Rubber Blends Research Articles

Construction and Characterization of Multi‐Stimuli Responsive Shape Memory Assisted Self‐Healing Thermoplastic Elastomeric Materials Based on TPU/ENR/Fe3O4 Blends

AbstractIn this work, multi‐stimuli responsive shape memory‐assisted self‐healing thermoplastic elastomeric materials are designed by incorporating Fe3O4 particles in dynamically vulcanized thermoplastic elastomeric materials based on thermoplastic polyurethane (TPU)/epoxidized natural rubber (ENR) blends. A thermodynamic perspective is employed to predict the potential distribution of Fe3O4 in the developed blends in which Fe3O4 is selectively distributed in the ENR phase. Interestingly, the Fe3O4‐loaded TPV exhibited multi‐stimuli responsive shape memory‐assisted self‐healing functionality, more specifically in the presence of an alternating magnetic field, infrared light, and heat. The resulting dynamically vulcanized TPU/ENR/Fe3O4 blends demonstrated healing efficiencies of ≈53%, ≈78%, and ≈69% under oven heat, under a magnetic field, and under infrared light exposure, respectively. Thermal image mapping is used to understand the stimulus‐dependent healing mechanisms. The developed Fe3O4 filled dynamically vulcanized TPV also shows excellent shape memory properties with a shape recovery ratio in the range of 88%–90% under the aforementioned conditions. The incorporation of Fe3O4 possibly induces coordination interactions with zinc dimethacrylate (ZDMA), used as a coagent during dynamic vulcanization, as evidenced by FTIR and XRD analyses, thereby enhancing the functional properties of the developed TPVs.

THE EFFECTS OF SEPIOLITE LOADINGS ON MECHANICAL, THERMAL, AND MORPHOLOGICAL CHARACTERISTICS OF NATURAL RUBBER/EPOXIDISED NATURAL RUBBER (NR/ENR-25) BLENDS

Sepiolite has been used widely as nanofillers to improve the properties and compatibility of rubber blends, and due to its magnesium silicate hydrates contents, the sepiolite may also function as a thermal stabilizer. These works investigate the effects of sepiolite loadings on curing, mechanical, thermal, and morphological characteristics of natural rubber/epoxidized natural rubber (NR/ENR-25) blends. The blends were made using a two-roll mill technique using standard vulcanization reagents of sulfur and carbon black as the main filler, and their vulcanization characteristics were investigated using the rheometry technique. Furthermore, the thermal, mechanical, and morphological characteristics of the blends were evaluated using thermogravimetry, tensile tests, and electron microscopy, respectively. It was found that an increase in the sepiolite loadings decreased scorch times (ts2 and t90), whereas optimum sepiolite loading with higher tensile strength was 3 phr, which lowered down when the sepiolite loading was increased up to 9 phr. The thermogram of blend specimen with 3 phr sepiolite loading also exhibited superior thermal stability, that is, has higher degradation temperature at 5% weight loss. Fracture surface SEM photographs of the blend specimens showed finely distributed sepiolite particles at optimum sepiolite loading 3 phr and exhibited agglomerations when the loadings were increased up to 9 phr.

β-crystals aied greater energy absorbing ethylene–propylene rubber in polypropylene blends for outstanding low-temperature toughness

β-crystals aied greater energy absorbing ethylene–propylene rubber in polypropylene blends for outstanding low-temperature toughness

Excellent compatibilization effect of (ENR/PP-g-MA) as a dual reactive compatibilizer on the immiscible thermoplastic elastomer based on nitrile rubber and polypropylene blends: Insights from experimental and computational studies

Excellent compatibilization effect of (ENR/PP-g-MA) as a dual reactive compatibilizer on the immiscible thermoplastic elastomer based on nitrile rubber and polypropylene blends: Insights from experimental and computational studies

Reconstruction of crosslinked network in terminal blend rubber powder modified asphalt with BR to enhance thermal storage stability and rheological properties

Reconstruction of crosslinked network in terminal blend rubber powder modified asphalt with BR to enhance thermal storage stability and rheological properties

New Chloroprene Rubber/Styrene-Butadiene Rubber (CR/SBR) Blends Cross-Linked with Tin(II) Oxide (SnO): Curing Characteristics, Swelling Studies, Mechanical Properties, and Flame Resistance.

This study aimed to investigate the properties of tin(II) oxide (SnO) as an unconventional cross-linking agent for chloroprene (CR) and styrene-butadiene (SBR) rubbers compositions. The use of tin(II) oxide results from the need to reduce the use of zinc oxide as a cross-linking agent due to environmental regulations and its toxic impact on aquatic environments. The studied elastomeric blends can be cross-linked with tin(II) oxide, and the results demonstrate the significant potential of this oxide in such applications. The CR/SBR vulcanizates cross-linked with SnO exhibit good mechanical properties and a high degree of cross-linking. The studies clearly show that the proportions of both rubbers as well as the amount of tin(II) oxide used influence the cross-linking of the CR/SBR blends and the properties of vulcanizates. FTIR spectrum analysis allowed the identification of the cross-linking mechanism, which followed the Friedel-Crafts alkylation reaction mechanism. The AFM analysis determined the miscibility of the rubbers and interelastomeric reactions, proving that the rubbers studied are partially miscible. The results of the oxygen index measurements indicated that the obtained vulcanizates showed flame resistance and self-extinguishing properties. Multivariate regression was performed to fit the models to the experimental value and to determine the influence of the content of the cross-linking agent and the CR and SBR proportions on the properties of the blends.

Unleashing the Power of Nanoparticles: Enhancing Natural Rubber (NR)/Nitrile Butadiene Rubber (NBR) Blends for Ultimate Performance

Our research described in this article examined the physical aging of natural rubber (NR) and nitrile rubber (NBR) compounds reinforced with nano-silica (n-SiO2) particles. The impact of NR and nano-silica content on the mechanical, spectral, and thermal properties of the composites was assessed using Shore hardness, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results showed that after 8 days of aging in toluene or xylene at room temperature, high NR content caused significant swelling in the non-polar solvents, unlike NBR, which prevented rubber chain stretching and reduced the free volume. The transport mechanism of the toluene and xylene was pseudo-Fickian and slightly dependent on the nano-silica content. The hardness of the vulcanized blends increased with NBR and silica incorporation due to better dispersion of the particules and rubber-filler interaction, leading to high cross-linking density. XRD patterns confirmed the filler intercalation within the polymer matrix, causing a diffraction shift to a lower 2θ value of the various reflectures. Differential thermogravimetric analysis (DTGA) revealed that the n-SiO2 nanoparticles enhanced the thermal stability due to strong polymer chain interactions. These findings suggest that nano-silica-filled NR/NBR blends have significantly improved physical, mechanical, and thermal properties, supporting their potential for advanced elastomer-based materials in industrial applications.

Reactive compatibilization of zinc dimethacrylate on dynamically vulcanized thermoplastic polyurethane/silicone rubber blends

AbstractThermoplastic polyurethane (TPU)/silicone rubber (SR) thermoplastic vulcanizates (TPVs) are considering to be a promising material for smart wearable technologies due to its low temperature and high temperature resistance and biological affinity. However, the poor compatibility between TPU and SR phases limits its practical application. In this paper, TPU/SR TPVs were prepared through dynamic vulcanization and zinc dimethacrylate (ZDMA) was used to improve the interface between TPU and SR phases. FTIR results and theoretical calculation showed that complex reactions including the graft‐polymerization of ZDMA occurred onto the main chains of TPU and SR in the presence of peroxides to form a strong interface and improve the compatibility. Dynamic mechanical analysis implied the difference of glass transition temperature of the two phases reduced from 86.4 to 67.3°C with the addition of 5 wt% of ZDMA compared to original TPVs. Scanning electron microscope showed that with the addition of 5 wt% ZDMA, the crosslinked SR phase formed a network structure when TPU phase was etched with dimethyl sulfoxide. By adding 5 wt% of ZDMA, the torques during mixing, tensile strength, and tear stress of TPVs were improved by 150%, 273%, and 217% respectively, compared to the TPVs without ZDMA.Highlights The compatibility between TPU and SR was improved by adding ZDMA. The mechanism for ZDMA enhancing the interface of TPU/SR TPVs was discussed. The addition of ZDMA improves the mechanical properties of TPU/SR TPVs. An appropriate loading of ZDMA used for TPU/SR TPVs was discussed.

Effects of Ethylene Propylene Diene Monomer (EPDM)-Based Polar Macromolecular Compatibilizers on the Low-Temperature Properties of Fluoroelastomer/EPDM Rubber Blends.

Integrating rubber with superior low-temperature capabilities, such as ethylene propylene diene monomer (EPDM), is a strategic approach to bolster the low-temperature performance of fluoroelastomer (FKM). However, FKM and EPDM are thermodynamically incompatible. This work synthetized three EPDM-based polar macromolecular compatibilizers, epoxidized EPDM (EPDM-EP), 2,2-trifluoroethylamine-grafted epoxidized EPDM (EPDM-TF), and 2,4-difluorobenzylamine-grafted epoxidized EPDM (EPDM-DF), to enhance the compatibility between FKM and EPDM. These compatibilizers were subsequently incorporated into FKM/EPDM rubber blends. The results revealed that the glass transition temperature (Tg) of FKM/EPDM decreased by 1.3 °C, 2.68 °C, and 2.78 °C, respectively, upon the addition of 10 phr of EPDM-EP, EPDM-TF, or EPDM-DF. Moreover, the Tg of the two phases converged. The tensile strength, elongation at break, and tear strength of the FKM/EPDM rubber blends were also enhanced by the inclusion of these compatibilizers. Notably, EPDM-TF and EPDM-DF exhibited remarkable compatibilization effects due to an increase in polarity. This research not only sheds light on the potential for developing new compatibilizers but also paves the way for innovative applications of FKM and its derivatives.

Effect of deep eutectic solvents on vulcanization kinetics and strain-softening behavior of natural rubber/styrene-butadiene rubber

Natural rubber/styrene-butadiene rubber (NR/SBR) blends are widely used as tyre sidewall compounds; however, discrepancies in vulcanization rates and the selective distribution of vulcanization additives in SBR and NR contribute to suboptimal dynamic properties. In this study, we propose a straightforward strategy to modulate the multi-scale structure in NR/SBR blends by incorporating an ionic liquid-like deep eutectic solvent (DES) as a novel reactive vulcanization agent. The addition of DES substantially enhances the dispersion of ZnO within NR/SBR blends, accelerates the vulcanization process of SBR and the NR/SBR blend and increases their crosslinking densities. Furthermore, DES interacts with the non-rubber components of NR, facilitating the vulcanization of NR. The impact of DES on the linear and non-linear rheological behavior of NR, SBR and NR/SBR vulcanizates is minimal, except for an enhancement in weak strain overshooting. The distribution of DES within NR/SBR blends can be manipulated by varying the mixing sequence of DES with NR and SBR, while selectively positioning DES within the SBR phase may synchronise the vulcanization rates of the NR/SBR blend, thereby improving tensile strength and reducing mechanical hysteresis. This approach may provide a viable method for producing NR/SBR blend products characterised by high strength and low hysteresis energy.

The Flexural Strength and the Effect of the Autoclave Sterilization of Polypropylene/Natural Rubber Blended Materials.

Background: Rubber dam clamps are used extensively in dentistry, especially during root canal treatment. However, existing rubber dam clamps have several drawbacks, including discomfort and potential damage to vital tissue in the oral cavity. To address these existing issues, a new rubber dam clamp should be developed. The aim of this study was to identify the optimum ratios of polypropylene and natural rubber (PP/NR) for a customized rubber dam clamp in dentistry. This study was focused on the flexural strength of PP/NR in various ratios. Moreover, the impact of autoclave sterilization was also considered. Methods: Six proportions of PP/NR blends (100/0, 90/10, 80/20, 70/30, 60/40 and 50/50) were prepared and assessed for flexural strength using a three-point bending test. After this test, the PP/NR blends with 100/0, 90/10 and 80/20 ratios were selected and underwent autoclave sterilization for 1, 5 and 10 cycles. Eventually, the flexural strength testing was repeated and investigated. An analysis of variance and Tukey's test were used to evaluate the flexural strength of various PP/NR blends before autoclave sterilization at p < 0.05. An analysis of variance and Dunnett's T3 test were used to evaluate the flexural strength of selected PP/NR blends before and after autoclave sterilization at p < 0.05. Results: The results revealed that the flexural strength of PP/NR blended materials showed a statistically significant difference in every group of this study. The autoclave sterilization test revealed that the flexural strength of the PP/NR 90/10 and 80/20 ratios was significantly increased after sterilization for 1, 5 and 10 cycles. In addition, the PP/NR 90/10 ratio was also comparable to the 100/0 ratio. The lower NR content in PP/NR blends resulted in significantly higher flexural strength, and autoclave sterilization had an effect on this property. Conclusions: This study suggested that the PP/NR blend with a 90/10 ratio might be considered as an alternative material for developing rubber dam clamps.

Study on the effect of halloysite nanotubes on the mechanical properties and swelling resistance of ethylene-propylene diene monomer (EPDM)/nitrile butadiene rubber (NBR) blend nanocomposites

Abstract Research was undertaken to explore the alteration of natural halloysite nanotubes (HNTs) using a blend of resorcinol and hexamethylenetetramine (RH), (γ-aminopropyl) triethoxysilane (APTES), and diethoxydimethyl silane (DMS). This investigation delved into the impact of incorporating various proportions of RH-modified HNTs (RH-HNTs), APTES-modified HNTs (APTES-HNTs), DMS-modified HNTs (DMS-HNTs), and unmodified HNTs into ethylene propylene diene monomer (EPDM) and nitrile butadiene rubber (NBR) for their potential as seal materials. The study assessed key properties such as tensile strength, stress at 100% elongation, elongation at break, compression set, hardness, and swelling and abrasion resistance to gauge the influence of HNT additions. As nanofiller content increased, the crosslinking rate rose, while scorch time and optimum cure time decreased. Findings indicated that incorporating nanofillers at 6 phr compositions notably enhanced composite strength initially, with a subsequent slight reduction. However, rebound resilience diminished with increasing filler content, though composite hardness experienced a slight improvement. Mole percent uptake decreased, particularly at higher filler loadings. Notably, systems containing 6 phr RH-HNTs exhibited a 140% increase in tensile strength. FESEM micrographs depicted a rough fracture surface with well-dispersed nanofillers within EPDM/NBR. Additionally, compression set data illustrated enhanced composite performance under compression, crucial for seal applications.&amp;#xD;

Advanced and sustainable EMI shielding composites: Natural rubber-nitrile rubber blends enhanced with hydrothermally synthesized Polyaniline Nanofibers and spinel strontium ferrites

Conductive fillers, such as metals and carbon compounds, often exhibit lower compatibility with polymer matrices, leading to agglomeration phenomena that negatively impact the processing and performance of composites. Polyaniline (PANI) nanofibers, with their high conductivity, rapidly create conductive pathways upon contact, reducing current leakage and dielectric loss in composites. To address the compatibility challenges between fillers and matrices, this study adopts a simple, cost-effective approach for synthesizing highly efficient EMI shielding composites. Specifically, we employ hydrothermal synthesis to enhance the properties of PANI nanofibers and spinel strontium ferrites, significantly improving their performance as filler particles. By modifying the morphology of the conductive fillers and incorporating magnetic particles wrapped with an insulating polymer layer, we enhance filler-matrix compatibility. Notably, the synthesized system is a composite made of natural rubber, highlighting its relevance and importance in the current era. This approach not only improves compatibility but also leverages the sustainable properties of natural rubber, making it a significant advancement in the field of EMI shielding materials. In this paper, we report a flexible EMI shielding composite with efficient EM wave absorption, prepared using a natural rubber-nitrile rubber blend as the matrix, and hydrothermally synthesized improves polyaniline nanofibers and spinel strontium ferrite as functional fillers. The shielding efficiency (SET) increases up to 36 dB with different PANI-SrFe2O4wt percentages. This demonstrates the potential of composite for high-performance applications.

Effect of Butadiene Rubber Crystallization on Low-Temperature Properties of Butadiene/Silicone Rubber Blends with Potential for Mars Applications

This study explores the impact of butadiene rubber (BR) crystallization on the low-temperature properties of butadiene/silicone (VMQ) rubber blends (BR/VMQ) designed for Martian applications. Two types of BR, semi-crystalline high-cis Buna CB24 and amorphous Buna CB550, were blended with VMQ, and their mechanical and thermal properties were evaluated. Kinetics of vulcanization, static mechanical properties, dynamical mechanical analysis, thermal shrinkage, and differential scanning calorimetry were utilized. The research demonstrates that the semi-crystalline BR improves mechanical properties but induces greater shrinkage at low temperatures. Conversely, using amorphous BR provided more consistent mechanical properties across the Martian temperature range and reduced material shrink by 6.71% for samples with carbon black, by 8.36% for samples with silica, and by 11.63% for unfilled samples. Future research will be required to evaluate the impact of volume change on the sealing properties of the BR/VMQ blends.

Synthesis of ion exchange film based on chemical grafting of styrene onto polyethylene/EPDM rubber blend for thorium removal.

Chemical grafting of low-density polyethylene film blended with ethylene propylene diene monomer rubber (PE/EPDM) using styrene monomer followed by a sulfonation process was investigated. Different factors affecting the grafting process, such as monomer and initiator concentrations, time of reaction, and grafting temperature, were studied. Sulfonation of the grafted films was carried out using chlorosulfonic acid in dichloromethane. Characterization of the grafted and sulfonated films was performed using ATR-FTIR, SEM, TGA, and XRD instruments. The grafting was successfully performed in aqueous media using sodium bisulfite as initiator, reaching a grafting yield of 130% and an ion exchange capacity of 1.2 meq/g. The removal of thorium ions from aqueous solution was studied using the obtained ion exchange films. The results showed that the maximum adsorption capacity of Th(IV) was 177.5 mg. g-1 (pH = 3, 298 K and 60 min). Removal isotherm and Kinetics were investigated, and the results revealed that the adsorption process was chemisorption homogeneous monolayer adsorption, exothermic, and spontaneous.

Tensile and Elastocaloric Properties of Natural/Devulcanized Waste Rubber Blends.

The need for eco-friendly cooling materials and material recycling are two urgent challenges to address. In this paper, the role of the ground tyre rubber treatment (cryo-grinding and devulcanization) is investigated on the tensile and elastocaloric properties of Natural rubber (NR)/ ground tyre rubber (GTR). The GTR particles that are sieved (<63µm) and devulcanized by microwave irradiation (1 min at 800Watts) exhibit a low network chain density (0.53 × 10-4mol.cm-3) resulting from crosslinks breakage and rubber chains scission, as supported by FTIR showing a decrease of S─S, C─S, and C─C bonds. The NR/GTR blends show a high elastocaloric effect as compared to the pristine NR, which can be ascribed to the high content of carbon black in the GTR (52wt.%) and also the high level of devulcanization of the GTR. NR/GTR blends reach a heating of +8°C and a cooling of >-6°C, resulting in a material's coefficient of performance COPmat = 2.8-3 compared to 2.6 for the pristine NR. The concomitant effect of cryogrinding and microwave devulcanization is proposed as a way to improve the tensile and elastocaloric properties of natural rubber/waste rubber blends for their possible integration into elastocaloric devices for heating/cooling applications.

Solid-state NMR of vulcanized natural rubber/butadiene rubber blends: Local organization and cross-linking heterogeneities

Elastomer blends, among which natural rubber (NR) and butadiene rubber (BR), are involved in many components of the automotive/tire industry. A comprehensive understanding of their mechanical behavior requires, among other features, a detailed description of the cross-link density in these mixtures. In the case of vulcanized immiscible blends, the distribution of the cross-link density within each of the NR- and BR-rich domains is key information, but difficult to determine using the conventional approaches used for one-component cross-linked elastomers. In this study, the vulcanization within NR/BR blends is investigated using a robust 1H double-quantum (DQ) MAS recoupling experiment, BaBa-xy16. Two kinds of cross-linked NR/BR blends were considered with two different microstructures for the BR component. The bulk organization of the resulting blends was first probed by analyzing the 1H spin-lattice relaxation behavior. In a second step, BaBa-xy16 was used to investigate, in a selective way, the cross-link heterogeneities within NR/BR blends. In particular, for immiscible NR/BR mixtures, the distribution of the cross-link density between both phases was compared and the observed differences were discussed.

Control by the curing time of the strain induced crystallization and elastocaloric properties in natural rubber and natural/waste rubber blends

This study provides a systematic investigation of the influence of the curing time on strain-induced crystallization (SIC) and elastocaloric (eC) effect in peroxide-cured natural rubber (NR) and NR/ground tyre rubber (GTR) blends. To do so, materials were prepared with three distinct curing times (t10, t50, and t90). Results reveal that extended curing times correlate with increased network hardness and elastic modulus, promoting the number of elastically active chains. GTR fillers accelerate vulcanization but reduce final network chain density due to their partially devulcanized state and their contribution to the vulcanization of the blends. Both SIC and eC effects improve with curing time, with properties at t50 closely matching those at t90, indicating an optimal crosslink density at such times. The temperature span during mechanical cycling increases linearly with curing time, largely unaffected by GTR presence. The material's coefficient of performance (COP) peaks at t50, suggesting this curing time offers the best balance between mechanical energy dissipation and temperature change, highlighting its potential for eco-friendly heating/cooling applications.

Influence of Tire Reclaimed Rubber (TRR) Loadings on Cure Characteristics and Mechanical Properties of Natural Rubber/Styrene Butadiene Rubber (NR/SBR) Blends

This investigation delves into the potential utilization of Tire Reclaimed Rubber (TRR) as a filler within Natural Rubber/Styrene Butadiene Rubber (NR/SBR) blends. TRR is obtained from discarded rubber tires and stands as a pertinent resource that necessitates its effective utilization in the production of eco-friendly, value-added rubber-based products. This is due to the rising of rubber waste tires which causes environmental concerns and all sorts of pollution. The TRR filled NR/SBR blends were fabricated using two-roll mills. The loadings of TRR were varied ranging from 20 phr to 100 phr. The aim of this study is to investigate the influence of TRR loading on the curecharacteristics and mechanical properties of blends in terms of tensile strength, rebound resilience, hardness, and density. It is found that the MH and Δ torque exhibited a decreasing trend which would indicate a reduction in crosslink density due to high loading of TRR. Meanwhile, the ts2 and tc95 increased with the increase of TRR loading. Furthermore, the tensile strength, hardness, density, and rebound resilience of blends experience a steady reduction with the incorporation of TRR. The decrement of those properties might be due to the low molecular weight of TRR. Regarding the collective findings, TRR emerges as a potentially viable candidate for waste rubber repurposing, serving as a non-reinforcing filler with optimal utility achieved at a 30 phr loading level.

Blends of polydimethylsiloxane-based polyurethane and poly (propylene glycol)-based polyurethane with co-continuous structures: Morphology evolution, synergistic effects and application in strain sensors

Blending is an effective way to improve properties of rubbers and develop new materials, so more than 75 % of the rubber consumption in the world is rubber blend. However, blending of thermoplastic elastomers has not yet been emphasized, and few successful examples have been reported. The main challenge for blend systems is compatibility of two components. Herein, a series of (polydimethylsiloxane-based PU)-g-(poly (propylene glycol)-based PU) ((PDMS-PU)-g-(PPG-PU)) graft copolymers with different graft chain lengths and hard segment contents (HSC) were synthesized and utilized as compatibilizers of PDMS-PU/PPG-PU blends. The influence of the structure of compatibilizers on the morphology of blends was investigated, and the compatibilization mechanism was proposed. With the solubilization, the phase structure of blends transforms from “droplet-in-matrix” morphologies to co-continuous ones, and the average size of PPG-PU dispersed phase decreases from 3.5 ± 0.45 μm to 230 ± 60 nm. This is the first time that thermoplastic PDMS-PU/PPG-PU blends with co-continuous structures have been successfully prepared. The properties of blends exhibit synergistic effects. For example, they show high tensile strength of PPG-PU in mechanical properties and unique properties of PDMS in dynamic mechanical properties, weather resistance, water resistance and biocompatibility. In addition, strain sensors were fabricated by introducing carbon nanotubes (CNTs) into the blends, which demonstrated remarkable sensing capability for diverse human body motions.