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Um estudo comparativo envolvendo técnicas de análise por espectroscopia no infravermelho com transformada de Fourier (FTIR) de transmissão, reflexão e fotoacústica é apresentado com análise de poliamida-6. O potencial e as limitações destes métodos são investigados para analisar as alterações espectrométricas que ocorrem no interior e na superfície da poliamida-6, reciclada, e irradiada na presença de oxigênio, com feixe de elétrons de 1,5 MeV, na dose de 500 kGy. As técnicas mostram-se sensíveis para detectar pequenas mudanças de estruturas que ocorrem na poliamida-6 reciclada e irradiada. Os espectros sugerem formação de grupos --OH, HOC=O-, e -C=O, e mudanças estruturais relacionadas com grupos NH e -CN-C=O. Basicamente, as mesmas alterações espectrométricas são observadas com o uso das técnicas, sendo mais evidenciadas no interior das amostras pela espectroscopia-FTIR de transmissão, e na sua superfície, pela microscopia-FTIR.

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The development of blends made from matrices of synthetic biodegradable polymers, and natural additives, are considered less environmentally aggressive materials. This work aimed to study the effects of gamma radiation on the properties of the thermoplastic starch (TPS)/poly(butylene adipateco-terephthalate) (PBAT). In this work, blends of TPS/PBAT were prepared with glycerol, castor oil and TWEEN ® 80, which were prepared by extrusion and then subjected to the radiation process and characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results demonstrated increased thermal degradation for the F2 (composed by OM) and F3 (composed by OM and TWEEN ® 80) regarding F0 (composed by glycerol) e F1 (composed by glycerol and TWEEN ® 80) blends. A good blend component chemical interaction and partial miscibility for the blends F0 and F1 was observed and compared to the others. However, F2 and F3 blends did not present co-continuous phases; being that the XRD curve patterns were not altered by the gamma radiation. The tests performed demonstrated that the irradiated and non-irradiated samples did not have their properties significantly altered. Thus, it was concluded that it is feasible to replace castor oil with glycerol in TPS/PBAT blends.

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This paper presents a comparison of traditional thermal and chemical reduction methods with more recent ionizing radiation reduction via gamma rays and electron beams (e-beams). For GO, all synthesis protocols were adapted to increase production scale and are a contribution of this work. The typical Raman D-band of the GO was prominent (ID/IG ratio increased sixfold). When comparing the GO reduction techniques, dramatic differences in efficiency and GO particle characteristics were observed. Although thermal and chemical reduction are effective reduction methods, as shown through the use of FTIR spectroscopy and the C/O ratio from EDS chemical analysis, the thermal process renders great weight losses, whereas chemical processing may involve the use of hazardous chemical compounds. On the other hand, comparing the gamma rays and e-beam for 80 kGy, the Raman spectra and chemical analysis suggested that the e-beam caused a greater GO reduction: C/O ratio from EDS of 5.4 and 4.1, respectively. In addition to being fast and effective, ionizing radiation reduction processes allow easier control of the reduction degree by adjusting the radiation dose. When the dose increased from 40 to 80 kGy, the Raman spectra and EDS showed that the ID/IG and C/O ratios increased by 15 and 116%, respectively.

This study aimed to prepare blends of natural polymers of TPS with PBAT by reactive extrusion with irradiation process, using the plasticizers (castor oil and glycerol) to evaluate the thermal and chemical properties. The blends were submitted to the irradiation process using a Cobalt-60 source at a 25 kGy dose and then characterized by FTIR and DSC analysis. According to the results obtained in the FTIR tests, the blends did not undergo chemical changes during the irradiation process and, thus, maintained their properties. In the DSC tests, it was observed that the blends F2 (castor oil) and F3 (castor oil and TWEEN® 80) showed higher values of heat flow for degradation than the samples F0 (glycerol) and F1 (glycerol and TWEEN® 80), probably due to the chemical interaction of castor oil and its constituents. There was no thermal variation in the irradiation process between blends F0 and F1 or F2 and F3. It was concluded that it is feasible to replace castor oil with glycerol in TPS/PBAT blends, and the irradiation using a Cobalt-60 source, not changed the final properties analyzed.