Interactions with water of mixed acetic-fatty cellulose esters

Cellulose powder was acylated with mixtures containing acetic, fatty and acetic-fatty anhydrides to form acetic-fatty cellulose esters. The total degree of substitution (DS) of the mixed cellulose esters (MCE) ranged from 2x10-2 to 2.92. MCE were characterized by their interactions with water. Static contact angles with water were measured on a regular smooth surface. The values found were dependent on the fatty acyl content and independent of the acetyl content. In the case of acetic-oleic cellulose esters, the minimum DS of the oleoyl moiety required to obtain permanent water repellency was 3x10-4. The microporosity of the samples may account for this exceptional hydrophobic character. Nevertheless, water vapor adsorption measurements on powder samples revealed only a limited increase in hydrophobicity of the MCE compared to cellulose acetate with the same acetyl content. It was thus demonstrated that water repellency and vapor water adsorption are not correlated

Determination of the degree of substitution (DS) of mixed cellulose esters by elemental analysis

Equations for transforming the results of elemental analysis (EA) into degree of substitution (DS) values for aliphatic cellulose esters were developed. The equations allow to determine the DS of cellulose derivatives bearing not only one but also two different acyl substituents. Error transmission studies revealed that the accuracy of the DS-values for a pure sample depends on both the number of carbon atoms in the substituents and on the uncertainty of the EA, especially from the hydrogen content. This method provides accurate DS-values (± 0.10 in most cases) if H-content determinations are within ± 0.1

Bi-acylation of cellulose: determining the relative reactivities of the acetyl and fatty-acyl moieties

The global reaction between acetic anhydride and a fatty acid yields, at equilibrium, an asymmetric acetic-aliphatic anhydride in a medium containing finally: acetic-fatty anhydride, acetic anhydride, fatty acid, acetic acid and fatty anhydride. No solvent or catalyst was used to evaluate the impact of the actual reactivity of the anhydrides. The competition between the formation of acetyl and fatty acyl ester functions was evaluated by determining the ratio of acetyl/fatty acyl groups grafted on solid cellulose. The influence of temperature, reaction time, and length of fatty chain on the total degree of substitution and on the ratio of acetyl/fatty acyl ester functions was investigated. For the first time, a correlation has been established between esterification and the length of the aliphatic chain of the fatty acid. Reactivity of the medium decreased with the number of carbons in the fatty acid, raised to the power 2.37

Industrial microalgae: do not shoot ahead!

Industrial microalgae: do not shoot ahead

Post-harvest tomato plants and urban food wastes for manufacturing plastic films

Poly(vinyl alcohol-co-ethylene) was compounded with 2-10% post-harvest tomato (PHT) plant powder and processed by single-screw extrusion to yield composite films. Upon increasing the filler content, the values of the mechanical properties indicators were found to decrease as follows: Young's modulus from 1797 to 750 MPa, stress at yield from 36 to 15 MPa, maximal stress from 39 to 15 MPa, stress at break from 35 to 14 MPa, and strain at break from 6.6 to 4.3%. The results are discussed in comparison with other composite films containing poly(vinyl alcohol-co-ethylene) and water soluble biopolymers obtained by alkaline hydrolysis of fermented municipal biowastes, and with other commercial materials, such as starch based and low density polyethylene mulch films. Depending on the intended application, the post-harvest tomato blend films may be competitive for cost, performance and sustainability

Caracterización de eventos negativos que se presentan en la cría y el levante de la codorniz (coturnix coturnix japónica) en sus primeros 45 días de vida en Granada y Villavicencio Meta.

Con el propósito de identificar los eventos negativos que se presentan en la etapa de levante de la codorniz raza coturnix coturnix japónica se desarrolló una investigación en Villavicencio y Granada Meta; para lo cual se evaluaron 400 hembras de 1 día de edad durante 4 periodos comprendidos en 180 días, el experimento se llevó a cabo en dos fincas ubicadas en Granada y Villavicencio allí se levantaron por un periodo de 45 días 100 cotupollos, finalizado este periodo se criaron 100 más hasta completar los 4 ensayos, se replicó la misma cantidad en cada uno de los cuatro periodo de crianza se evaluaron parámetros adversos que se presentaran durante el crecimiento, alimentación, desarrollo morfológico, densidad de población, manejo, Instalaciones y equipos que de una forma u otra incidiera negativamente en el desarrollo y evolución de las aves. Para profundizar en el tema se desarrolló y aplico una encuesta a criadores presentes en la zona de estudio, dicha encuesta se basó en preguntas que permitieran identificar información sobre aspectos relevantes que influyen en la crianza de las aves. La información obtenida se evaluó identificando los aspectos adversos que se presentan en esta importante etapa y la medida como se deben prevenir, controlar o mitigar para reducir su ocurrencia.In order to identify adverse events that occur in the stage race up quail coturnix coturnix japonica research was undertaken in Villavicencio and Granada Meta , for which 400 females were evaluated 1 day of age during a period of 180 days , the experiment was carried out in two farms located in Granada and Villavicencio there arose for a period of 45 days 100 cotupollos , ended the period grew another 100 , the same amount was replicated in Villavicencio , in each of the four breeding period adverse parameters were evaluated to be presented during the growth, feeding , morphological development , population density , management, facilities and equipment or in some way negatively incidiera development and evolution of birds . To deepen the theme was developed and applied a survey to breeders present in the study area , the survey was based on questions that identify relevant information on aspects that influence breeding birds. The information obtained was evaluated by identifying the adverse aspects presented in this important stage and measured as must prevent, control or mitigate to reduce their occurrence

Long chain cellulose esters with very low DS obtained with non-acidic catalysts

Long-chain cellulose esters with very low degree of substitution (DS<0.3), useful for specialty applications, were obtained by reaction with fatty acids (FAs) without solvent for cellulose. Non-acidic catalysts such as FA salts were used to limit the cellulose degradation when subjected to reaction at high temperatures. The surfactant character of this type of molecules was employed to create an emulsion with FA and water to favor the contact of hydrophobic FA and hydrophilic cellulose. Response surface methodology was used as a statistical optimization method to find the best proportions of octanoic acid, potassium laurate and water. A highly hydrophobic product with retention of fibrous structure was thus obtained. The reactions with higher saturated FAs (C10–C18) yielded lower DS values but still comparable hydrophobicity

Green composites of organic materials and recycled post-consumer polyethylene

International audienceAddition of organic fillers to post‐consumer recycled plastics can give rise to several advantages. First of all, the cost of these fillers is usually very low, the organic fillers are biodegradable contributing to an improved environmental impact and, last but not least, some mechanical and thermomechanical properties can be enhanced. Organic fillers are not widely used in the plastic industry although their use is increasing. Bad dispersion into the polymer matrix at high‐level content and poor adhesion with the matrix are the more important obstacles to this approach. In this work various organic fillers have been used with a post‐consumer plastic material originating from films for greenhouses. The properties of these green composites have been compared with those of materials filled with a conventional inorganic filler. The organic fillers cause slightly worse processability, due to an increase of viscosity, an enhancement of the rigidity and of the thermomechanical resistance similar to that measured for the inorganic filler, while a reduction of the impact strength is observed. Copyright © 2004 Society of Chemical Industry

Assessment of sustainability for the bioprocesses: Does it (really) follow life cycle thinking?

In the wake of eco‐design methodology development, the time has come to propose a sustainable process design that integrates not only environmental evaluation but also economic and social issues. All strategic decisions should respect the principles of sustainability. The environmental, economic, and social assessment of engineering choices is thus necessary and the agro‐industry is not exempt. Design or re‐design of any product relies on the choice of processes, which naturally leads to the development of an integrated product‐process approach to agro‐industrial processes