Acrylonitrile Content Research Articles

Control of the composition of matrix resin for the design of MABS resin with good transparency and toughness

Transparent methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) resin was prepared by blending the matrix resin with rubber toughened particles. The refractive index of matrix resin was characterized, which proved the transmittance of MABS resin improved with decreasing differences in the two-phase refractive index. Controlling the refractive index of the matrix resin was comparable to that of rubber, increasing acrylonitrile (AN) content in the matrix resin to improve toughening efficiency of the rubber particles to the matrix. When the proportion of poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) (PMMA/SAN) was 71.6/28.4 or the initial weight ratio of MMA/St/AN was 78/16.5/5.5, the MABS resin had an optimal transmittance of 90 %. The AN content of the former was 6.5 %, and the impact strength was 155 J/m. The actual AN content of the latter was 12.5 %, and the impact strength was 172 J/m. Additionally, the refractive index of methacrylate-styrene-acrylonitrile (MSAN) decreased with increasing monomer conversion. When the monomer conversion reached 76.5 %, the change in the composition of MSAN was insignificant as the monomer conversion continued to increase. Moreover, MABS resin had a broad processing temperature window with MSAN copolymer as the matrix resin compared to the blends of PMMA and SAN, which were 170–240 °C and 190–200 °C, respectively.

Study on the relationship between structure and acoustic performance of NBR composite materials

Rubber materials have been widely used in the field of noise absorption and vibration reduction due to the unique viscoelasticity. Among all the rubbers, nitrile-butadiene rubber (NBR) has strong polarity and excellent damping properties as a result of –CN groups, so it is often chosen as a matrix of damping materials. However, the effects of chemical structures and fillers on the damping and sound absorption properties of rubber materials have not been fully investigated. To achieve a high loss factor at room temperature, NBR materials with different acrylonitrile contents and crosslinking densities were investigated. The results showed that the changes in crosslink density and acrylonitrile content have limited improvements in damping and sound absorption properties. In order to improve the sound absorption performance of NBR, different kinds of fillers were introduced into rubber matrix. It is proved that poor interfacial interactions between fillers and rubber dissipated more sound waves. This work would provide further insights into the design of materials with good sound absorption performance. • Increasing Acrylonitrile Content Improves Acoustic Performance. • Lower crosslink density can improve sound absorption. • Weak interaction between filler and matrix is benefit to sound absorption.

In situ–produced polyurethane-based thermoplastic elastomers: the effect of the acrylonitrile content of the rubber phase

We prepared thermoplastic dynamic vulcanizates (TDVs) with an in situ–produced thermoplastic polyurethane (TPU) matrix. We used unfilled acrylonitrile butadiene rubber (NBR) with different acrylonitrile contents and investigated the effect of the polarity of the rubber phase on the properties of the TDV samples. The results show that the acrylonitrile (AN) content of the rubbers affects the tensile strength and modulus slightly but the strain at break of the TDVs only negligibly. The results of TDVs are in between those of TPU and unfilled NBRs, demonstrating the feasibility of the TPU/NBR combination.

Influence of Specific Structure on the Dielectric and Thermal Performance of Bulk Polymers: Atomistic Molecular Dynamics Simulations of XNBR

In this work, we investigate the influence of the molecular structure of carboxylated acrylonitrile-butadiene rubber (XNBR) on the dielectric properties through non-equilibrium molecular dynamics (NEMD) simulations. The NEMD simulations are performed for calculating the permittivity (ε) of XNBR under different alternating electric field strength (Ei), alternating electric field frequency (Ef), and temperature. The simulation results show a similar change trend with the reported experimental consequence of dielectric elastomer. Interestingly, a critical alternating Ei at which the dielectric properties of XNBR with different acrylonitrile contents change seriously is found. Moreover, a deep insight into the mechanisms of the dielectric and thermal performance of XNBR is explored through the analysis from the atomistic level, including intermolecular interaction, fractional free volume, molecular chain migration ability, hydrogen bonds breaking and re-formation, dipole autocorrelation function, phonon vibration power spectrum, and kinetic energy. The research results will inspire the design of polymer structures to obtain high-performance polymer materials. This article is protected by copyright. All rights reserved

Effect of Organoclay Addition on Rheological, Thermal, and Mechanical Properties of Nitrile Rubber/Phenolic Resin Blend.

In this study, the effects of NBR polarity and organoclay addition on the curing, rheological, mechanical, and thermal properties of an NBR/phenolic resin blend were investigated. The samples were prepared using a two-roll mill. The results showed that rheological and tensile properties improved due to the good distribution of nanoparticles, as well as the good compatibility of nitrile butadiene rubber with phenolic resin. The addition of 1.5 phr of nanoparticles to blends containing 33% and 45% acrylonitrile increased the curing torque difference by approximately 12% and 28%, respectively. In addition, the scorch time and curing time decreased in nanocomposites. Adding nanoparticles also increased the viscosity. The addition of phenolic resins and nanoparticles has a similar trend in modulus changes, and both of these factors increase the stiffness and, consequently, the elastic and viscous modulus of the specimens. Adding 1.5 phr of organoclay increased the tensile strength of the blends by around 8% and 13% in the samples with low and high content of acrylonitrile, respectively. Increasing the temperature of the tensile test led to a reduction in the tensile properties of the samples. Tensile strength, elongation at break, modulus, and hardness of the samples increased with increasing organoclay content. In addition, with increasing nanoparticle concentration, the samples underwent lower deterioration in tensile strength and Young’s modulus at different temperatures compared to the blends. In the samples containing 1.5 phr of organoclay, the thermal decomposition temperatures were enhanced by around 24 and 27 °C for low and high acrylonitrile content.

Fire Behavior of Polyamide 12/Rubber Formulations Made by Laser Sintering.

In the present work, the processability and fire behavior of parts made by the laser sintering (LS) of polyamide 12/rubber powder blends is studied. In order to evaluate some of the interactions that could take place during LS, three acrylonitrile butadiene rubbers (NBRs) were used, which included two that had different acrylonitrile (AN) contents, and one that had carboxylated rubber. The results show that the flowability of the powders is strongly dependent on the rubber used. For the carboxylated rubber, a good flowability of the blend was observed, whereas the use of rubbers with different AN contents led to significant changes in the powder flowability, with a heterogeneous powder bed, and differences in the porosity as a function of the AN content. Furthermore, the addition of rubbers to polyamide 12 (PA12) entails an increase in the sintering window and, in particular, a change in the melting temperature of PA12 is noticed. Even though some changes in the crystallization and melting temperatures are observed, formulations containing 10 and 20 wt.% of rubbers could be processed using the same process parameters as PA12. Furthermore, the formulations containing carboxylated rubber show improved fire behavior, which is measured by a cone calorimeter, with reductions of about 45 and 65% in the peak of the heat release rate, compared to the PA12. Moreover, almost all of the samples evaluated in this study are classed as “Good” by the Flame Retardancy Index. This result can be partially explained by the formation of an amide linkage between the polyamide and NBR during processing, which could result in increases in the melt viscosities of these samples.

Influence of Acrylonitrile Content on the Adhesive Properties of Water-Based Acrylic Pressure-Sensitive Adhesives.

A series of pressure-sensitive adhesives (PSA) were prepared by emulsion polymerization in order to obtain a PSA that meet with the current label market requirements. For it, the effect of the incorporation of acrylonitrile (ACN) as hard monomer was investigated in a n-butyl acrylate (n-BA) and acrylic acid (AA) system. Great differences were found in the adhesive performance according to the ACN weight ratio. Its increased resulted in a considerable rise in the average sol molecular weight and in the glass transition temperature. This was reflected in a decrease of adhesion forces (peel resistance and tack) and an increase of the cohesion forces (shear resistance). Moreover, the incorporation of the minimum amount of ACN studied showed a great change in the elastic modulus determined by dynamic shear resistance with respect to the based formulation that did not contain ACN. Finally, the ice bucket test was carried out to check the adhesive performance in cold and wet environments.

Influence of thermal runaway in styrene–acrylonitrile bulk copolymerization revealed by computational fluid dynamics modeling

AbstractThe computational fluid dynamics (CFD) and kinetic‐based moment methods coupled approach is adopted to simulate the bulk copolymerization of styrene–acrylonitrile (SAN) in a stirred tank reactor. Numerical simulations are carried out to investigate the impacts of impeller speed, monomer ratio, initiator ratio, and initial reaction temperature on the copolymerization process and product properties. Particularly, the Chaos theory is selected as a criterion for evaluating the occurrence of the thermal runaway. The Flory's and Stockmayer's distributions are employed to calculate chain length distribution and copolymer composition distribution of copolymer. The simulation results highlight that the appearance of thermal runaway can be postponed by properly increasing the rotation speed, decreasing the initiator loadings, initial acrylonitrile contents and initial reactor temperature. Furthermore, significant differences exist in the product properties that predicted by the ideal and non‐ideal models, which demonstrates that the temperature heterogeneity plays a crucial role in SAN copolymerization. This study could offer references for the safe operation and design of polymerization processes.

Termooxidaition destruction of butadiene-nitrile rubbers and industrial waste

The process of thermooxidation destruction of industrial butadiene-nitrile copolymers of the grades SKN-18, SKN-26 and substandard products is investigated. The process is carried out in aromatic solvents (toluene in the xylene) under the influence of air oxygen in the presence of an adduct of the radical initiator azodiisobutyronitrile with N-metilpirrolidone. The mass-average molecular weights of the resulting products were determined by gel permeation chromatography, and molecular weight distribution calculations were performed. The influence of the temperature and the content of the initiator on the change in the intrinsic viscosity of solutions of the resulting degradation products, depending on the time of the process, is considered. Based on a comparative analysis of the destruction parameters using toluene and xylene at 80 °C and an initiator concentration of 0.8% by weight. It was found that the type of solvent and the time of destruction practically do not affect the process of thermooxidative destruction with the production of low molecular weight polymers with a molecular weight of 40 ? 103. It is shown that in the course of the destruction of industrial rubbers differing in the content of acrylonitrile, the process proceeds with the formation of higher molecular weight compounds in rubbers with a higher content of acrylonitrile units. When carrying out the destruction of substandard rubber SKN-26SNT with high Defoe hardness, it is necessary to increase the concentration of the initiator to 1.1% of the mass. and temperature. The mechanism of thermooxidative destruction of the studied polymers is considered. According to the data of IR spectroscopy and chemical analysis, it was found that the products of thermooxidative destruction of nitrile butadiene rubbers contain oxygen-containing functional groups. Thus, a simple commercially method for producing low-molecular-weight butadiene-nitrile polymers based on special-purpose rubbers and substandard product with functional hydroxyl, carboxyl and epoxy groups has been developed.

Radiation Graft-Copolymerization of Ultrafine Fully Vulcanized Powdered Natural Rubber: Effects of Styrene and Acrylonitrile Contents on Thermal Stability.

Graft copolymers, deproteinized natural rubber-graft-polystyrene (DPNR-g-PS) and deproteinized natural rubber-graft-polyacrylonitrile (DPNR-g-PAN), were prepared by the grafting of styrene (St) or acrylonitrile (AN) monomers onto DPNR latex via emulsion copolymerization. Then, ultrafine fully vulcanized powdered natural rubbers (UFPNRs) were produced by electron beam irradiation of the graft copolymers in the presence of di-trimethylolpropane tetra-acrylate (DTMPTA) as a crosslinking agent and, subsequently, a fast spray drying process. The effects of St or AN monomer contents and the radiation doses on the chemical structure, thermal stability, and physical properties of the graft copolymers and UFPNRs were investigated. The results showed that solvent resistance and grafting efficiency of DPNR-g-PS and DPNR-g-PAN were enhanced with increasing monomer content. SEM morphology of the UFPNRs showed separated and much less agglomerated particles with an average size about 6 μm. Therefore, it is possible that the developed UFPNRs grafted copolymers with good solvent resistance and rather high thermal stability can be used easily as toughening modifiers for polymers and their composites.

Influence of Chemically Modified Ultra-High Molecular Weight Polyethylene on the Properties of Butadiene Nitrile Rubber

For the manufacture of frost-resistant oil and petrol-resistant rubber products, one of the most widely used rubbers is nitrile-butadiene rubber (NBR) with a low acrylonitrile content of 17–20 %. However, the technical properties of its vulcanizates do not always meet all high performance requirements. Therefore, the study of the possibility of improving the technical characteristics of vulcanizates based on frost-resistant NBR is an urgent task. This paper presents the results of studying nitrile-butadiene rubber BNKS‑18AMN filled with ultra-high molecular weight polyethylene (UHMWPE). A feature of this work is the study of the possibility of increasing the technical properties of the obtained elastomeric composites by increasing the interaction between chemically inert UHMWPE and BNKS‑18AMN using the chemical modification of UHMWPE. The modification of UHMWPE was carried out by chemical etching in a solution of chromic acid for 3 and 20 hours. A complex of laboratory studies of the obtained samples was carried out. The influence of the duration of chemical etching of UHMWPE on the rheological and vulcanization properties has been studied on the analyzer of the processing of rubber. It is shown that the filling of UHMWPE into BNKS‑18AMN, in general, leads to an increase in the viscosity of the rubber compound. Chemical etching of UHMWPE leads to a decrease in the rate of vulcanization and the density of the three-dimensional spatial structure of the vulcanizate. The study of the physical and mechanical properties in tension, wear resistance during abrasion and swelling in standard hydrocarbon liquid for testing rubbers SZR‑3 showed that chemical etching of UHMWPE leads to a decrease in strength characteristics, but at the same time leads to an increase in resistance to abrasion and has no significant effect on swelling. The study of changes in the properties of samples after heat exposure showed that chemical etching of UHMWPE significantly reduces the resistance to thermal oxidative destruction in the presence of atmospheric oxygen, but does not affect the resistance to thermal aging in the SZR‑3 hydrocarbon environment

Effect of the acrylonitrile content in nitrile-butadiene rubber on the relative residual deformation of vulcanizate

The paper presents the results of a study of rubbers based on butadiene-nitrile rubbers (NBR) grades BNKS-40 and BNKS-18. The influence of the content of acrylonitrile (NAC) on the rheological and physico-mechanical properties of vulcanizates has been evaluated. It is shown that the content of NAC in the NBR composition significantly affects the relative residual compression deformation of the vulcanizate both under normal conditions and at elevated temperatures. The dependencies revealed in the work make it possible to make the correct choice of the rubber grade in the development of rubber resistant to compression deformation.

PROPERTIES OF WATER-SWELLABLE COMPOUNDS BASED ON NITRILE RUBBER WITH VARIED ACRYLONITRILE CONTENT

ABSTRACT This article examines the development of water-swellable rubbers for oil and gas production packer equipment. The object of the investigation is to document the effect of rubber's acrylonitrile content on the swelling of the elastomers modified with sodium-carboxymethyl cellulose and a copolymer of acrylamide and potassium acrylate. After testing the samples at room temperature, the most influential factor in a material's swelling was discovered to be the mineral content in the liquids imitating well fluids. NBR polarity stemming from the inherent acrylonitrile (CN-group) level was not explicitly detected to affect the swelling rate and maximum ratio under the described conditions of the experiment. It was determined that in sodium chloride aqueous solutions with concentrations from 3 to 22%, swelling of nitrile rubber mostly depends on its cross-linking degree.

The thermal oxidation of hydrogenated acrylonitrile-co-butadiene rubber from ambient to 150 °C

Hydrogenated acrylonitrile-co-butadiene (HNBR) elastomers containing three concentrations of acrylonitrile (34, 39 and 50 wt%) and less than 1% residual double bond content were heat aged up to 150 °C. Fourier transform Infrared (FTIR) spectroscopy, elemental analysis and liquid proton Nuclear Magnetic Resonance (NMR) were used to analyze the thermo-oxidized samples. FTIR clearly shows the development of esters, ketones, carboxylic acids and secondary alcohols upon heat aging which were confirmed by NMR. The acrylonitrile content was not affected by the employed heat aging conditions. Using the carbonyl growth index and time-temperature superposition (T-TS), the long term thermo-oxidative kinetics possessed three distinct regions: 23-85 °C, 85-100 °C and 100-150 °C. The slower oxidation kinetics between 85 and 100 °C in combination with an induction period shown by T-TS likely contributes to the enhanced oxidative heat aging resistance of HNBR. Activation energies increased with temperature and lower acrylonitrile levels. A series of reaction mechanisms has been put forth to explain functional group development or loss during oxidative heat aging.

Flower-like Ni/N-doped carbon composites with core–shell synergistic structure for broad-band electromagnetic wave absorption

The novel microstructure of magnetic-carbonaceous composites has become a prevalent route to improve electromagnetic wave absorption (EMWA) performance. Flower-like Ni/nitrogen-doped carbon (Ni/NC-X) composites with core–shell synergistic structure, N-doping and Ni-N bonds were rationally constructed and fabricated by hydrothermal methods and thermal decomposition with carbon reduction. The Ni cores were encapsulated within approximately 15 layers of the graphene shell, leading to the generation of a Ni/NC-X core–shell configuration. The EMWA performances of Ni/NC-X composites could be adjusted by modulating the acrylonitrile (AN) content. Benefiting from the synergistic effects of the core–shell configuration, a hierarchically flower-like architecture and the components (Ni and C), the flower-like Ni/NC-0.80 composite showed remarkable EMWA performance with a reflection loss (RL) of − 40.1 dB and a broad effective absorption bandwidth (EAB) of 10.05 GHz. The result of this study establishes a new strategy to prepare magnetic-carbonaceous composites by carefully designing the microstructure.

Migration of mineral oil in elastomers

This work describes a newly introduced experimental procedure to quantify the diffusion progress of mineral oils locally resolved in NBR. Diffusion of reference oils IRM 901, IRM 902 and IRM 903 in NBR with various acrylonitrile contents was investigated. Classical sorption experiments were performed as a basic characterization and compared to the newly introduced method. Here, elastomer specimens are only being dipped with the bottom in a relatively small reservoir of mineral oil. This provides a determination of locally resolved concentration profiles of mineral oils, and the calculation of diffusion coefficients. These diffusion coefficients follow the same trends like those determined via sorption experiments. Despite differences in the absolute numbers, activation energies of diffusion can be applied as a suitable measure for the compatibility of elastomers and fluids.

Comparative study on the molecular chain orientation and strain-induced crystallization behaviors of HNBR with different acrylonitrile content under uniaxial stretching

Molecular chain orientation and strain-induced crystallization (SIC) behaviors of hydrogenated nitrile butadiene rubber (HNBR) with acrylonitrile content of 19%, 33%, 41%, 44%, i.e., HNBR-19 to HNBR-44, were characterized by using polarized FTIR spectroscopy and synchrotron radiation WAXD. Results demonstrated that the hydrogenated butadiene and acrylonitrile segments showed different orientation behaviors in these HNBRs. Orientation decreased with increasing acrylonitrile content, except for HNBR-44. HNBR-19 had the highest SIC ability and the crystals were composed of only hydrogenated butadiene homopolymer segments. HNBR-33 could not crystallize. As for HNBR-41 and HNBR-44 with high acrylonitrile content, HNBR-44 showed the better SIC ability and hydrogenated butadiene-acrylonitrile alternating copolymer segments were proved to participate in the crystallization. Relationship between microstructure and stress-strain characteristics was also discussed and results revealed that the relatively homogeneous crystal structure, higher crystal orientation and rapidly increasing molecular chain orientation were attributed to the highest stress value of HNBR-44 after SIC occurred.

Identification Method of Solid Waste Characteristic for Imported Recycled Engineering Plastics

The nitrogen content in imported recycled plastic particles was determined by elemental analyzer method and Kjeldahl method, respectively, and the acrylonitrile content was obtained by conversion to obtain the information on the consistency of polymer composition in recycled plastic particles. Two specific cases judged by this method were given. This method was available to provide a creative idea and method for the identification of solid waste characteristic of recycled engineering plastic particles containing acrylonitrile monomeric units such as acrylonitrile-styrene copolymer (SAN) recycled particles, acrylonitrile-butadiene-styrene copolymer (ABS) recycled particles, PC/ABS alloy recycled particles, PBT/ABS alloy recycled particles, PMMA/AS alloy recycled particles.

Radical polymerization of butadiene mediated by molecular iodine: A comprehensive kinetic study on solution copolymerization with acrylonitrile

Solution homo- and copolymerization of butadiene (Bu) and acrylonitrile (AN) in 1,4-dioxane (Dox) was carried out in the presence of molecular iodine (I2) and 4,4′-azobis (4-cyanovaleric acid) (ACVA), both acting as an in situ generator of carboxyl-functionalized alkyl iodide as a chain transfer agent (CTA), to synthesize α-carboxyl ω-iodine heterotelechelic polymer architectures. Effect of various variables including solvent concentration and type, ACVA to I2 molar ratio and reaction temperature (60 and 70 °C) on the overall conversion versus time data was investigated. It was found that before complete consumption by initiator-derived radicals during the induction period, molecular I2 inhibits the reaction. Polymerization period was then started in the presence of an in situ generated CTA. From conversion versus time data, rate constant of initiator decomposition (kd), induction time (tind ) and overall average rate constant of k‾p2/k‾t were estimated and compared with those reported for conventional free-radical homo- and copolymerization of Bu and AN. A good agreement between the theoretical and experimental variations in the conversion versus time was also observed, indicating accuracy of the kinetic constants calculated in the present work. Comparison of the theoretical and experimental induction times revealed that molecular I2 reacts with Bu, resulting in butadiene diiodide species (I−Bu−I) which can act along with carboxyl-functionalized alkyl iodide as CTAs. Formation of I−Bu−I was also confirmed by 1H NMR analysis. Also, fraction of I2 consumed by Bu (i.e. [I−Bu−I]/[I2]0) was estimated from kinetic data at hand. [I−Bu−I]/[I2]0 value as high as 20.8% was observed in the case of Bu homopolymerization and decreased by increasing the AN content in the initial feed. In the case of AN homopolymerization, no consumption of I2 by AN was observed.

Effect of Prestrain on the Actuation Characteristics of Dielectric Elastomers

Dielectric elastomers (DEs) represent a class of electroactive polymers that deform due to electrostatic attraction between oppositely charged electrodes under a varying electric field. Over the last couple of decades, DEs have garnered considerable attention due to their much-coveted actuation properties. As far as the precise measurement systems are concerned, however, there is no standard instrument or interface to quantify various related parameters, e.g., actuation stress, strain, voltage and creeping etc. In this communication, we present an in-depth study of dielectric actuation behavior of dielectric rubbers by the state-of-the-art “Dresden Smart Rubber Analyzer” (DSRA), designed and developed in-house. The instrument allowed us to elucidate various factors that could influence the output efficiency of the DEs. Herein, several non-conventional DEs such as hydrogenated nitrile rubber, nitrile rubber with different acrylonitrile contents, were employed as an electro-active matrix. The effect of viscoelastic creeping on the prestrain, molecular architecture of the matrices, e.g., nitrile content of nitrile-butadiene rubber (NBR) etc., are also discussed in detail.