Andréa Bercini Martins

Wood flour composites main applications are represented by outdoor furnishing. Therefore, it is important to evaluate their behavior under natural ageing conditions. This work aims to investigate the natural ageing impact on the mechanical, physical, thermal e morphological properties of recycled polypropylene/ethylene vinyl acetate/wood flour composites (PP/EVA/ITA). Samples were exposed to natural ageing for 12 months in Porto Alegre (BR). Mezilaurus itauba (ITA) wood flour was used at 30 % w/w. Results showed that PP filled wood flour retained a higher fraction of the original mechanical properties after natural ageing. Crystallinity degree for composites increased from 30.9 up to 37.5% Climatic conditions affected the colorimetric and morphological characteristics of composites, indicating that there was not only photo-degradation but also thermo-oxidative and hydrolytic degradation. In this way, the use of antioxidant additives and UV photo-absorbers is recommended to avoid stress-cracking, discoloration and loss the mechanical properties.

Butyl butyrate is an ester present in pineapple flavor, which is very important for the food and beverages industries. In this work, the optimization of the reaction of butyl butyrate synthesis catalyzed by the immobilized lipase Lipozyme TL‐IM was performed. n‐Hexane was selected as the most appropriate solvent. Other reaction parameters such as temperature, substrate molar ratio, biocatalyst content and added water, and their responses measured as yield, were evaluated using a fractional factorial design, followed by a central composite design (CCD) and response surface methodology. In the fractional design 2^4–1, the four variables were tested and temperature and biocatalyst content were statistically significant and then used for optimization on CCD. The optimal conditions for butyl butyrate synthesis were found to be 48°C; substrate molar ratio 3:1 (butanol:butyric acid); biocatalyst content of 40% of acid mass. Under these conditions, over 90% of yield was obtained in 2 h. Enzyme reuse was tested by washing the biocatalyst with n‐hexane or by direct reuse. The direct reuse produced a rapid decrease on enzyme activity, while washing with n‐hexane allowed reusing the enzyme for five reactions cycles keeping approximately 85% of its activity. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1416–1421, 2013