Content Of Nitrile Groups Research Articles

Research the effect of crosslinking degree on the overall performance of novel proton exchange membranes

As we all know, introducing crosslinking groups into the polymer chain can effectively improve the overall performance of proton exchange membranes, which are for the formation of intermolecular three-dimensional network. In this work, side-chain nitrile-based cross-linked sulfonated poly(arylene ether nitrile) (SPEN) membrane is expected to be an ideal material for preparing proton exchange membranes (PEMs). A series of SPEN-60-COOH-x with different carboxyl content have been synthesized through fixing the content of sulfonic group at 60% in the experiment and changing the molar fraction of phenolphthalein (PPL). Then, the SPEN-60-CN-x were prepared by grafting nitrile groups onto the SPEN-60-COOH-x via carboxyl groups. NMR and FTIR were used to characterize the construction of polymers. The TGA results showed that the thermal stability of CSPEN-60-CN-x was significantly improved by the cross-linking network structure formed by side chain nitrile groups. As the degree of cross-linking increases, the water uptake of CSPEN-60-CN-x membranes showed a downward trend. The results also indicated that the dimension stability of CSPEN-60-CN-x membranes was effectively improved by cross-linking reaction, and the dimension stability of CSPEN-60-CN-x membranes was further improved by increasing the content of nitrile groups. The selectivity of CSPEN-60-CN-x membranes increased significantly after crosslinking. CSPEN-60-CN-30 has the highest selectivity of 5.37 × 105 S·s·cm−3 among all the membranes, about 11.9 times that of Nafion 117.

Comb-shaped fluorene-based poly(arylene ether sulfone nitrile) as anion exchange membrane

A series of comb-shaped fluorene-based poly (arylene ether sulfone nitrile) (CFPESN–x) was synthesized as anion exchange membranes (AEMs). The well-designed architecture of fluorene-based main chains and comb-shaped C8 long alkyl side chains containing quaternary ammonium groups was responsible for the clear microphase-separated morphologies, as confirmed by small angle X-ray scattering and atomic force microscopy. Moreover, nitrile groups on main chains also showed a profound influence on membrane morphology and properties. CFPESN–x exhibited more interconnected ionic domains with increasing the nitrile group content resulting in higher conductivities and anti-swelling property. Then CFPESN–x exhibited high ionic conductivities in the range of 27.1–91.5 mS cm−1 from 30 to 80 °C and superior ratios of conductivity to swelling ratio at 80 °C at moderate IECs. Moreover, CFPESN–x also showed good mechanical properties and thermal stability, and optimizable alkaline stability and single cell performance.

Comb-shaped cardo poly(arylene ether nitrile sulfone) anion exchange membranes: significant impact of nitrile group content on morphology and properties.

A series of comb-shaped cardo poly(arylene ether nitrile sulfone) (CCPENS-x) materials were synthesized by varying the content of nitrile groups as anion exchange membranes (AEMs). The well-designed architecture of cardo-based main chains and comb-shaped C10 long alkyl side chains bearing imidazolium groups was responsible for the clear microphase-separated morphologies, as confirmed by atomic force microscopy. The ion exchange capacity (IEC) of the AEMs ranged from 1.56 to 1.65 meq. g−1. With strong dipole interchain interactions, the effects of nitrile groups on the membrane morphology and properties were investigated. With the nitrile group content increasing from CCPENS-0.2 to CCPENS-0.8, CCPENS-x revealed larger and more interconnected ionic domains to form more efficient ion-transport channels, thus increasing the corresponding ionic conductivity from 25.8 to 39.5 mS cm−1 at 30 °C and 58.6 to 83 mS cm−1 at 80 °C. Furthermore, CCPENS-x with a higher content of nitrile groups also exhibited lower water uptake (WU) and swelling ratio (SR), and better mechanical properties and thermal stability. This work presents a promising strategy for enhancing the performance of AEMs.

Side-chain-type phenolphthalein-based poly(arylene ether sulfone nitrile)s anion exchange membrane for fuel cells

A series of phenolphthalein-based poly(arylene ether sulfone nitrile)s containing imidazolium groups on the side chains was synthesized to prepare anion exchange membranes (AEMs) for alkaline fuel cells. Strong polar nitrile groups were introduced into the polymer backbone with the intention of improving the dimensional stability of the AEMs. The content of nitrile groups was varied to study the effect of nitrile groups on the morphology and properties of the AEMs. With imidazolium groups locating on the cardo side chains, all the AEMs exhibited well-defined microphase-separated structures. Furthermore, the imidazolium groups tend to aggregate with increasing the nitrile group content resulting in the formation of larger and more interconnected ionic domains in the AEMs. The ionic conductivity in the range of 2.21–8.14×10−2Scm−1 increased with increasing the nitrile group content and temperature. The AEMs showed superb ratios of conductivity to IEC or swelling ratio at 60°C, good mechanical properties, and thermal and alkaline stability. A single H2/O2 fuel cell using the as-prepared AEMs showed an open circuit voltage of 0.95V and a peak power density of 50.6mWcm−2 at 60°C.

Phthalonitrile‐containing poly(amide imide)s with nanoactuation properties

AbstractA series of aromatic poly(amide imide)s containing pendant phthalonitrile groups was prepared by solution polycondensation reaction of 4,4′‐diamino‐4″‐(3,4‐dicyanophenoxy)triphenylmethane, 1, or of different amounts of 1 and 1,3‐bis(4‐aminophenoxy)benzene, with a fluorinated imide diacid chloride, 2,2‐bis[N‐(4‐chloroformylphenyl)phthalimidyl]hexafluoroisopropane. The polymers were easily soluble in polar organic solvents, such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethylsulfoxide. They can be cast from solutions into thin flexible films showing nanoactuation properties in the range of 120–450 nm, depending on the nitrile group content, when an electric voltage is applied on their surface. Electrical insulating properties of the polymer films were evaluated on the basis of dielectric permittivity and dielectric loss and their variation with the frequency and temperature. The values of the dielectric permittivity at 10 kHz and 20°C were in the range of 3.01–3.43. All polymers exhibited high thermal stability, decomposition temperature being above 420°C. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Effects of rubber/filler interactions on the structural development and mechanical properties of NBR/silica composites

AbstractA study was carried out on the effects of interactions between nitrile–butadiene rubber (NBR) and silica on the developments of agglomerates by silica particles and of bound rubber in NBR/silica composites. The mechanical properties of the composites were also investigated in relation to the structure development. Transmission infrared spectra revealed the existence of hydrogen bonding between nitrile groups in NBR and silanol groups on the silica surface. The number of hydrogen bonds increased with the increasing nitrile group content of NBR. Transmission electron microscopy observations and thermal analysis revealed that the averaged size of agglomerates in composites decreased, and simultaneously the amount of filler–gel in silica‐filled NBR decreased with increasing nitrile group content of NBR. These results suggest that the hydrogen bonding between nitrile groups and silanol groups suppresses the development of agglomerates by silica particles, that is, the dispersion of silica is improved by the hydrogen bonding. At a given nitrile group content of NBR, the storage modulus and the initial slope of stress–strain curves for vulcanized composites increased with increasing the amount of filler–gel. Further, at a larger strain, the composites showed a clear pseudo‐yielding point on the stress–strain curves, with this tendency more prominent in the larger agglomerate size. These results suggest that the mechanical properties for NBR/silica composites are affected by the content of filler–gel. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 74–81, 2005

Degradation and stabilization of PVC in blends

AbstractPoly(vinylchloride) (PVC) was mixed with various poly(methacrylate)s, poly(carbonate)s and polymers containing nitrile groups (poly(acrylonitrile), poly(styrene‐co‐acrylonitrile), nitrile rubber, hydrogenated nitrile rubber) and/or C  C double bonds (nitrile rubber, high‐impact poly(styrene)). The thermal stability was measured at 180°C in nitrogen, and the evolved HCl was detected by conductometry.It is shown that the nature of the ester group and the content of nitrile groups and C ‐ C double bonds are the dominating factors for the thermal stability of poly(vinylchloride) in these blends. An influence of the miscibility of PVC with the various blend components on the thermal stability can not be clearly detected.Differential scanning calorimetry (DSC) was used as a powerful method to study the stabilizer distribution of heterogeneous PVC/poly(styrene‐co‐acrylonitrile) and PVC/poly(methylacrylate) blends. It is shown that the stabilizer can be solubilized either in the PVC phase (PVC/poly(methylacrylate)) or in both phases of the blends PVC/poly(styrene‐co‐acrylonitrile)).

Effect of the position of functional groups in oligobutadiene on structuring under the action of transition metal salts

Structuring under the action of FeCl3 and ZnCl2 in liquid butadiene rubbers with different positions and contents of nitrile and carboxyl groups in studied. It is shown that the effect of structuring is manifested much more in rubbers where the functional groups are located inside the macromolecular chain, and not at its ends. Increase in the carboxyl and nitrile group content promotes the appearance of coils of more convoluted form and more difficult access to the metal cations to the oligomer functional groups. This results in retarded vulcanization of the rubbers, impairment of their film forming power, and as a consequence, to a decrease in the protective properties of coatings based on them.

Transparent barrier resins with high nitrile content

AbstractThe effect of 30–49 wt‐% nitrile group content on the properties of copolymers is demonstrated. The nitrile is furnished by either acrylonitrile or methacrylonitrile. The exceptional resistance of such high nitrile content resins to the passage of gases and of solvents is shown and variations therein demonstrated for different comonomers. Transparent, tough, grafted polymers of good color are described which retain these properties. These qualities, combined with low second‐order transition temperatures and adequate heat deflection temperatures, provide polymers of interest wherever containment and barrier are desired. Bottles, thermoformed containers, etc., could benefit from the use of some of the polymers described.

Vulcanization of some synthetic rubbers without sulphur—IV. The effect of the nitrile-group content on the thermal vulcanization of butadiene-nitrile rubbers

Vulcanization of some synthetic rubbers without sulphur—IV. The effect of the nitrile-group content on the thermal vulcanization of butadiene-nitrile rubbers

Oxidation of Butadiene-Acrylonitrile Rubbers

Abstract 1. The authors investigate the inhibited oxidation of SKN-18, SKN-26 and SKN-40 butadiene-acrylonitrile rubbers in a micro-oxidation apparatus at various temperatures. 2. It is established that the rate of inhibited oxidation of butadiene-acrylonitrile rubbers is determined by their nitrile group content. On increasing the amount of acrylonitrile in the polymer the rate of oxidation decreases. 3. The energy of activation of inhibited oxidation of butadiene-acrylonitrile rubbers (29 to 30 kcal/mole) is calculated according to the Arrhenius equation. The energy of activation of inhibited oxidation of SKN rubbers is 5 kcal/mole higher than the energy of activation of inhibited oxidation of SKS-30 rubber and 10 kcal/mole higher than that of SKB rubber. 4. The structural changes in SKN rubbers in inhibited oxidation are determined by their nitrile groups. For SKN-26 and SKN-40 the predominant process in all stages of oxidation is the process of crosslinking. In the case of SKN-18 the process of degradation predominates at the beginning, and in the later stages the process of crosslinking. 5. A correlation is demonstrated between the behavior of SKN rubbers in oxidation and in thermal oxidative plasticization.