Short sisal fiber‐reinforced tire rubber composites: Dynamic and mechanical properties

The world tendency toward using recycled materials demands new products from vegetable resources and waste polymers. In this work, composites made from powdered tire rubber (average particle size: 320 μm) and sisal fiber were prepared by hot‐press molding and investigated by means of dynamic mechanical thermal analysis and tensile properties. The effects of fiber length and content, chemical treatments, and temperature on dynamic mechanical and tensile properties of such composites were studied. The results showed that mercerization/acetylation treatment of the fibers improves composite performance. Under the conditions investigated the optimum fiber length obtained for the tire rubber matrix was 10 mm. Storage and loss moduli both increased with increasing fiber content. The results of this study are encouraging, demonstrating that the use of tire rubber and sisal fiber in composites offers promising potential for nonstructural applications. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 670–677, 2004     

Morphology,mechanical and viscoelastic properties of nitrile rubber/epoxidized natural rubber blends

A new class of blend membranes from blends of nitrile rubber (NBR) and epoxidized natural rubber (ENR) has been prepared and their morphology, miscibility, mechanical, and viscoelastic properties have been studied. The ebonite method was used to study the blend morphology of the membranes. The morphology of the blends indicated a two‐phase structure in which the minor phase is dispersed as domains in the major continuous phase. The performance of NBR/ENR blend membranes has been studied from the mechanical measurements. The viscoelastic behavior of the blends has been analyzed from the dynamic mechanical data. An attempt was made to relate the viscoelastic behavior with the morphology of the blends. Various composite models have been used to predict the experimental viscoelastic data. The area under the linear loss modulus curve was larger than that obtained by theoretical group contribution analysis. The homogeneity of the system was further evaluated by Cole–Cole analysis. Finally, a master curve for the modulus of the blend was generated by applying the time–temperature superposition principle. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1561–1573, 2005     

Tailoring the structure of Kevlar nanofiber and its effects on the mechanical property and thermal stability of carboxylated acrylonitrile butadiene rubber

Water-dispersible hydrolyzed Kevlar nanofibers (hANFs) prepared by acid-assisted hydrothermal treatments of Kevlar nanofibers (ANFs) were first incorporated into carboxylated acrylonitrile butadiene rubber (XNBR) by a latex co-coagulation method. The obtained hANFs maintained the one-dimensional nanofibrous morphology and crystal structure as ANFs. There were amounts of polar groups appearing at the end of hANFs molecular chains after hydrothermal process, which led to the strong hydrogen bonding interaction between the filler and XNBR matrix. The results indicated that hANFs had significant reinforcement effects on the mechanical properties, crosslink density, and thermal stability of XNBR matrix. In comparison with those of neat XNBR, the tensile strength, tear strength, crosslink density, and maximum heat decomposition temperature (T_max) of XNBR/hANFs nanocomposites filled with 7 phr hANFs increased by 236%, 161%, 35%, and 19.64 °C, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47698.     

Experimental analysis of viscoelastic properties in carbon black‐filled natural rubber compounds

Processability and viscoelastic properties of natural rubber (NR) compounds filled with different carbon black loadings and types were investigated with the use of a steady shear rheometer, namely, the Mooney viscometer, and an oscillatory rheometer, namely, the Rubber Process Analyser (RPA2000). It was found that the type and amount of carbon black strongly influence the viscoelastic properties of rubber compounds. Both the dilution effect and filler transient network are responsible for the viscoelastic properties, depending on the vulcanization state. In the case of uncured compounds, the damping factor of the uncured NR decreases with increasing black loading. This is attributed to the reduction of mobilized rubber content in the compound (or the dilution effect). However, in the case of the cured NR vulcanizates, the filler transient network is the dominant factor governing the damping factor of the vulcanizate. With increasing black loading, the damping factor of the vulcanizate clearly increases. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2197–2203, 2005     

Mechanical and dynamical mechanical properties of chloroprene rubber and cellulose II composites

Vulcanized composites of chloroprene rubber (CR) with cellulose II (Cel II) as a filler were investigated. Cel II, obtained by the coagulation of cellulose xanthate, was incorporated in the rubber by the traditional method. The filler content varied from 0 to 30 phr. For comparison purposes, carbon black (CB)–CR composites were also studied. The CB amount varied from 0 to 45 phr. The mechanical and dynamic mechanical properties were determined, and the CR composite containing 20 phr of Cel II showed the best set of properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2425–2430, 2004     

Investigation of new composite materials based on activated EPDM rubber waste particles by liquid polymers

Despite of the variety of existing techniques, there is still a continuous demand in the development of more efficient recycling technologies, for economic and environmental reasons. A new approach for recycling EPDM rubber waste has been recently introduced utilizing a solvent free activation process by addition of liquid polymers (LP). The present study investigates the influence of the content and varying types of activated rubber waste particles (RWP‐LP) in new composites. By varying the proportion of RWP‐LP in the range from 25 up to 75 v/v % information about optimized compositions of new compounds were obtained. It was found that the ratio and type of RWP‐LP induce significant differences in terms of cure characteristics, mechanical properties, crosslink density and morphology. Promising results with high potential application for the production of seal and sealing systems on the industrial scale were obtained by using up to 50 v/v % of RWP‐LP with low ethylene amount. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42097.     

Vinyl-functionalized polyborosiloxane for improving mechanical and flame-retardancy performances of silicone rubber foam composites

In this work, we first synthesized vinyl-terminated polyborosiloxane (pBS) filler, and then incorporated it into silicone rubber foam (SRF) matrix to prepare composite materials through a simple chemical dehydrogenative foaming method under ambient conditions. The pBS filler with reactive groups could form physical and chemical crosslinking networks in SRF, leading to an excellent dispersion level of pBS in the SRF matrix. Moreover, the inserted pBS could remarkably improve the mechanical and flame-retardancy properties of SRF-pBS composites. Intriguingly, the SRF-pBS6 foam containing 6 wt% of pBS possessed a uniform porous structure and balanced mechanical properties (σ_b = 65.4 kPa, ε_b = 56.7%, compression stress 97.1 kPa), thermal conductivity (0.102 W (m K)^?1), limiting oxygen index (29.8%) and UL-94 rating (V-0) among the prepared foams. In addition, the incorporated pBS (6 wt%) could synergistically catalyze the formation of a silicon–boron strengthened ceramic-like protective layer under fire and was capable of suppressing heat and smoke production in the SRF-pBS6 foam. The present work provides a promising way for developing high mechanical and flame-retardant polymeric foam materials with good thermal insulation. © 2021 Society of Industrial Chemistry.     

Vulcanization characteristics and mechanical properties of nitrile rubber filled with short leather fibres

Leather shavings have been used as filler in short fibre form for nitrile rubber reinforcement. Shavings neutralized with sodium bicarbonate and ammonia showed improved vulcanization characteristics and mechanical properties, whereas sodium hydroxide neutralized shavings exhibited poor properties. Swelling of the vulcanizates in water and 1% NaOH was found to increase with leather loading, whereas in MEK a reversed trend was observed. Thermogravimetric analysis indicates that the thermal stabilities of the vulcanizates fall between those of pure leather and gum nitrile rubber vulcanizate.     

Mechanical and dynamic mechanical properties of natural rubber blended with waste rubber powder modified by both microwave and sol–gel method

Waste rubber powder (WRP) was modified by microwave, sol–gel method, and both microwave and sol–gel method, respectively. The mechanical and dynamic mechanical properties of natural rubber (NR)/modified WRP composite were investigated. The influence of bis‐(3‐(triethoxysilyl)‐propyl)‐tetrasulfide (TESPT) content on curing characteristics and mechanical properties of vulcanizate was also studied. The results showed that NR/WRP modified by both microwave and sol–gel method composite owned the best mechanical properties. Rubber processing analyzer was used to characterize the interaction between silica and rubber chains and the dispersion of silica. With increase of TESPT content, the Payne effect decreased. Scanning electron microscopy indicated the coherency and homogeneity of in situ generated silica filled vulcanizate. Dynamic mechanical analyzer showed that NR/WRP modified by both microwave and sol–gel method composite with 5 phr TESPT exhibited the lower tan δ at temperature range of 50–80°C, compared with composite without TESPT and the higher tan δ at temperature of 0°C, compared with the conventional modification of WRP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of carbon black on the mechanical and dielectric properties of rubber ferrite composites containing barium ferrite

Fine particles of barium ferrite (BaFe₁₂O₁₉) were synthesized by the conventional ceramic technique. These materials were then characterized by the X‐ray diffraction method and incorporated in the natural rubber matrix according to a specific receipe for various loadings of ferrite. The rubber ferrite composites (RFC) thus obtained have several applications, and have the advantage of molding into complex shapes. For applications such as microwave absorbers, these composites should have an appropriate dielectric strength with the required mechanical and magnetic properties. The N330 (HAF) carbon black has been added to these RFCs for various loadings to modify the dielectric and mechanical properties. In this article we report the effect of carbon black on the mechanical and dielectric properties of these RFCs. Both the mechanical and dielectric properties can be enhanced by the addition of an appropriate amount of carbon black. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 769–778, 2003     

Effect of bamboo charcoal powder on the curing characteristics,mechanical properties,and thermal properties of styrene–butadiene rubber with bamboo charcoal powder

Compounds of styrene–butadiene rubber (SBR) filled with bamboo charcoal powders (BCPs) were prepared with a laboratory‐sized two‐roll mill. The effects of the BCP loading on the curing characteristics and mechanical and thermal properties were investigated. The results indicate that the addition of BCP resulted in a longer curing time and a higher Mooney viscosity in the SBR materials. The incorporation of BCP into SBR improved the mechanical properties and dynamic properties. Furthermore, the mechanical properties of the vulcanizates after thermal aging were also studied, and the experimental results indicate that most of the mechanical properties improved after thermal aging. The overall results indicate that BCP could be used as a cheaper filler for SBR materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4534–4541, 2013     

Thermal and mechanical properties of liquid silicone rubber composites filled with functionalized graphene oxide

To improve the thermal and mechanical properties of liquid silicone rubber (LSR) for application, the graphene oxide (GO) was proposed to reinforce the LSR. The GO was functionalized with triethoxyvinylsilane (TEVS) by dehydration reaction to improve the dispersion and compatibility in the matrix. The structure of the functionalized graphene oxide (TEVS‐GO) was evaluated by Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD), and energy dispersive X‐ray spectroscopy (EDX). It was found that the TEVS was successfully grafted on the surface of GO. The TEVS‐GO/LSR composites were prepared via in situ polymerization. The structure of the composites was verified by FTIR, XRD, and scanning electron microscopy (SEM). The thermal properties of the composites were characterized by TGA and thermal conductivity. The results showed that the 10% weight loss temperature (T₁₀) increased 16.0°C with only 0.3 wt % addition of TEVS‐GO and the thermal conductivity possessed a two‐fold increase, compared to the pure LSR. Furthermore, the mechanical properties were studied and results revealed that the TEVS‐GO/LSR composites with 0.3 wt % TEVS‐GO displayed a 2.3‐fold increase in tensile strength, a 2.79‐fold enhancement in tear strength, and a 1.97‐fold reinforcement in shear strength compared with the neat LSR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42582.     

Cure characteristics,mechanical, thermal,and coloring properties of natural rubber/dye‐loaded shell powder composites

To explore the application of shell powder (SP) in rubber, a dye‐loaded SP (DSP) bio‐filler based on SP and Congo red was incorporated into natural rubber (NR). The adsorption experiments demonstrated that the maximum monolayer adsorption capacity of Congo red onto SP was 69.3 mg/g. The effect of aluminate coupling agent and DSP was investigated by evaluating the cure characteristics, mechanical, thermal, and coloring properties of NR/DSP composites. It was suggested that the optimum amount of aluminate coupling agent was 2 wt %, and the best tensile strength (24.80 MPa) of vulcanizates was achieved at the DSP content of 20 phr, while other mechanical properties such as tear strength kept increasing with the addition of DSP. Furthermore, the improved thermal stability and uniform color distribution of the NR composites was obtained. The results indicate that DSP is promising to become a low‐cost filler and pigment for rubber materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45750.     

Study on foaming water‐swellable EPDM rubber

A foaming ethylene propylene diene terpolymer (EPDM) water‐swellable rubber (WSR) was prepared using the multicomponent mechanical blending technology. The morphology of unfilled and silica‐filled foaming EPDM WSR was studied from micrographs. The average cell size, maximum cell size, and cell density of the foaming WSR had a peak value with a 4‐phr foaming agent loading in both unfilled and silica‐filled WSR. The addition of silica made the average cell size and maximum cell size decrease and the cell uniform. With incorporation of silica, the tensile strength of the unfoaming WSR increased three times, while that of the foaming WSR increased about six times before immersing it into water. After water‐swelling, the mechanical properties of both the unfilled WSR and silica‐filled unfoaming WSR decreased, but that of the silica‐filled foaming WSR increased. The silica filler accelerated the water‐swelling rate and cut down the water‐swelling equilibrium time at the same time. The foaming WSR had a better volume water‐swelling ratio than that of the unfoaming WSR in both the unfilled and silica‐filled WSR. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3712–3717, 2002     

Mechanical and viscoelastic properties of short fiber reinforced natural rubber composites: effects of interfacial adhesion,fiber loading,and orientation

The effect of a two-component dry bonding system consisting of resorcinol and hexamethylene tetramine on the mechanical and viscoelastic properties of short sisal fiber reinforced natural rubber composites has been studied. The studies were conducted with chemically treated and untreated short sisal fibers. Treated fibers impart better mechanical properties to the composites. By mixing with short fibers, the dynamic storage modulus (E') of natural rubber composites was improved. The effects of fiber-matrix adhesion on the mechanical and viscoelastic properties of the composites were investigated. The storage moduli and mechanical loss increased continuously with an increase in fiber loading but decreased with an increase of temperature. The influence of the fiber orientation on the mechanical and viscoelastic properties is discussed.     

Effect of hollow glass beads on density and mechanical properties of silicone rubber composites

In this work, low density hollow glass beads (HGB)/silicon rubber (SR) composites were prepared by solution method and flocculation process. The prepared samples were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, tensile test, and friction test. The results show that the densities of SR composites decrease from 1.140 to 0.792 g/cm³ with the addition of HGB. By comparing theoretical density with true density, it can be estimated that the ratio of shattered HGB increase from 8.79% to 24.76%. Especially, the mechanical properties of SR composites were improved by surface modification of HGB. By adding surface-modified HGB at 5 and 10 wt%, the tensile strengths of SR composites were enhanced by 17.8% and 28.2%, respectively. In addition, tear strength, shore A hardness, compression set, and friction property were significantly ameliorated. Furthermore, the mechanism of surface-modified HGB in mechanical properties was analyzed.     

Influence of starch on the properties of carbon‐black‐filled styrene–butadiene rubber composites

The influence of starch on the properties of carbon‐black‐filled styrene–butadiene rubber (SBR) composites was investigated. When the starch particles were directly melt‐mixed into rubber, the stress at 300% elongation and abrasion resistance decreased evidently with increasing starch amount from 5 to 20 phr. Scanning electron microscopy observations of the abrasion surface showed that some apparent craters of starch particles were left on the surface of the composite, which strongly suggested that the starch particles were large and that interfacial adhesion between the starch and rubber was relatively weak. To improve the dispersion of the starch in the rubber matrix, starch/SBR master batches were prepared by a latex compounding method. Compared with the direct mixing of the starch particles into rubber, the incorporation of starch/SBR master batches improved the abrasion resistance of the starch/carbon black/SBR composites. With starch/SBR master batches, no holes of starch particles were left on the surface; this suggested that the interfacial strength was improved because of the fine dispersion of starch. Dynamic mechanical thermal analysis showed that the loss factor at both 0 and 60°C increased with increasing amount of starch at a small tensile deformation of 0.1%, whereas at a large tensile strain of 5%, the loss factor at 60°C decreased when the starch amount was varied from 5 to 20 phr. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of palm ash loading and maleated natural rubber as a coupling agent on the properties of palm‐ash‐filled natural rubber composites

Natural rubber composites were prepared by the incorporation of palm ash at different loadings into a natural rubber matrix with a laboratory‐size two‐roll mill (160 × 320 mm²) maintained at 70 ± 5°C in accordance with the method described by ASTM D 3184–89. A coupling agent, maleated natural rubber (MANR), was used to improve the mechanical properties of the natural rubber composites. The results indicated that the scorch time and cure time decreased with increasing filler loading, whereas the maximum torque exhibited an increasing trend. Increasing the palm ash loading increased the tensile modulus, but the tensile strength, fatigue life, and elongation at break decreased. The rubber–filler interactions of the composites decreased with increasing filler loading. Scanning electron microscopy of the tensile fracture surfaces of the composites and rubber–filler interaction studies showed that the presence of MANR enhanced the interfacial interaction of the palm ash filler and natural rubber matrix. The presence of MANR also enhanced the tensile properties and fatigue life of palm‐ash‐filled natural rubber composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and performance of oleylamine modified silica-reinforced natural rubber composites

Oleylamine (OA) modified silica (SiO₂-g-OA) was prepared using γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH560) and OA, silica/natural rubber (NR) and SiO₂-g-OA/NR composites were prepared by mechanical blending in an internal mixer, and SiO₂-g-OA was characterized by Fourier transform infrared spectroscopy, thermal gravimetric analyzer, and contact angle analyzer. The mechanical properties, abrasion resistance, curing characteristics, Payne effect, and morphology of silica/NR and SiO₂-g-OA /NR composites were investigated using universal testing machine, Akron abrasion tester, rubber processing analyzer, and scanning electron microscope, respectively. The results showed that SiO₂-g-OA became more hydrophobic and had better compatibility with NR. Moreover, SiO₂-g-OA/NR had weaker Payne effect, better vulcanization performance, and more excellent mechanical properties. As the content of filler was more than 30 phr, SiO₂-g-OA/NR had lower rolling resistance and higher wet skid resistance. Compared with silica modified by other coupling agents, SiO₂-g-OA had the best reinforcement effect on NR.     

Dynamic mechanical properties of SBR and EPDM vulcanisates filled with cryogenically pulverized flexible polyurethane foam particles

The dynamic mechanical properties of rubber vulcanisates filled with cryogenically pulverized polyurethane foam particles, used as a reinforcing filler, were investigated with respect to storage modulus (E′), loss modulus, and the variation of glass transition temperature. Two rubbers were using styrene–butadiene rubber (SBR) and ethylene–propylene copolymer (EPDM). The effects of filler concentration and filler characteristics (such as particle size and moisture content) were also monitored. It was found that the optimum dynamic mechanical properties of the compounds were obtained when introducing the PU particles of 40–50 parts per hundred (pph) rubber in the SBR and 30 pph in the EPDM, the properties being affected by the size of PU particles and moisture content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1129–1139, 1999