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     

Preparation of thermoplastic vulcanizates based on waste crosslinked polyethylene and ground tire rubber through dynamic vulcanization

An environmental‐friendly approach called high‐shear mechanical milling was developed to de‐crosslink ground tire rubber (GTR) and waste crosslinked polyethylene (XLPE). The realization of partial devulcanization of GTR and de‐crosslinking of XLPE were confirmed by gel fraction measurements. Fourier transform infrared spectral studies revealed that a new peak at 1723.3 cm^?1 corresponds to the carbonyl group (? C?O) absorption was appeared after milling. The rheological properties showed that the XLPE/GTR blends represent lower apparent viscosity after mechanical milling, which means that the milled blends are easy to process. Thermoplastic vulcanizates (TPVs) could be prepared with these partially de‐crosslinked XLPE/GTR composite powders through dynamic vulcanization. The mechanical properties of the XLPE/GTR composites increased with increasing cycles of milling. The raw XLPE/GTR blends could not be processed to a continuous sheet. After 20 cycles of milling, the tensile strength and elongation at break of XLPE/GTR (50/50) composites increased to 6.0 MPa and 185.3%, respectively. The tensile strength and elongation at break of the composites have been further improved to 9.1 MPa and 201.2% after dynamic vulcanization, respectively. Re‐processability study confirmed the good thermoplastic processability of the TPVs prepared. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Partial replacement of EPDM by GTR in thermoplastic elastomers based on PP/EPDM: Effects on morphology and mechanical properties

The formulation of recycled thermoplastic elastomeric materials (TPE) based on ground tyre rubber (GTR), generated from end of life tyres, can be an alternative strategy to deal with a type of waste responsible for increasingly environmental problems over the past decades. The incompatibility of GTR with thermoplastics places several issues on the formulation of these materials, which this study tries to overcome. An encapsulation strategy of the GTR by an elastomeric phase is proposed in this work to overcome the lack of adhesion between the materials. Ternary blends, composed of a highly flowable polypropylene homopolymer, an ethylene propylene diene monomer (EPDM) and GTR were formulated and their morphology and mechanical properties analyzed. The morphology of the blends showed interaction between the materials, revealing that the encapsulation of GTR by a rubber phase can be an adequate strategy to formulate recycled‐based TPE materials, if the dimension of the GTR particles is controlled and taken into consideration. The mechanical properties revealed the replacement effect of EPDM by GTR, and its dependence on the amount of that replacement. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40160.     

EPDM rubber reclaim from devulcanized EPDM

Two types of ethylene–propylene–diene monomer (EPDM) rubbers, namely an efficient vulcanized (EV) and a semiefficient vulcanized (SEV), have been used to produce devulcanizates in a continuous setup. The devulcanizates are re‐cured using the same recipes as for the virgin rubber. The influence of mixing it with virgin rubber compound, the addition of extra sulfur, the operating devulcanization conditions, and the excess of devulcanizing agent on the mechanical properties (hardness, tensile strength, and compression set) of the reclaim rubbers are studied. Most of the reclaims produced show slightly inferior mechanical properties compared to the virgin rubber. Surface imperfection was observed on the devulcanizate with high devulcanizing agent content. Excellent mechanical properties (all above the standards) of the reclaim were found when the devulcanized profile material was used (EV‐EPDM) to replace the virgin one for application as a roofing sheet material (SEV‐EPDM). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5948–5957, 2006     

Natural rubber/leather waste composite foam: A new eco‐friendly material and recycling approach

This article describes a new approach of recycling the leather waste (shavings) using it as filler in natural rubber foams composites. The foams were prepared using different amounts of leather waste (0–60 parts per hundred of rubber) and submitted to morphological (SEM microscopy) and mechanical analyses (cyclic stress–strain compression). The increase of leather shavings on the composite causes an increase of viscosity in the mixture, which reflects in the foaming process. This results in smaller and fairly uniform cells. Furthermore, expanded rubber has the biggest cell size, with more than 70% of cell with 1000 µm, while the composite with the higher concentration of leather has around 80% of total number of cells with 100–400 µm. The mechanical parameters were found to depend on the leather dust concentration. Moreover, the stiffness rises with the increase of leather shavings; consequently, the compression force for expanded rubber was 0.126 MPa as well as the composite with higher concentration of leather was 7.55 MPa. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41636.     

An innovative material based on natural rubber and leather tannery waste to be applied as antistatic flooring

In recent decades, the production chain of beef and bovine leather has grown significantly because of an increase in the world's population and improved access to consumption. However, the generation of waste derived from this sector has grown simultaneously, and consequently, improved ways of adding value, reusing, and disposing these waste materials are being sought. In this article, we present a new and innovative composite material based on vulcanized natural rubber (NR), carbon black (CB), and leather waste (NR/CB/leather). The NR/CB/leather composites were prepared by thermal compression with 60 phr of CB and 60 or 80 phr of leather waste. In accordance with Brazilian sanitary laws, we exposed these composites for 24 h to bleach (B) and a disinfectant with the aim of simulating a true everyday cleaning use. The deconvolution of the impedance semicircles was carried out, and two relaxation phenomena around linear relaxation frequencies of about 10⁵ and 10⁶ Hz were found and associated mainly with charge carriers from CB and leather waste. With the addition of leather, the electrical conductivity of the composites increased two orders of magnitude from 5.70 × 10^?6 for the NR/CB to 7.97 × 10^?4 S/cm for NR/CB/leather‐60 phr B. These results point to the possibility of using these composites as an antistatic flooring once they exhibit acceptable values of electrical conductivity and once they withstand, from the structural, morphological, and electrical point of view, exposure to sanitizing agents. Furthermore, the production of these composites will add value to and enable an environmentally acceptable disposal of leather waste. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41297.     

Recycling of EPDM waste. I. Effect of ground EPDM vulcanizate on properties of EPDM rubber

Processing, cure characteristics, and mechanical properties of EPDM rubber containing ground EPDM vulcanizate of known composition were studied. Mooney viscosity increases and Mooney scorch time decreases by the addition of the ground vulcanizate. At higher loadings of the ground rubber, the maximum rheometric torque decreases. On addition of ground waste, stress–strain properties and tear resistance increase, whereas heat buildup marginally increases, resilience marginally decreases, low‐strain modulus remains constant, and abrasion resistance decreases. The interplay between the filler effect of the ground EPDM and the crosslink density changes of the EPDM matrix is believed to be the reason for the variation in mechanical properties. It is believed that sulfur migration occurs from the raw EPDM matrix (R‐EPDM) to the ground waste EPDM (W‐EPDM) particle while accelerator migration occurs from W‐EPDM to R‐EPDM. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3293–3303, 2001     

Modification of liquid silicone rubber by octavinyl‐polyhedral oligosilsesquioxanes

To develop an efficient, simple, and biocompatible method for improving the thermal and mechanical properties of an addition‐type liquid silicone rubber (LSR), octavinyl‐polyhedral oligosilsesquioxane (OPOSS) modified LSR samples were prepared through the addition of 0.5–4.0 wt % OPOSS as a modifier to a platinum‐based silicone curing system before vulcanization. The characterization and measurement of the OPOSS and LSR samples were carried out by Fourier transform infrared spectroscopy, X‐ray diffraction, NMR, gas chromatography/mass spectrometry (electron impact ionization), scanning electron microscopy, thermogravimetric analysis/differential scanning calorimetry, and universal testing. The experimental results show that the crosslinking of the OPOSS and LSR polymer had a significantly positive effect on the thermal and mechanical properties. Compared with the unmodified sample, its tensile strength was enhanced by 423–508%, its tear resistance was increased from 22 to 44%, the residue at 600 °C was increased by 36–75% in an N₂ atmosphere and 8–65% in an air atmosphere, respectively. These results were obviously superior to those from other similar reported methods that used larger molecular or nonreactive polyhedral oligosilsesquioxane (POSS) derivatives as modifiers at similar POSS loadings. Furthermore, a significant correlation was found between the loading rate of OPOSS and the thermal properties. However, the mechanical properties seemed negatively correlated with the OPOSS content within the experimental range; this may have been due to a material defect caused by the uneven distribution and agglomeration. The results of this study proved that the incorporation of OPOSS into an LSR polymer matrix by a hydrosilylation reaction could be an efficient way to improve the mechanical properties, thermal stability, and biocompatibility of LSR in the future. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43906.     

Oxidation‐grafting surface modification of waste silicone rubber composite insulator powder: Characterizations and properties of EPDM/modified waste powder composites

In order to broaden the applications of waste silicone rubber composite insulator powder (WSP), modified waste powder (WSP‐KH570) was prepared by a two‐step treatment process involving improved surface oxidation approach by using acidic H₂O₂ solution and subsequently grafting of KH570. Fourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR‐ATR) analysis revealed the presence of KH570 on the powder surface. The result was confirmed by thermogravimetric analysis (TGA). Blends of ethylene propylene diene monomer (EPDM) with WSP‐KH570 were prepared. The effects of WSP‐KH570 on mechanical properties and thermal properties of the blends were investigated. The WSP‐KH570 showed an observed improvement in tensile strength and elongation at break of EPDM/WSP‐KH570 blends compared with corresponding compositions of EPDM/WSP blends. The TGA cure showed that EPDM filled with WSP‐KH570 had higher thermal stability at 210–380 °C than EPDM/WSP. Dynamic mechanical analysis indicated EPDM and WSP‐KH570 were better miscible with the blend ratio (90/10). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45438.     

A novel grafting‐modified waste rubber powder as filler in natural rubber vulcanizates

Polycardanol was synthesized from cardanol, paraformaldehyde, p‐toluenesulfonic acid, phosphoric acid (H₃PO₄), and phosphorus pentoxide (P₂O₅) via a two‐step process. Results indicated that polycardanol is an acid with high molecular weight and can be self‐crosslinked at high temperature. A modified WRP (MWRP) grafted by long chain can be obtained from the reaction between WRP and polycardanol. The sulfur content of MWRP is 0.27%, which is lower than that of WRP by 0.47%. The oxygen content of MWRP is higher by 13% than that of WRP. The phosphorus content of MWRP reaches 5.25%. The water contact angle of MWRP is 91.5°, whereas that of WRP is 123.7°. The properties of the WRP/NR and MWRP/NR composites were also investigated. MWRP/NR possesses higher tensile strength than WRP/NR because of the enhanced interfacial interaction between MWRP and the NR matrix. Post‐treatment is also conducive for MWRP/NR to improve its tensile strength at high MWRP content. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42993.     

Studying the continuous wet mixing process based on the silica formula

Studies show that the mixing process is one of the most critical steps in the rubber processing, which directly affects the performance and service life of rubber products. However, unjustifiable complexity, high processing time, and low mixing quality of the conventional mixing technologies restrict the development of the rubber industry. Aiming at the deficiency of rubber mixing technology at present, the wet mixing technology and continuous mixing technology are complementary to each other, and the continuous wet mixing technology is developed. Then experiments are carried out to evaluate the performance of the proposed method. The obtained experimental results show that the wet mixing and continuous mixing technologies have synergetic effects, thereby simplifying the mixing process and improving the quality and continuity of the mixing process. It is found that the continuous wet mixing technology significantly improves the properties of the rubber compound compared with the conventional dry mixing method. The proposed method not only has reasonable processing properties but also significantly improves the physical, compressive fatigue, degree of dispersion and dynamic mechanical properties of the compound compared with those from the conventional dry mixing process.     

溶聚丁苯橡胶与不同结构顺丁橡胶并用的SiO2/SSBR/BR复合材料性能研究

传统的镍系顺丁橡胶BR9000和四种稀土顺丁橡胶以低并用比（25phr）与SSBR并用时,BR9000与SSBR并用的硫化胶性能与稀土顺丁橡胶并无明显差距,有些性能还要比一些稀土顺丁橡胶更加优良。稀土顺丁橡胶CB24在物理机械性能方面表现出较好的综合性能。具有长链支化结构的稀土顺丁橡胶Nd24EZ具有最高的直角撕裂强度和最低的裂纹扩展速率。具有长链支化结构和高门尼粘度的稀土顺丁橡胶Nd22EZ则具有最佳的滚动阻力和抗湿滑性能。CB24虽然在抗湿滑性能方面表现优良,但其滚动阻力性能在五种顺丁橡胶中是最差的。Nd22EZ与Nd24EZ与白炭黑的相互作用力最强,白炭黑分散最好,表现出最低的佩恩效应。CB24和SKD-NDII则与白炭黑相互作用力较弱,白炭黑分散较差,佩恩效应最强。     

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     

Thermal stability of butyl/EPDM/neoprene based rubber compounds

Tyre curing bladders are usually prepared by using butyl/neoprene based compounds. To demonstrate the heat resistance and to extend the service life of a bladder, the mechanical properties of butyl/neoprene/ethylene–propylene–diene rubber (EPDM) based compounds in different compositions were analyzed and compared. In this study, the effects of partial replacements of IIR with different types of EPDM in different proportions were studied. Rheological and mechanical properties of vulcanizates were measured before and after the thermal ageing. Curing characteristics of unvulcanized compounds and mechanical properties, permanent set, fatigue index, and IRHD hardness of vulcanized compounds were measured. The better results were obtained by using the recipes containing Keltan 27 type EPDM of 10–20 phr. Mechanical properties of recipes decreased due to high EPDM ratio in the recipes studied. The service life of tyre curing bladders can be increased by the replacement of EPDM with butyl rubber in appropriate type and quantity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 557–563, 2007     

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.     

Transfer function and working principle of a pressure/temperature sensor based on carbon black/silicone rubber composites

Pressure/temperature sensitive silicon rubber (SR) filled with carbon black (CB) was prepared by a liquid mixing method. The transfer function of a pressure/temperature sensor based on CB/SR was derived by general effective media theory. The results show that the transfer functions coincided well with the experimental data, and the negative pressure coefficient of the resistance/positive temperature coefficient of resistance are shown. The working principles of these two kinds of sensors are different. The working principle of the pressure sensor based on CB/SR was related to the volume fraction of CB. With increasing volume fraction of CB, the working principle of this kind of pressure sensor varied from a piezo‐resistive effect to a strain effect. In addition, the working principle of the temperature sensor based on CB/SR was that the resistivity changed with temperature; this was not related to the volume fraction of CB. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42979.     

Various nano-particles influences on structure,viscoelastic, Vulcanization and mechanical behaviour of EPDM nano-composite rubber foam

ABSTRACT

In this study, the effect of various nano-particle type and concentration on the structure, curing, viscosity variation during vulcanisation, and mechanical characteristics of ethylene–propylene–diene monomer (EPDM) rubber foam is reported. Three types of nanoparticle with various dimensional aspects (1D carbon nanotubes, 2D nano clay, and 3D nano silica) are employed to investigate their effect on the fabrication of EPDM rubber foam. It is observed that the properties of the foams were efficiently influenced by the nano-particle shapes and content in the matrix. Nanoparticles may increase cell density and change cell structures. In addition, they can change the curing behaviour of foam rubber by affecting curing rate and scorch time of rubber. In the end, mechanical properties of EPDM foam rubbers investigated by experimental tests and implementing few empirical and constitutional mechanical models. It is very helpful to use suitable nanoparticle to achieve desired properties out of fabricated foams.     

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.     

Thermoplastic polyurethane composites prepared from mechanochemically activated waste cotton fabric and reclaimed polyurethane foam

In this study, thermoplastic polyurethane (PU) composites were successfully prepared from waste cotton fabric (WCF) and reclaimed PU foam derived from the shoe manufacturing industry through melt mixing. A pan‐mill‐type mechanochemical reactor made in our laboratory was applied to determine the mechanochemical activation of WCF. The intramolecular and intermolecular hydrogen bonds of WCF could be broken up through pan milling because of the fairly strong shearing and squeezing forces. Moreover, the simultaneous reduction of particle size and the large increment of the specific surface area of pan‐milled WCF benefitted its dispersion and the interfacial adhesion with the PU matrix. Mechanochemically activated WCF could be used as a low cost but effective functional additive to enhance the melt processability and mechanical properties of PU/WCF composites. With the addition of 75‐phr WCF, the heat shrinkage of the melt‐reprocessed PU decreased sharply from its original 11.4 to 0.3%. Meanwhile, the tensile strength of the composites was enhanced from 10.3 to 23.2 MPa. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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