Thermosets and composites were prepared from blends of epoxidized waste vegetable oils and diglycidylether of bisphenol-A to investigate this material as an alternative triglyceride source for oleochemistry. Purifications were developed to remove impurities derived from thermal degradation in the frying process and different epoxidation methodologies were investigated.Effects of epoxidized vegetable oil content (up to 30 wt %) and origin on the tensile properties were studied and revealed that purified waste oils performed similarly to neat oil in contents up to 10 wt %, proving that this strategy does not compromise tensile properties when waste oils are used in suitable proportions. Furthermore, a more prominent plasticizing effect was observed when more than 15 wt% of bio-based resin was used as confirmed by DMA.Composites were prepared with recycled carbon fibres (up to 30 wt %) and thermosets with 10 wt% of bio-based epoxy resins, significantly improving the mechanical properties.

Aiming to manufacture biomaterials using renewable resources, we prepared, using a corotating and intermeshing twinscrew extruder, high-density green polyethylene composites reinforced with 20, 30, and 40 wt % of bleached cellulose fibers. Injection molded test samples are characterized for mechanical and thermal properties using thermogravimetry (TGA) and differential scanning calorimetry (DSC). These composites present improved mechanical properties relative to the pure matrix; the elastic modulus increases by 240% for the composite with 30 wt % of fiber. We characterize this composite, additionally formulated with lignin and a secondary antioxidant, by tensile and flexural mechanical properties, DSC, TGA, and oxidation induction time (OIT). Lignin has no effect on the mechanical properties; however, for the composite, the OIT increases from 24 to 77 min, clearly evidencing its effect as a stabilizer. Aging the composites for 1000 h, in a QUV chamber, confirms the stabilizing effect of lignin.

We prepared polyamide-6 (PA-6) composites using bleached and semibleached cellulose fibers from Eucalyptus species by processing in a corotating interpenetrating twin-screw extruder. PA-6 is a challenging matrix because of its high processing temperature, which overlaps the thermodegradation temperature of the fibers. The selection of the processing conditions for extrusion and the use of the lubricant ethylene bis (stearamide) permitted the production of composites with 20, 30, and 40 wt% of bleached fibers, which are lighter than the corresponding glass fiber composites. Composites with 30 wt% of bleached fibers yield the best mechanical properties and good fiber/matrix interaction, as demonstrated by mechanical tests and scanning electron microscopy. X-ray photoelectron spectroscopy studies showed that the natural moisture in the fibers promotes the fiber/matrix interaction through the formation of ester bonds. We assessed the effect caused by the presence of lignin in the fibers. Composites containing 30 wt% of semibleached fibers maintained the flexural properties and showed small improvements in thermal stability when compared with bleached fiber composites; however, there is a slight decrease in the tensile properties. Through accelerated aging tests, we observed that increased lignin concentration in the fibers reduced the formation of carbonyl compounds on sample surfaces, indicating a stabilization effect. POLYM. COMPOS., 00:000-000, 2015.

Different classes of wastes, namely wooden wastes, plastic fractions from automotive shredded residues, and glass fiber reinforced composite wastes obtained from dismantled wind turbines blades were analyzed in view of their possible recycling. Wooden wastes included municipal bulky wastes, construction and demolition wastes, and furniture wastes. The applied characterization protocol, based on Fourier transform infrared (FTIR) spectroscopy in attenuated total reflection (ATR) mode, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX), and thermogravimetric analysis (TG) coupled with FTIR spectrometry for the investigation of the evolved gases, revealed that the selected classes of wastes are very complex and heterogeneous materials, containing different impurities that can represent serious obstacles toward their reuse/recycling. Critical parameters were analyzed and discussed, and recommendations were reported for a safe and sustainable recycling of these classes of materials.

Laminates were produced with epoxy resins from waste vegetable oil (WVO) intended for the manufacturing of environmentally-friendly alternatives for the composites industry. Post-use cooking oil appears a promising source of triglycerides for polymer manufacturing. Matrices cured with methylhexahydrophthalic anhydride (MHHPA) were reinforced with glass and flax fibres, creating a library of composites that were compared to analogues from virgin oil and benchmarked against commercial diglycidyl ether of bisphenol A (DGEBA). Glass fibre-reinforced composites presented Young's moduli similar to the benchmark but reduced tensile strength. Chemical pre-treatment of the flax fibre (NaOH and stearic acid) countered the limited tensile performance observed for materials with untreated flax; improvements were evidenced by DMA and SEM. Moreover, WVO-based resins greatly improved impact properties and reduced density with no effect on thermal stability. Therefore, WVO-based composites appear as more sustainable alternatives in applications demanding toughness, stiffness and lightweight over strength.

No abstract

AgradecimentosÀ Deus, força superior, que independente de credo, rege o conhecido e o desconhecido; Aos meus pais, Roberto e Denise, e minha avó, Maria de Lourdes, pelos sacrifícios diários que permitiram chegar até aqui e pelos exemplos de caráter; À Paula, por todas as alegrias compartilhadas nos bons momentos, assistência nos momentos difíceis dessa jornada, e por permitir construirmos sonhos juntos; À minha família, meus avôs Roberto e Elizabeth, todos meus tios e primos que, mesmo à distância, acreditaram em mim e me incentivaram a continuar em frente; Ao Prof. Marco-Aurelio, pelas oportunidades e orientação que engrandeceram meu conhecimento e servirão de inspiração para o futuro; Ao Atsushi, Miiaco e Carla por me acolherem como parte da família e me apoiarem em todos os momentos; Ao Renan, pelo companheirismo dentro e fora do laboratório, e por me ensinar tudo o que sei hoje sobre processamento;