The nitration of polystyrene

Philippides, Aristides; Budd, Peter M.; Price, Colin; Cuncliffe, Anthony V.

doi:10.1016/0032-3861(93)90483-q

Cited by 25 publications

(15 citation statements)

References 3 publications

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“…On the other hand, the concentrated nitric acid can also react with the polymer carbon backbone by two pathways: (i) nitration and (ii) oxidation. Nitration of styrene polymers with HNO 3 is a well known process 25,26 and probably takes place at the aromatic ring according to equation 3:These -NO 2 groups have been clearly identified by IR spectroscopic analyses and TPD-MS experiments, which are in agreement with the increase in the N content observed in the elemental analyses. The polymer can also be oxidized by HNO 3 to produce oxygenated groups such as -OH and -COOH, as detected by IR and NMR spectroscopies and TPD-MS experiments.…”

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confidence: 73%

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Devulcanization of styrenebutadiene (SBR) waste tire by controlled oxidation

Rios

Gontijo

Ferraz

et al. 2006

J. Braz. Chem. Soc.

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Neste trabalho é descrita a desvulcanização da borracha SBR (Styrene Butadiene Rubber) via oxidação controlada com ácido nítrico. Análises por IV, RMN de 1 H e 13 C, CHN, TG, GPC e experimentos de DTP-EM (Decomposição a Temperatura Programada -Espectrometria de Massas) sugerem que o ácido nítrico promove dois processos: (i) a desvulcanização por oxidação das pontes de enxofre e (ii) a oxidação da cadeia carbônica levando à formação de grupos -COOH e -NO 2 . Em condições mais drásticas de reação, a cadeia polimérica é fortemente oxidada e se fragmenta formando uma fração altamente oxigenada, de baixo peso molecular e solúvel em água.This work describes the devulcanization of vulcanized SBR (Styrene Butadiene Rubber) based on controlled oxidation with nitric acid. IR, 1 H and 13 C-NMR, CHN elemental analyses, TG, GPC and TPD-MS (Temperature Programmed Decomposition-Mass Spectrometry) experiments suggest that nitric acid promotes two processes: (i) devulcanization by oxidation of the sulfide crosslinks and (ii) oxidation of the carbon framework leading to the formation of -COOH and -NO 2 groups. Under aggressive conditions (HNO 3, reflux) the polymer chain is strongly oxidized and fragmented to a highly oxygenated low molecular weight fraction, which is soluble in water. Keywords: devulcanization, HNO 3 , oxidation IntroductionThe disposal and reuse of waste tires remain not only a serious environmental concern but also an economical issue. Several alternatives, such as direct uses of scrap tires, combustion to produce energy, pyrolysis to produce fuels, the use of crumbles to asphalt roads and devulcanization to recycle the polymer have been extensively investigated in the last decades. Different chemical, physical and biological processes for the devulcanization of vulcanized rubber have been reported in the literature. 1 For the chemical devulcanization processes an extensive variety of agents such as: sulphides, e.g. diphenyl-disulphides, mercaptans, thiophenol, phosphorus compounds, e.g. triphenylphosphine and dibutylphosphite have been used. 2-13 Also, some reducing compounds have been studied for the devulcanization process, such as lithium aluminum hydride, 14 phenyl lithium, 15 CuCl/Bu 3 N, 16 alkaline metals (e.g. Na o ) and FeCl 2 / hydrazine. 17 On the other hand, oxidative processes for the devulcanization have been scarcely investigated. One example is the use of CHCl 3 /O 3 /H 2 O 2 , which showed low efficiency and high cost. 18 Nitric acid, HNO 3 , is a strong oxidizing agent which is well known to react with all types of sulfur groups, 19 offering the possibility to devulcanize rubber by oxidizing the sulfide crosslinks. The corrosion effect of nitric acid on rubber surface has been observed in 1985 by scanning electron microscopy. 20 Also HNO 3 and 30% H 2 O 2 have been used for the modification of the surface properties of rubber powder used as filler. 21 However, the use of the controlled oxidation with HNO 3 to devulcanize vulcanized rubbers has not yet been studied.In this work a detailed inv...

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confidence: 73%

Section: Reaction Mechanismmentioning

confidence: 99%

Devulcanization of styrenebutadiene (SBR) waste tire by controlled oxidation

Rios

Gontijo

Ferraz

et al. 2006

J. Braz. Chem. Soc.

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“…The cohesive energy density, which indicates the agglomeration characteristics of the polymer chain, of the synthesized DNDA_DEG prepolymer, was high due to the presence of the energetic nitramine group and which was also reflected by its higher T g than that of the SS-207 [30][31][32]. Furthermore, the formation of an amorphous polymer was confirmed by the lack of the change in the direction of the heat flow up to 100 • C. Prepolymer chemical structures that we use are shown in Figure 6 and detailed DSC thermograms are shown in Figures 7-9.…”

Section: Thermogravimetric Analysis Of Monomer and Prepolymermentioning

confidence: 98%

Nitramine-Group-Containing Energetic Prepolymer: Synthesis, and Its Properties as a Binder for Propellant

et al. 2019

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A composite solid propellant which generates high propulsive force in a short time is typically composed of an oxidizer, a metal fuel powder and a binder. Among these, the binder is an important component. The binder maintains the mechanical properties of propellant grains and endures several thermal and mechanical stresses in the engine. Several studies have been reported for the development of energetic propellant binders for increasing the propellant′s propulsive force. While several materials have been studied for the synthesis of energetic prepolymers, a nitramine-group-containing prepolymer is a suitable candidate because these types of prepolymers are less toxic and more cost-effective when compared to the traditional glycidyl azide polymers (GAP) and triazole-based prepolymers. Considering the lack of studies for the binder using a nitramine-group-containing prepolymers, we synthesized a nitramine-group-containing monomer and polymerized a nitramine-group-containing prepolymer. The prepolymer was then used for the preparation of the binder and its thermal and mechanical properties, as well as the effect of the plasticizer, were studied. The binder that was prepared using the prepolymer containing a nitramine-group showed very high elongation, tensile strength. Nitrate-ester (NE)-type plasticizer could reduce the glassy transition temperature (Tg)of the binder successfully. Also, high-energy is released due to the decomposition of the nitramine-group at around 245 °C, thus exhibiting the efficiency of the nitramine-group-containing prepolymer as an excellent energetic binder material.

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“…The wt.% of Br in sample 3 h was found equal to the calculated wt% of monobrominated PEEK, while in sample 9 h it was found to be close to the calculated wt.% of dibrominated PEEK that is about 37% ( Table 2). The wt% was correlated with degree of substitution (DS) by using [12,13].…”

Section: Characterization Of Brominated Peek (Br-peek)mentioning

confidence: 99%

Modification of Poly(ether ether ketone) Polymer for Fuel Cell Application

Shukla

Negi

Kumar

2013

Journal of Applied Chemistry

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Polyelectrolyte membrane (PEM) is an important part of PEM fuel cell. Nafion is a commercially known membrane which gives the satisfactory result in PEM fuel cell operating at low temperature. Present research paper includes functionalization of Poly(ether ether ketone) (PEEK) polymer with phosphonic acid group. The functionalization was done with the help of nickel-based catalyst. Further, the polymer was characterized by the FTIR, EDAX, DSC, TGA, and 1H NMR, and it was found that PEEK polymer was functionalized with phosphonic acid group with good thermal stability in comparison to virgin PEEK. Finally, the thin films of functionalized polymer were prepared by solution casting method, and proton conductivity of film samples was measured by impedance spectra whose value was found satisfactory with good thermal stability in comparison to commercially available Nafion membrane.

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The nitration of polystyrene

Cited by 25 publications

References 3 publications

Devulcanization of styrenebutadiene (SBR) waste tire by controlled oxidation

Devulcanization of styrenebutadiene (SBR) waste tire by controlled oxidation

Nitramine-Group-Containing Energetic Prepolymer: Synthesis, and Its Properties as a Binder for Propellant

Modification of Poly(ether ether ketone) Polymer for Fuel Cell Application

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