Effect of modification with rubber on properties and process of curing of epoxy–rubber adhesive compositions

The effect of SKN-30KTRA low molecular weight rubber on the elastic and strength properties of adhesive compositions made with epoxy-rubber composition, is shown. The data on the effect of rubber on curing of adhesive compositions are presented.     

Thermal stability and flammability of butadiene–styrene rubber nanocomposites

Heterobimetallic oxalato complex precursors, manganese(II)tetraaquatris(oxalato)lanthanate(III)hexahydrate (MnOLa), cobalt(II)pentaaquatris(oxalato)lanthanate(III)trihydrate (CoOLa), nickel(II)pentaaquatris(oxalato)lanthanate(III)hexahydrate (NiOLa) and copper(II)diaaquatris(oxalato)lanthanate(III)monohydrate (CuOLa) of the type, M₃[La(C₂O₄)₃(H₂O) _m ]₂·nH₂O have been synthesized in aqueous medium. The precursors were characterized by elemental analysis, IR, electronic spectral and powder X-ray diffraction studies. The good crystalline nature with monoclinic structures predominates in MnOLa and NiOLa whereas triclinic structures were found in CoOLa and CuOLa. The solid-state thermal behaviour of the precursors was explored using TG, DTG and DTA in air. The MnOLa generated a mixture species consisting mainly of MnO₂, Mn₃O₄, Mn₅O₈, La₂O₃ and LaMn₇O₁₂ at 1000 °C through the formation of several intermediate species at 380 and 570 °C. The studies revealed that CoOLa led mainly to LaCoO₃ and La₂CoO₄ along with some oxides of both the cobalt and lanthanum at 1000 °C. In case of nickel analogue the mixture species identified at 1000 °C are mainly of La₂NiO₄, La₂O₃, Ni₂O₃ and NiO_2. In case of CuOLa the product at 1000 °C consisted of La₂CuO₄, La₂Cu₂O₅ and oxides of copper and lanthanum. The nature of decomposition of the precursors in nitrogen were seen from DSC study and the kinetic parameters i.e., E ^* , lnk ₀, ΔH ^# , ΔS ^# and order of reaction of all the steps were evaluated and discussed.     

Effect of nature and extent of crosslinking on swelling and mechanical behavior of styrene–butadiene rubber membranes

The influence of crosslink type and crosslink density on the swelling and mechanical behavior of styrene–butadiene rubber (SBR) membranes were studied in four aliphatic hydrocarbons. To vary the crosslink type and crosslink density, SBR was vulcanized by four different vulcanizing systems viz conventional, efficient, peroxide and a mixture of sulfur and peroxide. SBR vulcanizates having mono or disulfidic crosslinks (efficient system) exhibited the highest solvent uptake whereas those with C–C bonds (peroxide system) showed the lowest. SBR crosslinked by the mixed system showed superior mechanical properties in the unswollen, swollen and deswollen conditions. Arrhenius and thermodynamic parameters were evaluated from the diffusion data. Finally, a comparison between theoretical and experimental diffusion results was carried out.     

The effect of chlorosulphonated polyethylene on thermal properties and combustibility of butadiene–styrene rubber

This article describes the test results of thermal properties and flammability of the unconventionally cross-linked blends of chlorosulfonated polyethylene (CSM) and butadiene–styrene rubber (SBR) by means of zinc oxide or nano-zinc oxide. The thermal curves have been interpreted from the point of view of the chemical transitions of elastomers and their blends. It has been found that the content of combined chlorine in CSM exerts a significant influence on the cross-linking kinetics of CSM/SBR blends, their thermal properties and flammability.     

Quantitative characterization of toughening mechanisms of rubber modified polymers

The volume changes of rubber modified polymers under creep at room temperature were successfully used to characterize the toughening mechanisms of blends with brittle polymer matrices such as high impact polystyrene.This approach cannot be applied to pseudo-ductile polymers such as polypropylene and polyamide,because they are ductile when stretched at low speed at room temperature.Based on the time-temperature equivalence princi ple,the volume change at low temperature is proposed to characterize quantitatively the toughening mechanisms of polymer blends with ductile matrices,which is illustrated by applying this approach to rubber modified polypropylene     

Thermal stability and flammability of styrene–butadiene rubber (SBR) composites

The article presents the effect of attapulgite (ATT) and its synergic action with carbon or silica on the thermal properties and flammability of cross-linked styrene–butadiene rubber. It has been shown that ATT is active filler improving the thermal and mechanical properties of composites containing this aluminosilicate. The decreased flammability of vulcanizates containing ATT compared to that of unfilled vulcanizates results from good insulating properties of the ATT used. The considerable reduction in the flammability of composites containing ATT and carbon nanofiber or silica is connected, first of all, with the formation of a homogeneous boundary layer.     

In situ silica reinforcement of natural rubber by sol–gel process via rubber solution

The in situ silica filling of natural rubber (NR) was carried out via the sol–gel reaction using tetraethoxysilane. The effect of the in situ silica content on the curing, mechanical, dynamic mechanical and thermal properties of the composite vulcanizate materials was investigated in comparison to that with a commercial silica preparation. The Mooney viscosity of the in situ silica filled NR vulcanizates showed a lower value compared with that of the commercial filled ones. The mechanical properties of the in situ silica composite materials, i.e., the moduli and compression set, were improved compared with the commercial silica filler NR vulcanizates. The reinforcement effect of in situ silica did not accord with the Smallwood equation but in contrast was in good agreement with the Guth and Gold equation using a shape factor (f) which itself was in close agreement with estimates derived from independent TEM analysis. The pseudo-network structure of the in situ silica was low, which resulted in a lower storage modulus at 25 °C. By filling NR with in situ silica, the thermal properties of the composite vulcanized material were also improved, and well dispersed in situ silica particles within the NR matrix were also observed.     

Relation between stress relaxation and aging resistance of rubber vulcanizates—some preliminary investigations

In this paper some details are given for the construction of a simple balance for the measurement of stress relaxation at constant elongation. A simple means of obtaining equal strain in the two parts of the strained specimen is provided. By means of four typical stocks covering the widest possible range of aging resistance it is shown that the stress relaxations give approximately the same estimate of stability as does the normal Geer test using 2 mm. dumbbell specimens. As a measure for stress relaxation the time is used that is required to obtain 50% of the value of the interpolated modulus at 200% elongation 6 seconds after the straining zero time at 110°C. The parameter for the aging test is the time in days at 70°C. for the 50% value of tensile strengths. The range for the stress relaxation parameter may be estimated to 8–1200 min. and the aging parameter from 10–600 days. Finally the concordance of temperature coefficient for relaxation and oxidation rates is shown.     

Effect of π–π interaction between carbon nanotubes and phenyl groups on the thermal stability of silicone rubber

Journal of Thermal Analysis and Calorimetry - To investigate the effect and mechanism of π–π interaction between carbon nanotubes (CNTs) and phenyl groups on the thermal stability...     

Effect of ZnO nanoparticles on kinetics of thermal degradation and final properties of ethylene–propylene–diene rubber systems

The morphology, thermal degradation behavior in addition to static and dynamic mechanical properties of various ethylene?Cpropylene?Cdiene (EPDM) rubber compounds containing nano-zinc oxide (NZnO) were investigated compared to those of EPDM with ordinary-sized ZnO (OSZnO). The field-emission scanning electron microscopy studies showed that unlike the conventional system, the formation of large size ZnO agglomerates was discouraged for NZnO filled systems. Thermogravimetric analysis (TG) revealed that the thermal degradation of EPDM system was delayed upon the inclusion of NZnO instead of OSZnO in the compound. The kinetic analysis of TG data based on Friedman and Kissinger methods showed that the nanocomposite samples exhibited higher activation energy (E _a ) and lower order of reaction (n) over the conventional system, suggesting the enhancement of thermal stability upon decreasing ZnO particle size. The results obtained from dynamic mechanical analysis and static mechanical characterizations in terms of hardness, resilience, and abrasion tests interestingly indicated that NZnO not merely could act as a thermal insulator, but also could perform as a nano-filler to improve the final performance of EPDM elastomers.     

A critical analysis of the effect of crosslinking on the linear viscoelastic behavior of styrene–butadiene rubber and other elastomers

The linear viscoelastic behavior in dynamic shear and tensile creep at temperatures from −30 to 70 °C is measured for an styrene–butadiene rubber (SBR) elastomer cured with dicumyl peroxide to crosslinking densities between 0 and 23.5 × 10⁻⁵ mol/cm³. The G′, G″, and tan δ isotherms are analyzed by time–temperature superposition (TTS), where the tan δ master curves are consistent with those of Mancke and Ferry. However, to achieve the TTS in the lightly crosslinked SBR systems, an anomalous vertical shift is required in the narrow temperature region from 10 to 30 °C. The vertical shift factor in this temperature region is not the standard from rubber elasticity. No anomalous behavior is detected in the equilibrium modulus, which is a linear function of temperature in accordance with the classical theory of rubber elasticity. In contrast to SBR, standard vertical shifts are required to effect TTS for uncrosslinked polybutadiene and an ethylene propylene diene monomer elastomer. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Application of multi-capillary column – ion mobility spectrometry (MCC-IMS) in rubber chemistry and technology

In this paper the possibility for authentication and differentiation of various styrene butadiene rubbers (SBRs) was investigated. Seven types of SBR were analyzed by multi-capillary column (MCC) ion mobility spectrometer (IMS) and their spectra compared. The analysis of volatile organic compounds (VOCs) releasing from the rubbers revealed the presence of characteristics signals, which can be assigned only to a specific material. Such “markers”, when defined for other polymer materials, can be used for their authentication. In the second part of the paper, the blend of epoxidized natural rubber and poly-3-hydroxybutyrate-co-4-hydroxybutyrate (ENR/P(3,4)HB) was subjected to different types of aging. MCC-IMS spectra of not aged, thermal, climatic and UV aged samples were collected and differences between the signals discussed. The study showed possibility of authentication of polymeric materials and processes. The paper is a some kind of introduction to the use of analytical properties and advantages of MCC-IMS technique in chemistry, technology and exploitation of polymer materials.     

Effect of epoxidation of natural rubber on the pervaporation separation of acetone–chlorinated hydrocarbon mixtures

The pervaporation separation and the swelling behavior of chlorinated hydrocarbon/acetone mixtures were investigated using natural rubber (NR) and epoxidized natural rubber (ENR) membrane with 25 and 50 mol% epoxidation, respectively. The swelling degree increases with increase in the epoxidation level. The flux and separation factor of the membranes were determined both as a function of mole percent epoxidation and of the feed mixture composition. The membranes were found to be permselective to chlorinated hydrocarbons from acetone–chlorinated hydrocarbon mixtures. The flux decreases with increase in epoxidation level, whereas the separation factor increases. The permeation decreases and separation factor increases with increase in the acetone feed concentration. The availability of raw materials, low cost of implementation and easy processability of the system makes this method of separation highly applicable and recommendable.     

Stabilization effect of potential antioxidants on the thermooxidative stability of styrene–butadiene rubber

Effects of several heterocyclic compounds containing nitrogen, trisubstituted amines and diamines and molecules based on N,N,N′,N′,N′′,N′′-substituted-[1,3,5]triazine-2,4,6-triamine in preventing thermooxidative degradation of styrene–butadiene rubber (SBR) have been studied using non-isothermal DSC measurements. The aim of this study was to determine and compare the stabilizing effect of individual compounds and to select the structures with the best antioxidative properties. In order to compare the stabilizing effect of the compounds, induction periods and protection factors have been calculated. The treatment of the experimental data was carried out using a method based on a non-Arrhenian temperature function. The results show that better antioxidative properties can be assigned to heterocyclic compounds. On the other hand, molecules containing triazine structures exhibited only negligible stabilizing effect on SBR at lower temperatures and even destabilizing effect at higher temperatures.     

Viscoelastic behaviour of silica filled natural rubber composites – Correlation of shear with elongational testing

Dynamic mechanical behaviour of natural rubber-silica composites was studied by a frequency sweep method at different temperatures (40 °C,70 °C and 100 °C) using a dynamic mechanical analyzer and a rotorless rheometer, RPA, in an attempt to establish a correlation between the two. The composites with silica content up to 40 phr were studied. It was found that the dependence of dynamic modulus on the frequency as obtained from both the instruments followed a similar trend. This suggests that the dynamic mechanical properties of rubber compounds can be determined even during curing. A correlation could be arrived at between the two sets of data, making it possible to predict one set knowing the other. The impact of silane coupling agent, bis (3-triethoxysilylpropyl tetrasulphide), TESPT, on viscoelasticity was also investigated. The mechanical properties were improved in the presence of TESPT. Additionally, an increase in thermal stability was also observed in the presence of TESPT. Scanning electron micrographs showed the better filler dispersion in the case of silane-coupled silica composites.     

Uptake of lead by carbonaceous adsorbents developed from tire rubber

The adsorption of lead in aqueous solution by discarded tire rubber (TR) and by carbonaceous adsorbents (CAs) prepared from it by thermal and chemical treatments is studied. TR was heated at 400 or 900?°C for 2 h in N₂ atmosphere or treated chemically with H₂SO₄, HNO₃, H₂SO₄/HNO₃, HCl, NaOH, HCl-NaOH or NaOH-HCl for 24 h. TR and CAs were characterized physico-chemically with regard to their texture, elemental composition and surface chemistry. The adsorption of lead was studied, mainly from the kinetic standpoint, using 4×10^?3 mol?L^?1 Pb²⁺ solutions at initial pH 2.0, 5.7 and 12.6. TR is practically a non-porous material. The heat treatment of TR mainly develops meso- and macroporosity. The effect on macroporosity is stronger when HNO₃ and H₂SO₄/HNO₃ are used. For all adsorbents, the adsorption of lead is not measurable when adsorptive solution at pH 2 is used. With an increase of pH from 5.7 to 12.6, the kinetics of adsorption becomes faster and the amount of lead adsorbed significantly increases. For the solution at pH 12.6 and an adsorption time of 8 h, the adsorption percentage is 36 wt% for TR. For the CAs prepared by heat treatment of TR, it is higher than 50 wt%. For longer adsorption times, the kinetics is much slower for the product of TR treatment with HNO_3. However, the corresponding adsorption percentage is as high as 93 wt% for an adsorption time of 264 h. TR and the CAs, in particular the product heated at 400?°C, are good adsorbents to be used in the rapid removal of a significant amount of lead from aqueous solution.     

Physicomechanical,thermal, and flame-retardant properties of elastomer compounds based on ethylene–propylene–diene rubber and filled with hollow aluminosilicate microspheres

The effect of hollow aluminosilicate microspheres on the Payne effect and on physicomechanical, thermal, fire-retardant, and heat-protecting properties of elastomer compounds based on ethylene–propylene–diene rubber was studied. Based on the results obtained, the mechanism of the interaction of the elastomer matrix with the microspheres was suggested. Enhancement of the filler–matrix and filler–filler interaction favors additional three-dimensional cross-linking, which influences the set of the physicomechanical and thermal properties, and manifestation of the reinforcing effect in a coke layer under the conditions of erosion removal and detachment of the material with a high-velocity gas flow.     

Composites based on polyurethane–urea and ground rubber from car tyres: relation between structure and properties

The basis of this work is an investigation of multicomponent systems containing a reactive polyurethane–urea matrix, recycled rubber filler, and porosity. Rubber crumb with varying particle sizes obtained from used car tyres was used as the filler. As a matrix, water-curable isocyanate pre-polymer was used. Porosity was caused by the inability of the matrix to fully fill space between rubber particles, combined with foaming from matrix curing. We report on dependences of PUU/rubber system mechanical properties on the composition and structural parameters. Mechanical property values were obtained via tensile loading of prepared rectangular slabs. We found that mechanical behaviour exhibits strong correlation with a structural parameter called interspace filling, which expresses how much the matrix fills space between filler particles. Interspace filling is dependent on the degree of porosity and the volume fraction of the PUU matrix in a hypothetical nonporous material. Therefore, this work offers a simple characterization of complex materials, of which the studied porous composite is an example. Our results could contribute to the development of applications for large volumes of recycled rubber in materials used in rapid repair of roads and pavements.     

Tensile property of cord reinforced rubber composites laminate double lap jointEI北大核心CSCD

According to the structural connection form of cord reinforced rubber composite，structural test samples with different lapping process parameters were designed and prepared. The dynamic and static tensile properties were studied by using two-dimensional digital image technology. The test results were as follows：The stiffness and tensile strength of double lap composites joints increased as the strain rate increasing，while the elongation at break unchanged. Compared with the no-lap samples，the tensile strength of the double lap composites sample was reduced by nearly 50%，and with the increase of the lap width，the elongation at break gradually decreased. The samples with lap width of 65 mm decreased by 24% compared with the no-lap ones. Compared with the elastic modulus of stage II，the elastic modulus of stage III increased significantly，that of the no-lap samples increased by 3 times，that of the lap samples were doubled，and the amplification of elastic modulus decreased with the increase of strain rate. © 2023, Youke Publishing Co.,Ltd. All rights reserved.