Rubber-filler Interaction Research Articles

Effect of the Epoxide Contents of Liquid Isoprene Rubber as a Processing Aid on the Properties of Silica-Filled Natural Rubber Compounds.

In this study, we examined the feasibility of using epoxidized liquid isoprene rubber (E-LqIR) as a processing aid for truck and bus radial (TBR) tire treads and investigated the effects of the epoxide content on the wear resistance, fuel efficiency, and resistance to extraction of the E-LqIRs. The results confirmed that, compared to the treated distillate aromatic extract (TDAE) oil, the E-LqIRs could enhance the filler–rubber interactions and reduce the oil migration. However, the consumption of sulfur by the E-LqIRs resulted in a lower crosslink density compared to that of the TDAE oil, and the higher epoxide content decreased the wear resistance and fuel efficiency because of the increased glass-transition temperature (Tg). In contrast, the E-LqIR with a low epoxide content of 6 mol% had no significant effect on the Tg of the final compound and resulted in superior wear resistance and fuel efficiency, compared to those shown by TDAE oil, because of the higher filler–rubber interactions.

How the silica determines properties of filled silicone rubber by the formation of filler networking and bound rubber

Aiming to unveil the correlation among formula, hierarchical structure, and performance of silica filled silicone rubber foams (SRFs), mechanical and structural investigations are performed on three selected samples. Precipitation (P) and fumed (F) silica filled SRFs with diameters of primary particles around 20 nm (PA), 16 nm (FB), and 14 nm (FC) are used, namely SRPA, SRFB, and SRFC. The hierarchical structures are obtained by contrast variation-small-angle neutron scattering (CV-SANS) with an established three-level unified Guinier-exponential/power-law approach. The sizes of both aggregates (agg) and agglomerates (agl) levels have the correlation of SRPA > SRFB > SRFC. Mass-fractals df, agg of SRPA, SRFB, and SRFC are 2.16, 2.16, and 2.54, while df, agl of the set are 2.90, 2.52, and 2.54, respectively. CV-SANS also indicates that the static thickness of bound rubber (TSBR) of SRPA, SRFB, and SRFC decreases from 10.3 nm to 7.5 nm, and then to 6.5 nm. Interestingly, low-field 1H nuclear magnetic resonance (NMR) indicates that the dynamics thickness of bound rubber (TNBR) of the set increases from 3.33 nm to 4.35 nm, and then to 4.41 nm. The discrepancy between TSBR and TNBR is ascribed to the interface interaction. Mechanically, three samples present different behaviors, while SRPA and SRFB have similar extension modules and compressive relaxations. According to a modified constitutive model fitting, and with combining the structural information, the roles of filler-filler and filler-rubber interactions on the reinforcement of SRFs are discussed.

Effect of the Functional Group Position in Functionalized Liquid Butadiene Rubbers Used as Processing Aids on the Properties of Silica-Filled Rubber Compounds.

Recently, research conducted on tread compounds with liquid butadiene rubber (LqBR) have been conducted in the tire industry. In particular, the introduction of functional groups into LqBRs is expected to lower hysteresis loss caused by the free chain ends of LqBR. To study this, LqBRs with functional groups at different positions were synthesized. The occurrences of in-chain and chain-end functionalization of functionalized LqBRs (F-LqBRs) were confirmed, the microstructure and functionalization efficiency of F-LqBRs were calculated through the characterizations. This novel functionalization technology was beneficial not only to immobilizing the free chain ends of LqBRs to the surfaces of silica to decrease the number of free chain ends, but also chemically bonding the LqBR chains on the base polymer through a crosslinking reaction to enhance the filler-rubber interaction. The effects of the functional group position and number of the free chain ends on the physical properties and hysteresis of the compounds were investigated by partially replacing the treated distillate aromatic extract (TDAE) oil with LqBR in silica-filled rubber compounds. The results showed that compounds that had applied DF-LqBR with both end functionalization performed better, including improving the silica dispersion, higher extraction resistance, and lower rolling resistance, than other F-LqBRs compounds.

Common Origin of Filler Network Related Contributions to Reinforcement and Dissipation in Rubber Composites.

A comparative study focusing on the visco–elastic properties of two series of carbon black filled composites with natural rubber (NR) and its blends with butadiene rubber (NR-BR) as matrices is reported. Strain sweeps at different temperatures are performed. Filler network-related contributions to reinforcement () are quantified by the classical Kraus equation while a modified Kraus equation is used to quantify different contributions to dissipation (, ). Results indicate that the filler network is visco-elastic in nature and that it is causing a major part of the composite dissipation at small and intermediate strain amplitudes. The temperature dependence of filler network-related reinforcement and dissipation contributions is found to depend significantly on the rubber matrix composition. We propose that this is due to differences in the chemical composition of the glassy rubber bridges connecting filler particles since the filler network topology is seemingly not significantly influenced by the rubber matrix for a given filler content. The underlying physical picture explains effects in both dissipation and reinforcement. It predicts that these glassy rubber bridges will soften sequentially at temperatures much higher than the bulk of the corresponding rubber. This is hypothetically due to rubber–filler interactions at interfaces resulting in an increased packing density in the glassy rubber related to the reduction of free volume. From a general perspective, this study provides deeper insights towards the molecular origin of reinforcement and dissipation in rubber composites.

Reinforcement of surface-modified cellulose nanofibrils extracted from Napier grass stem in natural rubber composites

Cellulose nanofibrils (CNFs) were prepared from Napier grass stems via alkalization, bleaching and sulfuric acid hydrolysis treatments and subsequently characterized by various techniques. Transmission electron microscopy (TEM) confirmed that CNFs with average diameter of 15 nm were successfully obtained in the diluted suspension. However, after freeze drying, CNFs aggregated and formed large fibrillar bundles. X-ray diffraction (XRD) results revealed that CNFs exhibited Cellulose I structure with crystallinity index of 74 %. Results from Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) confirmed the complete removal of noncellulosic compounds after the alkali and bleaching treatments. Surface treatment of CNFs by Bis-(triethoxysilyl-propyl) tetrasulfide (TESPT) was also carried out. Both untreated and TESPT-treated CNFs were added into natural rubber (NR) at various loadings (0–10 phr) to investigate their reinforcements. Regardless of the filler type, modulus and hardness of the NR composites increased continuously with increasing filler loading. Tensile strength increased with increasing filler loading up to 5 phr before leveling off. At any given filler loading, TESPT-treated CNFs exhibited greater reinforcement than untreated CNFs due to the improved rubber-filler interaction and the enhanced crosslink density. The results show the potential use of the TESPT-treated CNFs in rubber reinforcement.

Study on the Use of CTAB-Treated Illite as an Alternative Filler for Natural Rubber

Fillers are indispensable for rubber composites. Carbon black as an efficient reinforcing filler is most widely used in the rubber industry. However, the utilization of nonrenewable feedstock, energy consumption, and footprint for making carbon black lead to the seeking of alternative substitutes for carbon black, which is of great significance. Here in this work, the possibility of illite, a most common mineral in sedimentary rocks, as an alternative filler for natural rubber (NR) is determined. It is found that pristine illite slows the curing rate and decreases the cross-linking density of NR, which results in the inferior performance of NR. This is associated with the weak filler–rubber interaction, which is a vital factor in deciding the performance of rubber composites. Therefore, illite has been modified using hexadecyl trimethyl ammonium bromide (CTAB), a commonly used cation surfactant, for improving the filler–rubber interaction. The thus obtained C-illite is confirmed to be efficient for (i) enhancing the illite–NR interaction, (ii) improving the dispersion of illite in the NR matrix, and (iii) accelerating the curing process of NR with increased cross-linking density. All of these lead to significantly improved mechanical properties and wear resistance of the C-illite/NR composites, e.g., a 71.88% increase of the modulus at 300% strain compared to the pure NR and a 23.79% reduction of the DIN abrasion volume compared to the NR filled with 40 phr pristine illite. This illustrates the high possibility of CTAB-modified illite with an optimal particle size as a promising alternative filler of carbon black for reinforcing rubbers.

Effect of Epoxide Content on the Vulcanizate Structure of Silica-Filled Epoxidized Natural Rubber (ENR) Compounds.

The demand for truck–bus radial (TBR) tires with enhanced fuel efficiency has grown in recent years. Many studies have investigated silica-filled natural rubber (NR) compounds to address these needs. However, silica-filled compounds offer inferior abrasion resistance compared to carbon black-filled compounds. Further, the use of NR as a base rubber can hinder silanization and coupling reactions due to interference by proteins and lipids. Improved silica dispersion be achieved without the use of a silane coupling agent by introducing epoxide groups to NR, which serve as silica-affinitive functional groups. Furthermore, the coupling reaction can be promoted by facilitating chemical interaction between the hydroxyl group of silica and the added epoxide groups. Thus, this study evaluated the properties of commercialized NR, ENR-25, and ENR-50 compounds with or without an added silane coupling agent, and the filler–rubber interaction was quantitatively calculated using vulcanizate structure analysis. The increased epoxide content, when the silane coupling agent was not used, improved silica dispersion, abrasion resistance, fuel efficiency, and wet grip. Once a basic level of silica dispersion was secured by using the silane coupling agent, both the abrasion resistance and wet grip improved with increasing epoxide content. Furthermore, the silane coupling agent could be partially replaced by ENR due to the high filler–rubber interaction between the ENR and silica. Therefore, epoxidation shows potential for resolving the issues associated with poor coupling reactions and abrasion resistance in silica-filled NR compounds.

Analysis of effect of modification of silica and carbon black co-filled rubber composite on mechanical properties

Abstract Silica and carbon black (CB) co-filled rubber composite was widely used for tire tread and other rubber products because of combined advantages of binary fillers, such as low hysteresis, good abrasion resistance, and reinforcement. Numerous studies have been focused on the filler–rubber interaction with the aim of obtaining optimum performances. To investigate the effect of modification on properties of rubber composite, modified silica and CB co-filled rubber composite was prepared with a multi-functional silane coupling agent, 2-aminoethyl-2-(3-triethoxysilylpropyl)aminoethyl disulfide (ATD). Such modification significantly enhanced the filler–rubber interaction and improved the filler dispersion. For the modified composites, the state of cure, hardness, tensile strength before and after aging, stress at 300% elongation, tear strength, abrasion resistance, rebound resilience, compression set, temperature rise, and the value of dynamic loss coefficient ranging from −20°C to 80°C were significantly improved, especially with low ATD dosage (3.0 phr). This modification provides an effective route to prepare silica and CB co-filled rubber composites with improved mechanical properties and dynamic mechanical properties.

Treasuring waste lignin as superior reinforcing filler in high cis-polybutadiene rubber: A direct comparative study with standard reinforcing silica and carbon black

There has been ever raising concern in last few decades about the utilization of biomass for different commercial applications such as filler materials in rubber composites. In this context, an interesting pathway has been proposed to develop such composites by introducing waste lignin as a reinforcing constituent in high cis-polybutadiene rubber (BR). With a judicious selection of rubber curing ingredients and, simultaneously, adopting suitable solid-state mixing protocols, particularly, a relatively high-temperature multi-steps melt-mixing process (above the glass transition temperature of lignin), rubber composites with an outstanding mechanical performance were prepared. The reinforced rubber composites with 50 (weight) parts lignin loading per hundred parts of rubber (phr) offer ∼10 MPa tensile strength (TS), ∼276% elongation at break (EB), and ∼3.51 MPa tensile stress at 100% elongation (so-called rubber modulus M100). These values are superior when compared with the composites comprised with standard reinforcing carbon black (∼8.5 TS, ∼224% EB, ∼2.79 M100) and even with a silica-silane system (∼7.34 TS, ∼229% EB, ∼2.44 M100) with same filler loading. The unique combination of the curing packages and four-stage mixing process allowed us to establish a homogeneous and fine dispersion of lignin. Furthermore, this is the first time that available models of rubber reinforcement are applied to the description of the reinforcement mechanisms of lignin in a soft elastomer involving various aspects like filler-filler interaction, rubber-filler interactions, critical strains for destroying the filler-filler network, effective filler volume fractions, shape factor, etc. The developed compounding methods for BR and their characterization and modeling can be easily applied to other commercial rubbers facilitating a real breakthrough in developing cheap and bio-based high-performance rubber composites.

Dynamic Heterogeneity of Filler-Associated Interphases in Polymer Nanocomposites.

Dynamically inhomogeneous polymer systems exhibit interphases with mobility gradients. These are believed to play key roles in the material's performance. A prominent example is particle-filled rubber, a special case of a crosslinked polymer nanocomposite, where favorable rubber-filler interactions may give rise to a nanoscale immobilized layer around the filler, including regions of intermediate mobility. Such intermediate domains may either form a separate shell-like layer or be a manifestation of dynamic heterogeneities, in which case the intermediately mobile material would be dispersed in the form of nanometer-sized subdomains. In this contribution, bidirectional proton NMR spin diffusion (SD) experiments applied to silica-filled acrylate rubber are combined with numerical simulations to provide microscopic insights into this question. While model calculations for different scenarios fit the given data similarly well for longer SD mixing time, the short-time data do support the presence of dynamic heterogeneities.

Curing Behaviors, Mechanical and Dynamic Properties of Composites Containing Chloroprene and Butadiene Rubbers Crosslinked with Nano-Iron(III) Oxide.

This paper discusses the curing behaviors, mechanical and dynamical properties of composites containing chloroprene rubber (CR) and butadiene rubber (BR) reinforced with mineral fillers. The iron(III) oxide nanoparticles were used as a crosslinking agent of the CR/BR blends. The research aimed to evaluate the effectiveness of nano-iron(III) oxide (nano-Fe2O3) as a new crosslinking agent while producing elastomeric materials with good mechanical properties and reduced flammability. The CR/BR (chloroprene rubber/butadiene rubber) blends were filled with silicas from natural resources (chalcedony, Neuburg silica earth) or silicas used in elastomer technology in many fields (aerosil, ultrasil). The results revealed that all composites were characterized by satisfactory tensile strength, tear resistance, and high resistance to fire. The filler dispersion in the elastomer matrix was carried out by using scanning electron microscopy (SEM), while the possibility of the filler–filler or filler–rubber interaction in the designed compositions was determined using the Payne effect and the Mullins effect.

Vulcanization kinetics of styrene butadiene rubber reinforced by graphenic particles

AbstractThe present study discusses the effects of graphenic particles on the kinetics of sulfur vulcanization in styrene butadiene rubber composites. Using data obtained from a cure rheometer and fitted by an autocatalytic model, it was verified that graphenic particles follow our recently established catalytic‐networking model for the effect of particles on the sulfur vulcanization of rubber, regardless of the type of particles. The magnitude of the catalytic and networking effects depends on surface chemistry and interfacial interactions of particles with rubber that can be tailored by the chemical reduction of graphene oxide. Accordingly, the reduction process decreased the catalytic effect due to the elimination of surface functional groups and increased the networking effect due to the enhancement of filler–rubber interactions and immobilization of rubber. The latter was verified by differential scanning calorimetry and bound rubber measurements.

Sulfur-Modified Carbon Nanotubes for the Development of Advanced Elastomeric Materials.

The outstanding properties of carbon nanotubes (CNTs) present some limitations when introduced into rubber matrices, especially when these nano-particles are applied in high-performance tire tread compounds. Their tendency to agglomerate into bundles due to van der Waals interactions, the strong influence of CNT on the vulcanization process, and the adsorptive nature of filler–rubber interactions contribute to increase the energy dissipation phenomena on rubber–CNT compounds. Consequently, their expected performance in terms of rolling resistance is limited. To overcome these three important issues, the CNT have been surface-modified with oxygen-bearing groups and sulfur, resulting in an improvement in the key properties of these rubber compounds for their use in tire tread applications. A deep characterization of these new materials using functionalized CNT as filler was carried out by using a combination of mechanical, equilibrium swelling and low-field NMR experiments. The outcome of this research revealed that the formation of covalent bonds between the rubber matrix and the nano-particles by the introduction of sulfur at the CNT surface has positive effects on the viscoelastic behavior and the network structure of the rubber compounds, by a decrease of both the loss factor at 60 °C (rolling resistance) and the non-elastic defects, while increasing the crosslink density of the new compounds.

A Self-Healing System Based on Ester Crosslinks for Carbon Black-Filled Rubber Compounds

Carbon black-reinforced rubber compounds based on the blends of natural rubber (NR) and butadiene rubber (BR) for tire sidewall applications were formulated to investigate the self-healing efficacy of a modifier called EMZ. This modifier is based on epoxidized natural rubber (ENR) modified with hydrolyzed maleic anhydride (HMA) as the ester crosslinking agent plus zinc acetate dihydrate (ZAD) as the transesterification catalyst. The influence of EMZ modifier content in sidewall compounds on processing characteristics, reinforcement, mechanical and fatigue properties, as well as property retentions, was investigated. Increasing the content of EMZ, the dump temperatures and Mooney viscosities of the compounds slightly increase, attributed to the presence of extra polymer networks and filler–rubber interactions. The bound rubber content and Payne effect show a good correction that essentially supports that the EMZ modifier gives enhanced filler–rubber interaction and reduced filler–filler interaction, reflecting the improved homogeneity of the composites. This is the key contribution to a better flex cracking resistance and a high fatigue-to-failure resistance when utilizing the EMZ modifier. To validate the property retentions, molecular damages were introduced to vulcanizates using a tensile stress–strain cyclic test following the Mullins effect concept. The property retentions are significantly enhanced with increasing EMZ content because the EMZ self-healing modifier provides reversible or dynamic ester linkages that potentially enable a bond-interchange mechanism of the crosslinks, leading to the intermolecular reparation of the rubber network.

EPDM with Biochar, Carbon Black, Aramid Pulp and Ionic Liquid-compatibilized Aramid Pulp

Carbon black (CB) is a fossil fuel-derived product widely used as reinforcement in the rubber industry despite its pollution potential and its high energy-demanding production. Biochar, on the other hand, is a renewable source of carbon recently studied for the partial substitution of CB in elastomeric materials. Aramid pulp/fibers have also been used in a variety of applications in this sector, usually after a surface treatment. In this work, the use of aramid pulp (AP) and biochar in the preparation of ethylene propylene diene monomer (EPDM) composites and hybrid composites has been studied. The 1-n-butyl-3-methylimidazolium methanesulfonate ionic liquid (IL) was used as compatibilizer in AP, and the rubber-filler interaction was studied via thermal, rheometric, mechanical, and swelling analyses. The biochar-EPDM and the reference CB-EDPM compounds showed similar hardness, modulus at 50 % strain and tear strength results. Among the tested fillers, AP was identified as the most effective to obtain EPDM composites with enhanced properties. A synergistic effect of biochar and IL-treated AP was found, resulting in higher tensile strength for the hybrid formulation (EPDM/Bio05AP05IL) compared to those with just biochar or CB, and reasonable strain at break. In all, the hybrid composites of EPDM reinforced with biochar and AP showed the potential to partially or fully replace CB formulations.

Influence of Treated Distillate Aromatic Extract (TDAE) Content and Addition Time on Rubber-Filler Interactions in Silica Filled SBR/BR Blends.

High compatibility and good rubber–filler interactions are required in order to obtain high quality products. Rubber–filler and filler–filler interactions can be influenced by various material factors, such as the presence of processing aids. Although different processing aids, especially the plasticizers, and their effects on compatibility have been investigated in the literature, their influence on rubber–filler interactions in highly active filler reinforced mixtures is not explicit and has not been investigated in depth. For this purpose, the influence of treated distillate aromatic extract (TDAE) oil content and its addition time on interactions between silica and rubber chains were investigated in this study. Rubber–filler and filler–filler interactions of uncured and cured silica-filled SBR/BR blends were characterized by using rubber layer L concept and dynamic mechanical analysis, whereas mechanical properties were studied by tensile test and Shore A hardness. Five parts per hundred rubber (phr) TDAE addition at 0, 1.5, and 3 min of mixing were characterized to investigate the influence of TDAE addition time on rubber–filler interactions. It was observed that addition time of TDAE can influence the development of bounded rubber structure and the interfacial interactions, especially at short time of mixing, less than 5 min. Oil addition with silica at 1.5 min of mixing resulted in fast rubber layer development and a small reduction in storage shear modulus of uncured blends. The influence of oil content on rubber–filler and filler–filler interactions were investigated for the binary blends without oil, with 5 and 20 phr TDAE content. The addition of 5 phr oil resulted in a slight increase in rubber layer and 0.05 MPa reduction in Payne effect of uncured blends. The storage tensile modulus of vulcanizates at small strains decreased from 13.97 to 8.28 MPa after oil addition. Twenty parts per hundred rubber (phr) oil addition to binary blends caused rubber layer L to decrease from 0.45 to 0.42. The storage tensile modulus of the vulcanizates and its reduction with higher amplitudes were incontrovertibly high among the vulcanizates with lower oil content, which were 13.57 and 4.49 MPa, respectively. When any consequential change in mechanical properties of styrene–butadiene rubber (SBR)/butadiene rubber (BR) blends could not be observed at different TDAE addition time, increasing amount of oil in blends enhanced elongation at break, and decreased Shore A hardness and tensile strength.

Surface Modification of Rice Husk Ash by Ethanol-assisted Milling to Reinforce the Properties of Natural Rubber/Butadiene Rubber Composites

Rice husk ash(RHA), obtained by pyrolysis of rice husks, can be used as a potential reinforcing filler for rubber composites. In this work, ball milling in ethanol(ethanol-assisted milling) was used to hydroxylate the surface of RHA, promoting the graft modification of bis-(β-triethoxysilylpropyl)-tetrasulfide(Si69). The obtained modified RHA(RHA-EM-Si69) was filled into the natural rubber/butadiene rubber(NR/BR) composites, and the filler-rubber interactions were enhanced. In consequence, RHA-EM-Si69 filled NR/BR composites showed overall improvement in the mechanical properties compared with RHA filled NR/BR composites. The tear strength increased from 13.37 kN/m to 34.71 kN/m, and the tensile strength increased from 1.84 MPa to 7.75 MPa. Carbon black(N774) was also used for comparison under the same conditions. This method provides a potential for promoting the value of RHA in rubber industry.

Modified natural rubber glove with spent coffee grounds for prothesis arm cover

In this research, we developed modified rubber gloves that could cover prosthetic arms manufactured from Fused Deposition Modeling (FDM) 3D printing. FDM can produce customized prosthetic arms that are lightweight and fit the individual needs of patients. Currently, the gloves used to cover prosthetic arms are made from flexible and soft material such as silicone or polyurethane. In these studies, were use natural rubber latex (NR) to produce rubber gloves, that enhance the physical appearance of the prosthetic arm, producing a similar color and detail to the patients arm. The glove color was improved by mixing with spent coffee grounds (SCG) to produce a similar color to that of natural human skin. Moreover, SCG was not only used as a color pigment, it also contains coffee oil that creates a glossy textured on the surface similar to silicone oil. The modification process of NR used a SCG dispersion solution mixed with NR. Rubber gloves were prepared by a dipping process and use sulfur vulcanization at 75 °C, for 2 h in a hot air oven. The specimens were characterization by physical (morphology, color parameter, and %swelling), mechanical (tensile test) and thermal properties. Furthermore, the SCG can be used as a filler in natural rubber due to rubber-filler interactions that improve the tensile strength of the rubber glove with the SCG particles having a good distribution in the rubber phase. The SCG can improve the ageing stability (under 70 °C and Fluorescent light) of the rubber gloves as represented by the color parameter and tensile properties. After ageing showed a small difference in color parameter and a slight decrease in the tensile properties when greater amounts of SCG was presented in the rubber phase. Moreover, this can increase the economic value of natural rubber and spent coffee grounds in Thailand.

Tea waste/carbon black hybrid filled natural rubber composites

This paper aimed to present the potential use of tea waste (TW) as an alternative filler for natural rubber (NR). Because of the bigger particle size of TW and is considered to be in a class of non-reinforcing filler. Carbon black (CB) was then introduced as secondary filler for NR matrix. This is to improve the performance of the composite while maintaining the suitable amount of TW. TW was fixed at 30 parts per hundred rubber (phr) where the CB was varied from 10 – 30 phr. Incorporation of CB in the hybrid system can fasten the curing process of the composites, as the scorch and curing times increased with increasing the CB contents. CB has greatly influenced the maximum torque, tensile strength and tensile modulus due to its better rubber-filler interaction within the rubber matrix. However, the elongation at break of the composites drop continuously with the addition of the CB. This is simply due to dilution effect of the composite which refers to the less amount of flexible phase. The enhanced performance of the composite in the presence of CB can be verified by the calculation of rubber-filler interaction (Q f /Q g ) values, indicating higher rubber-filler interaction when higher amount of CB was used. Apart from that, the images obtained from scanning electron microscope (SEM) also provided some evidence relating to the tensile properties observed. From the experimental results, hybridization of 30/20 phr/phr of TW and CB is highly suggested to gain the synergistic strength and processing safety.

Application of silane-treated tea waste powder as a potential filler for natural rubber composites

The aim of this work was to develop sustainable composites based on natural rubber (NR) and tea waste (TW) composites. The main concern was the compatibility mismatch between NR and TW. The presence of polar groups in the TW contributes to the weak interaction between relatively hydrophobic NR and TW. Therefore, silane coupling agent was introduced to enhance the properties of the composites. Treating the TW by silane coupling agent greatly influenced the overall properties of the composites. It speeded up the curing process due to its ability to reduce possible adsorption of accelerator by TW. Better interaction between TW and rubber matrix was clearly observed as evidenced by the maximum torque (MH) and tensile properties of the composites. Such findings can be verified by the Qf/Qg values, indicating better rubber-filler interaction when silane was used. Moreover, scanning electron microscope (SEM) images also provided some evidence related to the tensile properties observed. It can be concluded that the new composite based on NR and TW was successfully prepared with the contribution of a silane coupling agent.