Oscillating Disk Rheometer Research Articles

Processing and Tensile Properties of Natural Rubber Filled with Calcium Carbonate or Silica in the Presences of Lauryl Alcohol

The processing and tensile properties of the compounds of natural rubber (NR) filled with calcium carbonate (CaCO3) or silica filler in the presence of lauryl alcohol have been investigated. The NR was filled with each of those fillers at a fixed concentration, i.e., 30 phr, and they were compounded with lauryl alcohol as a filler dispersant with varied concentrations on a laboratory mill by applying the semi-efficient vulcanization recipe. A typical oscillating disc rheometer (ODR) was utilized for the determination of processing properties. From the results, it was observed that CaCO3 or silica with lauryl alcohol had increased the rate coefficient of vulcanization (RV) of the filled NR compounds with a reduction in viscousness or minimal torsion. The results also showed that the lauryl alcohol additions have enhanced the tensile properties of obtained filled NR compounds. The greater the lauryl alcohol concentration, the greater the rate coefficient of vulcanization and tensile strength of both types of filled NR. The overall results have indicated that the lauryl alcohol performance in enhancements of processing and tensile properties was more pronounced on calcium carbonate than silica.

Accelerating the kinetics of curing reaction of SBR/BR blend by silicon carbide via modification of thermal diffusivity

In this work, the accelerating effect of nano-silicon carbide (SiC) as a high thermal conductive filler on the kinetics of curing reaction of styrene-butadiene rubber/butadiene rubber (SBR/BR) as a compound for tire tread was investigated. The oscillating disk rheometer (ODR) showed that the SiC filler reduced the scorch and optimum curing times by ∼10%. The SiC amount of 5 phr caused an unparalleled reduction of ∼50% in the time difference between the scorch and curing times. The calculated parameters of the autocatalytic kinetic model of Kamal–Sourour using ODR results indicated that SiC accelerated the curing reaction by ∼1.25 times. To find the main mechanism of action of SiC in the improvement of vulcanization kinetic of SBR/BR-SiC, thermal diffusivity of the compound was detected in the thermalization process using a special setup during the curing and also the dethermalization process after that. The results exhibited that the SiC particles led to enhanced heat transfer rate into the compound during the vulcanization by ∼30% and into the cured composite by ∼50%, particularly at 5 phr of SiC. Moreover, fitting the heat transfer equation on the dethermalization data showed that the amount of 5 phr SiC in the recipe enhanced the thermal diffusivity by ∼97%, which can prevent the tire explosion while deriving due to the increment of the air temperature within the tire. The SiC filler can save significant energy in the manufacturing process of the tire tread, which has been neglected so far.

Processing, Performance Properties, and Storage Stability of Ground Tire Rubber Modified by Dicumyl Peroxide and Ethylene-Vinyl Acetate Copolymers.

In this paper, ground tire rubber was modified with dicumyl peroxide and a variable content (in the range of 0–15 phr) of ethylene-vinyl acetate copolymers characterized by different vinyl acetate contents (in the range of 18–39 wt.%). Modification of ground tire rubber was performed via an auto-thermal extrusion process in which heat was generated during internal shearing of the material inside the extruder barrel. The processing, performance properties, and storage stability of modified reclaimed ground tire rubber were evaluated based on specific mechanical energy, infrared camera images, an oscillating disc rheometer, tensile tests, equilibrium swelling, gas chromatography combined with a flame ionization detector, and gas chromatography with mass spectrometry. It was found that the developed formulas of modified GTR allowed the preparation of materials characterized by tensile strengths in the range of 2.6–9.3 MPa and elongation at break in the range of 78–225%. Moreover, the prepared materials showed good storage stability for at least three months and satisfied processability with commercial rubbers (natural rubber, styrene-butadiene rubber).

Using chemical agent in microwave assisted devulcanization of NR/SBR blends: An effective recycling method

The aim of this research was using a new chemical devulcanizing agent (i.e. VitaX) in devulcanization of NR/SBR blend as a model compound of tire rubber by microwave (MW) irradiation. For this purpose, the rubber compounds were prepared at different natural rubber (NR) to styrene butadiene rubber (SBR) ratios (40:60, 50:50, 60:40, 70:30 and 80:20). The rubbers were cured and then ground to particles with different mesh sizes (3, 4, 8, 16 and 30). The effect of irradiation time, stirring speed and particle size on sol/gel fractions, crosslink density (CLD) and devulcanization percent (DP) of the microwave irradiated samples was evaluated. Thereafter, effects of using VitaX and its content (0.3, 0.6, 1, 2, 3 and 4 phr) on devulcanized samples was evaluated. Results showed that using VitaX along with microwave irradiation caused decrease in the CLD and increase in the DP (from 9.51 to 34.85%) compared to the microwave assisted devulcanized samples. Finally, the raw NR/SBR rubber compound were replaced by different contents (10, 20 and 30 phr) of the chemical-microwave assisted devulcanized sample. The mechanical and curing properties of the samples were evaluated by tensile test and Oscillating Disk Rheometer (ODR), respectively. The results showed that at replacing content of 10 wt.%, decrement in the curing time and increment in the scorch time, cure rate index (CRI) and CLD was occurred in the re-vulcanized compound. The chemical-MW irradiation based devulcanization method was found to be a promising method for effective recycling of NR/SBR based rubbers such as tire rubbers.

Enhancement of aging resistance ofEPDMrubber by naturalrubber‐g‐N(4‐phenylenediamine) maleimide as a grafted antioxidant

AbstractA new antioxidant was prepared by graft copolymerization ofN(4‐phenylenediamine) maleimide (pPDAM) onto natural rubber (NR). Fourier transform infrared technique was used to confirm the grafting of (pPDAM) onto the NR backbone. The grafted copolymer (NR‐g‐pPDAM) was incorporated into the ethylene propylene diene monomer rubber (EPDM) rubber mix as an antioxidant. For comparison purposes, a widely used antioxidantN‐(1,3‐dimethylbutyl)‐N′‐phenyl‐p‐phenylenediamine (6PPD) was used in addition to a blank sample without antioxidant. The rheometric characteristics of EPDM vulcanizates were determined using an oscillating disc rheometer. Different mechanical properties of the EPDM vulcanizates were measured before and after exposure to thermal and ultraviolet/ozone (UV/O3) accelerated aging. The results revealed that the grafted antioxidant NR‐g‐pPDAM is more efficient, for EPDM rubber vulcanizates than the commercial antioxidant (6PPD). EPDM containing grafted (NR‐g‐pPDAM) antioxidant exhibited promising properties, such that it is expected to fulfill major requirements of industrial, automotive, and construction applications.

Application of Silica Supported Calix[4]arene Derivative as Anti-reversion Agent in Tire Tread Formulation

In this research the influence of the silica supported calix[4]arene derivative (SS-Calix) on the reversion resistance, mechanical properties and thermal behavior of NR/BR tire tread formulation was investigated by the oscillating disc rheometer, FTIR, TGA and tensile testing. The results revealed that the reversion behavior of NR/BR vulcanizate is affected by SS-Calix. The data obtained from curing characteristics and thermal stability of test pieces indicate that, SS-Calix acts as an anti-reversion for rubbery materials that are exposed to thermal shock in the early stages of temperature rise. It's predicted that these results are due to the interaction between the OH groups present in the SS-Calix surface and the carbon of the polymer chains. The broad peak observed in the IR spectrum around 1824 cm-1 which is referred to C=O bond, confirms this prediction. In addition, the presence of SS-Calix in compound causes to increase modulus and hardness but reduce elongation and resilience.

A new route of cross‐linking of carboxylated acrylonitrile‐butadiene rubber via zinc oxide‐amino acid network formation

AbstractHerein, we present a strategy that leads to the formation of a high‐performance elastomeric material based on the carboxylated acrylonitrile‐butadiene rubber (XNBR). A unique cross‐linking route for XNBR has been designed, which does not involve typical cross‐linking agents such as sulfur. In this study, the show cause‐effect of zwitterionic compounds as the secondary cross‐linking agent for ionic elastomer has been investigated. Naturally occurring lysine (Ly) and tryptophan (Trp) amino acid are the zwitterionic compounds, which have been explored here. This approach results in the formation of a cross‐linked ionic elastomer that houses a dual ionic network structure formed by zinc oxide (ZnO) and amino acid. XNBR cross‐linked by ZnO and different amino acid compounds exhibit superior physical properties as compared to the conventional cross‐linking system. Fourier transform infrared spectroscopy, transmission electron microscope, and swelling study analyzes confirm the existence of zinc‐carboxylate and zwitterionic network in XNBR after the cross‐linking process. The dynamic mechanical analysis, differential scanning calorimetry, and oscillating disk rheometer analyzes show various thermal relaxations and transitions present in the dual cross‐linked XNBR. The ZnO and amino acid cross‐linked XNBR rubber with 2.5 phr of Ly and 5 phr of Trp show the highest tensile strength of 42.4 and 39.7 MPa, respectively, which is mostly higher than the previously reported values for ionic cross‐linked elastomers.

Vulcanization behavior and mechanical properties of isoprene-modified silica reinforced butyl rubber composites

Butyl rubber was reinforced by the isoprene-modified silica. The modified silica was prepared via chemical modification by a hydrophobic and reactive oligomeric liquid isoprene rubber in a solvent. Thereafter butyl rubber was compounded with the modified silica and vulcanized by thermal compression molding process. Their properties were studied using oscillating disk rheometer (ODR), differential scanning calorimeter (DSC), dynamic mechanical analyzer (DMA), and universal testing machine (UTM). The surface modification of the silica moved up the curing time and enhanced apparently tensile strength and modulus of the rubber composites. In conclusion, cure behavior and mechanical properties of butyl rubber/silica composites can be controlled by chemical modification of the silica surface using rubber molecules.

Investigating the Impact of Curing System on Structure-Property Relationship of Natural Rubber Modified with Brewery By-Product and Ground Tire Rubber.

The application of wastes as a filler/reinforcement phase in polymers is a new strategy to modify the performance properties and reduce the price of biocomposites. The use of these fillers, coming from agricultural waste (cellulose/lignocellulose-based fillers) and waste rubbers, constitutes a method for the management of post-consumer waste. In this paper, highly-filled biocomposites based on natural rubber (NR) and ground tire rubber (GTR)/brewers’ spent grain (BSG) hybrid reinforcements, were prepared using two different curing systems: (i) sulfur-based and (ii) dicumyl peroxide (DCP). The influence of the amount of fillers (in 100/0, 50/50, and 0/100 ratios in parts per hundred of rubber) and type of curing system on the final properties of biocomposites was evaluated by the oscillating disc rheometer, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, swelling behavior, tensile testing, and impedance tube measurements. The results show, that the scorch time and the optimum curing time values of sulfur cured biocomposites are affected by the change of the hybrid filler ratio while using the DCP curing system, and the obtained values do not show significant variations. The results conclude that the biocomposites cured with sulfur have better physico-mechanical and acoustic absorption, and that the type of curing system does not influence their thermal stability. The overall analysis indicates that the difference in final properties of highly filled biocomposites cured with two different systems is mainly affected by the: (i) cross-linking efficiency, (ii) partial absorption and reactions between fillers and used additives, and (iii) affinity of additives to applied fillers.

Elastomeric Composites Containing SBR Industrial Scraps Devulcanized by Microwaves: Raw Material, Not a Trash

Environmental concerns about waste management systems have stimulated the search for technological and economical alternatives that introduce waste as raw material for production cycles. In this sense, this study aimed to develop and characterize styrene-butadiene rubber (SBR) composites that contain industrial rubber scraps devulcanized by microwaves (SBR-r) as a reinforcing filler. The scraps were ground under ambient conditions. From the obtained powder (SBR-r), composites were prepared, varying the exposure time of the powder to the microwaves (1, 2, and 3 min), as well as the SBR-r content. These composites were compared to a Reference sample (base formulation without SBR-r). The vulcanization parameters were determined by an oscillating disk rheometer. After vulcanization, the composites were characterized by mechanical properties (tensile and tear strength, and compression set). These properties were also evaluated after accelerated aging in an air oven and a UV chamber (ultraviolet light). The results indicated that as a result of increasing the exposure time of the waste to the microwaves, no significant influence in the composite properties was observed. Aged samples presented higher results as compared with the Reference sample (tensile strength up to 175% higher, tear strength up to 107% higher, and compression set up to 91% higher), which indicates the possibility of using these materials in technological applications, such as in the civil and automotive industries.

Modification of Ground Tire Rubber—Promising Approach for Development of Green Composites

Ground tire rubber (GTR) was mechano-chemically modified using a road bitumen 100/150 and two types of organic peroxides: di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB) and dicumyl peroxide (DCP). The impact of used additives on reactive sintering efficiency and physico-mechanical properties of modified GTR was investigated using oscillating disc rheometer measurements, followed by tensile tests and swelling behavior studies. It was found that the application of bitumen and both used peroxides (DCP/BIB) improves processing and reactive sintering efficiency better than untreated GTR. However, the results indicate that BIB is more prone to blooming on the surface of modified GTR, thus limiting (especially at higher content) its application as a modifier and promotor of GTR reactive sintering.

Blending Poly (3-Hydroxybutyrate) with Polyethylene Glycol (PEG): Thermal behaviour and rheological study

Poly (3-hydroxybutyrate) (PHB) is a biodégradable polymer which its application in industrial was limited due to sensitive to high processing temperature and poor mechanical properties. The thermal and rheological behavior for blends of PHB extracted from dry weight of Jatropha and Poly (ethylene glycol) (PEG) were investigated. Blends of PHB/PEG (PHB 100, PHB 80, PHB 60 and PHB 50) have been prepared through solution blending method. The thermal using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) and rheological behavior using Oscillating Disk Rheometer have been investigated. The results indicate all PHb/PEG blends showed decreased at lowest melting temperature crystallinity (Xc). The TGA result showed that PHB 80 less degraded and suggest better thermal stability compared to PHB 60 and PHB 50. Adding PEG to PHB also improved the rheological behavior of PHB. At higher frequency range, PHB 100 showed less dependency on frequency indicating the elastic structure it has compared to PHB 80, PHB 60 and PHB 50.

Improvement properties of EPDM rubber using hybrid chitin/clay filler for industrial products

This work deals to synthesis chitin from Shrimp shells, that were collected from the local market scraped, washed, and ground. Deproteinization and decalcification process were applied on the ground shells to obtain pure chitin that identified and characterized by FTIR spectra, thermogravimetric analysis and scanning electron microscope SEM. The rubber compounds were prepared by incorporation of chitin as biomaterial and the other additive as curative system in ethylene propylene diene monomer (EPDM) rubber matrix using the laboratory two-roll mill. The rheological characteristics were tested using oscillating disc rheometer. The physico-mechanical properties of the prepared rubber vulcanizates before and after exposure to thermal oxidative ageing swelling properties, water uptake and chitin dispersion in rubber were investigated. It was found that at 5 phr of chitin the value of tensile strength of EPDM/chitin vulcanizates has higher value than the other concentrations of chitin. While the modulus at 50 % elongation and hardness increased with increasing chitin concentration. The samples containing 5 and 10 phr chitin show good thermal stability. Also, the effect of nanoclay concentration (3,5,7 and 10 Phr) as binary hybrid filler properties of EPDM rubber were evaluated. It was observed that, the rheological characteristics and the physico-mechanical properties were improved due to apply nanoclay as binary hybrid filler with chitin.

Phosphorylated cardanol prepolymer‐grafted carboxylated styrene–butadiene rubber for better processing with enhancing silica filler dispersion

ABSTRACTCardanol is a byproduct of cashew industry of semiforest origin. It is cheap and available in humongous amount and acts as a multifunctional additive in rubber compounds. It can be oligomerized with orthophosphoric acid to make phosphorylated cardanol prepolymer (PCP). Hence, cardanol has been chemically grafted on to the backbone chain of carboxylated styrene–butadiene rubber (XSBR) by employing melt grafting technique in presence of peroxide initiator to include multifunctional properties. The PCP‐grafted XSBR (PCP‐g‐XSBR) was characterized by using Fourier transform infrared spectroscopy and 1H‐NMR techniques and optimize the grafting conditions such as percent of grafting and grafting efficiency by using Taguchi methodology. PCP‐g‐XSBR was compounded with silica filler for a comparative study in terms of processing behavior with XSBR. The cure characteristics such as the cure rate and the optimum cure time of the unfilled PCP‐g‐XSBR compounds were determined by oscillating disc rheometer. The thermal analysis of PCP‐g‐XSBR vulcanizate exhibits slightly better thermal stability as well as plasticization effect. Morphological behaviors also display the less cracked and filled fracture surfaces with better filler dispersion in PCP‐g‐XSBR vulcanizate. The mechanical properties of the compounded PCP‐g‐XSBR vulcanizates also improve compare to XSBR vulcanizates. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47528.

Effect of Filler Types on Properties of the Natural Rubber Closed Cell Foam

In this research, effects of filler types and their loading on properties of the natural rubber closed cell foam were investigated. The azodicarbonamide was used as a blowing agent in 4 phr loading. The filler types that are the N-330 grade of carbon black, precipitated calcium carbonate and rubber grade china clay, their loading was varied from 0 to 50 phr (part per hundred dried rubber). The physical properties of the rubber foam that are the difference torque from the oscillating disk rheometer, hardness, tear strength, 300% modulus, tensile strength, elongation at break and compression set were analyzed. The results were found that the carbon black was yielded the highest of all properties in every loading. In conclusion, the suitable filler for closed cell rubber foam is the carbon black.

Compression set and damping properties of oil-extended elastomers for sealants production

Damping materials have been widely used in the vibration and noise control to reduce their harmful consequences in different areas such as their application in the drilling equipment, aerospace and naval vessels, transportation vehicles, bridges and high buildings. Because of severe environmental standards, the oil fabrication is developing synthetic environmentally friendly drilling fluids. For a vehicle, applications are produced: the outer and inner beltline seals and the glass run channel. The compression set is the important characteristic of elastomeric sealing materials as spontaneous stress release during application due to the internal pressure or external forces variations. The temperature and frequency-insensitive damping are of significance for industrial uses. Elastomeric hybrid materials based on terpolymers as network precursor are very common for sealants fabrication. The focus of this work was to prepare oil-extended elastomeric hybrid materials based on ethylenepropylene-diene monomer rubber (EPDM), ground calcium carbonate and furnace nano carbon black. Cure characteristics were carried out on oscillating disc rheometer. The crosslinking of rubber compounds was performed in a molding press. The compression set was assessed using the standard procedure. The morphology of the cryogenically fractured surface of samples with different content of paraffin oil was characterized by scanning electron microscopy (SEM). Mechanical properties and hardness were analyzed before and after the aging of obtained samples. Damping properties of prepared materials were determined using bending mode. The loss tangent, tan δ, was used as a measure of vibration energy dissipation.

Synergistic Effects of Bitumen Plasticization and Microwave Treatment on Short-Term Devulcanization of Ground Tire Rubber.

Ground tire rubber (GTR) was mechano-chemically modified with road bitumen 160/220 and subsequently treated using a microwave radiation. The combined impact of bitumen 160/220 content and microwave treatment on short-term devulcanization of GTR was studied by thermal camera, wavelength dispersive X-ray fluorescence spectrometry (WD-XRF), static headspace, and gas chromatography-mass spectrometry (SHS-GC-MS), thermogravimetric analysis combined with Fourier transform infrared spectroscopy (TGA-FTIR), oscillating disc rheometer and static mechanical properties measurements. The obtained results showed that bitumen plasticizer prevents oxidation of GTR during microwave treatment and simultaneously improves processing and thermal stability of obtained reclaimed rubber.

Plasma Modified and Unmodified Polyethylene as Filler in Natural Rubber Compounds: Morphology, Cure Behavior and Vulcanization Kinetics

The present paper investigates the influence of polyethylene (PE) and plasma modified polyethylene (PPE) as fillers in natural rubber (NR) compound. The NR/PE and NR/PPE compounds were prepared through mechanical mixing using two roll mill by varying their compositions. The morphology of the compounds was analyzed in detail using field emission scanning electron microscopy (FESEM) to understand the dispersion of PE and PPE in the NR matrix as well as its interfacial adhesion. Morphological analysis revealed that unmodified polyethylene was nicely dispersed in the NR matrix whereas plasma modified polyethylene showed agglomerated structure due to the polar functional groups on the PPE surface. The vulcanization kinetics and cure characteristics of natural rubber compounds containing PE and PPE were examined using an oscillating disc rheometer. The cure behavior of the composites were studied at different temperatures (140, 160, and 180 °C) using conventional sulphur vulcanization system. The addition of polyethylene influenced the cure properties to a great extent. Theoretical modeling was done to follow the mechanism of the cure reaction. The cure reaction was kinetically controlled at the beginning followed by the diffusion mechanism. The curing reaction was found to be autocatalytic and extent of reaction increased with increasing temperature.

Enhancing the efficiency of zinc oxide vulcanization in brominated poly (isobutylene-co-isoprene) rubber using structurally different Bismaleimides

It is a known fact that the bromobutyl rubber can form carbon-carbon crosslinks when it is heating with zinc oxide at a temperature greater than 160 °C. Generally, the rate of ZnO vulcanization is slow at this temperature. If any, attempt to enhance the rate of cure by rising the temperature will lead to an inferior state of cure. It has also been reported that heating of halobutyl rubber with ZnO at higher temperature produces conjugated diene butyl prior to the formation of carbon-carbon crosslinks. In the present work, we tried to exploit the possibility of Diels-Alder reaction between the in-situ formed diene butyl and the maleic moieties of bismaleimide to enhance the rate and extent of curing between BIIR and ZnO. For that, BIIR was heated with ZnO in combination with two types of bismaleimides such as N, N′ m-phenylene dimaleimide (HVA-2) and 1,3-Bis(citraconimidomethyl) benzene (Perkalink 900) in different concentrations from 1 to 5phr. The vulcanization studies using oscillating disk rheometer and isothermal scanning calorimetry have proved that the state and rate of curing in BIIR with ZnO have significantly enhanced in the presence of these bismaleimides. However, the efficiency of HVA-2 towards improving the state and rate of curing was considerably higher than that offered by Perkalink 900. The lowest activation energy for HVA-2 from the cure kinetic analysis confirmed the higher activity of HVA-2 over Perkalink 900.

Effect of organo clay on curing, mechanical and dielectric properties of NR/SBR blends

Natural rubber (NR) and styrene butadiene rubber (SBR) based elastomeric blends reinforced with organically modified Sodium bentonite clay were prepared by two roll mills. Vulcanization parameters such as minimum and maximum torque values scorch and cure times are measured by Oscillating Disc Rheometer. Mechanical properties such as Tensile strength, modulus at 100%, 200% and 300% elongation and elongation at break and Hardness were measured by Universal testing machine and Durometer Shore A hardness meter respectively. Dielectric properties such as dielectric constant (ε’), dissipation factor (tanδ) and volume resistivity (ρv) were measured at room temperature. The curing studies show that torque values are increasing in NR/SBR blends by increase NR content. The scorch and optimum cure time in NR/SBR blends reinforced organo modified clay was found through increase in the SBR content. This may be due to better processing safety of the NR/SBR blends reinforced with organo modified clay. Mechanical properties show that addition of SBR in blends, tensile strength, elongation modulus increases, but 100% modulus slightly increases and no change was observed in Hardness. Dielectric studies show that dielectric constant of NR and SBR rubbers are almost same, it may due to their non-polar nature. But addition of SBR in NR/SBR blend, dielectric constant gradually increases and maximum value observed at 50/50 ratio. But no considerable change was observed in dissipation factor. Frequency dependant resistivity shows that volume resistivity was not changed with respect to frequency up to 3.5 kHz and beyond that the frequency dependence resistivity was found.