Two-roll Mill Research Articles

HNBR elastomer composite with zero thermal contraction over a range of temperatures

Abstract Elastomers such as hydrogenated nitrile butadiene rubber (HNBR) are known to have inferior dimensional stability upon temperature changes compared to metallic materials. This can result in thermal contraction mismatches between metal and elastomer sealing components during cooling, possibly leading to seal leakage. It has also been reported that MnCoGe alloys have been developed that undergo a phase change which results in a volumetric expansion during cooling through the phase change temperature region. This article reports the effect of adding MnCoGe-alloy particles into a HNBR elastomer with the purpose using the thermal expansion of the alloy particles to counteract the thermal contraction of this elastomer during cooling. The composite material is produced using a combination of solvent casting and traditional shear mixing in a two-roll mill followed by compression moulding. With the MnCoGe volume fraction of ≈ 17%, a considerable suppression of the thermal expansion coefficient of the base elastomer was achieved, going from 185 × 10 − 6 ° C − 1 to nearly zero in the range of temperatures from -5 ° C to +15 ° C . The positive effect of the filler on the thermal expansivity was apparent in wider temperature range of -20 to +40 ° C .

Rheological Properties of Carbon Black/Silica Hybrid Filler in Acrylonitrile Butadiene Rubber

Filler is a common additive added into rubber vulcanizate to achieve reinforcing performance. Typically, filler is compounded via two-roll mill which results in filler agglomeration and lower reinforcing efficiency. To gain higher reinforcing efficiency, filler agglomeration must be minimized via masterbatch preparation. This study investigates colloidal stability of carbon black/silica (CB/SiO2) hybrid filler and effectiveness between typical compounding and masterbatch process for NBR vulcanizate production. CB/SiO2 hybrid filler was fixed at 20 wt.% with ratios of 100/0, 75/25, 50/50, 25/75 and 0/100 were dispersed separately in sodium hydroxide (NaOH) via ball milling. The zeta potential, particle size and viscosity results showed CB and SiO2 dispersions stabilized after 48 hours of ball milling. NBR masterbatch with 50/50 ratio has highest flow resistance. SiO2 reinforced NBR masterbatch showed higher flow resistance compared to CB due to finer silica particle size. However, scorch and cure time for SiO2 reinforced NBR is slower than CB reinforced NBR as silica deactivate the accelerator. CB/SiO2 at 50/50 has highest Tmax and ΔT while 100/0 and 0/100 has insignificant differences. As conclusion, CB and SiO2 dispersions were stable based on zeta potential analysis and particle size reduced as ball milling time increased.

Mechanical properties and curing characteristics of shape memory natural rubber

Natural rubber, which is a polydiene elastomer, is one of the attractive raw materials that could be developed as a shape memory polymer because of its high mechanical and elastic properties. This study aims to determine mechanical properties and curing characteristics of heat-induced shape memory polymer of natural rubber or herein after referred to shape memory natural rubber (SMNR). Natural rubber with different blend ratios of sulphur was prepared by a two-roll mill. The curing characteristics were determined using Moving Die Rheometer at 150°C. The effect of sulphur (0.75; 1.25; 1.5 phr) on mechanical properties such as tensile strength, tear strength and shape memory properties of the stearic acid swollen SMNR vulcanizates were investigated. This research showed that the higher sulphur amount gives the higher torque difference and higher mechanical properties. Shape memory compound swollen stearic acid exhibited shape recovery of 98-100% and shape fixity 59-88.5%.

Thermal and mechanical properties of chemical modification on sugarcane bagasse mixed with polypropylene and recycle acrylonitrile butadiene rubber composite

The goal of this research is to investigate the thermal, chemical, and tensile properties of chemical modification of sugarcane bagasse (SCB)-filled polypropylene (PP) and recycled acrylonitrile butadiene rubber (NBRr). The composites with different SCB loading (5, 15, and 30 per hundred resin) were prepared using a heated two-roll mill at temperature of 180°C.Thermal and the tensile properties of the modified SCB composite have shown improvement. The silane-treated composites have higher thermal stability compared to treated NaOH. The degradation temperature at 70% weight ( T70%) of NaOH and silane composite increase by 6% and 15%, respectively. Meanwhile, the tensile strength and Young’s modulus for the both treatment showed an improvement of 20% and 25% for NaOH and 30% and 32% for silane compared to untreated composites, respectively. The chemical properties were investigated using Fourier transform infrared analysis. The modification SCB fiber has improved the adhesion and interfacial bonding between SCB fiber and PP/NBRr matrices.

Reinforced, Extruded, Isotropic Magnetic Elastomer Composites: Fabrication and Properties

The study involves the development of isotropic magnetorheological elastomer composites (i-MREs) with improved mechanical properties, their preparations, and properties characterizations. The novelty of the research is the use of extrusion process in the preparation of composites containing two different fillers: carbonyl iron powder (CIP) as magnetic filler and carbon black (FEF, N550) as reinforcing one. So far, the process of extrusion has been used to prepare magnetic composites without filler that improve mechanical properties. It is worth mentioning that the polymer matrix (ethylene-octene copolymer, EOR) offers excellent performance in extrusion applications. In this research, two methods of magnetic composites preparation were reported: traditional, during two-roll mill, and a new one using extrusion process. It was found that the usage of new processing technology allowed forming more homogenous dispersion of particles in elastomer matrix and oriented polymer chains, resulting in an improved rheometric characteristic, increased crosslink density, and decrease of the storage modulus (Payne effect). Based on both static/dynamic mechanical properties and damping properties under the influence of compression stress, the positive influence of extrusion process on material characteristics was confirmed. Moreover, all composites proved very good magnetic properties and resistance to thermooxidative ageing.

Effect of Alternative Fillers on the Properties of Rubber Compounds

The paper is focused on the influence of alternative fillers on rubber compounds properties. Three different types of powder fillers, drinking water treatment sludge (DWTS), perlite and calcium carbonate, were mixed into rubber compound mixtures. The mixtures were composed of STR20, EPDM, zinc oxide, steric acid, paraffin wax, 2-mercaptobenzothiazole (MBT), sulphur, Wingstay L, and filler. The mixtures were mixed in a Kneader type mixer at temperature of 70°C and then continuously mixed using a two-roll mill at temperature of 70°C. The relationships between type and the amount of filler versus properties of rubber compounds were demonstrated. The results showed that tensile and elongation at break of rubber compounds gradually decreased with increasing the amount of filler. Rubber compounds filled with small particle size filler possessed higher tensile strength and elongation at break than those filled with large particle size filler. Values of DIN abrasion loss of rubber compounds prepared under proper mixing condition were not more than 300 mm3. Under appropriate condition, the rubber compounds with DWTS, perlite and calcium carbonate provided sufficiently high shore A hardness (not less than 50 Shore A hardness). Finally, alternative fillers such as DWTS and perlite were expected to replace calcium carbonate in normal formula.

Role of CNT/clay hybrid on the mechanical, electrical and transport properties of NBR/NR blends

Hybrid fillers are making a remarkable improvement in the properties of polymeric systems. In the present study, the influence of hybrid of multiwalled carbon nanotube (MWCNT) and nanoclay on the mechanical, electrical and transport properties of nitrile rubber (NBR)/natural rubber (NR) blends has been investigated. Attempts were made to prepare NBR/NR/CNT/nanoclay composites on a two-roll mill and to study various mechanical properties such as tensile strength, tear resistance, abrasion loss and compression set percent. Transport, thermal and electrical properties were also investigated. By virtue of the synergism between MWCNT and nanoclay, the composites exhibited enhancement in the mechanical properties by the immobilization of rubber chains via coupling action between the filler surface and the rubber molecules. The fine and uniform dispersion of both CNT and clay in composite samples supported the observation. The hybrid filler system had a great impact on the thermal and electrical properties of the composites.

Comparative Analysis of Tube Piercing Processes in the Two-Roll and Three-Roll Mills

Comparative Analysis of Tube Piercing Processes in the Two-Roll and Three-Roll Mills

Phase structure and electrical and mechanical properties of PLLA/ionic conductive polyether blends prepared by melt mixing

Poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) is known as an ionic conductive polymer and exhibits ionic conductivity when it forms a complex with a metal salt. In this study, poly(L-lactic acid) (PLLA)/POEGMA/poly(methyl methacrylate) (PMMA) blends were manufactured to develop high-performance polymer materials that exhibit high mechanical moduli (>1 GPa) and ionic conductivities in the semiconductive region (1.0 × 10 −9–1.0 × 10−7 cm−1) at room temperature. In addition, crystallized blends were prepared by annealing the amorphous blends and were subsequently evaluated. By mixing PLLA and the compound consisting of POEGMA and PMMA using a two-roll mill, a blend with a maximum ionic conductivity of ~1.1 × 10–7 S cm−1 was obtained. The scanning electron microscopy results indicated that the ionic conductive phases were finely dispersed within the blends. By comparing the storage modulus values of the crystallized blends to those of amorphous blends, we found that the crystallized blends were harder at approximately the glass transition temperature of PLLA. We prepared ionic conductive compound (ICC) by solution casting and the in situ polymerization of poly(ethylene glycol) methyl ether methacrylate (OEGMA) in the presence of PMMA and a cross-linking agent. Then, ionic conductive polymer blends was obtained by melt-mixing ICC and poly(L-lactic acid) (PLLA). We studied the relationship between phase structure and physical properties such as electrical and mechanical properties of the blends.

End-Use Properties of Pineapple Leaf Fibre Filled Natural Rubber

The effects of incorporating pineapple leaf fibre (PLF) as a filler on the end-end properties of natural rubber vulcanizates were studied at different filler contents and particle sizes. The pineapple leaf fibre was used within filler contents, 0 to 40 phr at the following filler particle sizes, 75, 150 and 300 μm. The PLF was characterized for filler properties while carbon black (N330) served as the reference filler. The natural rubber vulcanizates were compounded on a two-roll mill. Results showed that the abrasion resistance of filled natural rubber vulcanizates was generally higher than that of the unfilled natural rubber vulcanizate at filler content, 5 phr, and for PLF (150 and 300 μm) and carbon black filled natural rubber vulcanizates, the abrasion resistance decreased within filler content, 5 to 20 phr after which it increased with filler content. CB exhibited better abrasion resistance in the vulcanizates than PLF at filler contents greater than 20 phr. The hardness of filled natural rubber vulccanizates was generally greater than that of unfilled vulcanizate and increased with increases in filler particle size at filler contents, 10 and 20 phr. The specific gravity of the rubber vulcanizates increased gradually with the increase in filler content at filler content greater than 5 phr, and increased with increases in filler particle size at any filler content considered. The swelling index of filled natural rubber vulcanizates in toluene generally decreased with increasing filler particle size at filler contents, 5, 10 and 40 phr whereas the swelling index for PLF (150 μm) filled natural rubber decreased with increases in filler content. CB filled vulcanizates absorbed the highest amount of toluene (2.5%) in the vulcanizates at filler content, 40 phr. PLF (150 and 300 μm) generally gave optimum performances in the end-use properties of the rubber vulcanizates determined within filler contents, 30 and 40 phr. The incorporation of pineapple leaf fibre into natural rubber was found to improve the end-use properties of natural rubber vulcanizates and therefore, has potential in the formulation of natural rubber products.

Mathematical model of heat transfer in roll caliber

A physical model of the thermal process in the roll caliber during the rolling of the tape on a two-roll rolling mill was constructed. A mathematical model of the temperature field of a rolling hollow roll of a rolling state of a cylindrical shape rotating about its axis with constant angular velocity is proposed. The mathematical model takes into account different conditions of heat exchange of the inner and outer surfaces of the roll with the belt and its surrounding environment. The temperature field of a hollow roll of a rolling mill is considered as an initial boundary-value problem for a homogeneous non-stationary heat equation with inhomogeneous, nonlinear boundary conditions, which also depend on the angle of rotation of the roll around its axis. The equation describes the temperature field of the rolls during uncontrolled heat transfer during rolling. It significantly depends on the time and number of revolutions around its axis. With a large number of revolutions of the roll around its axis, a quasi-stationary temperature distribution occurs. Therefore, the simplified problem of determining a quasistationary temperature field, which is associated with a thermal process that is time-independent, is considered further in the work. In this case, the temperature field is described using the boundary value problem in a ring for a homogeneous stationary heat equation with inhomogeneous boundary conditions and heat transfer conditions outside the ring, which lie from the angular coordinate. After the averaging operation, the solution of this problem is reduced to solving the equivalent integral equation of Hammerstein type with a kernel in the form of the Green's function. The Mathcad computer mathematical system builds the temperature distribution of the roll surface. An algorithm for solving a inhomogeneous problem was developed and the temperature distribution of the roll was constructed.

Cellulose Nanocrystals and Jute Fiber-reinforced Natural Rubber Composites: Cure Characteristics and Mechanical Properties

A comparative study was conducted for three natural rubber (NR) composites: one containing raw jute fibers, one containing bleached jute fibers, and one containing cellulose nanocrystals (CNCs). The composites were prepared by adding each filler at 5 or 10 phr to the latex before chemical coagulation, and the composites were processed in a two-roll mixing mill. The mechanical, thermal, and vulcanization properties of the prepared composites were then determined. The NR stiffness increased with increasing fiber content, particularly when bleached fibers were added, as evidenced by the increased elastic moduli, maximum torques, glass transition temperature, and crosslinking density. Scanning electron microscopy showed agglomerates in the composite with 10 phr CNCs, which led to poorer mechanical performance compared to that of the bleached fiber-reinforced composite (10 phr). On the other hand, the addition of CNCs to the NR increased the cure rate index, thereby significantly advancing the optimum vulcanization time.

Effect of carbon black loading on mechanical, conductivity and ageing properties of Natural Rubber composites

Abstract Rubber is one of the important materials generally used to produce electrical rubber matting, insulators, gasket and pipe sealing rings due to good mechanical strength, conductivity and reasonable service life with addition of other compounding ingredients including fillers. Carbon black is the reinforcing fillers which added in NR composites to improve the mechanical properties and conductivity. The main objective of this study is to investigate the effect of different types of carbon black (N220, N330, N550, N660 and N774) and filler loading (0, 10, 20, 30, 40 and 50 phr) on mechanical, conductivity and ageing properties of natural rubber composites. The compounding was carried out using laboratory-sized two-roll mills. Tensile test were performed according to ASTM D 412 and tear test were performed according to ASTM D 624 by using Instron machine 3366. Electrical resistivity was studied by using Advantest R8340. Accelerated aging test was performed according to ASTM D 572 at 100°C for 3 and 6 days followed by tensile and resistivity test. It was found that N220 gives better mechanical and conductivity properties compared to other types of carbon black. Results also indicated that the optimum tensile strength was attained at 20 phr of carbon black filler loading. For tear resistance, the values were increased with increasing filler loading and for resistivity properties; the threshold was observed at 20 phr. The ageing behaviour for 3 days and 6 days at 100°C showed the optimum tensile strength obtained at 30 phr of carbon black loading. On the other hand, the resistivity properties were similar before and after ageing. Overall, the types of carbon black has significantly influenced in the mechanical properties and the resistivity threshold of NR composites.

Compatibilization of Vulcanized SBR/NBR Blends using Cis-Polybutadiene Rubber: Influence of Blend Ratio on Elastomer Properties

Blends composed of styrene butadiene rubber (SBR) and acrylonitrile-butadiene rubber (NBR) were fabricated by melt blending technique using two-roll mill blend machine. Cis- polybutadiene rubber (CBR) was used as a compatibilizer for enhancing the homogeneity between SBR and NBR phases in blends. Although, no previous reports were found to discuss improving electrical properties of vulcanized SBR/NBR blends using unfilled rubber system (i.e. no fillers incorporated). Raman spectra and SEM images indicate that a significant compatibility within the rubber matrix is observed, due to using CBR compatibilizer. The effect of SBR/NBR blend ratio on curing characteristics, physico-mechanical properties, and physicochemical properties (e.g. network characteristics and thermodynamic parameters) were studied. SBR/NBR blend showed comparatively better mechanical properties, compared to each other individually rubber system. Curing parameters e.g. Mooney viscosity and hardness were increased, while a reduction in cure time and specific gravity was observed with increasing SBR ratio in blends. Results revealed that increasing SBR resulted in an enhancement of the tensile strength, modulus at 300 % and elongation at break up to 40 phr, and then gradually decreased. The TGA results indicated that SBR/NBR blends were thermally decomposed at a temperature range of 340-520°C. The notable decrease of DC conductivity (?dc) of vulcanized blends is owing to the decrease of NBR, which is a polar portion and is responsible for increasing the conductivity of vulcanized blends. This proved that the targeted industrial applications for vulcanized blends are entirely depending upon SBR/NBR blend in elastomers matrix.

Compatibilization of Vulcanized SBR/NBR Blends using Cis-Polybutadiene Rubber: Influence of Blend Ratio on Elastomer Properties

Blends composed of styrene butadiene rubber (SBR) and acrylonitrile-butadiene rubber (NBR) were fabricated by melt blending technique using two-roll mill blend machine. Cis- polybutadiene rubber (CBR) was used as a compatibilizer for enhancing the homogeneity between SBR and NBR phases in blends. Although, no previous reports were found to discuss improving electrical properties of vulcanized SBR/NBR blends using unfilled rubber system (i.e. no fillers incorporated). Raman spectra and SEM images indicate that a significant compatibility within the rubber matrix is observed, due to using CBR compatibilizer. The effect of SBR/NBR blend ratio on curing characteristics, physico-mechanical properties, and physicochemical properties (e.g. network characteristics and thermodynamic parameters) were studied. SBR/NBR blend showed comparatively better mechanical properties, compared to each other individually rubber system. Curing parameters e.g. Mooney viscosity and hardness were increased, while a reduction in cure time and specific gravity was observed with increasing SBR ratio in blends. Results revealed that increasing SBR resulted in an enhancement of the tensile strength, modulus at 300 % and elongation at break up to 40 phr, and then gradually decreased. The TGA results indicated that SBR/NBR blends were thermally decomposed at a temperature range of 340-520°C. The notable decrease of DC conductivity (σdc) of vulcanized blends is owing to the decrease of NBR, which is a polar portion and is responsible for increasing the conductivity of vulcanized blends. This proved that the targeted industrial applications for vulcanized blends are entirely depending upon SBR/NBR blend in elastomers matrix.

Effects of Flame Retardants Additives on the Properties of Low-Density Polyethylene

Low-density polyethylene (LDPE) has many unique properties such as lightweight and high chemical resistance. Unfortunately, it burns rapidly when it is exposed to a flame which limits its applications especially when flame resistance is to be considered. Different percentages of magnesium hydroxide and decabromide diphenyl ether (3.0, 5.0, 7.0, and 9.0 wt.%) were mixed with LDPE using a two-roll mill machine at 1600C for 2 minutes. Then, the tensile and flame retardancy tests samples were prepared by an injection molding process using an industrial plastic machine at 1600C. Flammability, rheological, tensile and thermal properties of the produced samples were tested using a flammability test apparatus, a melt flow index machine, a universal testing machine, and a differential scanning calorimeter, respectively. It was observed that the flame resistance of LDPE was improved with the addition of both flame retardants up to 7.0 wt.%, then it was reduced when 9.0 wt.% of flame retardants were used. This may be attributed to the poor mixing due to the increase in the polymer melt viscosity as observed from the melt flow index results. An increase in elastic modulus and a reduction in ductility of LDPE were observed with the increasing of flame-retardant contents while the ultimate tensile strength of LDPE was increased from 5.7 to 7.6 and 7.5 MPa when 9.0 wt.% and 7.0wt.% decabromide diphenyl ether and magnesium hydroxide were added. This is due to the fact that the additives act as a load carried and/or their effects on the degree of crystallinity of LDPE.

Influence of blend ratio on the electrical characteristics of vulcanized SBR/NBR blends compatibilized by Cis-polybutadiene rubber

Blends composed of styrene butadiene rubber (SBR) and acrylonitrile-butadiene rubber (NBR) have been fabricated by melt-blending technique using two-roll mill blend machine. Cis-polybutadiene rubber (CBR) was used as a compatibilizer for enhancing the homogeneity between blend phases. No previous reports were found to discuss improving electrical properties of vulcanized SBR/NBR blends using unfilled rubber system (i.e. no fillers incorporation). SEM micrographs were utilized to verify the compatibility between two rubber ingredients in various blends, owing to the use of compatibilizer. Thermal stability of blends was investigated by differential thermal analysis (DTA) and differential scanning calorimetric (DSC) to evaluate the influence of blend ratio on the compatibility of investigated samples. Results revealed that the dielectric properties of blends are dramatically influenced by altering the blend ratio. The results revealed that the SEM observations confirmed the compatibilization effect of CBR on vulcanized SBR/NBR blends. Meanwhile, thermal properties of vulcanized SBR/NBR blends were enhanced with increasing of SBR contents in blends. The complex impedance graphs showed circular arcs showing the bulk contribution to overall electrical behavior for investigated vulcanized SBR/NBR blends. During I-V characteristics have been presented, where a remarkably change from linear behavior to nonlinear conduction at lower temperatures was found for 0SBR/100NBR blends. These findings supported and confirmed that the compatibilization effect and the blend ratio between rubber compositions have strongly influenced on their thermal and electrical properties of vulcanized blends.

Fabrication and characterization of natural rubber composite (sir 5)/organo-montmorillonite using cetil trimetil ammonium bromide as a surface modifier

The research on fabrication and characterization of natural rubber composites (SIR 5)/organo-montmorillonite using cetil trimetil ammonium bromide (CTAB) as an organic modifier has been conducted. Natural rubber SIR-5 was masticated at 60 °C by applying the time variations of 0, 5, 10, 15, 20, and 25 minutes using two-roll mill. SIR-5 which has been masticated for 4 minutes as an optimum time with the smallest moleecular-weight was then grafted by glysidil methacrylate (GMA) in order to obtain natural rubber-grafted-glysidil methacrylate (natural rubber-g-GMA) which was used as a compatibilizer material. A 10 g of montmorillonite was modified by using CTAB with different concentrations of 0, 0.01, 0.03, 0.05, and 0.07 molee and then was added into rubber SIR-5 and natural rubber-g-GMA using internal mixer to obtain the composite. The prepared composite sample was examined using ASTM D-638 in order to perform a low speed tensile test (1 mm/minutes) and a thermal test using thermogravimetri analysis (TGA) operated at 30-80 °C. The surface morphology of composite was analyzed by using scanning electron microscopy (SEM) operated at 15 kV. The result of optimum elasticity which was achieved by adding montmorillonit produced using CTAB concentration of 0.03 molee was 1.57 MPa and had the value of the elongation at break of 2396%. Thermal degradation analysis using TGA showed that the most decomposed mass was 63.11% at 426 °C. The analysis of the morphology using SEM showed homogenous surface of the composite.

Cure Characteristics and Physical Properties of SMR L/EPDM Blends: Effects of Blend Ratios

The effects of different blend ratios of Standard Malaysian Rubber (SMR L)/Ethylene Propylene Diene Monomer (EPDM) blend with different ratios on the cure characteristics (cure time, scorch time, minimum and maximum torque) and physical properties (swelling test, crosslink density and hardness test) were studied. The blends of (SMR L)/(EPDM) (100/0, 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90 and 0/100 phr) were prepared by using laboratory two-roll mill. The result showed that the ratio 80/20 showed the best properties compared to the other blend ratios. The blend at this ratio exhibited less scorch time, cure time and swelling percentage, and showed highest crosslink density.

Probing Dynamic Mechanical Analysis and Atomic Force Microscopy of Polypropylene/Kaolin Nanocomposite

The Dynamic mechanical analysis (DMA) and Atomic force microscopy (AFM) studies were conducted and evaluated on polypropylene/kaolin (P/K) nanocomposite treated with maleic anhydride (MA) and dicumyl peroxide (DCP) as additives in an in- situ process. Two-roll mill was used in compounding of the nanocomposites while moulding were done by injection moulding machine. Investigation in to the effect of K and MA/DCP on the nanocomposites (NCs) indicates that interfacial interactions between PP and K as filler was eminent. DMA analysis reveals an increase in the storage modulus which was at maximum significantly in P/K NC with 3 wt% and decrease in damping factor tan δ also at P/K NC of 3 wt%. The AFM study indicates that there was uniform and smooth surface roughness among the NCs. Thus, addition of MA/DCP on to P/K NC improves the reinforcing influence on the nanocomposites for better improvement.