Nanocarbon Reinforced Rubber Nanocomposites: Detailed Insights about Mechanical, Dynamical Mechanical Properties, Payne, and Mullin Effects

Kirigami-enabled stretchable laser-induced graphene heaters for wearable thermotherapy

Flexible and stretchable heaters are increasingly recognized for their great potential in wearable thermotherapy to treat muscle spasms, joint injuries and arthritis. However, issues like lengthy processing, high fabrication cost, and toxic chemical involvement are obstacles on the way to popularize stretchable heaters for medical use. Herein, using a single-step customizable laser fabrication method, we put forward the design of cost-effective wearable laser-induced graphene (LIG) heaters with kirigami patterns, which offer multimodal stretchability and conformal fit to the skin around the human body. First, we develop the manufacturing process of the LIG heaters with three different kirigami patterns enabling reliable stretchability by out-of-plane buckling. Then, by adjusting the laser parameters, we confirm that the LIG produced by medium laser power could maintain a balance between mechanical strength and electrical conductivity. By optimizing cutting-spacing ratios through experimental measurements of stress, resistance and temperature profiles, as well as finite element analysis (FEA), we determine that a larger cutting-spacing ratio within the machining precision will lead to better mechanical, electrical and heating performance. The optimized stretchable heater in this paper could bear significant unidirectional strain over 100% or multidirectional strain over 20% without major loss in conductivity and heating performance. On-body tests and fatigue tests also proved great robustness in practical scenarios. With the advantage of safe usage, simple and customizable fabrication, easy bonding with skin, and multidirectional stretchability, the on-skin heaters are promising to substitute the traditional heating packs/wraps for thermotherapy.

Thermal Treatment Impact on the Mechanical Properties of Mg3Si2O5(OH)4 Nanoscrolls

A group of phyllosilicate nanoscrolls conjoins several hydrosilicate layered compounds with a size mismatch between octahedral and tetrahedral sheets. Among them, synthetic Mg3Si2O5(OH)4 chrysotile nanoscrolls (obtained via the hydrothermal method) possess high thermal stability and mechanical properties, making them prospective composite materials fillers. However, accurate determination of these nano-objects with Young's modulus remains challenging. Here, we report on a study of the mechanical properties evolution of individual synthetic phyllosilicate nanoscrolls after a series of heat treatments, observed with an atomic force microscopy and calculated using the density functional theory. It appears that the Young's modulus, as well as shear deformation's contribution to the nanoscrolls mechanical behavior, can be controlled by heat treatment. The main reason for this is the heat-induced formation of covalent bonding between the adjacent layers, which complicate the shear deformation.

Shape memory polymer composites (SMPCs) using interconnected nanowire network foams as reinforcements

Shape memory polymers (SMPs), although offer a suite of advantages such as ease of processability and lower density, lag behind their shape memory alloy counterparts, in terms of mechanical properties such as recovery stress and cyclability. Reinforcing SMPs with inorganic nanowires and carbon nanotubes (CNTs) is a sought-after pathway for tailoring their mechanical properties. Here, inorganic nanowires also offer the added advantage of covalently binding the fillers to the surrounding polymer matrices via organic molecules. The SMP composites (SMPCs) thus obtained have well-engineered nanowire-polymer interfaces, which could be used to tune their mechanical properties. A well-known method of fabricating SMPCs involving casting dispersions of nanowires (or CNTs) in mixtures of monomers and crosslinkers typically results in marginal improvements in the mechanical properties of the fabricated SMPCs. This is owed to the constraints imposed by the rule-of-mixture principles. To circumvent this limitation, a new method for SMPC fabrication is designed and presented. This involves infiltrating polymers into pre-fabricated nanowire foams. The pre-fabricated foams were fabricated by consolidating measured quantities of nanowires and a sacrificial material, such as (NH₄)₂CO₃, followed by heating the consolidated mixtures for subliming the sacrificial material. Similar to the case of traditional composites, use of silanes to functionalize the nanowire surfaces allowed for the formation of bonds between both the nanowire-nanowire and the nanowire-polymer interfaces. SMPCs fabricated using TiO₂nanowires and SMP composed of neopentyl glycol diglycidyl ether and poly(propylene glycol) bis(2-aminopropyl ether) (Jeffamine D230) in a 2:1 molar ratio exhibited a 300% improvement in the elastic modulus relative to that of the SMP. This increase was significantly higher than SMPC made using the traditional fabrication route. Well-known powder metallurgy techniques employed for the fabrication of these SMPCs make this strategy applicable for obtaining other SMPCs of any desired shape and chemical composition.

Evolution of Shore Hardness under Uniaxial Tension/Compression in Body-Temperature Programmable Elastic Shape Memory Hybrids

Body-temperature programmable elastic shape memory hybrids (SMHs) have great potential for the comfortable fitting of wearable devices. Traditionally, shore hardness is commonly used in the characterization of elastic materials. In this paper, the evolution of shore hardness in body-temperature programmable elastic SMHs upon cyclic loading, and during the shape memory cycle, is systematically investigated. Upon cyclic loading, similar to the Mullins effect, significant softening appears, when the applied strain is over a certain value. On the other hand, after programming, in general, the measured hardness increases with increase in programming strain. However, for certain surfaces, the hardness decreases slightly and then increases rapidly. The underlying mechanism for this phenomenon is explained by the formation of micro-gaps between the inclusion and the matrix after programming. After heating, to melt the inclusions, all samples (both cyclically loaded and programmed) largely recover their original hardness.

Testing of Rubber Composites Reinforced with Carbon Nanotubes

Carbon nanotubes (CNTs) have attracted growing interest as a filler in rubber nanocomposites due to their mechanical and electrical properties. In this study, the mechanical properties of a NR/BR/IR/SBR compound reinforced with single-wall carbon nanotubes (SWCNTs) were investigated using atomic force microscopy (AFM), tensile tests, hardness tests, and a dynamical mechanical analysis (DMA). The tested materials differed in SWCNT content (1.00–2.00 phr) and were compared with a reference compound without the nanofiller. AFM was used to obtain the topography and spectroscopic curves based on which local elasticity was characterized. The results of the tensile and hardness tests showed a reinforcing effect of the SWCNTs. It was observed that an addition of 2.00 phr of the SWCNTs resulted in increases in tensile strength by 9.5%, Young’s modulus by 15.44%, and hardness by 11.18%, while the elongation at break decreased by 8.39% compared with the reference compound. The results of the temperature and frequency sweep DMA showed higher values of storage and loss moduli, as well as lower values of tangent of phase angle, with increasing SWCNT content.

Research and Development of High-Performance High-Damping Rubber Materials for High-Damping Rubber Isolation Bearings: A Review

At present, high-damping rubber materials, widely used in the field of engineering seismic isolation, generally have the problems such as narrow effective damping temperature range, low damping loss factor and strong temperature dependence, which lead to prominent dependence of temperature and load conditions of the isolation performance of high-damping rubber isolation bearings. Research and development of high-performance high-damping rubber materials with broad effective damping temperature range, high damping loss factor and weak temperature dependence are very urgent and necessary to ensure the safety of the seismic isolation of engineering structures. This paper mainly reviews the recent progress in the research and development of high-damping rubber materials using nitrile butadiene rubber (NBR), epoxidized natural rubber (ENR), ethylene propylene diene rubber (EPDM), butyl rubber (IIR), chlorinated butyl rubber (CIIR), and bromine butyl rubber (BIIR). This is followed by a review of vulcanization and filler reinforcement systems for the improvement of damping and mechanical properties of high-damping rubber materials. Finally, it further reviews the constitutive models describing the hyperelasticity and viscoelasticity of rubber materials. In view of this focus, four key issues are highlighted for the development of high-performance high-damping rubber materials used for high-damping rubber isolation bearings.

Studying the electrical conductivity and mechanical properties of irradiated natural rubber latex/magnetite nanocomposite

Nanocomposites have received voluminous interest due to the combination of unique properties of organic and inorganic component in one material. In this class, magnetic polymer nanocomposites are of particular interest because of the combination of excellent magnetic properties, stability, and good biocompatibility. This paper reports the preparation and characterization of nanocomposites films based on natural rubber in latex state (NRL) loaded with different concentrations of semiconducting magnetite nanoparticles (Fe3O4) (MNPs) (5, 10, 15, 20, and 30%). NRL (100%) and NRL/Fe3O4 nanocomposites were prepared by solution casting technique then, exposed to various irradiation doses (50, 70, 100 kGy).The nanocomposite’s morphological, and physical properties were investigated through various spectroscopic techniques such as Fourier-transformed infrared, X-ray diffraction, scanning electron, and transmission electron microscopies. The mechanical properties, including the tensile strength and elongation at break percentage (E b %) of the nanocomposites were also studied and compared with the 100% NRL films. Based on the results obtained from the mechanical study, it is found that the NRL/20% Fe3O4 nanocomposite film exhibited the highest tensile strength at 100 kGy. On the other hand, based on the conductivity study, it is found that, NRL/Fe3O4 nanocomposite with 10% magnetite exhibit the highest conductivity as the content of magnetite plays an important and effective role based on the high and homogeneous dispersity.

Disperse-and-Mix: Oil as an 'Entrance Door' of Carbon-Based Fillers to Rubber Composites

Oil was employed as an ‘entrance door’ for loading rubber with carbon-based fillers of different size and dimensionalities: 1D carbon nanotubes (CNTs), 2D graphene nanoplatelets (GNPs), and 3D graphite. This approach was explored, as a proof of concept, in the preparation of tire tread, where oil is commonly used to reduce the viscosity of the composite mixture. Rubber was loaded with carbon black (CB, always used) and one or more of the above fillers to enhance the thermal and mechanical properties of the composite. The CNT-loaded system showed the best enhancement in mechanical properties, followed by the CNT-GNP one. Rubber loaded with both graphite and GNP showed the best enhancement in thermal conductivity (58%). The overall enhancements in both mechanical and thermal properties of the various systems were analyzed through an overall relative efficiency index in which the total filler concentration in the system is also included. According to this index, the CNT-loaded system is the most efficient one. The oil as an ‘entrance door’ is an easy and effective novel approach for loading fillers that are in the nanoscale and provide high enhancement of properties at low filler concentrations.

Nanodiamond—Carbon Black Hybrid Filler System for Demanding Applications of Natural Rubber—Butadiene Rubber Composite

The objective of the study was to investigate the effect of the partial replacement of carbon black (CB) by nanodiamonds (NDs) on the vulcanization, mechanical and dynamic properties of a natural rubber—butadiene rubber compound, a typical elastomer compound found in several applications (the tire and mining industry, for example). A studied hybrid filler system resulted in a 28% increase in tensile strength and 29% increase in 300% modulus at low ND loadings even though the total weight fraction of the filler system was kept constant at 25 parts per hundred rubber. The hybrid filler system improved dispersion of both fillers as was proven by scanning electron microscopy and the Payne effect study. In addition, the replacement of 2.5 and 5 phr CB by NDs resulted in 62% improvement in wear resistance. The DMA study showed that a certain ND-CB filler combination has a positive effect on tire properties such as wet grip and rolling resistance.

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 (T_g). In contrast, the E-LqIR with a low epoxide content of 6 mol% had no significant effect on the T_g 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.

Safety Comes First: Novel Styrene Butadiene Rubber (SBR) and Ethylene Propylene Diene Monomer (EPDM) Surfaces as a Response to Sport Injuries

An athlete’s performance depends not only on the shoes they wear but also on the surface used in sports facilities. In addition, it can significantly contribute to reducing injuries, which are easy to get during sports competitions. In the present study, we wanted to investigate whether recycled styrene butadiene rubber (SBR) and ethylene propylene diene monomer (EPDM) could be used in the production of sports surfaces. For this purpose, we designed three different sports surfaces: (1) SBR covered with a thin EPDM spray layer on the top, (2) clean EPDM, and (3) bottom SBR layer with the top layer of EPDM. The test program of these surfaces included in its scope: shock absorption, vertical deformation, tensile strength, abrasion resistance, and slip resistance tests. Our research also involved the influence of the substrate under surface, temperature, and surface conditions. Presented results show that both materials, in the right proportions, can be used in the production of sports surfaces.

Silicone Composites with CNT/Graphene Hybrid Fillers: A Review

This review is dedicated to versatile silicone rubber composites based on carbon nanotube/graphene (CNT/G) hybrid fillers. Due to their unique mechanical, electrical, thermal, and biological properties, such composites have enormous potential for medical, environmental, and electronics applications. In the scope of this paper, we have explored CNT/graphene/silicone composites with a different morphology, analyzed the synergistic effect of hybrid fillers on various properties of silicone composites, and observed the existing approaches for the fabrication of hybrid composites with a seamless, assembled, and/or foamed structure. In conclusion, current challenges and future prospects for silicone composites based on CNTs and graphene have been thoroughly discussed.

Multifunctional Additives for High-Energy-Density Lithium-Ion Batteries: Improved Conductive Additive/Binder Networks and Enhanced Electrochemical Properties

Cylindrical-type cells have been widely adopted by major battery and electric vehicle manufacturers owing to their price competitiveness, safety, and easy expandability. However, placement of electrodes at the core of cylindrical cells is currently restricted because of high electrode curvature and the lack of specialized electrodes and electrode materials. Here, we report the realization of highly flexible high-energy-density electrodes (active material loading of >98.4%) that can be used at the cores of cylindrical cells. The improved properties result from the introduction of a multifunctional poly(melamine-co-formaldehyde) (MF copolymer) additive, which yields a relatively more fluidic and well-dispersed slurry using only 0.08 wt %. MF copolymer-mediated formation of completely wrapped CNT/PVDF networks on LiCoO₂ (LCO) and accompanying contact enhancement between LCO and carbon nanotubes (CNTs) resulted in an increase of electrical and mechanical properties of the two types (composites with or without collectors) of electrodes compared with those of additive-free electrodes. Flexibility tests were carried out by rolling electrodes onto cylinder substrates (diameters of ca. 1 and 10 mm); this process resulted in relatively lower resistance changes of the MF copolymer-containing electrodes than for the reference electrodes. In addition, capacity retention after 100 cycles for cells with and without MF copolymers was approximately 10-20% better for the samples with the MF copolymer than for those without. CNT/PVDF networks with MF copolymers were proven to induce a relatively thin and stable cathode electrolyte interface layer accompanying the chemical bond formation during cycling.

Influence of Carbon Nanotube-Pretreatment on the Properties of Polydimethylsiloxane/Carbon Nanotube-Nanocomposites

Incorporating nanofillers into elastomers leads to composites with an enormous potential regarding their properties. Unfortunately, nanofillers tend to form agglomerates inhibiting adequate filler dispersion. Therefore, different carbon nanotube (CNT) pretreatment methods were analyzed in this study to enhance the filler dispersion in polydimethylsiloxane (PDMS)/CNT-composites. By pre-dispersing CNTs in solvents an increase in electrical conductivity could be observed within the sequence of tetrahydrofuran (THF) > acetone > chloroform. Optimization of the pre-dispersion step results in an AC conductivity of 3.2 × 10⁻⁴ S/cm at 1 Hz and 0.5 wt.% of CNTs and the electrical percolation threshold is decreased to 0.1 wt.% of CNTs. Optimum parameters imply the use of an ultrasonic finger for 60 min in THF. However, solvent residues cause a softening effect deteriorating the mechanical performance of these composites. Concerning the pretreatment of CNTs by physical functionalization, the use of surfactants (sodium dodecylbenzenesulfonate (SDBS) and polyoxyethylene lauryl ether (“Brij35”)) leads to no improvement, neither in electrical conductivity nor in mechanical properties. Chemical functionalization enhances the compatibility of PDMS and CNT but damages the carbon nanotubes due to the oxidation process so that the improvement in conductivity and reinforcement is superimposed by the CNT damage even for mild oxidation conditions.

Designing Supertough and Ultrastretchable Liquid Metal-Embedded Natural Rubber Composites for Soft-Matter Engineering

Functional elastomers with incredible toughness and stretchability are indispensable for applications in soft robotics and wearable electronics. Furthermore, coupled with excellent electrical and thermal properties, these materials are at the forefront of recent efforts toward widespread use in cutting-edge electronics and devices. Herein, we introduce a highly deformable eutectic-GaIn liquid metal alloy-embedded natural rubber (NR) architecture employing, for the first time, industrially viable solid-state mixing and vulcanization. Standard methods of rubber processing and vulcanization allow us to fragment and disperse liquid metals into submicron-sized droplets in cross-linked NR without compromising the elastic properties of the base matrix. In addition to substantial boosts in mechanical (strain at failure of up to ∼650%) and elastic (negligible hysteresis loss) performances, the tearing energy of the composite was enhanced up to 6 times, and a fourfold reduction in the crack growth rate was achieved over a control vulcanizate. Moreover, we demonstrate improved thermal conductivity and dielectric properties for the resulting composites. Therefore, this work provides a facile and scalable pathway to develop liquid metal-embedded soft elastomeric composites that could be instrumental toward potential applications in soft-matter engineering.

Effect of silane modified microcrystalline cellulose on the curing kinetics, thermo-mechanical properties and thermal degradation of benzoxazine resin

In the frame of developing sustainable, eco-friendly and high performance materials, microcrystalline cellulose modified through silane coupling agent (MCC Si) is used as a reinforcing agent of benzoxazine resin to manufacture composites at different loadings of 5, 10, 15, 20 wt%. The structural, morphological and crystallinity characterizations of the modified MCC were initially performed to scrutinize the changes and confirm the modification. Then, an investigation on the crosslinking process of the prepared composites was held through curing kinetic study employing isoconversional methods. The kinetic data revealed a decrease in the average values of activation energy and the pre-exponential factor, particularly for composite supplemented with 10% MCC Si, whereas all samples disclosed a tendency of an autocatalytic curing mechanism. Furthermore, the study of the dynamic mechanical properties and degradation features of the cured specimens, respectively, indicated a superior stiffness attributable to the good interaction between BA-a and MCC Si, and enhanced thermal stability for the composites compared to pristine resin.

Self-Healing Polymer Nanocomposite Materials by Joule Effect

Nowadays, the self-healing approach in materials science mainly relies on functionalized polymers used as matrices in nanocomposites. Through different physicochemical pathways and stimuli, these materials can undergo self-repairing mechanisms that represent a great advantage to prolonging materials service-life, thus avoiding early disposal. Particularly, the use of the Joule effect as an external stimulus for self-healing in conductive nanocomposites is under-reported in the literature. However, it is of particular importance because it incorporates nanofillers with tunable features thus producing multifunctional materials. The aim of this review is the comprehensive analysis of conductive polymer nanocomposites presenting reversible dynamic bonds and their energetical activation to perform self-healing through the Joule effect.

Nature of Carbon Black Reinforcement of Rubber: Perspective on the Original Polymer Nanocomposite

Adding carbon black (CB) particles to elastomeric polymers is essential to the successful industrial use of rubber in many applications, and the mechanical reinforcing effect of CB in rubber has been studied for nearly 100 years. Despite these many decades of investigations, the origin of stiffness enhancement of elastomers from incorporating nanometer-scale CB particles is still debated. It is not universally accepted whether the interactions between polymer chains and CB surfaces are purely physical adsorption or whether some polymer-particle chemical bonds are also introduced in the process of mixing and curing the CB-filled rubber compounds. We review key experimental observations of rubber reinforced with CB, including the finding that heat treatment of CB can greatly reduce the filler reinforcement effect in rubber. The details of the particle morphology and surface chemistry are described to give insights into the nature of the CB-elastomer interfaces. This is followed by a discussion of rubber processing effects, the influence of CB on crosslinking, and various chemical modification approaches that have been employed to improve polymer-filler interactions and reinforcement. Finally, we contrast various models that have been proposed for rationalizing the CB reinforcement of elastomers.

Study on the Synthesis of Castor Oil-Based Plasticizer and the Properties of Plasticized Nitrile Rubber

A series of new environment-friendly plasticizers was synthesized from castor oil and used to plasticize nitrile rubber (NBR). The test results showed that tensile strength, elongation at break, and tear strength of NBR vulcanizates plasticized by castor oil-based plasticizers were found to be better than that of dioctyl phthalate (DOP). The aging test taken demonstrated that the castor oil-based plasticizers could improve the hot air and oil aging resistance of NBR vulcanizates. The thermal stability test illustrated that castor oil-based plasticizers enhanced the thermal stability of NBR vulcanizates, and the initial decomposition temperatures (T10%) were about 100 °C higher than that of DOP. In general, the studies manifested that EACO and EBCO can replace DOP to plasticize NBR and are used in fields that require high mechanical properties, aging resistance, and thermal stability. This study emphasizes the effects of sustainable, cost-effective, and high-efficiency plasticizers on NBR.

Rheological, Mechanical and Morphological Characterization of Fillers in the Nautical Field: The Role of Dispersing Agents on Composite Materials

Coatings have a fundamental role in covering the external surface of yachts by acting both as protective and aesthetic layers. In particular, fillers represent the essential layer from the point of view of mechanical properties and consist of a polymeric matrix, different extenders and additives, and dispersing agents, with the latter having the role to provide good extender-matrix compatibility. In the present work, the effects of dispersing agents with an ionic or steric action on the interactions between hollow glass microspheres and an epoxy-polyamide resin are evaluated. Un-crosslinked filler materials are studied via rheological tests, whereas the mechanical and morphological properties of the crosslinked samples are assessed. The results clearly indicate that steric dispersing agents provide a much greater compatibility effect compared to ionic ones, owing to their steric hindrance capability, thus leading to better-performing filler materials with a less-marked Payne effect, which is here proved to be an efficient tool to provide information concerning the extent of component interactions in nautical fillers. To the best of our knowledge, this work represents the first attempt to deeply understand the role of dispersing agents, which are until now empirically used in the preparation of fillers.

Gas Barrier, Rheological and Mechanical Properties of Immiscible Natural Rubber/Acrylonitrile Butadiene Rubber/Organoclay (NR/NBR/Organoclay) Blend Nanocomposites

In this paper, gas permeability studies were performed on materials based on natural rubber/acrylonitrile butadiene rubber blends and nanoclay incorporated blend systems. The properties of natural rubber (NR)/nitrile rubber (NBR)/nanoclay nanocomposites, with a particular focus on gas permeability, are presented. The measurements of the barrier properties were assessed using two different gases-O2 and CO2-by taking in account the blend composition, the filler loading and the nature of the gas molecules. The obtained data showed that the permeability of gas transport was strongly affected by: (i) the blend composition-it was observed that the increase in acrylonitrile butadiene rubber component considerably decreased the permeability; (ii) the nature of the gas-the permeation of CO2 was higher than O2; (iii) the nanoclay loading-it was found that the permeability decreased with the incorporation of nanoclay. The localization of nanoclay in the blend system also played a major role in determining the gas permeability. The permeability of the systems was correlated with blend morphology and dispersion of the nanoclay platelets in the polymer blend.

Utilization of Pyrolytic Carbon Black Waste for the Development of Sustainable Materials

The sustainable development of materials is one of the key targets in the modern era of engineering. These materials are developed by different waste products, following the concept of the circular economy. This study focuses on investigating the properties of concrete using carbon black as a partial replacement of natural fine aggregate at different percentages. Experiments were designed according to the British Standard (BS1881-Part-119) and American Standard (ASTM C-78) by including carbon black in concrete beams to perform as filler material to develop sustainable concrete. In this study, mechanical properties of concrete were targeted by developing beams using different percentages (0%, 25%, 50%, 75%, and 100%) as a replacement of fine aggregates. These beams were tested for flexural strength and, later on, the same beams were cut in the form of cubes, following the equivalent cube test mechanism for the compressive strength test. The waste carbon black lightweight concrete developed in this study was utilized for both structural and non-structural purposes. At 25% and 50% replacement, the strength of lightweight concrete varied from 20–18 MPa, and according to American Concrete Institute (ACI) standards, lightweight concrete at 28 days strength with ≥17 MPa can be used as structural concrete, and the remaining 75% and 100% replacement concrete can be used for non-structural purposes. This study will help in the development of economical eco-friendly sustainable concrete materials.

Titanium carbide ceramic nanocrystals to enhance the physicochemical properties of natural rubber composites

The mechanical strength of natural rubber (NR) was enhanced by incorporating novel titanium carbide (TiC) nanocrystals as a filling material. The rubber nanocomposites were prepared through mixing TiC nanoparticles with NR latex and the resulting NR/TiC masterbatch was further mixed at the solid stage with other chemicals via internal mixing. The final rubber composites prepared using TiC as the nanofiller were denoted as NR/TiC-0, NR/TiC-0.5, NR/TiC-1.0, NR/TiC-2.5, and NR/TiC-5.0; moreover, a comparative study was conducted using carbon black (CB-330) as the filler and the composites were denoted as NR/CB-1.0 and NR/CB-5.0. As per the results of tensile tests, the NR/TiC-1.0 composite revealed the highest tensile value of 31.13 MPa and this indicated improvement by 92% compared to that of the control (NR/TiC-0 (16.22 MPa)); moreover, it indicated improvements by 73% and 63% compared to the values of NR/CB-1.0 and NR/CB-5.0, respectively. Moreover, scanning electron microscopy (SEM) analysis revealed a better dispersion of the NR/TiC-1.0 composite compared to the other composites. Furthermore, dynamic mechanical analysis (DMA) was conducted to observe the energy storage and loss properties at dynamic conditions; the results revealed that the highest storage peak and lowest loss peak were observed for the NR/TiC-1.0 composite. Also, thermogravimetric analysis revealed the superior thermal stability of the NR/TiC-1.0 composite to that of the others at the NR degradation temperature of around 400 °C. Importantly, the curing time (t₉₀) of NR/TiC-1.0 was reduced considerably compared to that of the other composites even the NR/CB composites, which would be beneficial for industries to save energy at the curing stages of tire-like applications. The improvements were significant when compared to the industrially well-known NR/CB composites and well above the industrially required minimum parameters of the tire industry. Ultimately, this will open up a distinct avenue for natural rubber reinforcement.

The mechanical strength of natural rubber (NR) was enhanced by incorporating novel titanium carbide (TiC) nanocrystals as a filling material.

Relationship between dynamic fatigue crack propagation properties and viscoelasticity of natural rubber/silicone rubber composites

In this paper, dynamic fatigue crack propagation properties of natural rubber/silicone rubber (NR/VMQ) composites are studied under constant tearing energy (G) input. Through dynamic fatigue crack growth testing, it is found that with the increase of VMQ fraction, NR/VMQ exhibits a lower crack growth rate (dc/dN). The viscoelastic parameters have been recorded in real-time during crack propagation, including the storage modulus E', loss factor tan δ, and loss compliance modulus J'', and their relationships with crack propagation behaviour have been established. The improved crack propagation resistance is attributed to the reduced J'', resulting from the synergistic effect of increased E' and decreased tan δ, and thus more energy dissipation occurred in the linear viscoelastic region in front of the crack tip, which consumed part of the energy for crack growth. Finally, good correlation between dc/dN and J'' could be successfully established.

Mechanical Properties and Mullins Effect in Natural Rubber Reinforced by Grafted Carbon Black

The obvious polarity difference between the carbon black (CB) and the natural rubber (NR) causes the CB hard to be dispersed in the NR matrix when the addition amount is large. In this paper, polyethylene glycol (PEG) was grafted onto the surface of CB by the liquid phase. The grafted carbon black (GCB) was prepared and applied to reinforce NR. The main physical and mechanical properties of NR were improved because of the better compatibility between GCB and NR. The Mullins effect of the vulcanizate was calculated by the cyclic stress-strain experiment. The results showed that the Mullins effect both existed in the virgin NR system and filled NR system. The degree of Mullins effect was increased with the increase of the filler addition, but that was different for CB and GCB. When the filler addition was below 20 phr, the Mullins effect of NR/GCB was stronger than that of NR/CB. However, when the filler addition was over 30 phr, the Mullins effect of NR/CB was stronger than that of NR/GCB. The Mullins effect was affected by the heat treatment temperature and time. The mechanisms of the Mullins effect were analyzed.

High yield and simple one-step production of carbon black nanoparticles from waste tires

Carbon black (CB), a material consisting of finely divided particles, can be obtained by the partial combustion of heavy petroleum feedstock. The commercial preparation of CB nanoparticles require sophisticated equipment, chemical pre-treatment, and combination of complex separation and purification techniques. CB nanoparticles can also be recovered from scrubbed rubber, but yields are modest and the process is technically complex. Here, we report the development of a simple and inexpensive method for the preparation of CB nanoparticles from waste tires. Under optimal conditions, the yield of recovered CB nanoparticles (∼22 nm) was of approximately 81%; the nanomaterial presents good thermal stability and conductivity, and forms chain-like agglomerates; chemical composition analysis and solubility tests indicates that it is partly oxidized (C, 84.9%; S, 10.21%; O, 4.9%). The product was fully characterized by FTIR, Raman, TGA, BET, SEM and TEM. This preparation method could become a viable alternative to reduce the large amount of waste tires and decreasing their negative environmental impact, producing good quality CB nanoparticles useful for batteries, sensors, electronic devices, catalysis, pigments, concrete, and plastics, among many other applications.

Multiscale Simulation of Branched Nanofillers on Young's Modulus of Polymer Nanocomposites

Nanoscale tailoring the filler morphology in experiment offers new opportunities to modulate the mechanical properties of polymer nanocomposites. Based on the conventical rod and experimentally available tetrapod filler, I compare the nanofiller dispersion and elastic moduli of these two kinds of nanocomposites via molecular dynamics simulation and a lattice spring model. The results show that the tetrapod has better dispersion than the rod, which is facilitate forming the percolation network and thus benefitting the mechanical reinforcement. The elastic modulus of tetrapod filled nanocomposites is much higher than those filled with rod, and the modulus disparity strongly depends on the aspect ratio of fillers and particle-polymer interaction, which agrees well with experimental results. From the stress distribution analysis on single particles, it is concluded that the mechanical disparity between bare rod and tetrapod filled composites is due to the effective stress transfer in the polymer/tetrapod composites.