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The industry's mechanical equipment often faces a significant demand for damping rubber. Simultaneously improving damping and toughness of rubber materials is a challenging task. It was achieved by incorporating crystal particles into the chlorinated butyl rubber (CIIR) network, inspired by the "sliding crystal mechanism". To create the elastomers with high damping and toughness, polyurethane was used along with polyethylene glycol as a soft segment. The combination factors, including coordination and hydrogen bonds, played a crucial role in facilitating the formation of crystal particles within the material. These crystal particles acted as rigid fillers, enhancing the material's toughness. Additionally, the sacrificial reversible bonds present in the crystal particles allowed for energy dissipation during stress. These bonds can be repeatedly broken and regenerated, enabling the material to dissipate energy efficiently. Comparing these elastomers to pure CIIR, they exhibited a tensile strength and elongation at break of 5.76 MPa and 1973%, a fracture energy of 28.73 MJ/m3, a damping factor of 1.52, and a damping temperature range of 80 °C. These results indicate significant improvements in both damping and toughness properties. This advancement could have valuable implications for the industry's mechanical equipment, which often relies on effective damping rubber. [ABSTRACT FROM AUTHOR]

It is of interest to develop wide-temperature domain damped hydrophobic materials. In this paper, we designed incorporating bio-based phenolic resin into the IIR matrix and introducing dibenzyl fork acetone (DBA) into the main chain structure with sodium hydroxide activation to construct three-dimensional network. In this paper, we designed incorporating bio-based phenolic resin into the IIR matrix and introducing dibenzyl fork acetone (DBA) into the main chain structure with sodium hydroxide activation to construct three-dimensional network. The added bio-based phenolic resin has reticulated structure blended with butyl rubber, combined with sodium hydride activation-modified IIR. The results show that sodium hydride activated modification of DBA is introduced into the main chain structure of IIR by infrared and 1H NMR analysis. The material hydrophobic is realized by the introduction of DBA with static water contact angle of 103.5°. The addition of 10phr lignin-based phenolic resin (LPF) is compatible with IIR, and the torque can reach 7.0 N-m. The tensile elongation of the modified butyl rubber composite can reach 2400% with tensile strength up to 11.43 MPa, while the damping factor can reach 0.37 even at 70 °C. The thermal stability of the composites is enhanced with mass retention rate of 28%. The bio-based PF/NaH activation-modified butyl rubber damping material has potential applications in damping hydrophobicity with wide temperature range. [ABSTRACT FROM AUTHOR]

The development of a heat conductive formulation for rubber composites is essential for technical applications such as tire-curing bladders. The present study addresses the effects of three potential ceramic fillers, namely titanium carbide (TiC), silicon carbide (SiC), and alumina, on the mechanical and thermal properties of carbon black (CB)-filled butyl rubber composites. The composites were prepared using the melt compounding method. The curing, mechanical, and thermal conductivity properties of the composites were determined. The tensile strength and modulus of composites decreased slightly in the presence of ceramic fillers in lower amounts of filler loading (10 Phr). Further they reduced in a higher amount of filler loading (20 Phr). In addition, the thermal diffusivity coefficient of the composites increased in the presence of ceramic fillers with different values depending on the type and the amount of the filler with the rank of Al2O3 > SiC > TiC at 10 Phr of filler loading and SiC > TiC > Al2O3 at 20 Phr of filler loading. These different behaviors were discussed according to the state of filler dispersion in the rubber matrix and rubber–filler interactions according to the FeSEM visualization and the mechanical properties. [ABSTRACT FROM AUTHOR]

The damping performance of chlorinated butyl rubber (CIIR) cannot satisfy the rigorous requirements of damping and vibration reduction. Hindered phenol can endow rubber composites with good damping performance, but these small molecules may migrate from rubber matrices. Here, a novel type of damping agent based on the hyperbranched polyester grafted hindered phenol (AG-HP102) was prepared by grafting hindered phenol (AG) with hydroxyl terminated hyperbranched polyester (HP102). It was then incorporated into chlorinated butyl rubber (CIIR) to prepare damping rubber composites. The test results showed that tan δmax of CIIR/AG-HP102 (7 phr) was 1.40, which was 32.1% higher than that of pure CIIR, 1.05. In addition, the glass transition temperature (Tg) was increased from − 26.0 to − 16 ℃. The mechanical property tests showed that the tensile strength and elongation at break of the CIIR/AG-HP102 (7 phr) composite reached 8.21 MPa and 1192%, respectively, which was 290.9% and 39.5% higher than those of pure CIIR, 2.11 MPa and 858%. These experiment results can offer some useful information for the design and fabrication of high-performance polymeric damping materials. [ABSTRACT FROM AUTHOR]

Self-healing anticorrosive coatings in extreme environment have attracted considerable interest from researchers. In this work, 4-tert-butylpyridine (TBP) was incorporated into brominated butyl rubber (BIIR) polymer networks to form a reversible ionic bond with the highly reactive bromine anion. Based on the low glass transition temperature of the BIIR polymer and the electrostatic effects, a robust self-healing anticorrosive coating of TBP-BIIR was prepared. TBP-BIIR coating showed a maximum protection efficiency (PE) of more than 94% (TBP-BIIR-acid, 94.37%; TBP-BIIR-alkali, 94.95%; TBP-BIIR-salt, 95.49%) when treated with a strong acid (HNO3, pH=2), strong base (NaOH, pH=12) and high salt solution (3.5 wt% NaCl). In addition, the PE of coating repaired exceed 89%, and the maximum PE value was approximately 95% in different solutions, which demonstrated its extinguished self-healing abilities. These results indicated that the TBP-BIIR anticorrosive coating could provide excellent safety and durability in special environment, which would be extremely beneficial to improve the working life of metal parts used in aviation and shipping, oil and gas and related industries. [ABSTRACT FROM AUTHOR]

In this study, a modified Rayleigh–Lamb equation is derived that takes into account the radial oscillations of a gas bubble covered with a viscoelastic shell and an inner thin liquid layer is distributed. For the case of small perturbations, a dispersion equation is found that takes into account the interfacial heat transfer between the gas, liquid layer, viscoelastic shell, and carrier fluid. An analytical expression for the equilibrium speed of sound is written out, and its dependence on the dimensions of the liquid layer, viscoelastic shell, and frequency of perturbations is established. The difference in the size of the inner liquid layer in shell bubble on the dynamics of acoustic waves is illustrated. The influence of the dependences of the shear modulus and viscosity of butyl rubber on the frequency of perturbations at different temperatures on the curves of the phase velocity and damping coefficient is shown. The theory is compared with the experimental data. [ABSTRACT FROM AUTHOR]

The control of pests in agricultural systems is currently based on the widespread use of pesticides that efficiently control pests but have negative effects on the environment and humans. Thus, several studies have been conducted to develop alternative sustainable ways to control pests in agriculture. The use of semiochemicals presents a good alternative to develop a sustainable tool monitoring and control insect pests in crops areas. The dispensing carriers of semiochemicals are typically made of non-degradable material, often petroleum derivatives such as butyl rubber, that become polluting waste after application. To develop a biodegradable and low-cost dispenser for semiochemicals, particles of CaCO3 and a CaCO3/Kraft lignin composite were synthesized using CO2 bubbling, characterized and evaluated for 30 days as a dispenser of the limonene molecule, which is a common semiochemical in plants and also pheromone component is some insect species, such as the lesser mealworm Alphitobius diaperinus. Furthermore, limonene is volatile molecule that is easy to acquire and low-cost, which makes it an ideal semiochemical to evaluate the potential of the CaCO3 particles and CaCO3/Kraft lignin composite as a semiochemical dispenser for use in agriculture. The pure calcium carbonate I, pure calcium carbonate II, and composite I synthesized particles presented a larger specific surface area than the other composites. All the particles evaluated showed a slow limonene release rate between the 5th and 30th days evaluated, indicating the potential of these materials as pheromone dispensers. The composites with higher specific surface area, calcium carbonate II (19.5 m2/g) and composite I (23.1 m2/g), released a higher level of limonene during the 30 days evaluated. [ABSTRACT FROM AUTHOR]

Butyl rubber (BR) has been broadly used in many applications, including tires, vibration dampeners, adhesives, and sealants. Its processing generally relies on conventional methods such as injection molding and compression molding. The development of additive manufacturing or 3D printing strategy for BR would further expand its applications, but it is difficult to 3D print BR due to its unique chemistry and thermomechanical properties. Here, we report a strategy for 3D printing of BR and its hybrid materials at room temperature by direct-ink writing method followed by a convenient post-printing crosslinking. Its application in stretchable sensors was also demonstrated. [ABSTRACT FROM AUTHOR]

This study examines the efficacy of rubber, a non-toxic hydrocarbon polymer, as a shielding material against gamma rays and neutrons. We analyse four types of rubbers: Neoprene, Butyl, Natural, and Silicone, using computational methods and Monte Carlo simulations via MCNP (version 6.3) to evaluate their gamma ray and neutron shielding parameters. Notably, Neoprene, enhanced with chlorine, shows superior gamma ray attenuation capabilities with a mass attenuation coefficient (MAC) of 760.446 cm2/g at 0.015 MeV, indicating its potential as an effective material for gamma ray shielding applications. Conversely, Butyl rubber, with its high hydrogen content, exhibits exceptional neutron attenuation properties, with the highest ΣR value of 11.861 1/cm, making it a preferred choice for neutron shielding. This investigation underscores the versatility and environmental benefits of rubber materials in radiation protection, highlighting their potential as lightweight, customisable and sustainable alternatives to conventional shielding substances like lead. Our findings reveal prominent advantages of Neoprene for gamma ray shielding and Butyl rubber for neutron protection, contributing to the development of safer, more effective radiation protection solutions. [ABSTRACT FROM AUTHOR]

A method to identify cross-linked rubbers and elastomers is presented in this report. Three series of polyurethane elastomers with various chemical structures were swollen in selected solvents. The obtained results on the swelling degree of the studied elastomers Q, depended on the values of the solvent solubility parameters (δ1). It was found that the plots of the function Q = f(δ1) could be expressed in the forms of original diagrams useful for fast identification of rubbers and cross-linked elastomers. These diagrams were compared with each other and with the one for butyl rubber. The characteristic features of these diagrams (so-called swellograms) that were useful for the rubber identification are discussed. [ABSTRACT FROM AUTHOR]

In this study, the authors have reported pyrolysis of two different waste materials, lignocellulosic biomass, Delonix regia (DR), and butyl rubber tube waste, (TW), at 600 °C temperature and 1 bar pressure using nitrogen inert atmosphere. In pursuit of obtaining high-quality products, the thermochemical reaction between 95, 85, 75, 65 and 50 mass % of DR is tested with 5, 15, 25, 35 and 50 mass % of TW, respectively. The co-feed ratio 95:5, 85:15, 75:25, 65:35 and 50:50 of DR/TW correspondingly resulted in the bio-oil yield of 22.67, 24.00, 24.34, 25.00 and 36.67 mass % and bio-char yield of 37.00, 43.77, 44.67, 45.33 and 49.52 mass %. The higher heating values (HHV) of all bio-oils are in increasing order to that of the increasing fraction of TW in co-feed where 50:50 ratio resulted in bio-oil of maximum HHV with 32.61 MJ kg−1. Further increased mass % of tube waste may increase the energy content of the final liquid product; however, the present work focuses on co-feeding and management of both these two wastes and accordingly the mass % of tube waste has been limited to maximum of 50%. The bio-oil consists of more than 85 area % of aliphatic and aromatics, whereas phenols and acids occupy only 6.72 area % and 1.24 area %, respectively. Thus, this study provides waste minimization approach along with sustainable production of bio-oil that can be upgraded to transportation fuel, or utilized as furnace oil and for process heat purposes. The co-pyrolysis of these two waste materials resulted in popular hydrocarbons such as benzene, toluene, xylene, styrene and bigger fraction of C10 cut D-limonene. [ABSTRACT FROM AUTHOR]

Butyl rubber/hydrophobized graphene oxide (HG) nanocomposites were prepared by solution mixing followed by compression molding process, and evaluated their properties using scanning electron microscope (SEM), oscillating disc rheometer (ODR), universal testing machine (UTM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The hydrophilic graphene oxide (GO) obtained through the oxidation of graphite (GP) was first hydrophobized with octadecylamine. The HG exhibit excellent dispersibility in toluene and stable under stationary condition for over 30 days. The chemical structure and functionality of HG was analyzed by fourier transform infrared (FTIR), raman spectroscopies, and wide-angle X-ray diffraction (WAXD) patterns. HG was successfully dispersed within BR matrix and result in significant reduction of curing time (around 30%), enhanced tensile strength (around 35%) as compared to the pristine butyl rubber. The air permeability of the hydrophobized graphene oxide composites was also significantly reduced by 75% compared to unfilled butyl rubber. [ABSTRACT FROM AUTHOR]

The effect of adhesive additives of polar and nonpolar nature on the properties of uncurable sealants based on butyl rubber was studied. It has been found that alkylphenol–formaldehyde resins and rosin are effective additives that increase the cohesive and adhesive strength. [ABSTRACT FROM AUTHOR]

In this study, two macroporous butyl rubber (BR)–based sorbents prepared in benzene (H-BR) and in cyclohexane (L-BR) with different porosities were synthesized by cryogelation technique. Their performances as a passive sampler were studied and then compared with commercially available silicon rubber (polydimethylsiloxane, PDMS) passive sampler. For that aim, polycyclic aromatic hydrocarbon (PAH) absorption rates of the sorbents in the short-term and their accumulation capacities in the long-term periods were investigated. Four PAHs (naphthalene, phenanthrene, fluoranthene, and pyrene) with a different number of aromatic rings were utilized. The concentrations of the PAHs in solutions were quantified by fluorescence spectrophotometer. The results showed that the BR sampler prepared in benzene (H-BR) generally has the highest absorption rates for all PAHs. The rate constants k (h−1) of the H-BR, L-BR, and PDMS samplers were found as 1.07, 0.55, and 0.55 for naphthalene; 0.73, 0.16, and 0.09 for phenanthrene; 0.24, 0.26, and 0.08 for fluoranthene; and 0.97, 0.38, and 0.17 for pyrene, respectively. The highest PAH absorption capacity was found for the BR sorbents prepared in benzene for all PAHs. Thus, benzene was selected as the organic solvent rather than cyclohexane for further studies in the preparation of butyl rubber–based samplers. The H-BR possessing the highest absorption rate and capacity underlines their usage as a capable passive sampler for both short- and long-term monitoring activities in the aquatic environments. [ABSTRACT FROM AUTHOR]

Results of studies of the effect of carbon black of P-803, P-324, and P-234 brands on cohesion strength, adhesion (to glass and duralumin), and the viscosity of nonhardening sealants based on butyl rubber are given. It is shown that the degree of cohesion and adhesion strength, while effective viscosity correlates with the dispersion of carbon black. [ABSTRACT FROM AUTHOR]

A mathematical description of interconnected processes of mass transfer and chemical conversion in a copolymerization reactor is given. Two cases are investigated: simultaneous transfer of two monomers from a gas to a liquid with chemical reaction in the liquid (for example, copolymerization of ethylene and propylene in ethylene-propylene synthetic rubber production) and copolymerization in a liquid near a solid surface (for example, copolymerization of isobutylene and isoprene in butyl rubber production). The dependence of the component composition of the copolymer on the diffusion resistance to the transfer of monomers near the interface is established. [ABSTRACT FROM AUTHOR]

The effect of petroleum resins (PRs) and asphaltene–resin substances (ARSs) on the technological and physicomechanical properties of noncurable butyl rubber sealants has been studied. It has been shown that sealants containing PRs have higher water resistance and greater durability than do sealants with bitumens as technological additives. [ABSTRACT FROM AUTHOR]

The aim of this work was to examine the influence of new curing agents proposed for brominated butyl rubber (BIIR) on the cross-linking process of rubber compounds and the thermal behavior of the vulcanizates. Rubber blends that were filled with carbon black and contained acetylacetonates of different transition metals in the presence of triethanolamine (TEOA) as new cross-linking agents were prepared. The performed studies showed that metal acetylacetonates (Me(acac)) are effective cross-linking agents for BIIR, which was confirmed by high values of the torque increment (∆M) and significant cross-linking degree of the vulcanizates (α(T)). The most active curing agent seems to be iron acetylacetonate (Fe(acac)). Its application results in a shorter optimal vulcanization time, lower onset vulcanization temperature and similar vulcanization enthalpy compared to the BIIR cured with a sulfur curing system. The BIIR vulcanizates cured with Me(acac) reveal good mechanical properties with tensile strengths in the range of 9–14 MPa and better damping properties comparing to the sulfur-cured rubber. The proposed curing agents do not significantly affect the thermal stability of the BIIR vulcanizates. [ABSTRACT FROM AUTHOR]

The effect of thickness and reinforcement on the properties of the mastic layer of an incongealable sealant based on butyl rubber is studied, depending on the nature of the glued substrate. It has been established that the nature of the substrate affects the adhesive properties of the mastic. The effect of the thickness of the mastic layer on the adhesive properties is most pronounced in determining the bond strength by the tear-off method. The influence of the nature of the substrate on adhesion to the mastic layer is considered from the standpoint of acid–base interactions. The possibility and expediency of reducing the thickness of the incongealable mastic layer based on butyl rubber of the sealing coating of roofing purpose to the level of 0.5 mm without loss of quality is established. It is shown that the reinforcement of sealing coatings based on highly filled butyl rubber does not affect their vapor permeability and strength during peeling and tearing. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of the effect of the butyl rubber and dicumyl peroxide concentrations on the strength and thermophysical properties of polymer mixtures based on thermoplastic polyolefins. The principal possibility of synthesizing thermoplastic elastomers with predetermined physical and mechanical characteristics is shown. The butyl rubber concentration is varied from 0 to 50 wt %, and the dicumyl peroxide concentration is varied from 0.5 to 2.0 wt %. It is experimentally established that, in the process of studying the deformation–strength properties for thermoplastic polyolefins, the appearance of tensile yield stress and ultimate tensile stress is typical. However, as the concentration of butyl rubber in the thermoplastic composition increases, the difference between tensile yield stress and ultimate tensile stress is sharply reduced. And, when the difference between these strength parameters disappears completely, the polymer composition starts exhibiting the properties of a thermoplastic elastomer. The additional introduction of a crosslinking agent, namely, dicumyl peroxide, into the composition of polymer mixtures promotes the appearance of a high elasticity plateau on the thermomechanical curves, which, as is well known, is characteristic of vulcanized rubbers. The most optimal concentrations of dicumyl peroxide and butyl rubber are determined, as a result of which the highest physicomechanical properties are achieved in the polymer compositions. An interpretation for the observed regularities of the change in the physicomechanical and physicochemical properties of polymer composite materials is given. [ABSTRACT FROM AUTHOR]

The macrokinetics of the synthesis of butyl rubber in a cylindrical-type tubular turbulent reactor (cationic suspension copolymerization of isobutylene with isoprene, catalyst is aluminum chloride, solvent is methyl chloride, and the synthesis temperature is higher than 173 K) was described mathematically. A relation of the reaction mixture velocity and reactor diameter to the molecular weight characteristics of butyl rubber was found. [ABSTRACT FROM AUTHOR]

The authors have given experimental data on the change in the mass of a cylindrical specimen of a solid composite gas-producing formulation based on butyl rubber and ammonium perchlorate as a function of the holding time in seawater. The depth of surface washout of the oxidant has been assessed for these conditions. Consideration has been given to the questions of reduction of the gas-producing power of relevant full-scale blocks as applied to their possible use for blowing of deep-sea ship-raising pontoons depending on the residence time in the water medium, which is determined by the period of preparatory work. [ABSTRACT FROM AUTHOR]

Abstract: Any practical technique to determine the diffusivity of chemical warfare agents in protective barrier materials should require handling only miniscule volume of the chemicals and also require data analysis methods that are not computationally burdensome. Such an approach is described here based on imaging the time evolution of ~ 1 μL sessile drop profiles on the barrier surface and using an approximate analytical approach to analyze the time-dependent drop volume and contact angle data for extracting the diffusivity. The approximate analytical approach is validated by comparison against results from computationally intensive finite element simulations available in the literature. The domain of reliable use of the sessile drop technique in terms of the relative importance of the simultaneous evaporation and absorption is assessed using measurements on three challenging toxic chemicals in air and in butyl rubber. The ability of this approach to provide reasonable diffusivity estimates even if the substrate undergoes swelling is explored by studying water sessile drops on a Nafion membrane. The results allow one to conclude that the sessile drop technique coupled to the approximate analytical approach can be reliably used for rapid screening of new barrier materials for protection against chemical warfare agents if the screening is implemented using simulants with low vapor pressures.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Optical and dielectric dispersion parameters for butyl rubber-general purpose furnace carbon black (IIR-GPF CB) composites with various carbon black (CB) concentrations were determined using ultraviolet transmittance spectra. X-ray diffraction (XRD) for the composite samples was measured in the 2θ range from 5° to 50°. There was a slight increase in the XRD peak intensity by increasing CB content indicating some significant changes in the composite structure. Some structural parameters were calculated for the XRD fundamental peak. The crystallite size increased significantly with the increase in carbon black concentration. This suggested a tendency of the polymer toward a more crystal state. Analysis of refractive index dispersion was carried out using Wemple-DiDomenico single effective oscillator model. The energy of effective single oscillator (Eo) and the dispersion energy (Ed) were estimated for the composites of different CB loadings. Accordingly, the moments of optical spectra, static and high-frequency dielectric constants were calculated. The variation of the real part ε1 and imaginary part ε2 of the complex dielectric function with the incident photon wavelength was investigated. The recorded values of ε1 were greater than the values of ε2. The dielectric energy loss was specified by means of three important parameters: volume energy loss function, surface energy loss function and dielectric loss factor (tanδ). The dielectric relaxation time τ and plasma frequency were studied as a function of incident photon wavelength for different composite samples. There was a great dependence of τ on the wavelength and amount of the carbon black in the composite. [ABSTRACT FROM AUTHOR]

The kinetics of the activity of the butyl rubber (BR) curing system without and with various amounts of antioxidant P-23 at temperatures of 55 and 80°C was studied. The induction period of the vulcanization of the BR samples in the presence of sterically hindered phenol was found to exceed that for the samples without phenol. With rising temperature the rate of the rubber vulcanization tends to increase due to an increase in the initiation rate. [ABSTRACT FROM AUTHOR]

Abstract: The kinetics of water vapor permeability of insulating tapes of the Polyen, Poliken, Nitto, and Furukawa series was studied by the gravimetric method in the temperature range from 20 to 70°С. It is shown that for all the investigated tapes, in spite of their two-layer construction, normal Fikov kinetics of permeability is observed. Diffusion coefficients that vary in the range from 2.5 to 3.1 × 10-9 cm2/s are determined, the coefficients of vapor permeability vary in the range from 0.32 to 0.37 g/m2 s. Data on the kinetics of permeability, diffusion coefficients and solubility are of practical importance for predicting the barrier properties of insulating tapes during their operation. [ABSTRACT FROM AUTHOR]

Abstract: The adhesive properties of Polylen (Russia), Polyken (United States), Nitto (Italy), and Furukawa (Japan) insulating tapes and wrappers are described. The contribution is evaluated that primer layers make to the service properties of the insulating tapes providing the necessary adhesion bond between polyethylene tapes and a metal substrate. It is shown that the tackiness and creep of a Polylen tape butyl rubber layer exceeds the corresponding characteristics of other tapes. [ABSTRACT FROM AUTHOR]

Abstract: Studies have been carried out on the introduction of vinyltrimethoxysilane (VTMS) into compositions based on butyl rubber (BR) and ethylene-vinyl acetate copolymer (EVAC). Optimum amounts of VTMS are determined at which the adhesion and cohesion strength of sealants increase. It has been shown that an increase in the properties of sealants is due to chemical interaction between EVAC and VTMS, as a result of which structures are formed with the nature of a semi-interpenetrating grid. [ABSTRACT FROM AUTHOR]

The budding yeast Saccharomyces cerevisiae plays an important role in biotechnological applications, ranging from fuel ethanol to recombinant protein production. It is also a model organism for studies on cell physiology and genetic regulation. Its ability to grow under anaerobic conditions is of interest in many industrial applications. Unlike industrial bioreactors with their low surface area relative to volume, ensuring a complete anaerobic atmosphere during microbial cultivations in the laboratory is rather difficult. Tiny amounts of O2 that enter the system can vastly influence product yields and microbial physiology. A common procedure in the laboratory is to sparge the culture vessel with ultrapure N2 gas; together with the use of butyl rubber stoppers and norprene tubing, O2 diffusion into the system can be strongly minimized. With insights from some studies conducted in our laboratory, we explore the question ‘how anaerobic is anaerobiosis?’. We briefly discuss the role of O2 in non-respiratory pathways in S. cerevisiae and provide a systematic survey of the attempts made thus far to cultivate yeast under anaerobic conditions. We conclude that very few data exist on the physiology of S. cerevisiae under anaerobiosis in the absence of the anaerobic growth factors ergosterol and unsaturated fatty acids. Anaerobicity should be treated as a relative condition since complete anaerobiosis is hardly achievable in the laboratory. Ideally, researchers should provide all the details of their anaerobic set-up, to ensure reproducibility of results among different laboratories. [ABSTRACT FROM AUTHOR]

Butyl rubber as a commercial elastomer has got many applications in various products such as tires, protective clothes, sealants, hose (steam and automotive), inner coating of tanks, etc. Considering these usages, butyl rubber might be subjected to acidic or alkaline environments. Acid and alkaline materials can diffuse through the rubber and cause degradation of its structure which leads to deterioration of rubber properties including adhesion strength. In this study, the effects of environments having different pH values on adhesion strength between rubber compounds--based on butyl rubber and bromobutyl rubber--and aluminum surface are investigated. Samples were immersed in solutions with different pH values of 0.7, 3, 7, 11 and 13.7. By conducting tensile and tack tests, changes in adhesion strength and tackiness property of samples are studied. Considering the broad range of examined pH values, results demonstrate that solutions with more acidic and alkaline pH values severely reduce adhesion strength and leads to about 60% reduction in adhesion. However, pH values closer to neutral pH have a less negative effect and cause up to 49% decrement in adhesion strength. Furthermore, Samples which were immersed in alkaline solutions lost their tackiness property, whereas the samples which were immersed in acidic solution retained their tackiness. However, in these cases, tack property was reduced to 1/7 of its value before being immersed in the acidic solution. [ABSTRACT FROM AUTHOR]

Electrical properties of butyl rubber filled with General Purpose Furnace (GPF) carbon black were studied. The carbon black concentration ( X) in the compound was X = 40, 60, 70, 80, and 100 parts by weight per hundred parts by weight of rubber (phr). The corresponding volume fractions of GPF carbon black were 0.447 ± 0.022, 0.548 ± 0.027, 0.586 ± 0.029, 0.618 ± 0.031 and 0.669 ± 0.034, respectively. The concentration dependence of conductivity ( $$ \sigma $$ ) at constant temperature showed that $$ \sigma $$ follows a percolation theory; $$ \sigma \propto \left( {X - X_{o} } \right)^{\gamma } $$ , where X is the concentration at percolation threshold. The exponent $$ \gamma $$ was found as 6.6 (at room temperature 30°C). This value agrees with other experimental values obtained by many authors for different rubber-carbon black systems. Electron tunneling between the aggregates, which are dispersed in the insulator rubber, was mainly the conduction process proposed at constant temperature in the butyl-GPF carbon black composites. Temperature dependence of conductivity was investigated in the temperature range from 30°C up to 120°C. All samples exhibit negative temperature coefficients of conductivity (NTCC). The values obtained are − 0.130°C, − 0.019°C, − 0.0082°C, − 0.0094°C, and − 0.072°C for carbon black concentrations of 40 phr, 60 phr, 70 phr, 80 phr, and 100 phr, respectively. The samples of concentrations 40 phr and 60 phr have also positive temperature coefficients of conductivity (PTCC) of values + 0.031 and + 0.013, respectively. Electrical conduction at different temperatures showed various mechanisms depending on the carbon black concentration and/or the interval of temperature. The hopping conduction mechanism was noticed at the lower temperature region while carrier thermal activation mechanisms were recorded at the higher temperature range. [ABSTRACT FROM AUTHOR]

In this paper the modifications induced in butyl rubbers (pristine, chlorinated and brominated sorts) by γ-irradiation are investigated by swelling, chemiluminescence and FT-IR. The susceptibility of butyl rubbers for the generation of radicals orders their stabilities in the following sequence: IIR > IIR—Cl > IIR—Br. The incorporation of butyl rubbers into ethylene-propylene terpolymer matrix brings about increased densities of radicals initiating modifications in the oxidation state in respect with recombination, which are intensified as the processing dose increases. Based on the variation of carbonyl and hydroxyl indices the favorable route for the recycling EPDM based formulations would be suggested in this study. The chemiluminescence spectra proving the formation of peroxyl radicals at about 100 °C prove their availability as reclaiming solutions. IIR—Br is the recommendable butyl rubber for the recovery procedure by association with EPDM. The suitability of IIRs for recycling purposes is analyzed by the variation in their crosslink densities, free volumes and swelling degrees. The crosslinking behavior of stabilized EPDM/IIR blends that runs to the improvement of durability is depicted by Charlesby–Pinner representation, which involves the different simultaneous contribution of scission and crosslinking processes. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO), NaF and CaCl were mixed in their aqueous solutions to obtain a GO-CaF hybrid with CaF particles uniformly dispersed on GO surface, and further in situ reduced by hydrazine to obtain reduced-GO (RGO)-CaF hybrid. RGO-CaF/brominated butyl rubber (BIIR) composites were obtained by solution mixing, in which RGO-CaF was well dispersed in nano-sized as confirmed by transmission electron microscope images. The RGO-CaF/BIIR composites had much better mechanical properties than BIIR. The stress at 300% extension of BIIR increased 72% after the addition of 3 parts per hundreds of rubber (phr) RGO-CaF. The improved mechanical properties benefited from the strong interaction between RGO and BIIR. The dielectric constant of RGO-CaF/BIIR composites increased with increasing RGO-CaF loading. Because of the synergistic effect of RGO and CaF, the stresses at various extensions, dielectric constant and thermal conductivity of RGO-CaF/BIIR composites were higher than those of RGO/BIIR or CaF/BIIR composites. The improved mechanical, dielectric and thermal properties bring BIIR the potential to be used in a wider range of application areas. [ABSTRACT FROM AUTHOR]

Inorganic particles have been common fillers for processing butyl rubber (IIR). Studying the effect of inorganic particles on the molecular motions of IIR was important to both relevant theory and applications. In this paper, the morphology and dynamics of IIR/silica, IIR/carbon black and IIR/FeO blends were studied. It was found that silica was homogenously dispersed in IIR and it suppressed the molecular motions of IIR at all loads. In addition, the carbon black with a low load averagely dispersed in IIR and suppressed the molecular motions of IIR; however, it agglomerated and the suppression was weakened as the load was increased. Moreover, FeO had nearly no influence on the molecular motions of IIR. [ABSTRACT FROM AUTHOR]

The present research concerns with the preparation and characterization of isobutylene isoprene/butadiene-styrene rubber (IIR/SBR) blends with different blend ratios, in the presence and absence of styrene-isoprene-styrene (SIS) and styrene-isobutylene-styrene (SiBS) triblock copolymers to be tested as compatibilizers. Effect of the triblock copolymers on the blend homogeneity was investigated with the aid of scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) measurements. Characterization of the rubber blends was conducted by measuring the physico-mechanical properties after and before thermal aging, in presence and absence of the triblock copolymers. In addition, weight swell % in toluene, motor oil and brake fluid of the rubber blend vulcanizates was assessed. The incorporation of SIS and SiBS triblock copolymers improved the homogeneity of IIR/SBR blends as well as increased both tensile strength and elongation at break of the rubber blend vulcanizates. Of the entire blend ratios examined, IIR/SBR (25/75) blend containing SIS compatibilizer possessed the best physico-mechanical properties (12.6 MPa tensile strength and 425 % elongation at break) and (14 MPa tensile strength and 555 % elongation at break) after and before thermal aging, respectively. Utilization of SIS and SiBS triblock copolymers enhanced the thermal stability of IIR/SBR blend vulcanizates. Moreover, IIR/SBR blends of different blend ratios showed superior swelling resistance in the brake fluid. IIR/SBR (25/75) blend containing SIS compatibilizer and cured with CBS/ZDEC/S vulcanizing system possessed the best physico-mechanical properties (14.4 MPa tensile strength and 440 % elongation at break) and (16.5 MPa tensile strength and 610 % elongation at break) after and before thermal aging, respectively. [ABSTRACT FROM AUTHOR]

Extremely strong reinforced adhesion between a polytetrafluoroethylene (PTFE) film and butyl rubber is achieved using an atmospheric pressure plasma graft polymerization, involving argon and acrylic acid vapor. The treated PTFE film is then placed over a raw butyl rubber plate and hot-pressed under 157 N/cm for 40 min at 150 °C or for 10 min at 180 °C. This procedure results in molecular-level or chemical adhesion between the butyl rubber and the PTFE film. The 180° peeling test results show that a high peeling strength of 3.9 N, per 1 mm sample width, is achieved. Adherend failure of the rubber sheet occurs when the peeling is enforced. From X-ray photoelectron spectroscopy analysis of the treated films, chemical bonds with fluorine atoms are absent from the surface. From scanning electron microscopy analysis, a transparent hydrophilic poly(acrylic acid) layer composed of nanoscale spherical particles is formed. This PTFE-rubber composite material is suitable for high-quality, prefilled medical syringe gaskets. [ABSTRACT FROM AUTHOR]

The water vapor sorption and desorption kinetics were monitored in methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS), bromobutyl, ethylene-propylene-butadiene monomer (EPDM) rubber, and butyl rubber at various temperatures by gravimetric method. Modified thermogravimetric analysis system was built and used. The geometry of the samples was approximating that of the infinite two-sided plane sheet of certain thickness. The coefficients of water vapor diffusion in polymers were deduced by comparing the experimentally monitored kinetics and kinetics computed using diffusion coefficients as adjustable parameters. The activation energies of water vapor diffusion in these polymers were deduced in the temperature range from 30 to 75 °C. The activation energy of diffusion was 45.9 kJ mol in bromobutyl rubber, 46.4 kJ mol in butyl rubber, 60.3 kJ mol in EPDM rubber, and 43.5 kJ mol in MABS. Compensation effect was observed for water vapor diffusion in this series of polymers. Compensation effect parameters were determined to be, a = −23.9/ln(cm s) and b = 0.49/(mol kJ) × ln(cm s), in fair agreement with published data for water diffusion in polymers. [ABSTRACT FROM AUTHOR]

Comparative evaluation of the physicochemical properties of samples of antioxidant 2,4,6-tri- tert-butylphenol, produced by different plants and used as a vulcanization inhibitor for butyl rubber-based composite material, has been carried out. An IR-spectroscopic examination of the antioxidant and its aqueous extracts and a chromatographic examination have shown that the antioxidant lots currently produced by Lipetskkhimprodukt, Limited Liability Company, differ from those previously produced by Novocherkassk Synthetic Products Plant, Open Joint-Stock Company, by the presence of amine type impurities and content of some nonidentified compounds. These impurities are specifically responsible for a decrease in the inhibiting activity of the antioxidant, revealed by an electron paramagnetic resonance examination, and for a decrease in the compound viability observed while using the verified lots of 2,4,6-tri- tert-butylphenol for direct purpose. [ABSTRACT FROM AUTHOR]

A theoretical model has been developed for the macrokinetics of cationic isobutylene-isoprene copolymerization in a stirred reactor and in a tubular turbulent reactor. The model provides means to calculate the reaction mass temperature, velocity, and turbulence kinetic energy fields. The adequacy of the model has been demonstrated using the Fisher criterion. Computational experiments have been carried out to estimate the effects of the catalyst concentration and the rotational speed of the stirrer (in the case of the synthesis conducted in a stirred reactor) and the effects of reaction mixture velocity and apparatus diameter (in the case of the synthesis conducted in a tubular turbulent reactor) on molecular weight characteristics of the resulting copolymer (butyl rubber). [ABSTRACT FROM AUTHOR]

An analysis has been carried out with respect to the errors incurred in the determination of the thermophysical characteristics of the high-energy heterogeneous material "aluminum-ammonium perchlorate-butyl rubber" and associated with the radiation transfer of energy in the heated layer under conditions corresponding to the realization of the laser-pulse method in the course of action of a finite-length collimated laser pulse on the material surface. The influence of the radiation absorption process on the magnitude of this error has been established. [ABSTRACT FROM AUTHOR]

We have used H NMR spectroscopy to study commercial samples of chloro-substituted and bromo-substituted butyl rubbers. We propose calculation formulas for quantitative determination of the main forms in halobutyl rubber (1,4-isoprene, exo form) and its characteristics: unsaturation level, halogen content in the isoprene units. We show that it is possible to determine the main structural characteristics of bromobutyl rubber in the presence of filler. [ABSTRACT FROM AUTHOR]

The transport behavior of commercial R134a (1,1,1,2-tetrafuoroethane) refrigerant including its permeability, adsorption, and diffusion through rubber composites were investigated. Butadiene-acrylonitrile rubber (NBR), brominated butyl rubber (BIIR), and epichlorohydrin rubber (ECO) were used as a matrix, while silica, carbon black, mica sheet, and graphite were used as fillers in the present study. The effects of rubber structure and geometry, surface polarity, as well as loading of filler on transport behavior were studied to correlate transport parameters with the rubber structure and filler nature. The R134a permeation in rubber composites was largely dominated by diffusion rather than solubility. The polarities of rubber and filler played dominant roles in determining the solubility, whereas the structure of rubber and the shape and loading of filler exerted a stronger effect on diffusion than solubility. Nonpolar and layered graphite-filled BIIR rubber composites showed the lowest permeability to R134a. Additionally, shell-like free volume theory was applied to reasonably explain R134a transport behavior. [ABSTRACT FROM AUTHOR]

Butyl rubber-micron barium titanate (BR/BT) and butyl rubber-nano barium titanate (BR/nBT) composites were prepared by sigma mixing followed by hot pressing. The tensile tests show that both the composites were mechanically flexible. The microwave dielectric properties of both BR/BT and BR/nBT composites were investigated as a function of ceramic loading and were found to be improved with filler content. The butyl rubber has a relative permittivity (ε) of 2.4 and loss tangent (tan δ) of 0.0017 at 5 GHz. At a filler loading of 0.24 volume fraction (v) of micron sized barium titanate (BaTiO) powder loading, the composite attained a ε of 7 and tan δ of 0.014 and for the same filler content of nano BaTiO the composite have ε of 8.9 and tan δ of 0.019 at 5 GHz. The thermal and mechanical properties of both the composites were investigated. The experimental values of ε of both BR/BT and BR/nBT composites for different volume fractions were compared with theoretical models. [ABSTRACT FROM AUTHOR]

The results of mathematical simulation of the macrokinetics of butyl rubber synthesis (catalyst is aluminum chloride, solvent is methyl chloride, the synthesis temperature is T ≥ 173 K) in mixing and plug flow reactors were reported. A solution of inverse kinetic problem on identifying unknown rate constants of elementary reactions of a kinetic scheme was derived. A relation of speed of an agitator in the mixing reactor, concentration of a catalyst injected into the mixing reactor, a diameter of the plug flow reactor and velocity of the reaction mixture movement therein with the molecular weight characteristics of butyl rubber, its Mooney viscosity and strength properties of vulcanizates based on it were found. [ABSTRACT FROM AUTHOR]

We researched the electric heating property from butyl rubber-loaded boron carbide composite. The effects of boron carbide content on bulk resistivity, voltage-current characteristic, thermal conductivity and thermal stability of boron carbide / butyl rubber (IIR) polymer composite were introduced. The analysis results indicated that the bulk resistivity decreased greatly with increasing boron carbide content, and when boron carbide content reached to 60%, the bulk resistivity achieved the minimum. Accordingly, electric heating behavior of the composite is strongly dependent on boron carbide content as well as applied voltage. The content of boron carbide was found to be effective in achieving high thermal conductivity in composite systems. The thermal conductivity of the composite material with added boron carbide was improved nearly 20 times than that of the pure IIR. The thermal stability test showed that, compared with pure IIR, the thermal stable time of composites was markedly extended, which indicated that the boron carbide can significantly improve the thermal stability of boron carbide / IIR composite. [ABSTRACT FROM AUTHOR]

Industrial samples of a copolymer of isobutylene with isoprene (butyl rubber) produced through cationic polymerization via the conventional slurry process (a Lewis acid (AlCl) as a coinitiator, methyl chloride as a diluent) have been studied with the use of proton magnetic resonance spectroscopy at an Larmor frequency of 600 MHz. Spectra were recorded for different types of deuterated solvents and concentrations of test solutions. The signals were processed via selective improving the resolution and signal-to-noise ratio. The use of these procedures, in combination with conformational representations, made it possible to increase the information content of the spectra. [ABSTRACT FROM AUTHOR]

Butyl rubber-Ba(ZnTa)O (BR-BZT) composites and butyl rubber-silica (BRS) composites were prepared by sigma mixing. The dielectric properties at 1 MHz and 5 GHz of BR-BZT and BRS composites were investigated as a function of ceramic loading and were found to be improved with filler loading. For a optimum BZT loading of 0.26 v, the BR-BZT composite have ε = 4.88, tanδ = 0.0022 (at 5 GHz), coefficient of thermal expansion (CTE) = 112 ppm/°C, thermal conductivity (TC) = 0.30 Wm K and water absorption = 0.047 vol%. The BRS composites attained ε = 2.79, tanδ = 0.0039 (at 5 GHz), CTE = 102 ppm/°C, TC = 0.40 Wm K and water absorption = 0.078 vol% for the same loading of silica. The stress-strain curves of both composites showed good flexibility of the composite. The measured relative permittivity and TC of both composites were compared with different theoretical approaches. [ABSTRACT FROM AUTHOR]

The preparation of multilayered polymer films is of significant interest for various applications, but is often hindered by the inherent incompatibilities between polymers. Described here is the use of an epoxidized butyl rubber as a compatibilizer layer. This polymer can be coated onto butyl rubber, despite the small number of epoxidized units (~2.2 mol%), allows for the deposition of uniform layers of a diverse array of polymers including poly(vinyl stearate) (PVS), poly(methyl methacrylate) (PMMA), polycaprolactone (PCL), and poly(ethylene oxide) (PEO). The films on epoxidized rubber were compared with those prepared directly on unmodified rubber using techniques including atomic force microscopy and contact angle measurements. In addition, in the case of PEO, it was demonstrated that the uniformity of the coating plays a significant role in conferring the desirable property of resistance to protein adsorption. Thus, this oxygenated rubber derivative may serve as a versatile material for various coating applications. [ABSTRACT FROM AUTHOR]

The effect of the content, dispersity, and surface polarity of calcium carbonate on the physicomechanical and rheological properties of filled noncuring hot melt sealant formulations based on butyl rubber and various thermoplastics was examined. In the formulations based on nonpolar polymers, the cohesion strength and viscosity increase with an increase in the content and dispersity of calcium carbonate, with the strongest reinforcing effect observed with hydrophobized grades of calcium carbonate. With an increase in the polarity of the polymer base, untreated natural carbonate (chalk) becomes more efficient. [ABSTRACT FROM AUTHOR]

Accelerated thermal aging experiments were conducted on butyl rubber materials in order to investigate aging behavior using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), positron annihilation lifetime spectroscopy (PALS), and differential scanning calometry (DSC). The XPS results suggested that the thermal oxidation process took place heterogeneously along the samples thicknesses. The aging mechanism was identified to be crosslinking by means of the combined use of PALS and DSC results. Lifetime and intensity of ortho-positronium ( o-ps) diminished, and the glass transition temperature ( T) increased during aging. The dispersion condition of silica particles, observed by SEM images, showed that the filler agglomerated after aging. Time temperature superposition was carried out using compression set measurements in the temperature range of 100 to 60 °C. The Arrhenius plot clearly exhibited a curvature around 75 °C, and the activation energy dropped from 126.7 to 58.8 kJ/mol across this region. Relative importance of different processes, over the entire temperature range, was discussed; lifetime at room temperature was predicted. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]