Acrylic Rubber Research Articles

Effects of silicone rubber on properties of dielectric acrylate elastomer actuator

This article describes the effects of silicone rubber (SR) networks on the actuating behavior of acrylate rubber (AR)-based dielectric actuators. SR chains were diffused into a swollen AR networks in the presence of a co-solvent, and then the silicone chains were chemically crosslinked in an attempt to form an interpenetrating polymer network. The presence of SR in the AR network was confirmed by various instrumental analyses including attenuated total reflectance-Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The total crosslink density based on a swelling method and tensile properties increased with modification time. The Maxwell stresses were also determined using a pure-shear specimen. They increased in a parabolic fashion with the applied voltage, and depended on the type of compliant electrode and SR used. POLYM. ENG. SCI. 46:1455–1460, 2006. © 2006 Society of Plastics Engineers.

架橋剤／無機層状複水酸化物複合体の合成とゴム架橋特性

Intercalation products of crosslinking agents such as 6-R-1, 3, 5-triazine-2, 4-dithiol monoanion (R is a substituent) into Mg-Al layered double hydroxide (RTD/LDH) have been synthesized with the calcination-rehydration reaction using Mg-Al oxide precursors calcined at 500°C for 2h. RTD/LDH has been modified by anionic surface active agent (AS/RTD/LDH). These organic-inorganic nanohybrids have been characterized by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Vulcanization reaction of chlorinated acrylic rubber by AS/RTD/LDH has been investigated for the scorch time, the apparent cure rate constant and the induction period by a swing die rheometer at 170°C. The basel spacing (003) was found to be 0.83nm for the intercalated product of 1, 3, 5-triazine-2, 4, 6-trithiol monoanion (TT/LDH) and 0.81nm for that of 6-dibutyl-1, 3, 5-triazine-2, 4-dithiol monoanion (DB/LDH), 0.78nm for the carbonate anion-intercalated LDH by XRD. The absorption peaks due to triazine ring (1580cm-1) and methylene (2950cm-1) were shown in the FT-IR spectrum of the TT/LDH and DB/LDH. These results indicate that TT or DB was intercalated into the LDH. The AS/RTD/LDH has shown the diffraction peak similar to the RTD/LDH. The induction period (t10) was 0.7-1min using 1, 3, 5-triazine-2, 4, 6-trithiol monosodium salt, in contrast to 10min using AS/TT/LDH. The crosslinking of chlorinated acrylic rubber using the AS/TT/LDH showed a proper induction period.

Structure-Properties of Acrylic Rubber/Epoxy Adhesive by Reaction-Induced Phase Decomposition

The advancement in the miniaturization of electric devices requires high performance diebond adhesive films for semiconductor packages. The diebond film should have high thermal-stress resistance and good retention of adhesive properties. To achieve such performance and reliability, we choose a rubber-rich epoxy adhesive. In the present work, we investigated the influence of reactive site of acrylic rubber (ACM), cure agent and curing condition on the performance of diebond film. In the early stage of curing, ACM/epoxy/curing agent (e.g., DDM: diaminodiphenylmethane) system was a single-phase mixture. As the cure reaction proceeded, phase separation took place via the spinodal decomposition, induced by the increase in the molecular weight of epoxy. The reaction-induced spinodal decomposition was confirmed by the characteristic change in light scattering profile with curing time. Phase contrast microscopy and atomic force microscopy also revealed the formation of regularly phase-separated structure characteristic to the spinodal decomposition. The periodic distance of the structure varied in a wide range, from a few μm to ten nm. The higher amount of reactive site (glycidylmethacrylate) in ACM and the lower cure temperature rendered the shorter periodic distance. The shorter periodic distance yielded the higher adhesive strength. However, much shorter distance of 10 nm resulted in poor adhesive strength. The sub-μm structure seems to lead to optimum strength. The 10 nm structure material showed low thermal expansion and nice transparency.

Rheological Behavior of Hybrid Rubber Nanocomposites

Abstract Melt rheological behavior of acrylic rubber (ACM)/ silica and epoxidized natural rubber (ENR)/ silica hybrid nanocomposites prepared by using sol-gel technique at room temperature was studied for the first time in a Monsanto Processability Tester (capillary rheometer) at nine different shear rates and three different temperatures (100 °C, 110 °C and 120 °C). Tetraethoxysilane (TEOS) was used as the precursor for silica, and water to TEOS mole ratio was maintained at 2:1 throughout the experiments. The loading of TEOS was 10, 30 and 50 wt% with respect to the rubber and the pH of the medium was maintained in the range of 1.0–2.0 by the addition of appropriate amount of concentrated HCl. The shear viscosity showed marginal increment even at higher nanosilica loading for the rubber/ silica nanocomposites. All the compositions displayed pseudoplastic behavior and obeyed Power Law model within the experimental conditions. The reinforcement factor (RF) calculated from the ratio of the viscosities of the filled and the unfilled systems was found to increase with nanosilica content at a particular shear rate. ENR/ silica nanocomposites displayed higher increment of RF compared to ACM/ silica system, which may be due to better polymer-filler interaction in the former. The RF remained almost constant for both the systems with the variation of temperature. The die swell of the nanocomposites was always lower than that of the gum rubber sample, though the nature of variation of die swell with shear rates was different for ACM and ENR nanocomposites. In both the cases, the die swell was found to decease with increase in temperature. The variation in activation energy with the experimental shear rates was also calculated, where the hybrids displayed a decreasing trend in activation energy with the increase in shear rate.

The influence of clay and elastomer concentration on the morphology and fracture energy of preformed acrylic rubber dispersed clay filled epoxy nanocomposites

The influence of toughener and clay concentration on the morphology and mechanical properties of three-phase, rubber-modified epoxy nanocomposites was studied. Nanocomposite samples were prepared by adding octadecyl ammonium ion exchanged clay to a dispersion of pre-formed acrylic rubber particles in liquid epoxy, so as to minimize alteration to the rubber morphology in the final cured specimen. The state of clay platelet exfoliation and rubber dispersion in the cured nanocomposites was studied using transmission electron microscopy. The amounts of clay platelet separation and dispersion of clay aggregates in the epoxy matrix were found to be sensitive to clay and toughener concentration, and clay platelets preferentially adsorb to the rubber particles. Tensile modulus and strength increase and ductility decreases with increasing organoclay content, while rubber has the opposite effects on the properties of epoxy resin. When both additives are present in epoxy resin, a favorable combination is produced: ductility is enhanced without compromising modulus and strength. Modulus and strength are improved by nano and micro dispersion of nanoclay in the epoxy matrix, whereas elongation and toughness are improved by clay adsorption to the rubber particle surface, which promotes cavitation. The glass transition temperature of epoxy resin remains relatively unchanged with clay addition.

Properties of polymer-modified mortars using epoxy and acrylic emulsions

Water based polymer systems are often used for improvement in the properties of plain cement mortar or concrete. Presently, latexes of a single or combinations of polymers like polyvinyl acetate, copolymers of vinyl acetate–ethylene, styrene–butadiene, styrene–acrylic, and acrylic and styrene butadiene rubber emulsions are generally used. One of the limitations of these polymer systems is that they may re-emulsify in humid alkaline conditions. To overcome this problem, an epoxy emulsion based polymer system has been developed. In this paper the properties of the cement mortar modified with this newly developed epoxy emulsion are compared with those of the acrylic-modified mortar. The results showed that the mortars with the newly developed system have superior strength properties and better resistance to the penetration of chloride ions and carbon dioxide.

Compatibility Study of Blends of Acrylic Rubber (ACM), Poly(ethyleneterephalate) (PET), and Liquid Crystalline Polymer (LCP)

The ternary blends of acrylate rubber (ACM), poly(ethyleneterephalate) (PET), and liquid crystalline polymer (LCP) were prepared by varying the amount of LCP, but fixing the ratio of ACM and PET using melt mixing procedure. The compatibility behavior of these blends was investigated with infrared spectroscopy (IR), differential scanning calorimetry (DSC), and dynamic mechanical analyzer (DMA). The IR results revealed the significant interaction between the blend components. Glass transition temperature (Tg) and melting temperature (Tm) of the blends were affected depending on the LCP weight percent in the ACM/PET, respectively. This further suggests the strong interfacial interactions between the blend components. In the presence of ACM, the nucleating effect of LCP was more pronounced for the PET. The thermogravimetric (TGA) study shows the improved thermal stability of the blends.

Polymer–filler interactions in sol–gel derived polymer/silica hybrid nanocomposites

AbstractThe effect of polymer–filler interaction on solvent swelling and dynamic mechanical properties of the sol–gel derived acrylic rubber (ACM)/silica, epoxidized natural rubber (ENR)/silica, and poly (vinyl alcohol) (PVA)/silica hybrid nanocomposites has been described for the first time. Tetraethoxysilane (TEOS) at three different concentrations (10, 30, and 50 wt %) was used as the precursor for in situ silica generation. Equilibrium swelling of the hybrid nanocomposites in respective solvents at ambient condition showed highest volume fraction of the polymer in the swollen gel in PVA/silica system and least in ACM/silica, with ENR/silica recording an intermediate value. The Kraus constant (C) also followed a similar trend. In dynamic mechanical analysis, the storage modulus dropped at higher strain (>1%), which indicated disengagement of polymer segments from the filler surfaces. This drop was maximum in ACM/silica, intermediate in ENR/silica, and minimum in PVA/silica, both at 50 and 70 °C. The drop in modulus with theoretical volume fraction of silica (ϕ) was interpreted with the help of a Power law model ΔE′ = a1ϕ, where a1 was a constant and b1 was primarily a filler attachment parameter. Strain dependence of loss modulus was observed in ACM/silica hybrid nanocomposites, while ENR/silica and PVA/silica nanocomposites showed almost strain‐independent behavior. The storage modulus showed sharp increase with increasing frequency in ACM/silica system, while that was lower in both ENR/silica (at higher frequency) and PVA/silica systems (in the entire frequency spectrum). The increase in modulus with ϕ also followed similar model ΔE′ = a2ϕ proposed in the strain sweep mode. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2399–2412, 2005

Solution Rheology of Poly(vinyl alcohol)/Silica Hybrid Nanocomposites

The solution behavior of polymer/silica hybrid nanocomposites was investigated using a Brookfield viscometer. The nanocomposites were prepared using the sol-gel technique with tetraethoxysilane (TEOS) as the precursor for silica. The sol-gel reaction was carried out in the pH range of 1.0-2.0, which was maintained by the addition of concentrated HCl. Poly (vinyl alcohol) (PVA)/silica nanocomposites demonstrated a bigger rise in solution viscosity after continuous measurement for five days than either- acrylic rubber (ACM)/silica or epoxidised natural rubber (ENR)/silica nanocomposites. Detailed investigation of the PVA/silica system indicated that it exhibited Newtonian behaviour when the solutions contained (5 or 7.5 wt% of PVA,) even when increasing the TEOS concentration to 50 wt%, although at one particular TEOS concentration (10 wt%), the nanocomposite was pseudoplastic when the concentration of PVA was increased to 10 wt%. The reinforcement factor [Formula: see text] for those PVA/silica hybrid nanocomposites containing 5 wt% of PVA deviated strongly from the Guth-Smallwood prediction. Instead they obeyed a relationship of the type ηmax = η0(1 + aϕb), where a = 4.45 and b = 0.38, calculated for this system. The viscosity decreased with increasing temperature for both PVA and the representative nanocomposite with 30 wt% TEOS (PVA30), although the activation energy for flow of the nanocomposite did not vary to a great extent.

Surface modification of magnesium alloys using triazine dithiols

Polymer plating of 6-dihexylamino-1,3,5-triazine-2,4-dithiol monosodium (DHN), 6-diallylamino-1,3,5-triazine-2,4-dithiol monosodium (DAN), and 6-mercapto-1,3,5-triazine-2,4-dithiol (TTN) groups at 10 °C in 1 mol/dm 3 NaOH aqueous solution on the magnesium alloy AZ91D yielded poly(6-dihexylamino-1,3,5-triazine-2,4-disulfide) (PDH), poly(6-diallylamino-1,3,5-triazine-2,4-disulfide) (PDA), and poly(6-mercapto-1,3,5-triazine-2,4-disulfide) (PTT), respectively. PDH-plated magnesium alloys showed excellent corrosion resistance in air containing moisture and in corrosive water because PDH films have very low critical surface tension, are composed of ordered and closely packed layer structure like the LB-films, and have high crystallinity. An increase in film thickness of the PDH films suppressed the corrosion rate of the magnesium alloys and increased the induction period to initiate the corrosion. PTT-plated magnesium alloys showed outstanding adhesion to poly(phenylene sulfide) (PPS) compounds during injection molding in 140 °C. This is because PTT films have highly active points, such as SS bonds, and show excellent strength. PTT-film thickness in the range of 20 to 80 nm provided high tensile shear strength for the direct adhesion of PPS to PTT-plated magnesium alloys. PDA-plated magnesium alloys exhibited excellent adhesion to ethylene-propylene-diene terpolymer (EPDM) in a peroxide curing system and with acrylic rubber (ACM) under a triazine thiol curing system, although the peel strength was found to depend on film thickness.

合成ゴムの最近の動向 アクリル系ゴムの最近の動向

Acrylic rubbers are well known in automobile industry because of their good heat resistance and oil resistance. This paper reports recent trend of acrylic rubbers reviewing past ten years' patents. As a new trend, the patents of Acrylic rubber that have special cure site system, for example carboxyl cure site, and their curing systems are applied constantly. By way of the example, we report new curing system and durability of acrylic rubber copolymerized from ethylene, vinyl acetate and acrylic esters.

Synthesis and characterization of acrylic rubber/silica hybrid composites prepared by sol‐gel technique

AbstractThe organic–inorganic hybrid composites comprising acrylic rubber and silica were synthesized through sol–gel technique at ambient temperature. The composites were generated through the acid‐catalyzed hydrolysis and subsequent condensations of inorganic tetraethoxysilane (TEOS) in the organic acrylic rubber (ACM), solvated in tetrahydrofuran. The morphology of the hybrid materials was investigated by using the transmission electron microscope (TEM) and scanning electron microscope (SEM). Transmission electron micrographs revealed that the silica particles, uniformly distributed over the rubber matrix, are of nanometer scale (20–90 nm). The scanning electron micrographs demonstrated the existence of silica frameworks dispersed in the rubber matrix of the hybrid composites. The X‐ray silicon mapping also supported that observation. There was no evidence of chemical interaction between the rubber phase and the dispersed inorganic phase, as confirmed from the infrared spectroscopic analysis and solubility measurements. Dynamic mechanical analysis indicated mechanical reinforcements within the hybrid composites. The composites containing in situ silica, formed by sol–gel technique, demonstrated superior tensile strengths and tensile modulus values at 300% elongations with increasing proportions of tetraethoxysilane. However, the improvements in physical properties with similar proportions of precipitated silica were not significant. Maximum tensile strength and tensile modulus were obtained when the rubber phase in the hybrid composites was cured with ammonium benzoate and hexamethylenediamine carbamate system, as compared with benzoyl peroxide cured system. Thermal stability of the hybrid composites was not improved appreciably with respect to the virgin rubber specimen. Residue analysis from thermogravimetric study together with infrared spectroscopic analysis indicated the presence of unhydrolyzed tetraethoxysilane in the hybrid composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2579–2589, 2004

Electron beam initiated modification of acrylic elastomer in presence of polyfunctional monomers

The structural changes of an acrylic rubber (ACM) in presence and absence of polyfunctional monomers like trimethylolpropane triacrylate, tripropyleneglycol diacrylate, trimethylolmethane tetraacrylate and trimethylolpropane trimethacrylate at different doses of electron beam (EB) irradiations were investigated with the help of FTIR spectroscopy (in the attenuated total reflectance mode) and sol–gel analysis. As the radiation dose increases, the concentration of carbonyl group increases in the ACM rubber due to aerial oxidation. This is corroborated from the increase in the absorbance values at 1734 and 1160 cm −1, which are due to carbonyl and C–O–C stretching frequencies, respectively. The increase in crosslinking is revealed by the increase in percentage gel content with radiation dose. The lifetime of spurs formed and the critical dose, an important criterion for overlapping of spurs have been determined for both grafted and ungrafted ACM rubber using a mathematical model. The predominance of crosslinking by electronic stopping with energetic EB projectile and the increase in effective radius of crosslinking have also been verified by this model. The doses at which the synergistic occurrence of both dislinking and endlinking steps originate have been calculated using linear energy transfer of EB. The ratio of scissioning to crosslinking for ACM rubber has been determined by using Charlesby–Pinner equation. The mechanical properties have been studied for different modified and unmodified systems and the tensile strength is found to increase with grafting of polyfunctional monomers.

Acrylic, Elastomeric, Particle‐Dispersed Epoxy‐Clay Hybrid Nanocomposites: Mechanical Properties

AbstractSummary: Nanocomposites were formulated by curing a sonicated mixture of epoxy resin, C18 clay, and acrylic rubber dispersants. At 5.5 phr (parts per hundred) organoclay loading and a rubber concentration of 15 phr, the tensile‐failure strain of the nanocomposite was found to be higher than that of epoxy nanocomposite, rubber‐dispersed epoxy, and pristine epoxy. A plausible mechanism for improvement of the failure strain of nanocomposites is proposed.Stress strain curves of filled and unfilled epoxy specimen.magnified imageStress strain curves of filled and unfilled epoxy specimen.

Effect of filler on the mechanical, dynamic mechanical, and aging properties of binary and ternary blends of acrylic rubber, fluorocarbon rubber, and polyacrylate

AbstractWe studied the effects of fillers on the mechanical, dynamic mechanical, and aging properties of rubber–plastic binary and ternary blends derived from acrylic rubber, fluorocarbon rubber, and multifunctional acrylates. The addition of fillers, such as carbon black and silica, changed the nature of the stress–deformation behavior with a higher stress level for a given strain. The tensile and tear strengths increased with the addition of the fillers and with loading, but the elongation at break decreased, and the tension set remained unaffected. The aging properties of carbon‐black‐filled blends were better because of the thermal antioxidant nature of carbon black. The swelling resistance of the binary and the ternary blends in methyl ethyl ketone increased with the incorporation of fillers. From dynamic mechanical thermal analysis, we concluded that the filler altered the height and half‐width of the damping peak at the glass‐transition temperatures. There was little change in the loss tangent values at higher temperatures. A higher loading of the filler increased the storage modulus at all of the temperatures measured. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 278–286, 2003

Study of impact properties and morphology of 4,4′‐diaminodiphenyl methane cured epoxy resin toughened with acrylate‐based liquid rubbers

AbstractRandomized carboxyl poly(2‐ethylhexyl acrylate) (A‐1) and randomized epoxy poly(2‐ethylhexyl acrylate) (B‐1) rubbers were synthesized in the form of liquid rubber by a solution polymerization technique. The liquid rubbers A‐1 and B‐1 were characterized by 1H NMR and IR spectroscopic analysis, non‐aqueous titration, viscosity measurements and gel permeation chromatography. The liquid rubbers A‐1 (M̄n = 3900 g mol−1), B‐1 (M̄n = 4100 g mol−1) and a (1:1) mixture of A‐1 and B‐1 were pre‐reacted with epoxy resin separately and the modified epoxy networks were made by curing with high temperature curing agent. The modified epoxy networks were evaluated by unnotched Izod impact testing. The morphology and toughening behaviour were analysed by scanning electron microscopy. Optimum properties were obtained with the mixture of A‐1 and B‐1. Copyright © 2003 Society of Chemical Industry

Acrylic rubber‐fluorocarbon rubber miscible blends: Effect of curatives and fillers on cure, mechanical, aging, and swelling properties

AbstractThe cure characteristics and mechanical properties of gum and filled acrylic rubber (ACM), fluorocarbon rubber (FKM), and their blends of varying compositions were studied both under unaged and aged conditions. The rheometric study showed that optimum cure properties were obtained using a mixed curing system of blocked diamine, hexamethylenediamine carbamate (Diak #1), and ammonium benzoate. From varying the curing agents, the optimum levels of Diak #1 and ammonium benzoate were found to be 1.5 and 2.5 phr, respectively. The addition of different fillers and their loading influenced the cure properties, with increased torque and reduced scorch safety. The gum and filled 50:50 (w/w) ACM‐FKM showed overall performance in strength properties. Postcuring improved the strength of all the systems, especially the systems with a higher proportion of FKM. None of the properties changed significantly during aging of the blends. FKM and the blends containing a higher proportion of FKM were affected least by aging. Swelling of the blends was reduced by the addition of fillers. Dynamic mechanical thermal analysis showed a single tan δ peak corresponding to a single phase transition for both cured and filled blends. The storage modulus of the blend increased from the gum blend to the filled blend, indicating the presence of polymer‐filler interaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1442–1452, 2003

Polyamide, acrylic rubber and their blends studied by positron annihilation and other methods

Polyamide, acrylic rubber and their blends have been examined with use of PALS spectroscopy from 40 to 375 K. Free volume characteristics have been obtained from the PALS and PVT measurements. There is a great difference in the average size of free volume holes and the fractional free volume of PA and the rubber. The volume relaxation effects are seen at low temperature, especially in case of PA. The results of DSC and the impact strength measurements prove the compatibility of PA and acrylic rubber in the blends. The difference in the fractional free volume of the constituents of the blends found by us, supports the idea of the enhancement of mutual interaction of the blend constituents and the possibility of chemical reaction between them.

Rheological and viscoelastic properties of multiphase acrylic rubber/fluoroelastomer/polyacrylate blends

AbstractDynamic viscoelastic properties and dynamic mechanical properties of blends of acrylate rubber (ACM), fluoroelastomer and polyacrylate plastics have been investigated with a rheometer (ARES RDA III) at a frequency (ω) range of 0.1 to 100 rad.s−1. The analysis of thermorheological properties revealed that the dynamic moduli and dynamic viscosity of blends varied with the composition of the ACM/FKM blend and the level and type of polyfunctional acrylates. The blends showed negative deviation of the dynamic viscosity additive rule. Higher polyfunctional acrylates induced phase separations and showed temperature dependency. It was found that the data of the blends did not follow the Cole‐Cole plot of miscibility and the plot of log G′‐log G″ of the blend showed composition dependency. The dynamic mechanical analysis exhibited lower tan δ values for blends containing higher functional acrylates. Stress relaxation measurements showed longer periods of relaxation for all blends.

Dynamic vulcanization of acrylic rubber‐blended PVC

AbstractPoly(vinyl chloride) was blended with an acrylic rubber at a variety of blending ratio using a twin‐screw extruder. The acrylic rubber was compounded with sulfur and sodium stearate in a two‐roll mill prior to the blending. Dynamic vulcanization was performed in a compression mould at 170°C. Mechanical properties of the blends were determined by using a tensile testing machine. Scanning electron microscope was used to examine morphology of these blends. Degree of crosslinking of acrylic rubber in the blends was evaluated by using a differential scanning calorimeter. It was found that the normal blends are miscible regardless of the blending variables. By performing dynamic vulcanization, however, the blends became immisicible, showing a typical dispersed particle morphology, which was accompanied by a remarkable improvement of tensile properties. The screw‐rotating speed was an important parameter affecting particle size and crosslink density of the rubber phase, which in turn controlled the tensile toughness of the blends. On the one hand, tensile toughness increased with the speed because of the decreasing particle size. On the other hand, the toughness decreased with the speed because of the decreasing crosslink density of the rubber. As a result, there was an optimum speed for each blend ratio, which corresponded to the maximum toughness. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2657–2663, 2003