increase in stress at a certain strain, elongation at break, tensile strength and Shore A hardness, demonstrating an excellent reinforcing effect of the clay. The tensile strength of the SBR/CTAC/clay NC with 40 phr clay loading reached 14.0 MPa, which was 8.8 times that of the pure SBR and even better than the organoclay filled SBR NC.

Comparative Investigation of Nano-Sized Silica and Micrometer-Sized Calcium Carbonate on Structure and Properties of Natural Rubber Composites.

Fillers have been widely used in natural rubber (NR) products. They are introduced to serve as a strategy for modifying the final properties of NR vulcanizates. Silica and calcium carbonate (CaCO3) are among the fillers of choice when the color of the products is concerned. In this case, a special focus was to compare the vulcanizing efficiency of NR filled with two different filler types, namely nano-sized silica and micrometer-sized CaCO3. This study focused on the effects of the loading level (10-50 parts per hundred parts of rubber, phr) on the final properties and structural changes of NR composites. The results indicated that increased filler loading led to higher curing torques and stiffness of the rubber composites irrespective of the type of filler used. The better filler dispersion was achieved in composites filled with CaCO3 which is responsible for less polarity of CaCO3 compared to silica. Good filler distribution enhanced filler-matrix interactions, improving swelling resistance and total crosslink density, and delaying stress relaxation. The modulus and tensile strength of both composites also improved over the content of fillers. The CaCO3-filled composites reached their maximum tensile strength at 40 phr, exceeding, by roughly 88%, the strength of an unfilled sample. Conversely, the maximum tensile strength of silica-filled NR was at 20 phr and was only slightly higher than that of its unfilled counterpart. This discrepancy was ascribed to the stronger rubber-filler interactions in cases with CaCO3 filler. Effective rubber-filler interactions improved strain-induced crystallization, increasing crystallinity during stretching and reducing the strain at which crystallization begins. In contrast, large silica aggregates with poor dispersion reduced the overall crosslink density, and degraded the thermomechanical properties, tensile properties, and strain-induced crystallization ability of the NR. The results clearly indicate that CaCO3 should be favored over silica as a filler in the production of some rubber products where high performance was not the main characteristic.

Effects of Carbon Black Surface Modification on the Morphology and Properties in Blends with Natural Rubber Studied with High‐Resolution X‐Ray Computed Tomography

AbstractTo elucidate the specific mechanical impact of carbon black (CB) filler–rubber interactions on reinforcement, CB particles are subjected to graphitization at 1300 °C and oxidation through concentrated nitric acid treatment to modulate their surface activity. Alongside untreated CB particles, the influence of surface activity and the oxygen distribution are investigated to assess their role in shaping CB aggregate structures using X‐ray absorption spectrum (XAS) and X‐ray computed tomography (CT) with spatial resolution of 30 nm. Meanwhile, virgin and modified CBs are blended in natural rubber with varying amounts (10, 30, 50 phr) and the aggregates distributions in rubber are investigated by nano‐CT. Combined with the mechanical properties of rubber composites and parameters of filler networks, the mechanical contributions arising from filler–rubber interactions are quantified. The findings underscore the robust interactions between oxidized CB and rubber matrix, exhibiting a mechanical property enhancement ratio of ≈59.2% at low strains in comparison to normal CB filler. The results indicate the synergies encompass of filler network, rubber chains, and filler–rubber interactions all play important roles for reinforcement, which aligns with the broader understanding of filler–rubber interactions and CB reinforcement mechanisms.

New role of ionic liquid as accelerator activator in rubber compounds and its influence on curing and mechanical properties

AbstractThis study focuses on the effect of ionic liquids (ILs) on the cure characteristics and filler dispersion of natural rubber (NR) and styrene‐butadiene rubber (SBR) gum and filled compounds. The complexation of ionic liquid with zinc oxide (ZnO) increases the activity of ZnO and the cure rate together with improved filler dispersion. This has also increased the rubber filler interaction. Imidazolium and chloride based ionic liquids with different cationic groups were compared and characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, and differential scanning calorimetry to understand the thermal and chemical behavior of the compounds. Interestingly, it was found that the ionic liquid can act as an activator and is able to accelerate the vulcanization rate with improved rubber filler interaction. The complexes formed by IL‐Zn were shown to be much more reactive than Zn‐stearic acid complexes. The dispersion of carbon black in the NR and SBR compounds was studied by using Field Emission Scanning Electron Microscope and Transmission Electron Microscope and the results demonstrate that ILs could significantly improve the filler dispersion. Thus, this study has revealed the multifunctional role of ionic liquids in rubber compounds.Highlights This article describes the dual role of the ionic liquid (IL) in rubber compounds. It can act both as an accelerator‐activator as well as an efficient dispersing aid. The complexation of IL with zinc oxide (ZnO) plays a crucial role in enhancing the activity of ZnO. As a result, the physico‐mechanical properties of both natural rubber and styrene‐butadiene rubber based compounds are significantly improved.

Enhanced rheological properties of carbon nanotubes reinforced natural rubber/butadiene rubber nanocomposites

AbstractEffects of carbon nanotubes (CNTs) content and the in situ surface modification via bis(triethoxysilylpropyl) disulfide (Si75) and (3‐aminopropyl) triethoxysilane (KH550) on the rheological properties of rubber nanocomposites are explored. Results from the strain sweep demonstrate that the filler network of the nanocomposite is enhanced when the hydroxylated CNT (HCNT) is incorporated. The promotion of filler–rubber interaction in nanocomposite reinforced with modified CNT is validated by both stress relaxation and strain sweep measurements. The die swell ratio (B) declines with increasing HCNT content and rises with a heightened shear rate. Compared to those without HCNT, B of the nanocomposites, which contained 5 phr HCNT, decreased by 5.4%, 7.0%, and 17.3% at 50, 200, and 500 s−1, respectively. The Si75‐modified HCNT and the carboxylated CNT (CCNT) reduce the B‐value of the extrudates at 500 s−1 by 3.7% and 3.0%, respectively. However, the extrudates filled with KH550‐modified HCNT or CCNT showed a larger B due to pre‐crosslinking, as demonstrated by stress relaxation and swelling tests. Furthermore, it is also found that the application of KH550 has an acceleration effect on the curing reaction, increasing the curing efficiency by 8.5%.Highlights The promotion of filler–rubber interaction is validated by RPA. The dimensional stability of the composites is improved after incorporating CNT. The extrudates with Si75 exhibit a reduced B and improved surface morphology. CNT content increase raises MH, ML, and shortens the t10 of the composite.

Sustainable Composites: Analysis of Filler-Rubber Interaction in Natural Rubber-Styrene-Butadiene Rubber/Polyurethane Composites Using the Lorenz-Park Method and Scanning Electron Microscopy.

This study examined micronized polyurethane residues as a reinforcing filler in elastomeric composites made from natural rubber (NR) and styrene-butadiene rubber (SBR). Due to growing environmental concerns, this research aimed to find sustainable alternatives to synthetic materials. The results indicated that adding micronized polyurethane improved the mechanical properties of the composites, reinforcing the polymer matrix and increasing the cross-link density as a barrier against solvents. The composites met the requirements for industrial applications, though; at 40 phr of polyurethane filler, material deformation was reduced, indicating saturation. FTIR analysis confirmed the homogeneity of the materials without chemical reactions, while electron microscopy revealed an increase in the number of particles and irregularities with the filler. The composite with 10 phr showed a lower volume loss in abrasion resistance, meeting the standards for soles. The composite with 30 phr of polyurethane achieved the best results without the filler's saturation and met the footwear industry's requirements. The results show the potential for sustainable practices in industry using this elastomeric blend.

Influence of Processing Oil Content on Rubber-Filler Interactions in Silica/Carbon Black-Filled Natural Rubber Compounding

To ensure the production of high-quality rubber products, establishing effective compatibility and robusting interactions between rubber and fillers is crucial. Since the rubber production industry faces significant environmental challenges, sustainability is becoming a necessity in the rubber business. Various materials, such as the presence of processing aids, might influence rubber-filler and filler-filler interactions. Petroleum oil as general processing oil has environmental issues, thus it is urgent to replace it with bio-based oil. This study addresses these concerns by investigating the impact of paraffinic oil and bio-based oil content on the interactions between silica/carbon black and natural rubber chains. Ranging from 0 to 10 phr, different dosages of these oils were employed. The rubber compound underwent milling using two rolled laboratory open mills post-blending with a laboratory internal mixer. Subsequently, mechanical properties were assessed. A Rubber Processing Analyzer was utilized to characterize interactions between uncured and cured silica/carbon black-filled natural rubber blends. The results revealed that all variations were distributed uniformly. Tan Delta results confirm that a chemical with a high bio-based oil concentration is easier to process. The carbon black with the largest peak of modulus values at low strain has the highest reinforcing or the poorest dispersion. Compounding with paraffinic oil has a high peak modulus value, resulting in poor dispersion when compared to bio-based oil. This research sheds light on the potential of bio-based oils as an eco-friendly alternative in rubber processing, contributing to sustainability efforts in the industry.

Renewable Compatibilizing Agent for Silica Reinforced Natural Rubber

The main problem in utilizing silica as an alternative reinforcing filler for natural rubber (NR) compounds is a weak rubber-filler interaction and poor filler distribution due to their incompatibility feature. The particles of silica have a strong tendency to filler interactions which leads to form silica agglomeration. To solve this drawback, this work has utilized ethanolamine-modified palm stearin (EMPS) as a renewable compatibilizer agent to improve NR-silica compatibility. The EMPS was prepared by a typical chemical reaction between ethanolamine and refined bleach-deodorized palm stearin (a byproduct of cooking oil production) on a laboratory scale. The influence of the EMPS on the improvement of rubber-filler interaction was investigated by studying the processing characteristics and the tensile properties of silica-reinforced NR compound (silica content was fixed at 30 phr). Compared to the silica-reinforced NR with no EMPS, it was found that EMPS caused a greater coefficient of vulcanization, tensile strength, and reinforcement effect for the silica-reinforced NR. It was due to an active reaction between silanol groups of silica with EMPS which increased the NR-silica compatibility, and the Fourier Transform Infra-Red (FTIR) analysis has confirmed the typical reaction.

Effect of functionality and loading procedure of liquid butadiene rubber on properties of silica-filled tire tread compounds

This study explores the utilization of liquid butadiene rubber (LqBR) as a processing aid in tire tread compounds, as a replacement for treated distillate aromatic extract (TDAE) oil, which is known to contribute to the extraction of organic materials during tire aging. Additionally, the influence of the silane-terminated functional group in LqBR and the procedure of LqBR addition are investigated. The results demonstrate a significant reduction in organic extraction when employing silane-terminated LqBR as a processing aid. Moreover, the performance of tire tread compounds is comparable or even superior to those incorporating TDAE oil, particularly when 80 % silane-terminated LqBR is added after the mixing of silica and coupling agent. The enhanced performance is attributed to homogeneous silica dispersion and robust filler-rubber interaction. These findings offer valuable insights into the optimization procedure for developing tire tread compounds utilizing functionalized LqBR as a processing aid, with the aim of improving tire tread applications.

Dual modification of natural rubber/halloysite nanotubes composites by silane and maleated natural rubber

As the performance of natural rubber (NR) and halloysite nanotube (HNT) composites is uncertain due to low compatibility between the materials, malleated natural rubber (MNR) is then used as a compatibilizer to encourage filler–rubber compatibility. However, the properties of these composites remain unsatisfactory, and the treatment of HNT requires further improvement. Therefore, this study introduced acid treatment and silane coupling agents to increase the interactions between NR and HNT. Besides, this study also introduced the methods of compounding the rubber composites, either with single-stage or two-stage treatments. The application of a two-stage treatment to acid-treated HNT has given tensile strength a 26.5% improvement. Two-stage treatment enabled better silanization, while acid-treated HNT provided effective silanols for such interactions. The use of silane with acid-treated HNT was found to enhance the tensile strength, modulus, and tear strength of the composites, which was clearly due to better filler–rubber interactions. The Payne effect, which decreased up to 64.03% after applying a two-stage treatment, served as further confirmation of better filler–rrubber interactions. This conclusively proved that modifying both the rubber matrix and HNT enhances the performance of NR/HNT composites.

Use of vegetable oils as an alternate to naphthenic oil for extension of emulsion styrene butadiene rubber

Various petroleum based mineral oils like Distillate Aromatic Extract (DAE), Treated Distillate Aromatic Extract (TDAE), Residual Aromatic Extract (RAE) and Naphthenic oils are used for extension of emulsion polymerized Styrene Butadiene Rubber (E-SBR). Vegetable oils are alternate to these petroleum oil from sustainability point of view as vegetable oils have no Polycyclic Aromatic (PCA) content. They improve abrasion resistance leads to less rubber particulates spread in the environment and reduce rolling resistance leads to lower fuel consumption. However, introduction of few vegetable oils leads to slow down the cure reaction due to high unsaturation to saturation ratio. Presence of high fatty acid content in vegetable oils help in better rubber-filler interaction. In the present research, vegetable origin oils as such without any modification (Decas, Palmolein, Groundnut, Soybean, Mustard and Coconut) extended Styrene Butadiene Rubber (OE-SBR) were characterized in standard American Society for Testing and Materials (ASTM) compound recipe for various processing, different vulcanizate and other performance properties. Curative’s dosages were adjusted in the recipe of vegetable oil extended SBR’s to achieve the 300% modulus value like naphthenic oil. Vegetable oil extended Emulsion Styrene Butadiene Rubber (E-SBR) grades (Prepared with Palmolein and Coconut oils) were showing comparable rheometric and stress-strain properties, high reinforcement index (around 5%), better rubber-filler interaction parameter (around 12%), better abrasion resistance (around 23%) and comparable tanδ value @0°, 30° and 60°C as compared to naphthenic oil extended SBR based compound.

Enhanced fatigue resistance of plasma modified pyrolysis carbon black filled natural rubber composites

Owning to the requirement of cost reduction and environmental protection, the application of pyrolysis carbon black (CBp) in dynamic rubber products becomes a hot topic in recent years. However, the fatigue resistance of CBp filled rubber composite is poor. Therefore, the evolution of micro- mesoscopic structure in modified CBp filled natural rubber (NR) composites during the tensile fatigue process is investigated to find the influencing factor for enhancing the fatigue resistance in this study. Results indicate that the particle/aggregate size distribution turns to be narrower after the aggregate size filtering treatment while a decreased particle/aggregate size and an improved polarity can be observed after argon plasma treatment. As a result, the average fatigue life of NR composites filled with CBp treated by air classifier, plasma modification and their combination are increased by 21%, 57% and 107%, respectively. It is found that the filler dispersion and the filler-polymer interaction deteriorate during the fatigue process. This evolution is inhibited by filler modification. Besides, the fatigue lives of filled rubber show a correspondence to their total and physical cross-linking densities as well as the bound rubber contents. The filler-polymer interaction can be proposed as an important factor in extending the fatigue life of rubber composites. These findings provide not only a promotion on the application value of CBp in fatigue resistance of rubber composite by different modification methods, but also an innovative perspective for exploring the fatigue resistance of rubber material from the aspects of filler-rubber interaction, and a scientific guidance for the development of long-life dynamic rubber products.

Introducing "MEW2" Software: A Tool to Analyze MQ-NMR Experiments for Elastomers.

Low-field time-domain proton Nuclear Magnetic Resonance (NMR) spectroscopy is an attractive and powerful tool for studying the structure and dynamics of elastomers. The existence of crosslinks and other topological constraints in rubber matrices (entanglements and filler-rubber interactions, among others) renders the fast segmental fluctuations of the polymeric chains non-isotropic, obtaining nonzero residual dipolar couplings, which is the main observable of MQ-NMR experiments. A new software, Multiple quantum nuclear magnetic resonance analyzer for Elastomeric Networks v2 (MEW2), provides a new tool to facilitate the study of the molecular structure of elastomeric materials. This program quantitatively analyzes two different sets of experimental data obtained in the same experiment, which are dominated by multiple-quantum coherence and polymer dynamics. The proper quantification of non-coupled network defects (dangling chain ends, loops, etc.) allows the analyzer to normalize the multiple quantum intensity, obtaining a build-up curve that contains the structural information without any influence from the rubber dynamics. Finally, it provides the spatial distribution of crosslinks using a fast Tikhonov regularization process based on a statistical criterion. As a general trend, this study provides an automatic solution to a tedious procedure of analysis, demonstrating a new tool that accelerates the calculations of network structure using 1H MQ-NMR low-field time-domain experiments for elastomeric compounds.

Synthesis of sonochemical chloroacetated natural rubber and its potential use in passenger car tire tread

This article describes the preparation of chloroacetated natural rubber (CNR) through the epoxidation of natural rubber (NR) latex with performic acid, followed by the reaction with chloroacetic acid. Ultrasound waves were utilized to accelerate the epoxidation reaction. The CNR samples obtained at various epoxidation durations were analyzed by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, and differential scanning calorimetry techniques. Results showed that the chloroacetate content in CNR increased with increasing epoxidation time, i.e., the chloroacetate contents were 17.4, 18.5, and 19.7% at epoxidation times of 30, 45, and 60 min, respectively. The prepared CNR samples were then employed to replace NR in silica-filled tire tread compounds based on a 70/30 solution styrene butadiene rubber (SSBR)/NR blend. It was found that, compared with NR, CNR provided significantly higher rubber-silica interaction, leading to improved mechanical and dynamic properties. Such replacement not only reduced heat build-up and rolling resistance, but also increased the wet grip index, which is highly beneficial for the production of high-performance passenger car tires. It could be observed that the improvements in rubber properties and tread performance were more obvious when the chloroacetate content of CNR was increased, probably due to the enhanced rubber-filler interaction, as demonstrated by the increased bound rubber content.

Vegetable oil extended emulsion styrene butadiene rubbers for passenger car radial tire tread application

Currently emulsion polymerized Styrene Butadiene Rubber (E-SBR) is extended with various petroleum based mineral oils like Distillate Aromatic Extract (DAE), Treated Distillate Aromatic Extract (TDAE), Residual Aromatic Extract (RAE) and Naphthenic oils. It is obvious that introduction of vegetable oil should result in almost zero Polycyclic Aromatic Content (PCA) content and therefore, are environmentally friendly, renewable, and sustainable. In the present work, vegetable oil extended Styrene Butadiene Rubber (OE-SBR) were characterized for chemical properties and found that all the properties were meeting the specification requirements of mineral oils extended grades. These rubbers were also evaluated in standard Passenger Car Radial (PCR) tire tread compound recipe for various processing, different vulcanizate and other performance properties. The developed grades with vegetable oils required less mixing energy (around 10% for master batch and 15% for final batch) and shown better flow behavior (around 15% power law index and 20% activation energy reduction), better carbon dispersion (around 20%), high reinforcement index (around 15%), better rubber-filler interaction parameter (around 20%), better abrasion resistance (around 20%) and lower tanδ value @60°C (around 15%) as compared to TDAE oil extended SBR based compound. This may help to improve life of a PCR tire and reduction in fuel consumption of the vehicle.

Enhancing tire tread performance with combined nano and micro-silica particles in styrene butadiene rubber/butadiene rubber compound

The influence of fumed nano-SiO2 on the performance of a typical tire tread compound, fabricated by mechanical mixing process, was investigated in the present research. The tire tread compound contained styrene-butadiene rubber (SBR)/ cis-butadiene rubber (BR) blend reinforced with a well-developed commercial highly dispersive silica filler at 70 phr loading. Nano-SiO2 with higher specific surface area, e.g., ∼240 m2/g, was substituted partially with silica particle at three different concentrations of 5, 10, 15 phr. Improvement in various aspects of the control sample including crosslink density calculated based on the swelling test and tube theory, bound rubber content, and physico-mechanical properties was observed for nano-SiO2 loading below 10 phr due to its effective role in refinement of filler dispersion state and enhancement of rubber-filler interactions. However, most of the properties were sacrificed at 15 phr nano-SiO2 loading even with respect to the control sample which emphasized the effectiveness of nano-SiO2 within an optimum loading. Moreover, nano-SiO2 at optimum loading exhibited great improvement in initial decomposition temperature about 50°C, considerable improvement in rolling resistance (more than 8%) and enhancement in wear resistance which could be crucial for tire tread manufacturers.

Development of exfoliated mica waste/natural rubber composites by latex stage mixing

ABSTRACT Raw mica powder may not show better physico-mechanical properties in rubber owing to its large particle sizes and low degree of surface activeness. Here, mica waste; a green filler was modified by partially exfoliating before incorporating it into natural rubber (NR). The latex stage mixing was conducted to incorporate different loadings of exfoliated mica waste (eWM). The incorporation of eWM had no significant effect on cure and scorch time. The reduction of viscosities indicated better processability of the compounds. The overall improvement of moduli, tensile, abrasion resistance, and cross-link densities supported by SEM and TGA data suggested improved rubber–filler interactions.