Elizabeth da Costa Mattos

Determination of the HMX and RDX content in synthesized energetic material by HPLC, FT-MIR, and FT-NIR spectroscopies

A new method has been developed for determining the content of mixtures of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), the HMX/RDX ratio, in explosive compositions by Fourier transform infrared spectroscopy (FT-IR), in the regions MIR (mid infrared) and NIR (near infrared) with reference values obtained by chromatographic analysis (HPLC). Plots of relative MIR (A917 / A783) or NIR absorbance values (A4412 / A4317) versus HMX/RDX ratio determined by HPLC analysis revealed good linear relationships.

Aplicação de metodologias FTIR de transmissão e fotoacústica à caracterização de materiais altamente energéticos: parte II

Materials obtained during the synthesis of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were characterized by Fourier transform infrared (FTIR) transmission spectroscopy and/or Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS). By these techniques the spectrometric alterations that occurred during the process were observed. The characterized species during the synthesis of HMX were a-HMX, b-HMX, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and HMX/RDX mixtures. The FTIR-PAS was verified to be a promising technique of great usefulness of the characterization of highly energetic materials because it is fast, simple and requires no sample preparation unlike Fourier transform infrared transmission technique (KBr pellet). The FTIR-PAS analysis showed that with small sample quantity is possible to distinguish between thea-HMX and b-HMX and to detect even in a qualitative way different HMX / RDX ratios.

Aplicação da calorimetria exploratória diferencial no estudo da cinética de transição alfa -> delta HMX

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) or octogen is a white crystalline substance which occurs in four polymorphous forms. It is used in a wide variety of military and industrial formulations owing to its suitable properties. Researchers have demonstrated the usefulness of this energetic material in explosive components. In the present work we apply differential scanning calorimetry (DSC) to measure the a ® d solid-solid phase transition energy of HMX. The results obtained by Kissingers and Ozawas methods were 487 and 495 kJ/mol, respectively.

Determinação por FT-IR de transmissão e reflexão (UATR) de etileno e propileno em EPDM

Resumo: Foi desenvolvida uma metodologia para a determinacao dos teores de etileno (ET) e propileno (P) em amostras de borracha (elastomero puro, crua e vulcanizada), a base do copolimero de etileno-propileno-dieno monomero (EPDM), por espectroscopia no infravermelho com transformada de Fourier (FT-IR) de reflexao total atenuada universal (UATR) e de transmissao, sendo as amostras analisadas tal como recebidas ou apos pirolise, respectivamente. Embora ambas as tecnicas tenham apresentado boa precisao, com a analise UATR sendo mais adequada para o elastomero puro, a realizada por transmissao/pirolise mostrou-se mais adequada a analise de todos os tipos de EPDM (elastomero puro, crua e vulcanizada), podendo ser usada para formulacoes similares. Palavras-chave: EPDM, etileno, propileno, FT-IR, UATR, transmissao, pirolise, quantificacao. Determination of Ethylene and Propylene Content in EPDM by Transmission and Reflection FT-IR (UATR) Techniques

Avaliação do uso de técnicas FT-IR para caracterização de cobertura polimérica de material energético

Tecnicas FT-IR de transmissao, reflexao e fotoacustica (PAS) foram utilizadas para a caracterizacao da cobertura polimerica do hexahidro-1,3,5-trinitro-1,3,5-triazina (RDX) usando um poliuretano (Estane). Verificou-se no decorrer deste trabalho que, embora seja possivel observar as bandas do polimero por meio das diferentes tecnicas, as de transmissao (filme vazado) e fotoacustica foram aquelas que melhor evidenciaram as absorcoes do poliuretano na amostra analisada da cobertura polimerica do material energetico. Entre as tecnicas consideradas de analise de superficie, a espectroscopia PAS apresentou melhor resultado, provavelmente em funcao da espessura de poucos micra da camada polimerica.

Determinação do teor de ENB em EPDM (elastômero puro) por FT-IR de transmissão, por meio de banda relativa

A methodology was developed for determining the 5-ethylidene-2-norbornene (ENB) content in unvulcanized (pure elastomer) ethylene-propylene-diene (EPDM) elastomer, by transmission Fourier Transform infrared spectroscopy (FT-IR), after pyrolysis with and without temperature (T) control. Although both techniques have shown good accuracy, the pyrolysis without T control technique, with relative bands and concentrations, was more suitable for the ENB content determination and for the complementary calculations of ET and P.