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![Chemical structure of both silane types (a) and structure of the chemical polymer‐silica bonding by Si 75 (b). [Color figure can be viewed at wileyonlinelibrary.com]](profile/Manfred-Klueppel/publication/335468068/figure/fig1/AS:11431281254106506@1719030060087/Chemical-structure-of-both-silane-types-a-and-structure-of-the-chemical-polymer-silica.png)
Chemical structure of both silane types (a) and structure of the chemical polymer‐silica bonding by Si 75 (b). [Color figure can be viewed at wileyonlinelibrary.com]
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The mechanical performance of natural rubber (NR), synthetic poly‐isoprene rubber (IR), and styrene–butadiene rubber (SBR) composites filled with various silica/silane systems is investigated. The results are analyzed by referring to micro‐mechanical material parameters, which quantify the morphological and structural properties of the polymer and...
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Citations
... thus affording low roll resistance, high wear resistance, and low energy consumption for rubber materials [15][16][17][18][19]. However, the silica has a small particle size, and its surface contains abundant hydroxyl groups, resulting in the easy adsorption and aggregation of common tread rubbers, such as natural rubber (NR), styrene butadiene rubber (SBR), and butadiene rubber (BR) [20][21][22]. ...
Silica, as a high-quality reinforcing filler, can satisfy the requirements of high-performance green tread rubber with high wet-skid resistance, low rolling resistance, and low heat generation. However, the silica surface contains abundant silicon hydroxyl groups, resulting in a severe aggregation of silica particles in non-polar rubber matrix. Herein, we explored a carbon black (CB)/silica hybrid reinforcing strategy to prepare epoxidized natural rubber (ENR)-based vulcanizates. Benefiting from the reaction and interaction between the epoxy groups on ENR chains and the silicon hydroxyl groups on silica surfaces, the dispersion uniformity of silica in the ENR matrix was significantly enhanced. Meanwhile, the silica can facilitate the dispersity and reinforcing effect of CB particles in the ENR matrix. By optimizing the CB/silica blending ratios, we realized high-performance ENR vulcanizates with simultaneously improved mechanical strength, wear resistance, resilience, anti-aging, and damping properties, as well as reduced heat generation and rolling resistance. For example, compared with ENR vulcanizates with only CB fillers, those with CB/silica hybrid fillers showed ~10% increase in tensile strength, ~20% increase in elongation at break, and ~20% increase in tensile retention rate. These results indicated that the ENR compounds reinforced with CB/silica hybrid fillers are a promising candidate for high-performance green tread rubber materials.
... 8,19,29 Silane coupling agents provide efficient reinforcement by improving the dispersion of the filler by reducing filler-filler interactions and increasing the compatibility of the filler with the rubber. 8,30,31 Vishvanathperumal and Anand 8 studied the effect of nano-silica on the mechanical properties and swelling resistance of EPDM/SBR nanocomposites with and without (triethoxysilyl)propyl]tetrasulfide (TESPT). The results showed that the mechanical and swelling properties were improved for composites with TESPT than for those without TESPT. ...
In this study, ethylene propylene diene rubber (EPDM)/ styrene–butadiene rubber (SBR) blend nanocomposites filled with alumina (Al2O3) nanoparticles were prepared. Al2O3 nanoparticles were used with or without surface treatment by the silane coupling agent bis[3 (triethoxysilyl)propyl]tetrasulfide (TESPT), and Al2O3 nanoparticle-filled EPDM/SBR was compared with carbon black (CB). The influences of the filler type, size, concentration, and surface property on the curing characteristics, degree of filler dispersion, mechanical properties, and morphological characteristics of the EPDM/SBR nanocomposites were investigated. We found that the mechanical and curing properties of the nanocomposites were enhanced owing to the presence of Al2O3 nanoparticles. The addition of the silane coupling agent further improved the properties of the nanocomposites.
... It is noteworthy, that the former resembles the typical shape of a rubber compounded with silica using a chemical coupling agent, while the latter resembles a rubber compounded with "raw" or silane-covered silica, see e.g. [55]. Figure 15a shows the residual strain of the third cycle, determined by extrapolating the receding curve via a Neo-Hookean material law to zero stress, as lined out in [7], vs. maximum applied stress. ...
Many theories on the origin of rubber reinforcement have been presented over the last decades. None of them explains beyond reasonable doubt why the dispersion of carbon black into a polymer matrix induces an immense improvement of ultimate properties.
We present a throughout analysis of ethylene-propylene-diene rubber (EPDM), filled with carbon blacks treated at temperatures between 900 °C and 2500 °C. The fillers are investigated extensively using static gas adsorption, transmission-electron microscopy and elemental analysis. Afterwards, correlations between filler surface properties of the filler and properties of the compounds are drawn with a special focus on large-strain softening effects (Mullins’ softening). The latter successively vanishes with temperature treatment of carbon black. Moreover, the softened samples do not recover at temperatures below 100 °C or by swelling. A very simple model involving a stress-limiting process at the polymer-filler interface is derived, which reproduces the experimental results well. Equilibrium hysteresis is found to be originated in physical interaction only. It turns out that the softening-generating effect (“reinforcement”) is best explained by chemical filler-polymer bonds, successively breaking down during stretching, and low-strain modulus and equilibrium hysteresis by physical compatibility.
... Hence, composites based on IR could be the ideal alternative to NR in some fields. 25 Actually, the synthesized IR has already been used in automobile tires, rubber hose, and shoemaking in replace of NR with comprehensive performances. 26,27 To date, unfortunately not all NR could be replaced by IR in all fields, especially in highperformance aircraft tires because the IR composites prepared by traditional dry mixing method is still short for requirements. ...
In this work, well-dispersed fumed SiO2/cis-1,4-polyisoprene rubber (IR) masterbatch was first obtained through an effective wet mixing method, and the properties of the corresponding vulcanizate were studied. Before curing with activator and sulfur, IR solution was blended and co-coagulated with SiO2 suspension modified by bis(3-trimethoxysilypropyl) tetrasulfide in n-hexane. The modification of TESPT imparted evenly distributed SiO2 particles in IR and improved interfacial binding among SiO2 and IR. Hence, the prepared compound presented better processability and the corresponding vulcanizate presented higher physical performance, including higher tensile strength, lower heat buildup, and better fatigue resistance than that prepared in the dry mixing method. Additionally, higher wet skid resistance and lower rolling resistance could be observed in fabricated SiO2/IR vulcanizate. The employed wet mixing method is economical and efficient, which is promising in preparing rubber composites with comprehensive performance.
... It is noteworthy, that the former resembles the typical shape of a rubber compounded with silica using a chemical coupling agent, while the latter resembles a rubber compounded with "raw" or silane-covered silica, see e.g. [55]. Figure 15a shows the residual strain of the third cycle, determined by extrapolating the receding curve via a Neo-Hookean material law to zero stress, as lined out in [7], vs. maximum applied stress. ...
Many theories on the origin of rubber reinforcement have been presented over the last decades. None of them explains beyond reasonable doubt why the dispersion of nanoscopic carbon black into a polymer matrix induces an immense improvement of ultimate properties. We present a throughout analysis of ethylene-propylene-diene rubber (EPDM), filled with carbon blacks treated at temperatures between 900 °C and 2500 °C. The fillers themselves are investigated extensively using static gas adsorption, transmission-electron microscopy and elemental analysis. Afterwards, correlations between filler surface properties of the filler and final properties of the compounds are drawn with a special focus on large-strain softening effects (Mullins' softening). True softening, expressed by a significant decrease of cross-link density and a reduction of large-strain modulus, successively vanishes with temperature treatment of carbon black. Moreover, the softened samples do not recover at temperatures below 100 °C or by swelling in cyclohexane. A very simple model involving a stress-limiting process at the polymer-filler interface is derived, which reproduces the experimental results well. Equilibrium hysteresis is found to be originated in physical interaction only. Finally, theories concerning rubber reinforcement are benchmarked against the results of this work. It turns out that reinforcement is best explained by chemical filler-polymer bonds, successively breaking down during stretching, and low-strain modulus and equilibrium hysteresis by physical compatibility.
... The differences between both approaches will be evaluated by comparing fitting results obtained for stress-strain cycles of ethylene-propylene-diene monomer rubber (EPDM) composites with various thermo-oxidative aging histories, which will be analyzed by the variation of fitting parameters. This is in close relation to recent investigations of the structure-property relationships of silica/silane formulations in different rubber composites [27] delivering microscopic information about the material properties of the systems. Finally, we will introduce a frame-invariant version of the stress-softening part of the DFM that allows for an easy implementation into a finite element code for fast finite element (FEM) applications of the isotropic discontinuous damage effects in engineering rubber science. ...
... The adaptation of stress-strain cycles to Equation (28) , where mod, and exp, represent the th model and experimentally obtained 1. Piola-Kirchhoff ("engineering") stress data point. The set stress parameter sset,0 was included in the fitting procedure as defined by referring to Equation (27). The remaining two stress contributions of Equation (28), which involve seven fitting parameters, were obtained iteratively by using Equations (4)-(6) for the intrinsic stress of the rubber matrix , and Equations (24), (25) for the evaluation of cluster stress , . ...
A micromechanical concept of filler-induced stress-softening and hysteresis is established that describes the complex quasi-static deformation behavior of filler reinforced rubbers upon repeated stretching with increasing amplitude. It is based on a non-affine tube model of rubber elasticity and a distinct deformation and fracture mechanics of filler clusters in the stress field of the rubber matrix. For the description of the clusters we refer to a three-dimensional generalization of the Kantor–Webman model of flexible chain aggregates with distinct bending–twisting and tension deformation of bonds. The bending–twisting deformation dominates the elasticity of filler clusters in elastomers while the tension deformation is assumed to be mainly responsible for fracture. The cluster mechanics is described in detail in the theoretical section, whereby two different fracture criteria of filler–filler bonds are considered, denoted “monodisperse” and “hierarchical” bond fracture mechanism. Both concepts are compared in the experimental section, where stress–strain cycles of a series of ethylene–propylene–diene rubber (EPDM) composites with various thermo-oxidative aging histories are evaluated. It is found that the “hierarchical” bond fracture mechanism delivers better fits and more stable fitting parameters, though the evolution of fitting parameters with aging time is similar for both models. From the adaptations it is concluded that the crosslinking density remains almost constant, indicating that the sulfur bridges in EPDM networks are mono-sulfidic, and hence, quite stable—even at 130 °C aging temperature. The hardening of the composites with increasing aging time is mainly attributed to the relaxation of filler–filler bonds, which results in an increased stiffness and strength of the bonds. Finally, a frame-independent simplified version of the stress-softening model is proposed that allows for an easy implementation into numerical codes for fast FEM simulations
The increase in static stiffness of rubber pad during winter in cold regions reduces track elasticity and ride comfort. To improve low‐temperature properties, a rubber pad was prepared using a blend of polybutadiene rubber (BR) and styrene–butadiene rubber (SBR). The effects of the blending ratio on the low‐temperature and mechanical properties of the rubber pad were analyzed using a material testing machine, a differential scanning calorimeter, and a dynamic mechanical analyzer. The static stiffness change rate at low temperatures ( R LT ) of rubber pads prepared from NR, BR, and SBR were 27.3%, 651.6%, and 52.6%, respectively. The rubber blending had a great effect on the R LT . The results showed that the R LT of the SBR/BR blend was lower than that of natural rubber (NR)/BR and NR/SBR blends. The SBR and BR showed good compatibility, while the crystallinity of BR was destroyed, and the glass‐transition temperature of SBR decreased in the SBR/BR blend. At an SBR/BR blending ratio of 60/40, the R LT was 15.6% at −35°C and other properties met the required standards. This work can provide help for the development of rubber pad with excellent low‐temperature properties.
Abstract
Copolymer thin films of isoprene with acrylic acid were synthesized using PECVD. In that way, the stretchable functionality of polyisoprene (PI) was combined with the hydrophilic functionality of poly(acrylic acid) (PAA) to obtain stretchable thin films with adjustable wettabilities. Deposition rates were found to change between 9 and 5.5 nm/min depending on the monomer flowrates. The analysis of water contact angle (WCA) values indicated that films having more AA units in their structures were more wettable. The stretchability of the films was assessed on laboratory gloves through stretch-release test and on PET sheet through bend-release test. No significant changes in the WCA values with no observable cracks and failures after successive tests were indication of stretchability of the copolymer films.
