Effect of silane coupling agent on the polymer‐filler interaction and mechanical properties of silica‐filled NR

The effects of filler loading and a new silane coupling agent 3‐octanoylthio‐1‐ propyltriethoxysilane (NXT silane) on the polymer‐filler interaction and mechanical properties of silica‐filled and carbon black‐filled natural rubber (NR) compounds were studied. Silica (high dispersion silica7000GR, VN2, and VN3) and carbon black (N330) were used as the fillers, and the loading range was from 0 to 50 phr. The loading of NXT silane was from 0 to 6 phr. Experimental results show that the maximum and minimum torques of silica and carbon black‐filled NR increase with increasing filler loading. With increasing filler loading, the scorch time and optimum cure time decrease for carbon black‐filled NR, but increase for silica‐filled NR. The minimum torque, scorch time, and optimum cure time decrease because of the presence of NXT silane. For the carbon black and silica‐filled NR, the tensile strength and elongation at break have maximum values, but the hardness, M300, M100, and tear strength keep increasing with filler loading. The mechanical properties of silica‐filled NR were improved in the presence of NXT silane. With increasing filler loading, the storage modulus of filled NR increases, but the loss factor decreases. Carbon black shows the strongest polymer‐filler interaction, followed by VN3, 7000GR, and VN2. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 573–584, 2005     

The Effect of 3-aminopropyltrimethyoxysilane (AMEO) as a Coupling Agent on Curing and Mechanical Properties of Natural Rubber/Palm Kernel Shell Powder Composites

This research is conducted using palm kernel shell powder (PKS) as filler in natural rubber The effect of 3-aminopropyltrimethoxysilane as coupling agent on composites were studied at different palm kernel shell loading i.e, 0 5, 10, 15 and 20 phr The palm kernel shell was crushed and sieved to an average particle size of 5.53 μm The palm kernel shell filled natural rubber composites were prepared using laboratory size two roll mill The curing characteristics such as scorch time, cure time and maximum torque were obtained from rheometer The palm kernel shell powder filled natural rubber composites were cured at 150^oC using hot press according to their cure time Curing characteristics, tensile properties, rubber-filler interaction and morphological properties of palm kernel shell powder filled natural rubber were studied Scorch time and cure time show reduction but tensile strength, elongation at break, modulus at 100% (M100) and modulus at 300% (M300) increased with the presence of 3-aminopropyltrimethyloxysilane Rubber-filler interaction studies showed that rubber filler interaction in natural rubber filled with palm kernel shell powder improved with incorporation of 3-aminopropyltrimethyoxysilane.     

Radiation effect on properties of carbon black filled NBR/EPDM rubber blends

Rubber blend of acrylonitrile butadiene rubber (NBR) and ethylene-propylene diene monomer (EPDM) rubber (50/50) has been loaded with increasing contents, up to 100 phr, of reinforcing filler, namely, high abrasion furnace (HAF) carbon black. Prepared composites have been subjected to gamma radiation doses up to 250 kGy to induce radiation vulcanization under atmospheric conditions. Mechanical properties, namely, tensile strength (TS), tensile modulus at 100% elongation (M₁₀₀), and hardness have been followed up as a function of irradiation dose and degree of loading with filler. On the other hand, variation of the swelling number as a physical property, as a function of same parameters, however, in car oil as well as brake oil has been undertaken. In addition, the electrical properties of prepared composites, namely, their electrical conductivity, were also evaluated. The thermal behavior of the prepared composites was also investigated. The results obtained indicate that improvement has been attained in different properties of loaded NBR/EPDM composites with respect to unloaded ones.     

Development of Natural Rubber-Fibrous Nano Clay Attapulgite Composites: The Effect of Chemical Treatment of Filler on Mechanical and Dynamic Mechanical Properties of Composites

Common nano clay fillers have layered structure. Some nano clays like Attapulgite (AT), Sepiolite have rod like fibrous structure. Compared to layered structured clay fibrous clay AT can undergo better dispersion in polymer matrix leading to better improvement in composite properties. Chemical modifications of AT are done through amine treatment as well as by amine+silane treatment to get chemically modified fillers AAT and SAT respectively. In the present investigation, nano composites are prepared using natural rubber (NR) filled with AT, AAT and SAT. Three different loadings of each filler are used namely 2.5, 5, and 10 phr (parts per hundred of rubber). Mechanical properties like tensile strength, elongation at break increase with the increase in filler loading up to 5 phr there after these properties marginally fall when loading is increased to 10 phr due to problem of filler dispersion at higher loading. However, modulus at 300% elongation and tear strength increases with the increase in filler loading up to 10 phr. Very similar trend can also be observed for composites with chemically modified fillers, AAT and SAT. But the degree of reinforcement is higher in the case of AAT and SAT compared to that of unmodified filler AT for the same filler loading. This difference is mainly due to better polymer-filler interaction and filler dispersion in the case of chemically modified clays AAT and SAT compared to unmodified AT. Tear strength of composites increases remarkably with the addition of AT and which is further enhanced when chemically modified clays AAT and SAT are added. Dynamic-mechanical analyses of different clay composites give idea about the difference in the degree of polymer–filler interaction due to chemical treatment of filler.     

The influence of nano silica particles on gamma-irradiation ageing of elastomers based on chlorosulphonated polyethylene and acrylonitrile butadiene rubber

The goal of this work was to study gamma irradiation ageing of rubber blends based on acrylonitrile butadiene rubber (NBR) and chlorosulphonated polyethylene rubber (CSM) reinforced by silica nano particles. The NBR/CSM compounds (50: 50, w/w) filled with different content of filler (0–100 phr) were crosslinked by sulfur. The vulcanization characteristics were assessed using the rheometer with an oscillating disk. The vulcanizates were prepared in a hydraulic press. The obtained materials were exposed to the different irradiation doses (100, 200, 300 and 400 kGy). The mechanical properties (hardness, modulus at 100% elongation, tensile strength and elongation at break) and swelling numbers were assessed before and after gamma irradiation ageing.     

Fabrication of thermoplastic polyurethane composites with a high dielectric constant and thermal conductivity using a hybrid filler of CNT@BaTiO3

Thermoplastic polyurethane composites with an excellent dielectric constant and high thermal conductivity were obtained using CNT@BaTiO₃ as a filler through a low-speed melt extrusion method. Before preparing the hybrid filler for the composite, the filler particles were surface modified to ensure that the outer surfaces could facilitate the reaction among particles to form the hybrid and ensure complete dispersion in the thermoplastic polyurethane matrix. After confirming the proper surface treatment of the filler particles using infrared spectroscopy, thermal degradation analysis and field emission scanning electron microscopy, they were used to prepare the composite materials at a processing temperature of 200 °C. The thermal stability, thermomechanical properties, mechanical properties, thermal conductivity, and dielectric properties of the composites were investigated. Compared to the neat thermoplastic polyurethane matrix, the prepared composite exhibited a higher thermal stability, approximately 300% higher storage modulus, higher tensile strength and elongation at break values, approximately three times higher thermal conductivity (improved from 0.19 W/(m.K) to 0.38 W/(m.K), and approximately five times larger dielectric constant at high frequencies (at 1 MHz a dielectric constant of 19.2 was obtained).     

Formation of Network by Carbon Black，Silica and Their Mixing Fillers in Isoprene Rubber北大核心CSCD

The network formed by fillers has great influence on the mechanical properties of rubber materials. To understand the formation of network by carbon black,silica,and carbon black/silica mixing fillers in rubber and its influence on the properties of rubber,isoprene rubber/filler composites with different filler loadings are prepared and their micromorphology,rheological and tensile properties are investigated. It is found that the dispersion of fillers is better in rubber after cure than that in rubber before cure for all three rubber systems,and the filler size of silica is smaller than that of carbon black,but the aggregation is more severe in silica filled rubber system. In mixed filler system,the two fillers tend to aggregate separately, leading to the low modulus at small strain than that in single filler system. With the increase of the filler loading,the tensile strength increases first and then decreases,the elongation at break decreases,and the temperature rise in compression flexometer tests increases. Moreover,the temperature rise in mixed filler system is higher than that in single filler system at high filler loading. © 2022, Science Press (China). All rights reserved.     

Fly ash particles and precipitated silica as fillers in NR/CR vulcanizates under thermal and thermal‐oil ageing

The loading effect of precipitated silica (PSi) and fly ash‐based silica (FASi) on mechanical properties of natural rubber/chloroprene (NR/CR) under thermal and thermal‐oil ageing was investigated with variation in NR content in the NR/CR blends. The selected results were compared with vulcanized NR/nitrile rubber (NR/NBR) blends. The cure time of CR vulcanizate was found to decrease with increasing NR content, but increased with silica fillers. The Mooney viscosity for CR vulcanizates reduced with increasing NR content. The addition of NR had no effect on tensile modulus and tensile strength for the FASi filled NR/CR, but the opposite trend was observed for the PSi filled NR/CR. The post‐curing effect was more significant in PSi filled NR/CR than in FASi filled NR/CR. The tensile strength of the NR/CR vulcanizates was slightly reduced after thermal ageing especially at high NR content, more extreme reduction being found by thermal‐oil ageing. The elongation at break of NR/CR with both silica fillers ranged from 400 to 900%. The hardness results were similar to the tensile modulus. The addition of PSi in NR/CR considerably increased the tear strength, but less pronounced effect was found for FASi. The resilience properties of NR/CR tended to decrease with increasing silica content. The compression set became poorer when NR content was increased. The PSi showed higher improvement in compression set than the FASi. The effects of silica and ageing on the mechanical properties for NR/CR vulcanizates were similar to those for NR/NBR vulcanizates. Copyright © 2009 John Wiley & Sons, Ltd.     

Optimisation of physical and mechanical properties of rubber compounds by response surface methodology--Two component modelling using vegetable oil and carbon black

Response surface methodology was used for predicting the optimal composition of vegetable oil and carbon black in rubber compounding. Central composite rotatable design for two variables at five levels was chosen as the experimental design. The data obtained from measurement of properties was fitted as a two variable second order equation and were plotted as contour plots using programme developed in MATLAB v.5. It is observed from the contour plots that the increase in cross-link density caused by the formation of rubber mono-layer from its multi-layer on increasing the carbon black loading upto the central point (50 phr) of experimental region increases 300% modulus and elongation at break and reduces the ultimate properties like tear strength and tensile strength. On the other-hand hardness increases with increase in solid inclusion of carbon black. From the contours it is observed that the addition of vegetable oil upto 2-3 phr, cross-link density increases due to its coupling action leading to increase in hardness and modulus and lowering of ultimate properties like tensile strength and elongation at break. Addition of further amount of vegetable oil shows less coupling and more plasticising effect leading to increase in tear strength, tensile strength and elongation at break and decrease in hardness and 300% modulus.     

The effects of a silane coupling agent on curing characteristics and mechanical properties of bamboo fibre filled natural rubber composites

The effects of a silane coupling agent on curing characteristics and mechanical properties of bamboo fibre filled natural rubber composites were studied. Scorch time, t₂ and cure time, t₉₀ of the composites decrease with increasing filler loading and with the presence of a silane coupling agent, Si69. Mooney viscosity also increases with increasing filler loading but at a similar filler loading shows lower value with the presence of Si69. The mechanical properties of composites viz tensile strength, tear strength, hardness and tensile modulus were also improved with the addition of Si69.     

Preparation and Properties of Layered Silicate Nanocomposites Based on Ethylene Vinyl Acetate Copolymers

(Nano)composites based on ethylene vinyl acetate copolymers (EVA) and montmorillonite modified by various alkylammonium cations were processed by mechanical kneading. Polymer intercalation and filler exfoliation were evidenced by X‐ray diffraction and transmission electron microscopy, respectively. Nanocomposites tensile properties showed that Young's modulus increases significantly even at very low content of the organo‐modified filler while preserving high ultimate elongation and tensile stress. The matrix thermal stability in air was increased by 40°C and, interestingly, the obtained nanocomposites present flame retardant properties.     

Barium Titanate-reinforced Acrylonitrile-Butadiene Rubber: Synergy Effect of Carbon-based Secondary Filler

Acrylonitrile rubber(NBR) composites filled with barium titanate(BT) were prepared using an internal mixer and a two-roll mill. Also, a secondary filler, namely carbon nanotubes(CNT), was added in order to find a potential synergistic blend ratio of BT and CNT. The cure characteristics, tensile and dielectric properties(dielectric constant and dielectric loss) of the composites were determined. It was found that NBR/BT composites with CNT secondary filler, at a proper BT:CNT ratio, exhibited shorter scorch time(t_(s1)) and cure time(t_(c90)) together with superior tensile properties and reinforcement efficiency, relative to the one with only the primary filler. In addition, the NBR/BT-CNT composite with 80 phr BT and 1-2 phr CNT had dielectric constant of 100-500, dielectric loss of 12-100 and electrical conductivity below 10~(-4) S/m together with high thermal stability. Thus, with a proper BT:CNT mix and filler loading, we can produce mechanically superior rubber composites that are easy to process and low-cost, for flexible dielectric materials application.     

The effect of grass fiber filler on curing characteristics and mechanical properties of natural rubber

Natural rubber is reinforced with a novel type of grass fiber (Cyperus Tegetum Rox b). The effects of fiber loading of different mesh sizes on curing characteristics and mechanical properties of grass fiber filled natural rubber composite are studied. Since 400 mesh grass fiber loaded natural rubber composite shows superior mechanical properties, therefore the effect of silane coupling agent was studied for this particular composite. Here composites were prepared by using water leached grass fiber. Optimum cure time increases with the increase in fiber loading but the change in scorch time is less. The same trend of increase in optimum cure time is observed in the presence of Si69. But the value is higher compared to that of rubber composite without Si69. With increase in the fiber loading, modulus and hardness of the composite increases but tensile strength decreases. The mechanical properties of the composite, namely moduli at 200 and 300% elongation and hardness increase in the presence of Si69 but tensile strength is less compared to that of the composite without Si69. Elongation at break is not much affected due to the presence of Si69. Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of Electron Beam Irradiation and Ethylene Vinyl Acetate Copolymer on the Properties of NBR/HDPE Blends

The mechanical and physical properties of blends based essentially on nitrile butadiene rubber (NBR) and different ratios of high density polyethylene (HDPE) up to 25 parts per hundred part of rubber (phr) before and after electron beam irradiation were investigated. The values of tensile strength (TS), tensile modulus at 50% elongation (M₅₀), hardness and gel fraction % (GF%) of NBR/HDPE blends were increased with both irradiation dose and by increasing the content of HDPE in the blends. On the other hand, the values of elongation at break (E _b ) were decreased with both irradiation dose and the content of HDPE in the blends. By loading NBR/HDPE (100/25) blend with ethylene vinyl acetate (EVA) copolymer the mechanical and physico-chemical properties were improved. Moreover, the degree of improvement is proportional to the loading content of EVA.     

Curing and Physical Properties of Natural Rubber/Wood Flour Composites

Natural rubber based composites were prepared by incorporating Wood flour of two different particle size ranges (250–300 µm) and (300–425 µm) and concentrations (15 and 30 phr) into the matrix, using a Banbury® internal mixer according to a base formulation. Curing characteristics of the samples were studied. Influence of particle size and loading of filler on the properties of the composites was analyzed. Results obtained show that the addition of wood flour to natural rubber increased scorch time and curing time and caused improvement in modulus at 300% strain and in tear properties. However, it decreased tensile strength and elongation at break. The particle size range of 300–425 µm was found to offer the best overall balance of mechanical and dynamic properties (tan δ and viscous torque). Swelling behavior of the composites in toluene was also analyzed in order to determine the rubber volume fraction and crosslinking density. Composites with the bigger particle size wood flour were found to have greater crosslinking density than the ones with smaller particle size, fact that could possibly indicate a better rubber-filler interaction in the former. Major percentage of filler increased slightly this interaction. Water absorption behavior of the composites with wood flour reached a maximum of 12% w/w when 30 phr of filler were incorporated; nonetheless, particle size did not affect this property. The ageing study in presence of air at 70 °C revealed that natural rubber composites with wood flour maintained the same classification cell with temperature as the pure rubber. A compound with 30 phr of carbon black was prepared for comparative purposes. Results obtained were as expected. Scorch time decreased and higher values of modulus at 300% strain and tensile strength were achieved, due to strongest interaction between filler and elastomer.     

Investigation of sub‐micron size cenosphere fillers and filler loading on the mechanical and tribological peculiarity of polyester composites

This paper investigates the effect of sub‐micron size cenosphere filler and filler loading on mechanical and dry sliding wear property of polyester composites. Composites are fabricated by filling with 10 and 20 wt% of 800 and 200‐nm size of cenosphere filler particles. Neat polyester composite is also prepared for comparison analysis. Dry sliding wear test is conducted for these composites over a range of sliding distance with different sliding velocities and applied loads on a pin‐on‐disc wear test machine. Taguchi methodology and analysis of variance (ANOVA) is used to analyze the friction and wear characteristics of the composites. The artificial neural network (ANN) approach is implemented to the friction and wear data for corroboration. In this work, mechanical properties of composites such as hardness, tensile strength, tensile modulus, flexural strength, and compressive strength revealed that mechanical properties and wear resistance of the composites increase with a decrease in the particle size. The measured Young's moduli are comparable to standard theoretical prediction models. The morphology of worn composite specimens has been examined by scanning electron microscopy to understand the dominant wear mechanisms. Finally, optimal factor settings are determined using a genetic algorithm (GA). Copyright © 2017 John Wiley & Sons, Ltd.     

Thermogravimetric,differential scanning calorimetric,and experimental thermal transport study of functionalized nanokaolinite-doped elastomeric nanocomposites

A simple technique to synthesize and functionalize kaolinite nanoparticles having analogous shape and size in single step using layered silicate microclay as starting material is presented. The morphology, composition, and functionalization study of the activated nanokaolinite were determined by scanning electron microscopy/energy-dispersive spectroscopy, atomic-force microscope, and Fourier transform infrared spectroscopy, correspondingly. Various concentrations of activated nanokaolinite were doped in acrylonitrile butadiene rubber (NBR) by conventional industrial elastomeric mixing techniques to fabricate composite specimens. The accumulated data simulated that the thermal conductivity was diminished 92 % by increasing 15 mass% filler loading in the polymer matrix. Thermogravimetric analyzer showed that thermal stability and heat-absorbing capability were remarkably augmented by increasing activated nanokaolinite concentration in the NBR base formulation. Differential scanning calorimetric study revealed that glass transition and crystallization temperatures were reduced, whereas first and second melting phase temperatures were enhanced by increasing filler-to-host matrix ratio. Tensile strength, elongation at break, and elastic modulus at 200 % elongation were remarkably improved to a level of 144, 66, and 90 %, respectively, with increasing filler-to-matrix ratio. Efficient enhancement in elastomeric hardness was also observed.     

Effect of electron beam irradiation on mechanical and thermal properties of waste polyamide copolymer blended with nitrile‐butadiene rubber

In the present study, the effect of electron beam irradiation on the morphological, thermal, and mechanical properties of waste polyamide copolymer (WPA‐66/6) blended with different contents of acrylonitrile butadiene rubber (NBR) were studied. The prepared blends were subjected to irradiation doses up to 150 kGy and the structural modifications were discussed; non‐irradiated blends were used as control. Mechanical properties, namely, tensile strength (TS), yield strength, elongation at break, and hardness, were followed up as functions of irradiation dose and degree of loading with rubber content. On the other hand, the influence of irradiation dose on the thermal parameters, melting temperature, heat of fusion, ΔH_m of the recycled PA copolymer, and its blend with NBR were also investigated. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,properties, and fungal degradation of castor-oil-based polyurethane composites with different cellulose contents

Different contents of bonded cellulose were dispersed in a matrix of castor-oil-based polyurethane to produce composites with high susceptibility to fungal attack. We chose to bond the cellulose filler with free diisocyanate, to increase the crosslinking density. Measurements indicated physical and chemical interactions between the polyurethane matrix and cellulose filler. The cellulose network significantly enhanced the interfacial adhesion and thus improved the thermal stability and Young’s modulus of the composites. The influences of the amount of cellulose on the surface chemical structure, surface morphology, and mechanical properties after fungal attack were also investigated. The tensile strength and elongation at break of these composites substantially decreased after exposure to fungus. These composites with high content of renewable raw materials present an optimal balance of physical properties and biodegradability, with potential applications as ecofriendly biomaterials.     

Bio-Based Nanocomposites of Cellulose Acetate and Nano-Clay with Superior Mechanical Properties

Summary: Bio-based nanocomposites were manufactured by melt intercalation of nanoclays and cellulose acetate (CA) with and without plasticizer. Glycerol triacetate (triacetin) as plasticizer up to 30 mass%, and different types of organo-modified and unmodified montmorillonites (MMTs) as filler were used. X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), were used to study clay dispersion, intercalation/exfoliation, and structure of the composites. XRD and TEM revealed very good dispersion and exfoliation of modified clay throughout the CA matrix. While for unmodified clay agglomeration and poor dispersion but an intercalated structure was observed. The mechanical properties of injection moulded test bars were determined by a tensile experiment giving tensile strength, Young's modulus and elongation at break. Adding plasticizer facilitated the processing and up to 20 mass%, increased the tensile strength, Young's modulus and elongation at break as well. Higher amount of plasticizer diminished the tensile properties except elongation showing a slight increase. In all plasticized composites, organo-modified clay improved the tensile strength and at the same time, young's modulus and elongation almost remained constant. On the other hand, plasticized CA compounded with unmodified clay revealed lower properties. In a particular case, compounding of unplasticized CA with unmodified clay resulted in superior mechanical properties with a novel structure. So that, in optimum percentage –5 mass%- of unmodified clay, tensile strength and young's modulus increased significantly by 335% and 100%, to 178 MPa and 8.4 GPa, respectively. This is a dramatic improvement in strength and stiffness of CA. Adding organo-modified clay resulted in a little improvement in tensile properties. SEM pictures of the optimum composite showed a core/shell structure with high orientation in the shell part. It is supposed that this behaviour is caused by the interaction between CA hydroxyl groups and free cations existing in the galleries of unmodified clay.