A study of the influence of a new promoter on the adhesion of rubber to a metal cord

A promoter of adhesion of a rubber to a metal cord based on precipitated silica modified by cobalt was developed. The analysis of its qualitative and quantitative composition was carried out. The effect of the obtained compounds on the technological and physico-mechanical properties of filled elastomeric compositions based on synthetic polyisoprene rubber and on the properties of metal cord–rubber systems was studied. It was shown that application of modified precipitated silica allows both making elastomeric compositions cheaper and improving their adhesive properties.     

A calorimetric study of spontaneous polymerization in acrylamide systems containing metal nitrates

A calorimetric study of the kinetics of spontaneous polymerization of acrylamide in systems containing Cr(III) and Er(III) nitrates has been carried out. At 20–25 °C, the process is characterized by a considerable induction period (20–40 min), a fast increase of the polymerization rate, up to its maximum value (5–10 min), and its subsequent slow decrease to insignificant values. It has been established that the composition of the reaction mixture significantly affects the recorded polymerization rates, and practically does not change the time parameters and the integral degrees of conversion of the process, which are 20 and 80 % for the nitrates of Cr(III) and Er(III), respectively. The effect of the addition of water or inhibitors of radical reactions on the process has been studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1070–1074, June, 1993.     

A note on the determination of Young's modulus of rubber compounds from the tire cord adhesion test

The cord pull-out force of the tire cord adhesion test (TCAT) is dependent on both cord-rubber adhesion energy and the Young's modulus of the matrix rubber of the TCAT testpiece. In order to determine the adhesion energy from the cord pull-out force, the rubber modulus must also be known. This paper describes a simple procedure for determining the rubber modulus from the load-deflection curve, which is obtained when the cord pull-out force is determined. An extra test operation (for determining modulus) is thereby avoided.     

A SAXS and swelling study of cured natural rubber/styrene–butadiene rubber blends

A small‐angle X‐ray scattering (SAXS) and swelling study of natural rubber and styrene–butadiene rubber blends (NR/SBR) is presented. To this aim, specimens of NR and SBR and blends with 75/25, 50/50, and 25/75 NR/SBR ratios (in phr) were prepared at a cure temperature of 433 K and the optimum cure time (t₁₀₀). This time was obtained from rheometer torque curves. The system of cure used in the samples was sulfur/n‐t‐butyl‐2‐benzothiazole sulfenamide. From swelling tests of the cured samples, information about the molecular weight of the network chain between chemical crosslinks was obtained. For all cured compounds, in the Lorentz plots built from SAXS scattering curves, a maximum of the scattering vector q around 0.14 Å^?1 was observed. However, the q position shows a linear‐like shift toward lower values when the SBR content in the SBR/NR blend increases. In pure NR or SBR the q values show a different tendency. The results obtained are discussed in terms of the existence of different levels of vulcanization for each single phase forming the blend and the existence of a third level of vulcanization located in the interfacial NR/SBR layer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2320–2327, 2009     

A smart adhesive joint: entropic control of adhesion at a polymer/metal interface

The study of adhesion has a long and rich history, with theory, experiments, and applications bridging numerous disciplines, including physics, chemistry, engineering, and medicine. This diverse interest has led to the development of a large number of methods for both enhancing and inhibiting adhesion at specific interfaces of interest. We report herein "smart" adhesion at a polymer/metal (oxide) interface that responds reversibly to changes in temperature by increasing or decreasing in magnitude. The temperature dependence in this system arises from the rubber elasticity of the polymer, 1,4-polybutadiene, and mirrors the interfacial behavior of the same polymer against water. Such systems offer unique opportunities for designing responsive materials whose properties can be actively controlled.     

A study of the AMO method as applied to the lithium metal. I. Review,results, and discussion

The total electronic energy per atom in the lithium metal has been calculated for three different Fermi surfaces as a function of the internuclear distance. In each case the optimized AMO energy as well as the total energy corresponding to doubly filled molecular orbitals (MO ) has been calculated. For densities around the equilibrium density the spherical Fermi surface yields the lowest energy whereas a cubic Fermi surface is preferred for low densities. For densities around the equilibrium there is no band splitting: the AMO energy coincides with the MO energy. The computations have been carried out within an LCAO approximation with overlap and multicenter-integrals calculated accurately.     

Transition metal iodates. I. Preparation and characterization of the 3d iodates

The transition metal iodates provide a group of compounds with centric and acentric structures and magnetic alignment at low temperature, optical absorption and emission, as well as piezoelectric, ferroelectric, and related properties, and possibilities of cross-interactions.Many inconsistent reports on these iodates and their hydrates exist, mainly due to lack of characterization. We report the occurrence of 13 compounds: Cr(IO₃₃; Mn(IO₃)₂; Fe(IO₃)₃; Co(IO₃)₂ and its 2 and 4 hydrates; Ni(IO₃)₂ in α and β forms, its dihydrate, and α and β tetrahydrates; Cu(IO₃)₂ and 3Cu(IO₃)₂ · 2H₂O (bellingerite). Some of these compounds are unstable in the presence of water but form metastably from solution. All but four of these compounds have now been prepared as single crystals and all have been characterized by differential thermal and thermogravimetric analyses, optical absorption from 35 to 33,000 cm^?1, and in terms of refractive indexes and related optic parameters. In Part II structural, magnetic, and some nonlinear optical properties are reported.     

A molecular orbital study of lithium ion association with bases. I. The carbonyl bases R2CO

Ab initio SCF calculations have been performed to determine the relative lithium ion affinities of the carbonyl bases R₂CO and the structures of the complexes R₂COLi⁺. The predicted order of lithium ion affinity for the bases R₂CO with respect to R is NH₂ > CH₃ > OH> H> F. Except for (OH)₂COLi⁺ which has C_a, symmetry, the complexes R₂COLi⁺ have C_2v symmetry, with the lithium ion located on the symmetry axis near the oxygen. The major structural changes in the intramolecular coordinates of the bases which occur upon lithium ion complexation include an increase in the carbonyl C---O bond length, a decrease in the length of the bond from the carbonyl carbon to the substituent atom X, and an increase in the X---C---X angle at the carbonyl carbon. The energetic, structural, and electronic properties of the complexes indicate that the interaction between the lithium ion and a carbonyl base is predominantly an ion-dipole attraction rather than a covalent interaction.     

Chemical modification of butyl rubber. I. Synthesis and properties of poly(ethylene oxide)-grafted butyl rubber

A new amphiphilic polymer, i.e., poly(ethylene oxide) (PEO)-grafted butyl rubber (IIR-g-PEO), was synthesized by chemical modification of chlorinated butyl rubber (CIIR). This synthesis was based on the reaction between chlorine in CIIR and potassium salt of polyethylene glycol monomethyl ether (PEGM). PEGM's with molecular weights of 750 and 2000 were used. The maximum grafting percent of the resulted copolymers after the purification was ca. 45%, regardless of the molecular weight of PEGM. The microphase separated structure was observed in the films of IIR-g-PEOs. IIR-g-PEO, whose PEO molecular weight was 2000 and whose PEO content was 23.8 wt %, swelled 3.1% in water, and it was six times larger than the swelling of CIIR. The hydrophilicity of grafted polymers depended on the molecular weight of PEO side chains and PEO content. Even when the PEO contents were same in the polymers which were grafted PEGM-750 and PEGM-2000, their swellings in organic solvents were not equal. It was due to the difference of the microphase-separated structures of the grafted polymers. IIR-g-PEO, whose PEO molecular weight was 750 and whose PEO content was 10.3 wt %, swelled 1.5% in water, but showed an excellent emulsifying ability, where an oil-in-water-type emulsion was formed. © 1993 John Wiley & Sons, Inc.     

Study on interfacial adhesion of the aramid fibers/rubber matrix by grafting mercapto hyperbranched polysiloxane

In order to improve the interfacial adhesion between aramid fiber (AF) and rubber matrix, the mercapto hyperbranched polysiloxane (HPSi) was grafted onto the AFs via a novel in-situ growth strategy, which combines the formation of polydopamine (PDA) precursor layer and the co-dehydration condensation between (3-aminopropyl) trimethoxysilane and (3-mercaptopropyl) trimethoxysilane. Based on the results of characterizations including morphology observations and chemical structure analyses, the growth process of mercapto HPSi with the reaction time was investigated and discussed. The pull-out force tests of AFs/rubber composites, which were carried out by universal testing machine, showed that the modification strategy proposed in this study could increase the interfacial adhesion up to approximately 96.5%, and the key factor could be inferred to be the covalent interaction between mercapto groups and double bonds. It is also worth mentioning that the phenomenon of excessive surface modification will occur with the overlong growth time, which would result in the reduction of the interfacial adhesion.     

Nonoxidative crosslinking reactions in natural rubber. I. Determination of crosslinking groups

The presence of both epoxide and amine groups as integral constituents of the natural rubber macromolecule have been demonstrated, by application of an HBr double titration technique. The number of such groups is dependent on the clonal source of the rubber and is found to decrease on storage in step with an increase in the plasticity of the rubber. The groups are believed to be involved in nonoxidative crosslinking reactions which occur in rubber on storage. Possible crosslinking mechanisms are proposed.     

Diethylzinc/metal salt initiator systems. I. Stereospecific polymerization of N-vinylcarbazole by ZnEt2/CoCl2-quinoline

In the presence of ZnEt₂ the CoCl₂-quinoline complex polymerizes NVC with a rate increasing with ZnEt₂ and CoCl₂-Q concentrations up to a certain concentration of ZnEt₂ or CoCl₂-Q, thereafter becoming independent of either. At a fixed concentration of ZnEt₂ and CoCl₂-Q the rate is second order with respect to NVC. The poly(NVC) obtained is freely soluble in benzene but leaves some insoluble fraction in methyl ethyl ketone, which has been characterized by ¹³C-NMR to be a stereoblock polymer. X-ray diffraction, IR, and thermal characteristics of the polymer have also been reported. [η] is virtually independent of monomer, in the concentration range 0.1–0.25 mol/L ZnEt₂ and CoCl₂-Q concentrations. Oxygen as an additive inhibits the polymerization. A cationic coordination mechanism has been proposed and appropriate rate and degree of polymerization equations have been suggested.     

Gas-phase negative ions of platinum metal fluorides. I. Electron affinity of platinum metal tetrafluorides

Knudsen cell mass spectrometry was used in studies of a number of ion/molecule equilibria involving platinum metal tetrafluorides. Using a combined ion source made it possible to extend considerably the series of tetrafluorides under investigation. This yielded electron affinities of 4.75±0.28, 5.43±0.28, 3.87±0.24, 4.67±0.29 and 5.50±0.25 eV ¹ for Ru, Rh, Os, Ir, and Pt tetrafluorides, respectively.     

Fast gel-permeation chromatography. I. A study of operational parameters

A systematic study of factors affecting the GPC separation showed that peak spreading with increasing flow rate was much less than predicted from the Van Deemter equation. Viscous fingering decreased and peak symmetry improved at increased flow rates. As a result, fast GPC analysis was shown to be readily attainable through optimization of operating parameters.     

A relativistic C.I. study on theJ=1/2 even spectrum of Sr II

We present a method for performing relativistic CI calculations in ground and excited atomic and ionic levels. An electron occupying a relativistic shellnκ in a given electronic configuration is described by a single numerical four-component Dirac-Fock orbital having the samen and κ quantum numbers to those of the shellnκ. Application of this method yields estimates for the I.P. (88 741 cm^?1) and the core correlation energy (?30916 cm^?1) for Sr II and for the total correlation energy in Sr III (?30916 cm^?1). Core-valence correlation energies for the |core 5s〉 (?4379 cm^?1), |core 6s〉 (?1191 cm^?1) and |core 13s〉 (?32 cm^?1) levels have been calculated for Sr II. Estimates for the total relativistic, Breit, vacuum polarization and self energy corrections for these levels are also reported. Configurations in which the core is not fully occupied have been found to yield significant contributions to the correlation energies of both ground and excited levels. Our results show that full scale relativistic CI calculations using numerical four-component Dirac-Fock orbitals are feasible and provide a useful ab-initio tool for the investigation of atomic properties within the framework of fully relativistic theories.     

A theoretical study of electrocatalytic ammonia synthesis on single metal atom/MXene

Electrocatalytic ammonia synthesis under mild conditions is an attractive and challenging process in the earth's nitrogen cycle, which requires efficient and stable catalysts to reduce the overpotential. The N₂ activation and reduction overpotential of different Ti₃C₂O₂-supported transition metal (TM) (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, Cd, and Au) single-atom catalysts have been analyzed in terms of the Gibbs free energies calculated using the density functional theory (DFT). The end-on N₂ adsorption was more energetically favorable, and the negative free energies represented good N₂ activation performance, especially in the presence Fe/Ti₃C₂O₂ (?0.75 eV). The overpotentials of Fe/Ti₃C₂O₂, Co/Ti₃C₂O₂, Ru/Ti₃C₂O₂, and Rh/Ti₃C₂O₂ were 0.92, 0.89, 1.16, and 0.84 eV, respectively. The potential required for ammonia synthesis was different for different TMs and ranged from 0.68 to 2.33 eV. Two possible potential-limiting steps may be involved in the process: (i) hydrogenation of N₂ to *NNH and (ii) hydrogenation of *NH₂ to ammonia. These catalysts can change the reaction pathway and avoid the traditional N–N bond-breaking barrier. It also simplifies the understanding of the relationship between the Gibbs free energy and overpotential, which is a significant factor in the rational designing and large-scale screening of catalysts for the electrocatalytic ammonia synthesis.     

A method for improving the adhesion strength of UV-curable polymer compositions to metal

A method for improving the adhesion strength of UV-curable polymer compositions to metal is suggested that is based on the production of an adhesion layer at a metal surface, which is able to undergo polymerization with the components of the applied composition under the action of UV irradiation.     

A Fourier transform Raman study of the cold crystallization of natural rubber and deproteinized natural rubber

The FT-Raman spectra of natural rubber and deproteinized natural rubber are presented as a function of time cold soaking at −25°C. The changes which occur in the spectra are related to the crystallization of the sample and are compared with those reported during the stress induced crystallization of crosslinked natural rubber.     

A study of biodegradation of polyethylene and biodesulfurization of rubber

Applied Biochemistry and Biotechnology - The present study provides preliminary data on the involvement of such microorganisms asAspergillus niger in the biodegradation of commercially available...