Properties Of Rubber Composites Research Articles

Utilization of spent graphite from lithium-ion batteries waste as sustainable reinforcing filler for thermal, vibration-damping, and noise control applications

This study explores the practical application of using spent graphite (SG) derived from lithium-ion battery waste as a sustainable reinforcing filler for fabricating rubber composites. Two types of rubber, natural rubber (NR) and butyl rubber (BR), were employed as matrices, and eight composites were fabricated by increasing SG loadings [0, 10, 20, and 30 parts per hundred rubber (phr)]. The effects of these SG loadings on the composites' morphological, physical, thermal, wettability, mechanical, dynamic mechanical, vibration-damping, and acoustic properties were thoroughly investigated. The findings demonstrate significant improvements with increasing SG loading, particularly in the BR/SG30 composite. By reinforcing 30 phr of SG into the BR matrix, the density, hardness, thermal degradation, and sound-insulating properties improved by approximately 3.50%, 15.64%, 6.05%, and 5%, respectively, compared to the NR/SG0 composite. The damping ratio (ξ) of MSBB + BR/SG30 was approximately 18.04 at the second vibration mode, and the overall sound power level of MSBB was reduced by about 12.20 dB(A) when the BR/SG30 composite layer was applied, highlighting its potential for real-world vibration and noise control applications. These results underscore the significant role of SG as a sustainable reinforcing filler in enhancing the properties of rubber composites, particularly in the BR matrix, making it a promising option for applications requiring effective vibration and noise control. This research opens new possibilities for using SG in various engineering applications, inspiring further exploration and innovation.

Learning based model for predicting mechanical properties and sustainable filler band for NBR composites using lignin and carbon black

Experimental determination of mechanical properties of rubber composites, such as tensile strength and hardness, involves complex multistage preparation procedures that are laborious and expensive. In this study, a hybrid filler of carbon black (CB) along with a sustainable filler of lignin is added for reinforcement in the nitrile butadiene rubber (NBR) matrix, with the total filler content varying from 10 parts per hundred rubber (phr) to 80 phr. This work aims to develop a data-driven predictive model for the mechanical properties of rubber composites. An artificial neural network (ANN) model using multilayer feed-forward back-propagation has been created to forecast the tensile strength (Ts) and hardness (Hd) of rubber composites. The model predicts the uniaxial tensile response and hardness using input parameters that include total filler and lignin loading levels. The effectiveness of the suggested prediction method was demonstrated by statistical analysis using confidence intervals, showing a prediction error between 5.47% and 3.23% for the Ts and between 3.03% and 1.85% for Hd at 95% confidence intervals. A sustainable green band could be defined in the developed model, which is handy for designers to replace CB with lignin in various NBR based products, such as hoses, seals, etc., without compromising on tensile strength and hardness.

Preparation and characterization of lignin copolymerized phenolic resins with superior stiffening effect for natural rubber composites

The development of lignin-derived functional additives for rubber composites has gained growing importance in light of biomass valorization. This work aims at preparing phenolic novolak resin with lignin as one building block for reinforcing natural rubber. A one-pot two-step synthetic approach involving phenolation and copolymerization was developed to prepare lignin-phenol-formaldehyde resins (LPF), wherein 30 wt% of phenol was substituted by lignin. With increasing the ratio of formaldehyde/phenol functionality (F/P), resins show increased molecular weight, elevated glass transition temperature and declined curing activity. The resin with F/P of 0.68/1 exhibits a higher stiffening effect compared to the control without lignin. This enhancement is attributed to lignin's ability to form a hyperbranched structure with multiple phenolic arms as implied by GPC results, acting as a crosslinking hub and facilitating the formation of an effective network. Furthermore, we introduced cardanol with a flexible alkene chain to prepare cardanol-lignin-phenol-formaldehyde resins (CLPF). The CLPF15 resin with cardanol/lignin/phenol of 15/30/55 wt% achieves the maximum stiffening effect due to improved compatibility with natural rubber. This study provides insights into the design and optimization of lignin-copolymerized resins for enhancing the mechanical properties of rubber composites.

Influence of carbon black surface characteristics on CB-NR interfacial interaction: Molecular simulation and experimental study

Carbon black (CB) is the most widely used reinforcing filler in rubber industry, but the effects of CB surface characteristics on interfacial interaction of CB-filled rubber composites are still not fully described. Combined the experimental and molecular simulation techniques, the aim of this study is to individually investigate the influence of various CB surface characteristics, such as surface area, surface crystallite size, roughness and surface energy, on CB-natural rubber (NR) interfacial interaction to obtain a deep interpretation on the properties of rubber composites. Experimental results showed that the specific surface area is the primary factor affecting overall CB-NR interaction, followed by filler network. Meanwhile, CB surface model with different roughness based on experimental parameters were constructed, and the simulation results revealed that CB-NR interfacial interaction mainly occurred at the interface 2–3 nm. The binding energy distribution on CB surface was analyzed, and rough region is weaker than crystal region and amorphous region. The strongest binding sites are located at the junction of rough region and amorphous region. The results in this study are expected to provide a theoretic guide for optimizing the CB characteristics and developing new rubber-grade CB.

High Barrier Properties of Butyl Rubber Composites Containing Liquid Rubber and Graphene Oxide.

The high elasticity and excellent gas barrier properties of rubber composites make them irreplaceable in the field of sealing. Constructing a complicated barrier network to reduce free volume is crucial to improving gas barrier properties. In this research, liquid acrylonitrile-butadiene rubber/γ-Methacryloxypropyl trimethoxy silane (KH570) modified graphene oxide/butyl rubber composites (LNBR/KGO/IIR) were fabricated. A KGO lamellar network was constructed to resist gas diffusion in the IIR matrix. Meanwhile, LNBR macromolecules further occupied the free volume inside the IIR composites, thereby maximizing the retardation of the path of small molecule gas permeation. The modification of GO by KH570 was successfully demonstrated through FTIR and XRD. The grafting rate of KH570 was calculated to be approximately 71.4%. KGO was well dispersed in IIR due to emulsion compounding and the formation of lamellar networks. The 300% modulus, tensile strength and tear strength of KGO/IIR were improved by 43.5%, 39.1% and 14.8%, respectively, compared to those of the IIR composite. In addition, the introduction of LNBR resulted in a 44.2% improvement in the gas barrier performance of nitrogen permeability relative to the original IIR composite.

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.

The Electrical Conductivity, EMI Absorption Shielding Performance, Curing Process, and Mechanical Properties of Rubber Composites.

Three types of composites were tested for electromagnetic interference (EMI) absorption shielding effectiveness, the curing process, and their physical-mechanical properties. For the first type of composites, nickel-zinc ferrite, manganese-zinc ferrite, and both fillers in their mutual combinations were incorporated into acrylonitrile-butadiene rubber. The overall content of the filler, or fillers, was kept at 200 phr. Then, carbon black or carbon fibers were incorporated into each rubber formulation at a constant loading of-25 phr, while the content of magnetic fillers was unchanged, at -200 phr. This work focused on the understanding of correlations between the electromagnetic shielding parameters and electrical conductivity of composites in relation to their EMI absorption shielding effectiveness. The absorption shielding abilities of materials were evaluated within a frequency bandwidth from 1 MHz to 6 GHz. This study revealed good correlation among permittivity, conductivity, and EMI absorption effectiveness. Although the absorption shielding efficiency of composites filled only with ferrites seems to be the highest, the absorption maxima of those composites reached over 6 GHz. The application of carbon-based fillers resulted in the higher electrical conductivity and higher permittivity of composites, which was reflected in their lower absorption shielding performance. However, the composites filled with ferrites and carbon-based fillers absorbed electromagnetic radiation within the desired frequency range. The presence of carbon-based fillers caused improvement in the tensile behavior of composites. This study also demonstrated that the higher the ratio of nickel-zinc ferrite in combined magnetic fillers, the better the absorption shielding efficiency.

Influence of environmental conditions on the degradation of rubber compounds

Rubber compounds are complex, chemically active and viscoelastic materials. In this material type, transient and transient changes in the individual rubber properties occur during the manufacturing processes. A large number of rubber compounds consist of a large number of elastomers and virtually all of them are made up of fillers such as (carbon black, silica, kaolin, calcium carbonate, etc.). A very important element of which rubber compounds are composed is sulphur. Its important function is to ensure the cross-linking process during vulcanisation. Lubricants, plasticizers and various organic substances used to modify the properties are also essential components of rubber compounds. The aim of this work is to assess the influence of natural environmental conditions (temperature, time, humidity, microorganisms, UV radiation) on the modification of the properties of rubber composites.

Study on micromolecular mechanical properties of C-atom reinforced SBR polymer composites

A three-layer microscopic model with Fe atoms as the top and bottom layer and SBR polymer composites as the middle layer and SBR polymer composite was established and studied. By adding C atoms as reinforcement, the stability and elastic modulus and frictional coefficient changes of SBR polymer composites before and after adding C atoms were studied. In this study, the molecular dynamics method was used to change of elastic modulus was observed by stretching, compression and shear of the SBR polymer composite; The simulation shows that after adding C atom the elastic modulus of SBR polymer composite increased, the friction coefficient of polymer composite upper and lower decreases and the relative atomsic concentration, temperature, velocity, overall temperature average, kinetic energy, total energy and MSD in the thickness direction are reduced after adding C atoms. The stability of SBR polymer composites is enhanced, and the deformation under shear is weakened. In addition, it is found that the binding energy between SBR polymer composites and Fe atoms is reduced after adding C atoms.The stability of SBR polymer composites is improved during use. This work provides a method for studying the properties of rubber composites by studying the enhancement of the stability of SBR polymer composites from the microscopic point of view.

The Effect of Silica Filler Source on the Mechanical Properties of Composite Rubber

Rubber composite is a high molecular weight polymer, produced from natural or synthetic rubber with sulfur as its common crosslinking agent. To improve the mechanical properties of rubber, filler with high silica content was usually added. Hence in this experiment, due to their high silica content, Risk husk ash (RHA), along with chemizil and zeosil were used as the composite filler. Sulfur was chosen as the crosslinking agent of a rubber mixture that consists of polyisoprene rubber (IR), acrylonitrile butadiene rubber (KNB), and polybutadiene rubber (BR). The composition of the other component was fixed at Per Hundred Rubber (PHR) of 51.43. During mixing, the temperature and mixing time were kept constant at 60-70oC and 6 minutes. The properties of rubber composite were characterized based on their physical and mechanical properties. Based on the rheological test, RHA has a faster vulcanization time compared to chemisil and zeosil. Improvement of the mechanical properties of the RHA rubber mixture was also observed, with 300% modulus, elongation, and tear at 42 kg/cm2, 867%, and 51 kg/cm2. Meanwhile, insignificance differences in tensile strength, hardness, and specific gravity of RHA compared to chemisil and zeosil, were observed.

Electromagnetic absorption shielding effectiveness and physical‐mechanical properties of rubber composites

AbstractManganese‐zinc ferrite, nickel‐zinc ferrite, and the combinations of both ferrites in constant level 200 phr were incorporated into acrylonitrile‐butadiene rubber. The amount of carbon black was constant in each composite −25 phr. The second series of composites was fabricated with similar composition, but the total content of ferrites or ferrites combinations was 300 phr, while the content of carbon black was 25 phr. The work was focused on investigation of electromagnetic absorption shielding effectiveness of composites and their physical‐mechanical properties. During the study, good correlation between conductivity, permittivity, and electromagnetic absorption parameters was established. Higher conductivity was reflected in higher permittivity of composites, which subsequently resulted in their lower absorption shielding performance. The experimental outputs revealed that absorption shielding effectiveness was enhanced with increasing with proportion of nickel‐zinc ferrite, which pointed out to higher absorption shielding potential of nickel‐zinc ferrite. The physical‐mechanical properties were found not to be influenced by the type of ferrite or ferrites combinations. The higher overall content of ferrites in rubber matrix caused the decrease in tensile characteristics of composites, suggesting that ferrites are inactive fillers considering the physical‐mechanical properties.

Performance of thermally conductive NR composites reinforced with stearic acid‐modified microcrystalline cellulose: A combined experimental and molecular dynamic simulation study

AbstractWith the increasing environmental requirements for improving products and materials using renewable and sustainable resources, cellulose has been seen as one of the most attractive and promising alternatives to traditional inorganic fillers. We developed a new modification method to improve the interface compatibility between natural rubber and sisal cellulose, to improve the mechanical and thermal conductivity properties of rubber composite. Microcrystalline cellulose (MCC) was extracted from sisal cellulose and then the hydrophobic cellulose (SA‐MCC) was prepared by grafting stearic acid on the surface of MCC. MCC and SA‐MCC were added to the thermal conductivity composite material composed of natural rubber and boron nitride. The results showed that the thermal conductivity and tensile properties of the natural rubber composites increased by 17.3% and 20%, respectively, under the addition of 1.8 wt% SA‐MCC. Furthermore, the interfacial interaction between the components in the composite was studied by molecular dynamics simulation. The solubility parameters, free volume fraction, and molecular binding energy were calculated to verify the effectiveness of the modification. This work is expected to provide a theoretical basis for the design and preparation of high‐performance natural rubber composite materials.Highlights Cellulose microcrystals were successfully extracted from sisal fiber and modified. Through the combination of boron nitride and the modified cellulose microcrystals, the thermal conductivity and tensile properties of thermal rubber were successfully improved synchronously. A reasonable molecular simulation model was established to analysis the strengthening mechanism from the microscopic point of view. The molecular simulation conclusions on interface enhancement are in good agreement with the experimental properties.

Effect of surfactants on the properties of rubber composites prepared from pyrolytic carbon black/natural latex via wet blending method

Pyrolytic carbon black (CBp) is the main by-product of waste tire pyrolysis. CBp has high ash content and poor surface activity which leads to the composites reinforced with CBp has lower performance than composites reinforced with commercial carbon black, making it difficult to meet the requirements of tire. In order to realize the application of CBp in tires, the effect of surfactants on the properties of rubber composites prepared by wet mixing of CBp/natural latex was investigated. In the experimental process, sodium stearate (C17H35COONa), sodium dodecylbenzene sulfonate (C18H29NaO3S), and sodium p-styrenesulfonate (C8H7NaO3S) were used to improve the surface activity and uniform dispersion of the CBp in the natural rubber matrix. The experimental results showed that the dispersity of C18H29NaO3S and C8H7NaO3S modified CBp in rubber matrix has [X] and [Y] values of 7.5 and 7.9, and 9.3 and 9.5, respectively, and the dispersion of these rubber composites is significantly better than that of C17H35COONa. The rubber composites prepared by C18H29NaO3S and C8H7NaO3S surfactants has the better physical and mechanical properties. The rubber composite prepared by C18H29NaO3S has the highest tensile strength of 25.63 MPa, which increment in tensile strength is 15.6% compare to the rubber composite prepared by C17H35COONa. Meanwhile the dynamic mechanical properties of rubber composites prepared by modifying CBp with C18H29NaO3S and C8H7NaO3S are better than CBp with C17H35COONa. The C8H7NaO3S modified CBp/rubber composite has the lowest loss factor (tanδ) value at 60°C, and the C18H29NaO3S modified CBp/rubber composite has the highest tanδ value at 0°C.

Effect of low‐temperature plasma modified pyrolysis carbon black on the properties of rubber composites prepared by wet process

AbstractPyrolysis carbon black is the pyrolysis product of waste tires. The high‐value utilization of pyrolysis carbon black can reduce black pollution of the environment, achieve sustainable development, and solve the problem of energy supply and consumption in the world. This paper mainly studies the modification and excitation of low‐temperature plasma on pyrolysis carbon black. It proposes a micro flocculation wet process (DMLI process) for preparing master rubber by wet mixing. Combined with DMLI process, the vulcanization performance, physical and mechanical properties, Payne effect, and dynamic mechanical properties were also analyzed and characterized. The results showed that the properties of the rubber compound prepared by low‐temperature plasma modification of pyrolytic carbon black were significantly improved. The modified pyrolytic carbon black had the characteristics of less ash, higher activity, and stronger affinity with rubber, and the wettability was significantly improved. In wet mixing, the new DMLI process can effectively improve the degree of combination and dispersion of carbon black and natural rubber latex. Therefore, the modified pyrolytic carbon black can completely replace the industrial carbon black N330, thereby preparing high‐performance rubber composites, realizing the high‐value utilization of pyrolytic carbon black and sustainable green development.

Enhancing silica dispersion and interfacial interaction in styrene butadiene/silica rubber composites by using epoxidized styrene butadiene rubber as interfacial compatibilizer

AbstractIt is usually desired but often challenging to improve the wet traction, and reduce the abrasion and rolling resistance simultaneously in tread rubber, which is referred to as “magic triangle” in tire industry. To fulfill this goal, the filler dispersion and interfacial interaction required to be improved, as they are two essential factors to concurrently govern the ultimate properties of rubber composites. Herein, we synthesized the epoxidized solution polymerized styrene butadiene rubber (ESSBR) with different epoxy level, and used them as interfacial compatibilizer to promote the silica dispersion and silica/rubber interfacial interaction. The epoxy of ESSBR would react with silanol on silica surface and co‐crosslink with SSBR simultaneously, therefore build a strong bridge between rubber matrix and filler. By incorporation of 20 phr of ESSBR‐15% (15% of double bonds on main chain was epoxidized), the wet grip was improved by 40%, and DIN abrasion and rolling resistance were reduced by 38% and 21%, respectively with hardly sacrifice the mechanical properties. We envisage that this study provides an approach for the fabrication of rubber composites with improved silica dispersion and strengthened interfacial interaction.

The influence of crystalline component with varied chain sequence structure and crystallinity on properties of NR based nanocomposites

The influences of polymer network structures on the properties of natural rubber (NR) based products were investigated in this work through blending NR with trans-1,4-poly(butadiene-co-isoprene) (TBIR) copolymers with varied crystallinity. Series of TBIR copolymers with varied chain sequence structure and crystallinity were synthesized. Blending 10 phr TBIR-1 (crystallinity 9.4%) with NR, the vulcanized NR/TBIR-1 composite presented the highest fatigue resistance, reduced rolling resistance and abrasion, reduced tear strength when compared with NR composite. While NR/TBIR-3 (crystallinity 4.1%) vulcanizate presented satisfied dynamic properties, like much lower rolling resistance and abrasion, excellent fatigue resistance and tear strength. The chain sequence structures of TBIR had significant effects on the dynamic properties of NR composites by constructing polymer ternary-network structures. This work is dedicated to understand the key parameters determining the dynamic properties of rubber composites and proposed the ideal polymer network structure for high performance rubber composites.

Correlating surface topography of relaxed layer of ZA/ZrB2 in situ composites to wear and friction

In the present study, the correlation between the surface topography of relaxed layer and wear and friction has been investigated. For this purpose, the lubricating tribology and surface topography of insitu formed ZrB2 reinforced Zn-Al (ZA) composites have been studied. The wear and friction properties of composites have been evaluated on a pin-on-disc tribometer under synthetic SAE20W40 motor oil. The worn surface has been studied by SEM, AFM, and profilometer. Results indicate high wear resistance and low COF with smoother topography with ZrB2 reinforcement. The composite with 9 vol. % ZrB2 exhibits lower kurtosis and negative skewness values confirming the smoother topography with higher load-carrying capacity. This composite exhibits little wear and COF even at higher loads and sliding distances in the presence of lubricant. A comparative study with existing tribological materials indicates that the present materials have huge potential to be used as bearings and bushings.

Preparation and performance of natural rubber latex treatment for silica filled natural rubber composites

AbstractNatural rubber latex filled with silica can be used to prepare low‐cost green tires with low rolling resistance. However, low mixing efficiency and reduction of properties have become the major difficulty in the industry, because there are many polar groups on the surface of silica, and it is difficult to produce a strong interaction with a nonpolar rubber. In this paper, natural rubber latex masterbatch with silica was prepared, and easily mixed with natural rubber (NR) to obtain NR/silica composites. The silica after NRL treated in the rubber matrix characterized with well dispersion, good compatibility with rubber, and composites had weaker Payne effect and higher wet‐skid resistance. Meanwhile, the 100% and 300% tensile modulus increased by 8.5% and 14.47%, respectively, notably decreasing heat build‐up by 41.88%, compared to the composite prepared by dry mixing technology. Overall, both the dispersion and interfacial adhesion of silica in the rubber matrix have a significant synergistic effect on the properties of rubber composites. The strategy of preparing NR/silica composites provides new research avenues for the preparation of green tires and other rubber industries in the future.

Microstructure and frictional properties of copper-tin composites containing graphite and MoS2 by rapid hot-press sintering

Rapid hot-press sintering was employed to prepare the self-lubricating composites using Cu-Sn alloy, Cu-coated graphite, and Cu-coated MoS2 powder as raw materials. The effects of the sintering temperature on the microstructure, interfacial characteristics, and friction properties of the composites were primarily examined. The findings demonstrated that as the sintering temperature rose from 680 °C to 780 °C, the copper alloy matrix's grain size grew. The composites' density and hardness increased and subsequently declined as the sintering temperature rose. Moreover, the interfacial bonding between the copper-coating lubricant and the copper alloy matrix was improved by raising the sintering temperature. The average friction coefficient of the composite grew and then fell as the sintering temperature rose, and the wear initially increased, then decreased, and then increased again. The copper-tin composite had good frictional properties because a composite lubricating film made of graphite, MoS2, and metal oxides formed on the worn surface. Among them, the comprehensive friction performance was best at the sintering temperature of 760 °C, with an average friction coefficient of 0.11 and a wear rate of 2.332 × 10−6 mm3N−1·m−1. The wear mechanism was the combined coupling effect of abrasive wear, adhesive wear and oxidative wear.

Rheometeric, ultrasonic and acoustical shielding properties of Cu-alloy/silicone rubber composites for electronic applications

Silicone rubber (SR) is a highly adaptable material that is attractive for a variety of applications, including electronics, construction, and aerospace. In general, adding Cu-Al-Zn alloy to the SR matrix improved the mechanical properties of rubber composites and noise attenuation. The mechanical, magnetic, ultrasonic, and acoustic characteristics of the resulting SR-composites were characterized. According to variations in treated Cu-alloy loading, ultrasonic measurements were performed as the ultrasonic velocities, Poisson’s ratio, Young’s modulus, acoustic impedance, ultrasonic attenuation coefficient, and micro-hardness. Results indicated that adding treated Cu-alloy to SR-composites improves them significantly. They showed that curing time decreases gradually, tensile strength increases constantly and elongation at break of SR-composites has maximum value at 15% treated Cu-alloy. The coupling agent 3-(Trimethoxysilyl) propyl methacrylate (TMSPM) improves the mechanical properties of the composites by forming a network structure in the SR matrix and enhancing the interfacial interaction between the Cu-alloy and the SR matrix. The acoustic sound absorption coefficient, reflection coefficient, and damping factor calculations were studied in addition to the decibel drop ranging from 0.4–4.9 dB. The composite sample SR-4 is considered to have the optimal percentage of the selected acoustic properties studied. Thus, the shielding efficiency of SR-composite increased with increasing content of Cu-alloy which makes it applicable in ear plugs and electronic applications.