Laboratory Size Two-roll Mill Research Articles

Evaluation of morphological, mechanical, and rheological properties of vulcanized styrene–butadiene rubber/modified corn starch blends

The starch-filled styrene–butadiene rubber (SBR) was prepared using a laboratory-sized two-roll mill. Starch was modified by yeast fermentation for 1 day before it was blended with SBR. The hydrophilicity of SBR was enhanced by grafting with modified starch (MST) by utilizing tetramethyl thiuram disulfide as a catalyst. The effect of modified corn starch loading on morphological, mechanical, and rheological properties of vulcanized SBR blends was investigated. Scanning electron microscope result revealed that the adhesion between the MST and SBR was weak, and the starch pulled out due to poor interfacial bonding. The lowest ultimate tensile strength, elongation at break, and tensile modulus of the SBR- g-MST were found in the sample containing 150 phr of starch. The variation of the percentage elongation of neat rubber and MST/rubber composites was 91.34%. The significant decrease in cure times was observed with the loading of MST in all blends up to 100 phr starch, while no significant change in scorch time was observed. The maximum torque, minimum torque, and cross-linking density increased as the starch loading increases up to 100 phr MST. The water absorption by the composite increases with immersion time and MST loading, although the rate of absorption decreases with increased time. The current product could be especially advantageous in agricultural and horticultural applications as a good controlled fertilizer release and for water retention.

Soil Burial Study of Palm Kernel Shell-Filled Natural Rubber Composites: The Effect of Filler Loading and Presence of Silane Coupling Agent

Palm kernel shell (PKS) was incorporated into natural rubber composites at loadings ranging from 0 to 20 phr using a laboratory-size two-roll mill. A soil burial study of the PKS-filled NR composites as a function of filler loading and silane coupling agent incorporation was then conducted over a period of six months. The degraded composites were evaluated by means of tensile testing. To study the degradation of the composites after soil burial, their morphological properties were observed by scanning electron microscopy. Prior to the soil burial tests, as the PKS filler loading increased, the tensile strength and elongation at break of the composites both with and without the silane coupling agent decreased, while the tensile moduli (M100 and M300) increased. At identical filler loading values, the NR/PKS composites with the incorporated silane coupling agent exhibited better tensile properties than the NR/PKS composites without the silane. Following the soil burial tests, the tensile strength, elongation at break, and the tensile moduli (M100 and M300) all decreased because of microbial attacks on the composites. The addition of silane enhanced the retention of the tensile properties of the NR/PKS composites after soil burial because of the improved adhesion at the filler-rubber matrix interface.

Curing characteristics and mechanical and aging properties of ethylene propylene diene monomer/calcium carbonate/bentonite hybrid composites

Ethylene propylene diene monomer (EPDM)/calcium carbonate/bentonite (Bt) hybrid composites were prepared via a laboratory size two-roll mill. In this work, loading ratio of calcium carbonate to Bt was varied, that is, 30/0, 5/25, 15/15, 25/5 and 0/30 parts per hundred rubber. The effect of partial replacement of calcium carbonate with Bt on the curing characteristics, tear properties, morphology, aging and fatigue life of the hybrid composites was studied. On increasing Bt loading, cure time, scorch time and maximum torque of EPDM/calcium carbonate (CaCO3)/Bt composites decreased, whereas minimum torque increased. The tear strength and fatigue life of EPDM/CaCO3/Bt hybrid composites showed improvement with increasing Bt loading. The results also showed that the retention of aging of EPDM/CaCO3/Bt hybrid composites decreased with increasing Bt loading.

Preparation and properties of natural rubber/organo-montmorillonite: from lab samples to bulk material

<p>Focusing on application aspects of the rubber nanocomposites and the production and testing of industrial-sized samples, this study was performed in two phases. First, natural rubber (NR)/organo-montmorillonite (OMMT) nanocomposites containing 2–14 phr OMMT were prepared on a laboratory-sized two-roll mill. The vulcanization behavior and mechanical properties of NR/OMMT composites were compared with a referent NR compound containing 60 phr carbon black (N330) as a reinforcing filler. The x-ray diffraction (XRD) analyses showed a predominant intercalated structure for all OMMT nanocomposites. As a result, the organoclay behaved as an effective reinforcement for NR, even at loadings as low as 2 phr. This nanocomposite exhibited an improvement in tensile strength of 29% and in elongation at break of 61% in comparison with the referent NR/N330 compound. With the estimated optimal filler content, in the second phase, bulk NR/OMMT-5/steel samples were successfully produced for dynamic testing. The dynamic moduli were investigated by the method of forced vibrations. Compared to the NR/N 330 samples, NR/OMMT-5 samples showed improved hysteresis, with very low dissipating energy per cycle and significantly reduced Mullins effect.</p>

Preparation and properties of recycled poly(ethylene terephthalate) powder/halloysite nanotubes hybrid-filled natural rubber composites

Recycled poly(ethylene terephthalate) (R-PET) was partially replaced with halloysite nanotubes (HNTs) as fillers in natural rubber (NR) composites. The composites were prepared by incorporating hybrid filler into NR using a laboratory size two-roll mill. The total amount of hybrid filler in each formulation was kept constant at 20 phr. Results revealed that scorch time, cure time, maximum torque, cross-link density and thermal stability increased with the replacement of R-PET by HNTs. Due to its reinforcing effect and ductility of the HNTs, the moduli, tensile strength, elongation at break and fatigue life were found to increase consecutively with increasing HNTs content. Morphological study of the tensile fracture surfaces of the composites exhibited that HNTs has better adhesion and is well-dispersed in NR matrix as compared to R-PET particles. However, R-PET exhibited positive effect by reducing the curing time of the hybrid NR composites.

EFFECTS OF PARTIAL REPLACEMENT OF RATTAN POWDER BY COMMERCIAL FILLERS ON THE PROPERTIES OF NATURAL RUBBER COMPOSITES

The effects of partial replacement of rattan powder (RP) by carbon black (CB), mica, and calcium carbonate (CaCO3) on the curing characteristics, tensile properties, rubber-filler interaction, and morphological studies of natural rubber (NR) composites were investigated. Rattan powder with an average particle size of less than 180 µm was used in this study. NR/RP/CB, NR/RP/mica, and NR/RP/CaCO3 composites with five different RP/commercial fillers loadings (i.e. 30/0, 20/10, 15/15, 10/20, 0/30 phr) were prepared using a laboratory size two-roll mill. Results showed that the maximum torque (MH) of the NR/RP/CB, NR/RP/mica, and NR/RP/CaCO3 composites increased with increasing the commercial filler-loading ratio. The scorch time (ts2) and cure time (t90) of NR/RP/CB composites decreased as the ratio of CB loading was increased, whereas, ts2 and t90 of NR/RP/mica and NR/RP/CaCO3 composites increased as mica and CaCO3 loading ratio were raised, respectively. The tensile strength, elongation at break (Eb), stress at 100% elongation (M100), and stress at 300% elongation (M300) of all the composites increased as the commercial filler-loading ratio increased. This is due to the presence of the commercial filler, which brought a better rubber-filler interaction, as confirmed by the rubber-filler interaction and scanning electron microscopy (SEM) studies.

Studies on natural weathering of rattan powder-filled natural rubber composites

This article investigates the effect of natural weathering on mechanical and morphological properties of rattan powder-filled natural rubber (NR) composites as a function of filler loading and silane coupling agent. The rattan powder samples in the range of 0 to 30 phr were compounded with NR using a laboratory size two-roll mill. The natural weathering test was carried out for six months. The degradation of the samples was evaluated by performing a tensile test, a Fourier transform infrared spectroscopy (FTIR), and a scanning electron microscopy (SEM) test. The results indicated that after natural weathering, an increase in stress at 100% elongation (M100) can be seen for samples without the silane coupling agent, whilst M100 was reduced for samples with silane coupling agent. A drastic reduction in tensile strength and elongation at break were observed for all samples due to the photo-oxidation process that occurred during the degradation of the samples. The extent of degradation on the samples’ surfaces and the presence of oxygenated products were confirmed by SEM and FTIR studies, respectively.

Curing Characteristics, Morphological, Tensile and Thermal Properties of Bentonite-Filled Ethylene-Propylene-Diene Monomer (EPDM) Composites

Bentonite (Bt) with irregular shape and surface morphology was used as a new type of filler in EPDM. EPDM/Bt composites were prepared using a laboratory size two-roll mill by adding 0 to 70 phr Bt. The effects of Bt loading on curing characteristics, morphology, tensile and thermal properties of EPDM/Bt composite were studied. Scorch and curing time were decreased with 0 to 30 phr loading and increased subsequently at 50 and 70 phr. Tensile strength and elongation at break (Eb) were increased with increasing Bt loading from 0 to 50 phr and decreased at 70 phr, whereas the tensile modulus (M100%) shows an increasing trend with increasing Bt loading. Thermogravimetric analysis shows the enhancements of thermal properties with increasing Bt loading. Morphological studies of tensile fracture surfaces of EPDM/Bt composite proves good interaction between Bt particles and EPDM at 50 phr and formation of Bt agglomerates at 70 phr.

Processibility and Mechanical Properties of Mullite-Filled Styrene Butadiene Rubber Composites

Mullite (3A12O3·2SiO2) is an aluminosilicate ceramic of great technological importance. We investigated its potential as fillers in rubber. Mullites untreated or treated with 3% γ-mecapto-propyltrimethoxysilane (A-189) were added into styrene-butadiene rubber (SBR) materials on a laboratory-sized two-roll mill. For comparison, commercial precipitated silica was also used. The effect of these fillers on the cure characteristics, processibility and mechanical properties of SBR at various loadings, ranging from 0 to 50 phr was investigated. The results showed that mullite was a semi-reinforcing filler for SBR materials and exhibits better overall cure properties, lower Mooney viscosity, lower tensile set, better resilience as compared to precipitated silica, while it is inferior to precipitated silica especially with regard to tensile strength, tear strength and abrasion resistance. The presence of the silane coupling agent can enhance mechanical properties of filled SBR vulcanizates to some extent.

Curing characteristics, tensile properties and morphology of palm ash/halloysite nanotubes/ethylene-propylene-diene monomer (EPDM) hybrid composites

Palm Ash (PA)/Halloysite Nanotubes (HNTs)/Ethylene-Propylene-Diene Monomer (EPDM) hybrid composites were prepared by incorporation of hybrid nanotubes into EPDM rubber matrix on a laboratory size two-roll mill. The effects of palm ash/halloysite nanotube weight ratio on the curing characteristics, tensile properties and morphology of the hybrid composites were studied. Curing time (t 90), scorch time (t 2), maximum torque, tensile strength and tensile modulus (M100 and M300) were increased whereas elongation at break was decreased with increasing halloysite nanotube content. Morphological studies of tensile fracture surfaces of PA/HNTs/EPDM hybrid composites indicated that HNTs has better adhesion to the EPDM matrix as compared to palm ash.

The Influence of Fiber Length and Concentration on the Physical Properties of Wheat Husk Fibers Rubber Composites

Ethylene-propylene-diene terpolymer (EPDM)/wheat husk fibers (WHFs) composites were prepared using a laboratory size two-roll mill. Cure characteristics and some physical properties such as swelling, mechanical, and thermal properties of the vulcanizates were studied. The adhesion status between the WHF and rubber matrix is lacked in general, but it started to reinforce the matrix at higher WHF contents where a higher restriction to molecular motion of the macromolecules with uniformed stress distribution of the fibers is produced. From the TGA analysis, a thermally stable property is exhibited, which in turn partially enhanced the reinforcement of the WHF-EPDM composites due to the natural adhesion during vulcanization.

Effect of the Electroplating Process Waste upon Vulcanization and Mechanical Properties of Natural Rubber (NR) Compositions

The potential of EWPS (electroplating waste of the polishing step) as activator for vulcanization process has been evaluated. EWPS was incorporated into natural rubber (NR) formulation in replacement partial or total to ZnO. The different mixtures were obtained in a laboratory-size two-roll mill and conventional vulcanization system (CV) was chosen for vulcanization. Rheometer parameters (ts1, t90, and Mh), mechanical properties (tensile and tear strength) and cure studies at 150, 160 and 170°C for a kinetic model were carried out. EWPS shows some catalytic effect upon NR vulcanization with reduction of scorch and optimum cure time. However, the compounds where EWPS is present in major quantity, in relation to ZnO, or alone as activator present a depleted performance with a continuous reduction of properties, such as, tensile strength.

Design and analysis of single-factor experiments: Analysis of variance of the effect of rice husk ash and commercial fillers in NR compounds

White rice husk ash (WRHA) and black rice husk ash (BRHA) were incorporated into natural rubber (NR) using a laboratory-sized two-roll mill. A conventional vulcanization system was used for curing and physical tests of the NR vulcanized involved determining of tensile and tear resistances. For comparison purposes, precipitated silica (Zeosil-175) and carbon black (N774) were used too. Using the analysis of variance of single-factor experiments, it can be concluded that: BRHA is non-reinforcing filler and its use is limited to 20 phr; WRHA is semi-reinforcing filler and the variation of filler loading (0 up to 50 phr) causes the maximum variation upon tensile strength of NR compounds; and, that although carbon black and silica are reinforcing fillers, a real reinforcement is reached up to 20 phr for tensile strength.

The Effect of Filler Loading and Epoxidation on Paper-Sludge-Filled Natural Rubber Composites

The effect of filler loading and epoxidation on curing characteristics, dynamic properties, tensile properties, morphology, and rubber-filler interactions of paper-sludge-filled natural rubber compounds have been studied. Two different types of natural rubber, SMR L and ENR 50, having 0% and 50% of epoxidation and conventional vulcanization were used. Paper sludge was used as a filler and the loading range was from 0 to 40 phr. Compounding was carried out using a laboratory-sized two-roll mill. The scorch time for both rubber compounds decreased with filler loading. The cure time was found to decrease with increasing filler content for SMR L vulcanizates, whereas for ENR 50, the cure time seemed to be independent of the filler loading. Dynamic properties, i.e., maximum elastic torque, viscous torque, and tan delta, increase with filler loading in both grades of natural rubber. Results also indicate that both rubbers show increment in tensile modulus but inverse trend for elongation at break and tensile strength. However, for a fixed filler loading, ENR 50 compounds consistently exhibit higher maximum torque, modulus at 100% elongation, and modulus at 300% elongation, but lower elongation at break than SMR L compounds. In the case of tensile strength, ENR 50 possesses higher tensile strength than SMR L at 10 to 20 phr, but the difference is quite small at 30 and 40 phr. These findings might be associated with better rubber-filler interaction between the polar hydroxyl group of cellulose fiber and the epoxy group of ENR 50.

Cinética de vulcanização de composições de borracha natural com incorporação de cinza de casca de arroz

Cinza da casca de arroz foi incorporada em borracha natural (NR) utilizando-se um misturador de cilindros. O sistema de vulcanização convencional (CV) foi escolhido e os estudos sobre a cura das composições foram conduzidos em um Curômetro TI-100. As curvas de torque foram obtidas em 150, 160, 170 e 180 °C. A velocidade global e a energia de ativação aparente para o processo de vulcanização foram calculadas para cada composição, assumindo que a vulcanização segue uma cinética de primeira ordem. Para fins de comparação, duas cargas comerciais, sílica precipitada (Zeosil-175) e negro de fumo (N762), foram também usadas. Foi observado que a adição da cinza da casca de arroz às composições de NR, em comparação às outras cargas utilizadas, aumentou a velocidade de reticulação e diminuiu a energia de ativação aparente de modo mais marcante.

The effect of coupling agent and chemical treatment on rice husk ash‐ filled natural rubber composites

Rice husk ash was incorporated into natural rubber (NR) using a laboratory size two-roll mill. Curing using a conventional vulcanization system (CV) was chosen, and cure studies were carried out on a Monsanto rheometer. Physical testing of the NR vulcanizates involved the determination of tensile, tear, and abrasion resistances, and hardness. Fourier transform infrared spectroscopy (FTIR) analysis was done to verify the presence of the characteristic functional groups of precipitated silica in MHA (milled husk ash) and THA (treated husk ash). The effect of the coupling agent, bis(3-triethoxysilylpropyl)-tetrasulfane (Si-69), on the curing and physical properties of the vulcanizates was investigated. A chemical treatment on a rice husk ash was done, and the effects of this procedure are also reported. For comparison, two commercial fillers, precipitated silica (Zeosil-175) and carbon black (N774), were also used. Although the presence of the silane coupling agent had not brought the expected increase in properties, treated husk ash showed exceptional performance in terms of tensile strength and abrasion resistance of the filled vulcanizates. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1019–1027, 2000