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Synthetic polymers often present increased life span, taking decades or even centuries to fully degrade in the environment. Due to the increasing demand for polymeric materials in the last decades, an overwhelming amount of waste materials are generated, creating a major pollution problem. The polymer composite industry consists of synthetic materials for matrices and reinforcements. Most of these are petroleum derivatives leading to major environmental issues. In this context, the use of renewable and biodegradable agro-based materials, such as lignocellulosic fibers, has recently increased. The lignocellulosic fiber reinforced polymer composites (LFRPC) are produced by the combination of the fibers with thermoset, thermoplastic or natural polymer matrices. Synthetic polymers are generally resistant to fungal and bacterial attack, however, vegetal fibers in the composite remains susceptible to biological degradation. Biodegradation is defined as the conversion of a material to CO2 or CH4 (under anaerobic conditions), H2O, trace inorganic products and biomass by microorganisms (bacteria, fungi, algae…). To ensure LFRPC structural stability over its service life, biodegradation mechanisms have to be properly accessed and understood. The present chapter brings an overview of the studies focusing on the biodegradability of LFRPC and the current standards/methods utilized to evaluate this property. Biodegradation can be translated as changes in the material physical properties (mass, mechanical, visual, etc.), the evolution of CO2/CH4 generated by microorganisms and the incorporation of carbon-14 labeled polymers into their biomass. Since environmental factors influence the microbial population and the activity of the different microorganisms, the symbiotic effect of abiotic degradation (weathering) combined with biotic degradation is also addressed.

Due to the environmental impact caused by incorrect disposal and the non-biodegradability of synthetic polymers, the packaging sector seeks renewable raw materials. An alternative is the utilization of natural renewable polymer, such as thermoplastic starch (TPS), mixed with synthetics. However, the chemical incompatibility between these two materials leads to the use of a compatibilizer agent. Even though the compatibilizer effect of carboxylic acid on TPS blends have been studied, the correlation between the carboxylic acid and the starch source has not been investigated yet. Thus, this study focuses on the effects of added carboxylic acids (myristic (C14) and stearic (C18) acid) and the starch sources (corn, cassava, and potato) on the properties and microstructure of blends with TPS/PP (70/30). The results suggested that the compatibilizer effect of acids depends on the starch source and the length of the acid chain, where cassava blends with C14 showed better results. Acid insertion increased tensile strength and deformation at break, but reduced the elastic modulus, indicating a plasticizer effect. This behavior was related to the formation of amylose and lipid complexes (endogenous or added) during heating. Torque reduction and Tg displacement were also observed for acid blends. The SEM images showed two different morphological dispersions and a non-gelatinization effect due to the acid insertion. Results suggested that acids act differently according to the starch source.

Thermoplastic starch (TPS) can be added to a synthetic polymer, including linear low-density polyethylene (LLDPE), as a low-cost renewable and biodegradable source, to reduce the PE content. Nevertheless, this mixture leads to a mechanical performance decrease due to the immiscibility between both polymers. The aim of this work was to investigate the effect of three different organic acids (3% phr): citric, capric, and palmitic on LLDPE/TPS blends, with a mass ratio of 70/30. The introduction of capric or palmitic acid strengthened TPS and LLDPE interfacial adhesion and improved the mechanical properties of the blends. The glass transition of the glycerol-rich phase (measured by DMA) occurs at higher temperatures for LLDPE/TPS/CITRIC blends, suggesting a plasticizer effect of this acid. It also could be seen by SEM, the images showed that improvements in the compatibility between the immiscible components were achieved by capric or palmitic acid incorporation. TPS’s incorporation had increased the water absorption because of its hydrophilic characteristic; however, acid incorporation reduced this property. In relation to colorimetric aspects, all blends had loss of brightness, but the ones with citric acid were darker, presenting higher color change than the blends with others acids.

In this work, polypropylene/thermoplastic starch (PP/TPS) blends were prepared as an alternative material to use in disposable packaging, reducing the negative polymeric environmental impact. Unfortunately, this material displays morphological characteristics typical of immiscible polymer blends and a compatibilizer agent is needed. Three different carboxyl acids: myristic (C14), palmitic (C16) and stearic acids (C18) were used as natural compatibilizer agent (NCA). The effects of NCA on the mechanical, physical, thermal and morphological properties of PP/TPS blends were investigated and compared against PP/TPS with and without PP-grafted maleic anhydride (PPgMA). When compared to PP/TPS, blends with C18, PPgMA and C14 presented an improvement of 25, 22 and 17% in tensile strength at break and of 180, 194 and 259% in elongation at break, respectively. The highest increase, 54%, in the impact strength was achieved with C14 incorporation. Improvements could be seen, through scanning electron microscopy (SEM) images, in the compatibility between the immiscible components by acids incorporation. These results showed that carboxylic acids, specifically C14, could be used as compatibilizer agent and could substitute PPgMA.

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 24-1, 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., This work was supported by grants from Fundação de Amparo a Pesquisa do Rio Grande do Sul (FAPERGS–ARD/2011) from CNPq (Brazilian Bureau of Science and Technology), and CTQ2009‐07568 from Spanish Ministerio de Ciencia e Innovación. The authors would like to thank Mr. Ramiro Martínez (Novozymes, Spain) for kindly supplying the enzymes used in this research. They also thank Ministerio de Ciencia e Innovación by a fellowship for C. Garcia‐Galan and CNPq–Brazil for a fellowship to J. L. R. Friedrich and FAPERGS–Brazil for a fellowship to A. B. Martins.

The synthesis of pineapple flavour (butyl butyrate) catalysed by lipase from Rhizomucor miehei has been optimized using central composite design and response surface methodology. Initially, the best butyric acid concentration in the mixture was defined and found that 1 m butyric acid presented the highest initial reaction rate. The reaction parameters substrate molar ratio, enzyme content, and initial added water were evaluated in the central composite design with the reaction conversion yield as the dependent variable. The optimal conditions for butyl butyrate synthesis were found to be substrate molar ratio of 3.6:1 butanol:butyric acid; enzyme content of 6.5% of substrate mass fraction; added water 0.0% of substrate mass fraction. Under these conditions, over 90% of conversion was obtained in 16 h of reaction. Enzyme reuse was tested performing a treatment before each batch by washing the enzyme system with n-hexane, or simply reusing the biocatalyst in a new fresh reaction. Direct enzyme reuse caused a rapid decrease on the enzyme activity, while washings with n-hexane allowed the enzyme to be reused for six cycles keeping around 75% of its original activity. Copyright © 2012 John Wiley & Sons, Ltd.

A new biocatalyst of lipase B from Candida antarctica (MCI-CALB) immobilized on styrene–divinylbenzene beads (MCI GEL CHP20P) was compared with the commercial Novozym 435 (immobilized lipase) in terms of their performances as biocatalysts for the esterification of acetic acid and n-butanol. The effects of experimental conditions on reaction rates differed for each biocatalyst, showing different optimal values for water content, temperature, and substrate molar ratio. MCI-CALB could be used at higher acid concentrations, up to 0.5 M, while Novozym 435 became inactivated at these acid concentrations. Although Novozym 435 exhibited 30% higher initial activity than MCI-CALB for the butyl acetate synthesis, the reaction course was much more linear using the new preparation, meaning that the MCI-CALB allows for higher productivities per cycle. Both preparations produced around 90% of yield conversions after only 2 h of reaction, using 10% (mass fraction) of enzyme. However, the main advantage of the new biocatalyst was the superior performance during reuse. While Novozym 435 was fully inactivated after only two batches, MCI-CALB could be reused for six consecutive cycles without any washings and keeping around 70% of its initial activity. It is proposed that this effect is due to the higher hydrophobicity of the new support, which does not retain water or acid in the enzyme environment. MCI-CALB has shown to be a very promising biocatalyst for the esterification of small-molecule acids and alcohols. © 2012 American Institute of Chemical Engineers Biotechnol. Prog.,, 2012

In this paper is described the optimization of the esterification reaction of butyl acetate synthesis catalyzed by Candida antarctica lipase B (Novozym 435). The reaction parameters temperature, substrate molar ratio, enzyme content, and added water, and their responses measured as conversion yields, were evaluated using central composite design and response surface methodology. The best acid concentration for the reaction without enzyme inactivation was determined to be 0.3 M. The optimal conditions for butyl acetate synthesis were found to be temperature of 40 degrees C; substrate molar ratio of 3:1 butanol:acetic acid; enzyme content of 7.5% of substrate wt.; added water 0.25% of substrate wt. Under these conditions, over 90% of conversion was obtained in 2.5 h. Enzyme reuse was tested performing three different treatments before each batch: washing the enzyme system with either n-hexane or water, or suspending the immobilized enzyme in water for 24 h. Direct enzyme reuse or washing with water produced a rapid decrease on enzyme activity, while washing with n-hexane allowed enzyme to be reused for 6 reactions cycles keeping around 70% of its activity. This fast and high yield of conversion represents a large improvement to previously reported results. (C) 2011 Elsevier Ltd. All rights reserved.

In this work, it is compared the performance of three commercial lipase preparations (Novozym 435, Lipozyme TL-IM, and Lipozyme RM-IM) in the synthesis of flavor esters obtained by esterification of acetic, propionic, and butyric acids using ethanol, isopropyl alcohol, butanol, or pentanol. A comprehensive comparison was performed verifying activities of these three enzyme preparations versus the different couples of substrates, checking the obtained yields. In general, the longer the acid chain, the higher the reaction yields. Novozym 435 was the most efficient enzyme in most cases, and only Lipozyme RM-IM offered better results than Novozym 435 in the production of ethyl butyrate. Reactions with butyric acid showed the highest conversion rates using all biocatalysts. Using optimal substrates, the reactions catalyzed by the three enzymes were optimized using the response surface methodology, and the catalytic performance of the biocatalysts in repeated batches was assessed. After optimization, yields higher than 90% were obtained for all three enzymes, but Lipozyme TL-IM needed four-times more biocatalyst content than the other two preparations. Novozym 435 kept over 80% of its activity when reused in 9 successive batches, whereas Lipozyme RM-IM can be reused 5 times and Lipozyme TL-IM only 3 times. In general, Novozym 435 showed to be more suitable for these reactions than the other two enzyme preparations., This work was supported by grants and scholarships (first and second authors) from FAPERGS (Fundação de Amparo a Pesquisa do Rio Grande do Sul process 11/0485-0 ARD/2011), CNPq (Brazilian Bureau of Science and Technology process 478169/2011-6 Universal 2011), and CTQ2009-07568 (Ministerio de Ciencia y Innovación, Spain).

The influence of low-frequency ultrasound (40 kHz) in the esterification reaction between acetic acid and butanol for flavor ester synthesis catalyzed by the commercial immobilized lipase B from Candida antarctica (Novozym 435) was evaluated. A central composite design and the response surface methodology were used to analyze the effects of the reaction parameters (temperature, substrate molar ratio, enzyme content and added water) and their response (yields of conversion in 2.5 h of reaction). The reaction was carried out using n-hexane as solvent. The optimal conditions for ultrasound-assisted butyl acetate synthesis were found to be: temperature of 46 °C; substrate molar ratio of 3.6:1 butanol:acetic acid; enzyme content of 7%; added water of 0.25%, conditions that are slightly different from those found using mechanical mixing. Over 94% of conversion was obtained in 2.5 h under these conditions. The optimal acid concentration for the reaction was determined to be 2.0 M, compared to 0.3 M without ultrasound treatment. Enzyme productivity was significantly improved to around 7.5-fold for each batch when comparing ultrasound and standard mechanical agitation. The biocatalyst could be directly reused for 14 reactions cycles keeping around 70% of its original activity, while activity was virtually zeroed in the third cycle using the standard mixing system. Thus, compared to the traditional mechanical agitation, ultrasound technology not only improves the process productivity, but also enhances enzyme recycling and stability in the presence of acetic acid, being a powerful tool to improve biocatalyst performance in this type of reaction., This work was supported by grants from Fundação de Amparo a Pesquisa do Rio Grande do Sul (FAPERGS – ARD/2011), from CNPq (Brazilian Bureau of Science and Technology), and CTQ2009-07568 from Spanish Ministerio de Ciencia e Innovación.

Two immobilized preparations from Thermomyces lanuginosus lipase (TLL) were compared in the synthesis of butyl butyrate. The commercial Lipozyme TL-IM, and TLL immobilized on styrene–divinylbenzene beads (MCI-TLL) were tested in the esterification reaction using n-hexane as solvent. The variables temperature (30–60 °C), substrate molar ratio (1:1 to 5:1), added water (0–1%), and biocatalyst content (3–40%) were evaluated in terms of initial reaction rate for each biocatalyst. SDS–PAGE analysis revealed that MCI-TLL had an immobilized enzymatic load twice as high as Lipozyme TL-IM, but with an activity 3-fold higher. MCI-TLL presented high initial reaction rates up to 1.0 M butyric acid, while Lipozyme TL-IM showed a decrease in its activity above 0.5 M. Moreover, MCI-TLL allowed a productivity of 14.5 mmol g−1 h−1, while Lipozyme TL-IM 3.2 mmol g−1 h−1, both by mass of biocatalyst., This work was supported by grants from FAPERGS – ARD/2011, from CNPq – Universal/2011, both from Brazil, and CTQ2009-07568 from Spanish Ministerio de Ciencia e Innovación. The authors wish to thank Mr. Ramiro Martínez (Novozymes, Spain) for kindly supplying the enzymes used in this research. We also thank Ministerio de Ciencia e Innovación (Spain) for a fellowship for C. Garcia-Galan, the PhD Program Fellowship-2008 from COLCIENCIAS (Colombia) for a fellowship for O. Barbosa, CNPq (Brazil) for a fellowship to J. L. R. Friedrich, and FAPERGS (Brazil) for a fellowship to A. B. Martins.