Novel in situ coordination copper sulfate/ acrylonitrile–butadiene rubber composite

A novel rubber composite of acrylonitrile–butadiene rubber (NBR) filled with anhydrous copper sulfate (CuSO₄) particles was investigated. Dynamic mechanical analysis, differential scanning calorimetry, X‐ray photoelectron spectroscopy, tensile testing, and an equilibrium swelling method were used for the characterization of this novel CuSO₄/NBR composite. The results indicated that the composite had wonderful mechanical properties, which profited from the in situ coordination crosslinking interactions between the nitrile groups (? CN) of NBR and solid CuSO₄ particles. Scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and transmission electron microscopy results showed that CuSO₄ particles played two roles, acting as both crosslink agents and reinforcing fillers in the matrix. The double actions of CuSO₄ gave the CuSO₄/NBR composites their excellent mechanical properties. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 571–576, 2007     

Investigation on crosslinking behaviors of NBR/PVC filled with anhydrous copper sulfate particles by dynamic mechanical analysis

Crosslinking behaviors of acrylonitrile butadiene rubber (NBR)/poly (vinyl chloride) (PVC) alloy, filled with anhydrous copper sulfate (CuSO₄) particles, were investigated for the first time by dynamic mechanical analysis (DMA) under hetero and isothermal modes, respectively. In the heterothermal testing, (NBR/PVC)/CuSO₄ compound showed two marked increases in the storage modulus (E′), corresponding to coordination crosslinking of NBR-CuSO₄ and self-crosslinking of NBR and PVC respectively. During the isothermal testing, a dramatic increase in E′ was found at the initial stage while that of original NBR/PVC alloy was not detected. The marked increase in E′ of (NBR/PVC)/CuSO₄ compound was mainly due to the crosslinking induced by coordination between  CN and Cu²⁺. The increasing extent of E′ increased with the rise of CuSO₄ content, suggesting the formation of a greater number of crosslinks. Moreover, the activation energy (E_a) of crosslinking process was about 139 kJ/mol. In this work, fourier transform infrared spectrum (FT-IR) and equilibrium swelling method were also performed for the characterization of the compound. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 41–51, 2007     

Crosslinking behavior and enhanced mechanical properties of acrylonitrile‐butadiene rubber composites by incorporating aluminum ammonium sulfate particles

The crosslinked structure formed by the metal coordination bonding provides excellent and new properties for rubber materials. Herein, the crosslinking of acrylonitrile‐butadiene rubber (NBR) is induced by introducing aluminum ammonium sulfate (NH₄Al(SO₄)₂·12H₂O) particles. The crosslinking behavior, morphology, mechanical properties, and the Akron abrasion resistance of NBR/NH₄Al(SO₄)₂·12H₂O composites were fully explored. The results show that the three‐dimensional crosslinking structure is held together by metal–ligand coordination bonds between the nitrile group and AI(III). The coordination crosslink density exhibits a considerable increase with the addition of NH₄Al(SO₄)₂·12H₂O. Thus, the mechanical properties and abrasion resistance of the obtained composites are better than that of NBR/sulfur system. Interestingly, the elongation at break for NBR/NH₄Al(SO₄)₂·12H₂O composites is over 2000% due to the nature of coordination bonds. The abrasion volume loss decreases to 0.4 cm³ for NBR/NH₄Al(SO₄)₂·12H₂O composites with 20 phr NH₄Al(SO₄)₂·12H₂O particles as compared to 0.75 cm³ for NBR/sulfur system. The obtained NBR composites with facile preparation and excellent mechanical properties make the composites based on metal coordination bonding attractive for practical use. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 879–886     

Transport properties of crosslinked acrylonitrile butadiene rubber/poly(ethylene‐co‐vinyl acetate) blends

The diffusion and transport of organic solvents through crosslinked nitrile rubber/poly(ethylene‐co‐vinyl acetate) (NBR/EVA) blends have been studied. The diffusion of cyclohexanone through these blends was studied with special reference to blend composition, crosslinking systems, fillers, filler loading, and temperature. At room temperature the mechanism of diffusion was found to be Fickian for cyclohexanone–NBR/EVA blend systems. However, a deviation from the Fickian mode of diffusion is observed at higher temperature. The transport coefficients, namely, intrinsic diffusion coefficient (D*), sorption coefficient (S), and permeation coefficient (P) increase with the increase in NBR content. The sorption data have been used to estimate the activation energies for permeation and diffusion. The van't Hoff relationship was used to determine the thermodynamic parameters. The affine and phantom models for chemical crosslinks were used to predict the nature of crosslinks. The experimental results were compared with the theoretical predictions. The influence of penetrants transport was studied using dichloromethane, chloroform, and carbon tetrachloride. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1815–1831, 1999     

Crosslinking of styrene–butadiene rubber with 1,2-bis(benzocyclobutenyl)ethane

1,2-Bis(benzocyclobutenyl)ethane (BBCB) was used as a thermally activated crosslinking agent in styrene–butadiene rubber (SBR), both in the raw and carbon black-filled materials. Diels–Alder crosslinking reactions occurred to a significant degree, despite the lack of substituents of opposing electronic effects. The reaction is free of toxic crosslinking promoters and evolved by-products. Various physical properties such as ultimate elongation, tensile strength, and modulus were measured and compared to those properties of a sulfur-cured sample of SBR. Linear relationships were found between the amount of BBCB present and the modulus of the materials, as well as the amount of BBCB and solvent uptake in swell tests. © 1993 John Wiley & Sons, Inc.     

Dynamic mechanical behavior of acrylonitrile butadiene rubber/poly(ethylene‐co‐vinyl acetate) blends

The dynamic mechanical behavior of uncrosslinked (thermoplastic) and crosslinked (thermosetting) acrylonitrile butadiene rubber/poly(ethylene‐co‐vinyl acetate) (NBR/EVA) blends was studied with reference to the effect of blend ratio, crosslinking systems, frequency, and temperature. Different crosslinked systems were prepared using peroxide (DCP), sulfur, and mixed crosslink systems. The glass‐transition behavior of the blends was affected by the blend ratio, the nature of crosslinking, and frequency. sThe damping properties of the blends increased with NBR content. The variations in tan δ_max were in accordance with morphology changes in the blends. From tan δ values of peroxide‐cured NBR, EVA, and blends the crosslinking effect of DCP was more predominant in NBR. The morphology of the uncrosslinked blends was examined using scanning electron and optical microscopes. Cocontinuous morphology was observed between 40 and 60 wt % of NBR. The particle size distribution curve of the blends was also drawn. The Arrhenius relationship was used to calculate the activation energy for the glass transition of the blends, and it decreased with an increase in the NBR content. Various theoretical models were used to predict the modulus of the blends. From wide‐angle X‐ray scattering studies, the degree of crystallinity of the blends decreased with an increasing NBR content. The thermal behavior of the uncrosslinked and crosslinked systems of NBR/EVA blends was analyzed using a differential scanning calorimeter. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1556–1570, 2002     

Chemical alteration of poly(tetrafluoroethylene) Teflon induced by exposure to vacuum ultraviolet radiation and comparison with exposure to hyperthermal atomic oxygen

The chemical alteration of poly(tetrafluoroethylene) Teflon by vacuum ultraviolet radiation (VUV) (115–400 nm) has been examined with X‐ray photoelectron spectroscopy (XPS). The initial F/C atom ratio of 1.98 decreases to 1.65 after a 2‐h exposure. The F/C atom ratio is further reduced to a steady‐state value of 1.60 after a 74‐h exposure. The high‐resolution XPS C1s data indicate that new chemical states of carbon form as F is removed and that the relative amounts of these states depend on the F content of the near‐surface region. The states are most likely due to C bonded only to one F atom, C bonded only to other C atoms, and C that has lost a pair of electrons through the emission of F^?. The exposure of the VUV‐damaged surface to research‐grade O₂ results in the chemisorption of a very small amount of O, and this indicates that large quantities of reactive sites are not formed during the chemical erosion by VUV. Further exposure to VUV removes this chemisorbed oxygen. A comparison of the XPS data indicates that the mechanisms of chemical alteration by VUV radiation and hyperthermal (～5 eV) atomic oxygen are different, as expected, because the excitation sources are quite different. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 552–561, 2005     

Wettability of poly(styrene‐co‐acrylate) ionomers improved by oxygen‐plasma source ion implantation

The surfaces of poly(styrene‐co‐acrylic acid) copolymers and their Na‐ and Cs‐neutralized ionomers were modified by O₂‐plasma source ion implantation (PSII) treatment to improve the surface wettability. The changes in the surface wettability, composition, and structure upon the PSII treatment were examined with contact‐angle measurements and X‐ray photoelectron spectroscopy. The untreated surfaces of the acid copolymers and ionomers exhibited different surface energies; this implied clearly that the type of ion species affects the surface hydrophilicity. Also, the PSII treatment induced oxygen‐containing groups to reside on the surface and ionic groups to come out toward the surface; this made the surfaces of the ionomers more hydrophilic as compared with that of the acid copolymers. The ionomers also showed slow hydrophobic recovery. Thus, it was suggested that the reduced mobility of the polymer chain because of the presence of ionic aggregates results in restricted reorientation of oxygen‐containing groups. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1791–1797, 2003     

New block copolymers V. Synthesis,characterization and morphological studies of poly(pentamethylene terephthalate)-b-(acrylonitrile butadiene rubber)

A block copolymer was prepared by low temperature polycondensation between (acid chloride)-terminated poly(pentamethylene terephthalate) as the hard block, and amine-terminated acrylonitrile-butadiene rubber, as the soft block. The polymer was characterized by nitrogen analysis, IR and NMR spectroscopy. The polymer showed two glass transition temperatures (T _g ) and exhibited two-phase morphology.     

Efficient photoinduced In situ preparation of clay/poly(glycidyl methacrylate) nanocomposites using hydrogen‐donor silane

Clay/poly(glycidyl methacrylate) nanocomposites (clay/PGMA) were prepared by in situ radical photopolymerization using N,N‐dimethylaminopropyltrimethoxysilane(DMA)‐modified bentonite clay acting as hydrogen donor for benzophenone in solution. This initiating system permits to photopolymerize glycidyl methacrylate between the lamellae of the DMA‐modified clay. The approach provides exfoliated nanocomposites as judged by the measurements of X‐ray diffraction. However, a low fraction of persistent intercalated clay regions was visible by transmission electron microscopy. X‐ray photoelectron spectra analyses indicate that the nanocomposites have PGMA‐rich surface. The clay/PGMA nanocomposites can be readily dispersed in ethanol. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 800–808     

Radiation‐induced conductance in the blends of poly(aniline‐base) with poly(vinyl chloride) and poly[(vinylidene chloride)‐co‐(vinyl acetate)]

In this study blends of Poly(Aniline‐Base)/Poly(Vinylidene Chloride) co‐(Vinyl Acetate) were exposed to radiation to increase the conductance of Poly(Aniline‐Base). Aniline was polymerized by following the procedure of Focke's chemical oxidation method and Poly(vinyl acetate/poly(vinylidene chloride), (PVAc/PVnCl), copolymer was synthesized by solution polymerization Various Poly(Aniline‐Base)/Poly(Vinylidene Chloride) co‐(Vinyl Acetate) films were prepared which were then exposed to gamma rays. The change in the structure was investigated by FT‐IR and UV‐visible spectorphotometer.     

Simultaneous synthesis of silver nanoparticles and poly(2,5‐dimethoxyaniline) in poly(styrene sulfonic acid)

Silver nanoparticles were formed in situ along with poly(2,5‐dimethoxyaniline) (PDMA) in an interconnected network matrix (reactor), comprising the electronic conductive polymer, PDMA, and a polyelectrolyte, poly(styrene sulfonic acid) (PSS), through the simultaneous reduction of Ag⁺ ions and polymerization of 2,5‐dimethoxyaniline. In situ ultraviolet‐visible spectroscopy showed that peaks corresponding to the plasmon resonance of silver nanoparticles at 411 nm and the polaronic transition of PDMA at 438 nm provided evidences for the simultaneous formation of silver nanoparticles and PDMA. Transmission electron microscopy and size distribution analysis revealed the presence of spherical silver nanoparticles with an average diameter of 12 nm in the composite. X‐ray photoelectron spectroscopy showed that the amine units in PDMA changed to imine units upon the formation of silver nanoparticles. A comprehensive mechanism for the formation of the PDMA‐PSS‐Ag nanocomposite is proposed. A 10‐fold increase in the conductivity was noticed for the PDMA–PSS–Ag nanocomposite (1 S/cm) in comparison with the PDMA–PSS composite (0.1 S/cm). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3843–3852, 2006     

Conductivity,morphology, interfacial chemistry,and stability of poly(3,4‐ethylene dioxythiophene)–poly(styrene sulfonate): A photoelectron spectroscopy study

X‐ray photoelectron spectroscopy (XPS) has been used to characterize poly(3,4‐ethylene dioxythiophene)–poly(styrene sulfonate) (PEDT/PSS), one of the most common electrically conducting organic polymers. A correlation has been established between the composition, morphology, and polymerization mechanism, on the one hand, and the electric conductivity of PEDT/PSS, on the other hand. XPS has been used to identify interfacial reactions occurring at the polymer‐on‐ITO and polymer‐on‐glass interfaces, as well as chemical changes within the polymer blend induced by electrical stress and exposure to ultraviolet light. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2561–2583, 2003     

Silicone‐based impact modifiers for poly(vinyl chloride), engineering resins,and blends

Silicone‐based impact modifiers were prepared in a previous study. The modifiers were composed of silicone/acrylic rubber cores and grafted acrylic shells. They improved the toughness of poly(vinyl chloride) (PVC) and poly(methyl methacrylate). The silicone emulsion that was used to produce the silicone‐based impact modifiers was prepared via two routes: emulsion polymerization and bulk polymerization of octamethyltetracyclosiloxane. Many silicone‐based impact modifiers were produced that had different silicone/acrylic rubber characteristics. Through a toughness examination of modified PVC, the best composition of the silicone‐based impact modifiers was obtained, and the silicone content in the rubber composition was 25 wt %. The morphology of the silicone‐based impact modifiers, determined by transmission electron microscopy, was as follows: core and second shell polymers were mainly poly(butyl acrylate), and the first shell polymer was silicone. The silicone‐based impact modifiers were blended with engineering resins such as PVC, polycarbonate (PC), poly(butylene terephthalate) (PBT), and PC/PBT mixtures. The impact strength under standard conditions and after weathering test conditions for blends of the silicone‐based impact modifiers were investigated with respect to two commercially available acrylic and methyl methacrylate/butadiene/styrene impact modifiers. The results showed good weatherability and good toughness under low‐temperature conditions for the silicone‐based impact modifiers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1112–1119, 2004     

Robust Poly(allylamine)‐graft‐poly(N‐isopropylacrylamide) Particles Prepared by Physical Crosslinking with Poly(styrene sulfonate)

Summary: Robust thermosensitive PAH‐g‐PNIPAAm/PSS particles were prepared by addition of a poly(allylamine)‐graft‐poly(N‐isopropylacrylamide) particle suspension into poly(styrene sulfonate) solution above the LCST of PAH‐g‐PNIPAAm. Scanning force microscopy revealed stable and well‐separated particles in water at room temperature. The zeta‐potential showed a negative surface charge of the particles. Their thermosensitive behavior was demonstrated by dynamic light scattering. The release of rhodamine 6G loaded particles could respond to the incubation temperature.

Fabrication of thermosensitive and robust particle by suspension of in situ formed PAH‐g‐PNIPAAm particle above the LCST in PSS solution.     

Terpyridine‐modified poly(vinyl chloride): Possibilities for supramolecular grafting and crosslinking

Commercially available poly(vinyl chloride) (PVC) was covalently modified with terpyridine supramolecular binding units in a two‐step reaction. First, PVC was modified with aromatic thiols to introduce OH functionalities into the polymer backbone, which were subsequently reacted with an isocyanate‐functionalized terpyridine binding unit. The resulting functionalized material contained metal‐ion binding sites, which could be used for grafting and crosslinking reactions. A grafting experiment was performed with a small organic terpyridine ligand. The complexation of the modified PVC with several transition‐metal ions was studied with ultraviolet–visible spectroscopy and gel permeation chromatography. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2964–2973, 2003     

Synthesis of Poly(vinyl acetate) Nanogels by Xanthate‐Mediated Radical Crosslinking Copolymerization

Poly(vinyl acetate) (PVAc) nanogels are synthesized by a radical crosslinking copolymerization (RCC) in solution of vinyl acetate and divinyl adipate (DVA) or 2,4,6‐tris(allyloxy)‐1,3,5‐triazine (TAT) as the crosslinker, in the presence of a xanthate as a reversible chain transfer agent. Higher concentrations of crosslinker and lower concentrations of xanthate produce PVAc nanogels of higher molar masses, for a given concentration of xanthate and for a fixed concentration of crosslinker, respectively. The xanthate end‐groups allow for the synthesis of ‘second generation’ nanogels through a subsequent RCC from precursors. The chemical cleavage of the crosslinks yields individual poly(vinyl alcohol) chains, which attests that the length of the constitutive chains is controlled by the xanthate.

     

Surface characterization of plasma‐modified poly(ethylene terephthalate) film surfaces

Poly(ethylene terephthalate) (PET) film surfaces were modified by argon (Ar), oxygen (O₂), hydrogen (H₂), nitrogen (N₂), and ammonia (NH₃) plasmas, and the plasma‐modified PET surfaces were investigated with scanning probe microscopy, contact‐angle measurements, and X‐ray photoelectron spectroscopy to characterize the surfaces. The exposure of the PET film surfaces to the plasmas led to the etching process on the surfaces and to changes in the topography of the surfaces. The etching rate and surface roughness were closely related to what kind of plasma was used and how high the radio frequency (RF) power was that was input into the plasmas. The etching rate was in the order of O₂ plasma > H₂ plasma > N₂ plasma > Ar plasma > NH₃ plasma, and the surface roughness was in the order of NH₃ plasma > N₂ plasma > H₂ plasma > Ar plasma > O₂ plasma. Heavy etching reactions did not always lead to large increases in the surface roughness. The plasmas also led to changes in the surface properties of the PET surfaces from hydrophobic to hydrophilic; and the contact angle of water on the surfaces decreased. Modification reactions occurring on the PET surfaces depended on what plasma had been used for the modification. The O₂, Ar, H₂, and N₂ plasmas modified mainly CH₂ or phenyl rings rather than ester groups in the PET polymer chains to form C? O groups. On the other hand, the NH₃ plasma modified ester groups to form C? O groups. Aging effects of the plasma‐modified PET film surfaces continued as long as 15 days after the modification was finished. The aging effects were related to the movement of C?O groups in ester residues toward the topmost layer and to the movement of C? O groups away from the topmost layer. Such movement of the C?O groups could occur within at least 3 nm from the surface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3727–3740, 2004     

Study of electrical,mechanical, and nanoscale free‐volume properties of NBR and EPDM rubber reinforced by bentonite or kaolin

The effect of Na bentonite, Ca bentonite, and kaolin fillers on the macrostructure and microstructure of acrylonitrile butadiene rubber, ethylene propylene diene rubber, and their blend (50/50) was studied through electrical and mechanical measurements, as well as with positron annihilation lifetime spectroscopy. The real part of permittivity (ε′), dielectric loss (ε″), and the crosslinking density were found to increase with increasing filler content. The increase of crosslinking density of the blend with increasing amount of fillers reflects a decrease in the equilibrium swelling up to 21.50 wt % compared with that of the unfilled blends. The mechanical investigation showed pronounced increase in the tensile strength, and in elongation at break with the addition of up to 21.50 wt % of filler. In addition, comparing between different fillers showed that the reinforcing effect of Na bentonite is more effective than Ca bentonite and kaolin but the physico‐mechanical of Ca bentonite is less than that for kaolin. The positron annihilation lifetime measurements revealed that the free‐volume properties were strongly affected by the amount and type of filler, in particular, the free‐volume fraction was dramatically decreased with increasing filler content. Furthermore, correlations were made between the free‐volume parameters and both electrical and mechanical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1825–1838, 2009