Development and characterization of corn starch films by blending with more hydrophobic compounds

Tesis por compendio[EN] Different strategies were used to improve physical properties of corn starch based films, with glycerol (30%) as plasticizer, based on increasing their hydrophobic character in order to reduce the materials' water sensitivity. Starch was blended with different components (surfactants and more hydrophobic polymers), with and without compatibilizers, to obtain blend films through different processing techniques (casting, melt blending, compression molding and extrusion). Bilayer film formation by compression molding with starch and poly(e-caprolactone) (PCL) was also studied. The addition of surfactants to starch films obtained by casting gave rise to a decrease in water vapor permeability (WVP), but an increase in the film fragility was observed. Surfactants with lower hydrophilic-lipophilic balance (HLB), solid at room temperature, promoted a fine microstructure in the matrix with smaller lipid particle, which enhanced water vapor barrier properties. Thermo-processing was used to obtain the other films due to its broader industrial application. Starch blends with hydroxypropyl methylcellulose (HPMC) showed an HPMC dispersed phase in the starch matrix and better water barrier properties, but they were more permeable to oxygen, especially when they contained citric acid (CA) as compatibilizer. CA induced cross-linking in the polymeric matrix, thus slightly increasing film hardness, but decreasing its extensibility. The incorporation of PCL in different ratios to starch films obtained by compression molding gave rise to polymer phase separation, although a small PCL miscibility in the starch rich phase was detected, which reduced the glass transition temperature of the starch phase. The structural heterogeneity and lack of interfacial adhesion between polymers gave rise to fragile films. Nevertheless, small amounts of PCL (10%) reinforced the matrix (increase in the elastic modulus). When the PCL ratio increased, WVP was reduced but oxygen permeability increased. The incorporation of CA as compatibilizer of these blends provoked an increase in the water solubility of the films, by hydrolysis, and improved the mechanical properties of the films when PCL ratio was low (10%), but it did not affect the film barrier properties. The incorporation of polyethylene glycol (PEG 4000) to the blends with a low proportion of PCL did not imply an improvement in the film properties, since it promoted phase separation. Starch-PCL blends with 1:0.05 mass ratio, without compatibilizer, were quite homogenous and exhibited good mechanical properties and stability. In order to incorporate greater amounts of PCL, thus improving film hydrophobicity and stability, PCL was chemically modified by grafting glycidyl methacrylate or glycidyl methacrylate and maleic anhydride (PCL-g), to be used as compatibilizers. Films with 20 % PCL and 2.5 or 5 % of PCL-g showed very good mechanical and barrier properties and stability, inhibiting starch retrogradation. Their barrier properties met the food packaging requirements for a wide number of food products. Bilayer films obtained by compression molding of starch (or starch with 5% PCL) and PCL layers showed very low WVP and oxygen permeability and adequate mechanical properties. The adhesion of bilayers was greatly improved by the application of ascorbic acid and, especially, potassium sorbate, as aqueous solutions, at the interface before compression molding. These compounds, in turn, imparted antioxidant and antimicrobial properties, respectively, to the films, thus improving their potential use as active packaging material for food uses.[ES] Se han utilizado diversas estrategias para mejorar las propiedades físicas de films a base de almidón de maíz, con glicerol (30 %) como plastificante, basadas en el incremento de su carácter hidrofóbico, para reducir su sensibilidad al agua. El almidón se mezcló con diferentes compuestos (surfactantes y polímeros más hidrofóbicos), con y sin compatilizadores, para la obtención de films mixtos por diferentes técnicas de procesado (casting, mezclado en fundido, moldeo por compresión y extrusión). Se estudió también la formación de films bicapa almidón-poli-e-caprolactona (PCL) mediante moldeo por compresión. La adición de surfactantes a los films de almidón elaborados por casting dio lugar a una disminución de su permeabilidad al vapor de agua (WVP), pero aumentó su fragilidad. Los surfactantes con menor balance hidrófilo-lipófilo (HLB), y sólidos a temperatura ambiente, proporcionaron una microestructura de los films con menor tamaño de partícula, que potenció las propiedades barrera al vapor de agua. Por su mayor aplicabilidad industrial, se emplearon técnicas de termo-procesado para la obtención del resto de films estudiados. Los obtenidos por mezcla con hidroxipropil metilcelulosa (HPMC) presentaron una fase dispersa de HPMC en la matriz de almidón y mejores propiedades barrera al vapor de agua, pero fueron algo más permeables al oxígeno, sobre todo cuando se incorporó ácido cítrico (CA) como compatibilizador. Este provocó entrecruzamiento en la matriz polimérica, incrementado ligeramente su dureza y reduciendo su extensibilidad. La incorporación de PCL en diferentes proporciones a los films de almidón obtenidos por termo-compresión, dio lugar a la separación de fases polímericas, detectándose una pequeña miscibilidad de la PCL en la fase rica en almidón que redujo la temperatura de transición vítrea de la fase amilácea. La heterogeneidad de su estructura y la falta de adhesión entre fases dio lugar a films demasiado frágiles, aunque en pequeña proporción (10%), la PCL reforzó la matriz (aumentó el módulo de elasticidad). Al aumentar la proporción de PCL, disminuyó la WVP de los films, pero aumentó la permeabilidad al oxígeno. La incorporación de CA como compatibilizador de estas mezclas aumentó la solubilidad en agua de los films por efecto de hidrólisis y supuso una mejora en las propiedades mecánicas de los films con baja proporción de PCL (10 %), pero no afectó a sus propiedades barrera. La incorporación de polietilenglicol (PEG 4000) a las mezclas con baja proporción de PCL no mejoró las propiedades de los films, potenciando la separación de fases. Las mezclas almidón:PCL con proporción másica 1:0.05, sin compatibilizador, fueron bastante homogéneas y exhibieron buen comportamiento mecánico y estabilidad. Para incorporar una mayor proporción de PCL, y mejorar la hidrofobicidad y estabilidad de los films, se modificó la PCL por reacción con glicidil metacrilato o anhídrido maleico y glicidil metacrilato (PCL-g), para su uso como compatibilizadores. Los films con 20% de PCL y 2.5 y 5 % de los PCL-g presentaron muy buenas propiedades mecánicas y de barrera al vapor de agua y a los gases y buena estabilidad al inhibir la retrogradación del almidón. Sus propiedades de barrera cumplieron con los requisitos de envasado de un número importante de productos alimentarios. La obtención de films bicapa por termo-compresión a partir de almidón (o almidón con 5% PCL) y PCL proporcionó un material con muy baja permeabilidad al vapor de agua y al oxígeno y buenas propiedades mecánicas. La adhesión entre las capas mejoró en gran medida con la incorporación de ácido ascórbico, y sobre todo de sorbato potásico, en la interfase en forma de disolución acuosa antes de la termo-compresión. Estos compuestos impartieron, a su vez, propiedades antioxidantes y antimicrobianas, respectivamente, a los films, mejorando su uso potencial para el envasad[CA] S'han utilitzat diverses estratègies per a millorar les propietats físiques de films a base de midó de dacsa, amb glicerol (30 %) com plastificant, basades en l'increment del seu caràcter hidrofòbic, per a reduir la seua sensibilitat a l'aigüa. El midó es va mesclar amb diferents compostos (surfactants i polímers més hidrofòbics), amb i sense compatibilitzadors, per l'obtenció de films mixtos mitjançant diferents tècniques de processat (càsting, mesclat en fos, modelatge per compressió i extrusió). Es va estudiar també la formació de films bicapa midó-poli-e-caprolactona (PCL) mitjançant modelatge per compressió. L'addició de surfactants als films de midó elaborats per càsting va donar lloc a una disminució de la seua permeabilitat al vapor d'aigüa (WVP), però va augmentar la seua fragilitat. Els surfactants amb menor balanç hidròfil-lipòfil (HLB), i sòlids a temperatura ambient, varen proporcionar una microestructura dels films amb menor grandària de partícula, que varen potenciar les propietats barrera al vapor d'aigüa. Per la seua major aplicabilitat industrial, es van emprar tècniques de termo-processat per l'obtenció de la resta de films estudiats. Aquells obtinguts per mescla amb hidroxipropil-metilcellulosa (HPMC) varen presentar una fase dispersa de HPMC en la matriu de midó i millors propietats barrera al vapor d'aigüa, però varen ser un poc més permeables a l'oxigen, sobretot quan es va incorporar àcid cítric (CA) com compatibilitzador. Aquest va provocar entrecreuament en la matriu polimérica, incrementant lleugerament la seua duresa i reduïnt la seua extensibilitat. La incorporació de PCL en diferents proporcions als films de midó obtinguts per termo-compressió, va donar lloc a la separació de fases polimèriques, detectant-se una xicoteta miscibilitat de la PCL en la fase rica en midó que va reduir la temperatura de transició vítria de la fase amilàcea. L'heterogeneïtat de la seua estructura i la falta d'adhesió entre fases va donar lloc a films massa fràgils, encara que en xicoteta proporció (10%), la PCL va reforçar la matriu (augmentant el mòdul d'elasticitat). Al augmentar la proporció de PCL, va disminuir la WVP dels films, però va augmentar la permeabilitat a l'oxigen. La incorporació de CA com compatibilitzador d'aquestes mescles va augmentar la solubilitat en aigüa dels films per efecte d'hidròlisi i va suposar una millora en les propietats mecàniques dels films amb baixa proporció de PCL (10 %), però no va afectar les propietats barrera. La incorporació de polietilenglicol (PEG 4000) a les mescles amb baixa proporció de PCL no va millorar les propietats dels films, potenciant la separació de fases. Les mescles midó:PCL amb proporció màssica 1:0.05, sense compatibilitzador, varen ser prou homogènies i varen exhibir un bon comportament mecànic i una bona estabilitat. Per a incorporar una major proporció de PCL i millorar l'hidrofobicitat i estabilitat dels films, es va modificar la PCL per reacció amb glicidil metacrilat o anhídrid maleic i glicidil metacrilat (PCL-g), per al seu ús com compatibilitzadors. Els films amb 20% de PCL i 2.5 i 5 % dels PCL-g varen presentar molt bones propietats mecàniques i de barrera al vapor d'aigüa i als gasos i bona estabilitat al inhibir la retrogradació del midó. Les seues propietats de barrera varen complir amb els requisits d'envasament d'un nombre important de productes alimentaris. L'obtenció de films bicapa per termo-compressió a partir de midó (o midó amb 5% PCL) i PCL va proporcionar un material amb molt baixa permeabilitat al vapor d'aigüa i al oxigen i bones propietats mecàniques. L'adhesió entre les capes va millorar en gran mesura amb l'incorporació d'àcid ascòrbic, i sobretot de sorbat de potassi, en la interfase en forma de dissolució aquosa abans de la termocompressió. Aquestos compostos varen impartir, a la vegada, propietats antioxidants i antimicrobianes, respecOrtega Toro, R. (2015). DESARROLLO Y CARACTERIZACION DE PELÍCULAS DE ALMIDÓN DE MAÍZ POR MEZCLADO CON COMPUESTOS MÁS HIDROFÓBICOS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52521TESISCompendi

Efecto de la incorporación de tensoactivos en las propiedades físicas de films a base de almidón de maíz

[ES] El objetivo de este trabajo fue estudiar el efecto de la adición de tensoactivos sobre las propiedades mecánicas, ópticas y de barrera (al oxígeno y vapor de agua) de films a base de almidón de maíz y glicerol, para su posterior aplicación en el envasado de alimentos, con especial atención en el efecto de la estructura del film sobre dichas propiedades. Los tensoactivos adicionados fueron sorbitan-monopalmitato (Span 40), sorbitan-monoestearato (Span 60) y sorbitan-monooleato (Span 80). Por un lado se caracterizaron las dispersiones formadoras de films (pH, densidad, comportamiento reológico, potencial-¿, tamaño de partícula y ángulo de contacto) y por el otro los films aislados. Esta última caracterización se realizó a dos tiempos distintos en aras a evaluar el efecto de los tensoactivos sobre el envejecimiento de los films. Todos los tensoactivos redujeron la tensión superficial en comparación con la formulación control dando lugar a dispersiones con reducido tamaño de partícula y con un potencial zeta negativo significativamente mayor que la dispersión de almidón. El ángulo de contacto de las dispersiones varió en función de la superficie utilizada, siendo en PET donde se obtuvieron los menores valores. Los tensoactivos se integraron bien en la matriz de almidón aunque dieron lugar a films menos extensibles, menos resistentes y ligeramente más opacos. Las propiedades barrera al vapor de agua mejoraron en los films con Span 40 y Span 60 de acuerdo con el contenido de humedad. Sin embargo, no se observaron mejoras en sus propiedades barrera al oxígeno.[CA] L'objectiu d'aquest treball va ser estudiar l'efecte de l'addició de surfactants sobre les propietats mecàniques, òptiques i de barrera (a l'oxigen i vapor d'aigua) de films de midó de dacsa i glicerina, per a la seua posterior aplicació en l'envasament d'aliments, amb especial atenció en l'efecte de l'estructura del film sobre aquestes propietats. Els surfactants addicionats van ser Span 40, Span 60 i Span 80. D'una banda es van caracteritzar les 2 dispersions formadores de films (pH, densitat, comportament reològic, potencial-¿, grandària de partícula i angle de contacte) i per l'altre, els films aïllats. Aquesta última caracterització es va realitzar a dos temps diferents en llaures a avaluar l'efecte dels surfactants sobre l'envelliment dels films. Tots els surfactants van reduir la tensió superficial en comparació amb la formulació control, donant lloc a dispersions amb reduït grandària de partícula i amb un potencial zeta negatiu significativament major que la dispersió de midó. L'angle de contacte de les dispersions va variar en funció de la superfície utilitzada, sent en PET on es van obtenir els menors valors. Els surfactants es van integrar bé en la matriu de midó encara que van donar lloc a films menys extensibles, menys resistents i lleugerament més opacs. Les propietats barrera al vapor d'aigua van millorar en els films amb Span 40 i Span 60 d'acord amb el seu contingut en humitat. No obstant això, les films no tenen bones propietats de barrera a l'oxigen.[EN] The aim of this work was to study the effect of surfactants addition on mechanical, optical and barrier properties (oxygen and water vapor) of corn starch based films, for subsequent application in food packaging, with a focus on the effect of film structure on these properties. The surfactants used were sorbitan monopalmitate (Span 40), sorbitan monostearate (Span 60) and sorbitan monooleate (Span 80). The film forming dispersions were characterized (pH, density, rheology, ¿-potential, particle size and contact angle) and the obtained films were characterized. Films characterization was performed at two different times in order to evaluate the effect of surfactants on the films¿ ageing. All surfactants decreased the surface tension in comparison with the control formulation, giving rise to dispersions with small particle size and a negative zeta potential, significantly higher than the starch dispersion. The contact angle of the dispersions varied depending on the surface used; on PET the lowest values were obtained. The surfactants were well integrated in the starch matrix although the resultant films were less extensible, its tensile strength was slightly lower and these were more opaque. Span 40 and Span 60 improved the water vapor barrier properties in the films, in agreement with its moisture content. However, the films did not have good oxygen barrier properties.Ortega Toro, R. (2012). Efecto de la incorporación de tensoactivos en las propiedades físicas de films a base de almidón de maíz. http://hdl.handle.net/10251/29368.Archivo delegad

Theoretical–Experimental Study of the Action of Trace Amounts of Formaldehyde, Propionaldehyde, and Butyraldehyde as Inhibitors of the Ziegler–Natta Catalyst and the Synthesis of an Ethylene–Propylene Copolymer

The copolymer synthesis process can be affected by failures in the production process or by contaminating compounds such as ketones, thiols, and gases, among others. These impurities act as an inhibiting agent of the Ziegler–Natta (ZN) catalyst affecting its productivity and disturbing the polymerization reaction. In this work, the effect of formaldehyde, propionaldehyde,and butyraldehyde on the ZN catalyst and the way in which it affects the final properties of the ethylene-propylene copolymer is presented by analyzing 30 samples with different concentrations of the mentioned aldehydes along with three control samples. It was determined that the presence of formaldehyde 26 ppm, propionaldehyde 65.2 ppm, and butyraldehyde 181.2 ppm considerably affect the productivity levels of the ZN catalyst; this effect increases as the concentration of aldehydes is higher in the process; likewise, these impurities affect the properties of the final product, such as the fluidity index (MFI), thermogravimetric analysis (TGA), bending, tension, and impact, which leads to a polymer with low-quality standards and less resistance to breakage. The computational analysis showed that the complexes formed by formaldehyde, propionaldehyde, and butyraldehyde with the active center of the catalyst are more stable than those obtained by the ethylene-Ti and propylene-Ti complexes, presenting values of −40.5, −47.22, −47.5, −5.2 and −1.3 kcal mol−1 respectively

Isolation and characterisation of microcrystalline cellulose and cellulose nanocrystals from coffee husk and comparative study with rice husk

[EN] Cellulosic material from coffee husk has not been previously studied despite being a potential source of reinforcing agents for different applications. This material has been extracted and characterised from coffee husk, in parallel with previously studied rice husk. Samples have been analysed as to their ability to obtain cellulosic fibres and cellulose nanocrystals (CNC) by applying alkali and bleaching treatments and final sulphuric acid hydrolysis. Microstructural changes were analysed after treatments, and the size and aspect ratio of CNCs were determined. Crystallinity and thermal stability of both materials progressed in line with the enrichment in cellulosic compounds. The CNC aspect ratio was higher than 10, which confers good reinforcing properties. These were tested in thermoplastic starch films, whose elastic modulus increased by 186 and 121% when 1 wt% of CNCs from rice and coffee husks, respectively, was incorporated into the matrix. Coffee husk represents an interesting source of cellulosic reinforcing materials.The authors thank the Ministerio de Economia y Competitividad (Spain) for the financial support provided through Project AGL2016-76699-R. Authors also thank the Electron Microscopy Service of the UPV for their technical assistance.Collazo-Bigliardi, S.; Ortega-Toro, R.; Chiralt, A. (2018). Isolation and characterisation of microcrystalline cellulose and cellulose nanocrystals from coffee husk and comparative study with rice husk. Carbohydrate Polymers. 191:205-215. https://doi.org/10.1016/j.carbpol.2018.03.022S20521519

Dimethylformamide Impurities as Propylene Polymerization Inhibito

This research study examined how the use of dimethylformamide (DMF) as an inhibitor af fects the propylene polymerization process when using a Ziegler–Natta catalyst. Several experiments were carried out using TiCl4/MgCl2 as a catalyst, aluminum trialkyl as a cocatalyst, and different amounts of DMF. Then, we analyzed how DMF influences other aspects of the process, such as catalyst activity, molecular weight, and the number of branches in the polymer chains obtained, using experimental and computational methods. The results revealed that as the DMF/Ti ratio increases, the catalyst activity decreases. From a concentration of 5.11 ppm of DMF, a decrease in catalyst activity was observed, ranging from 45 TM/Kg to 44 TM/Kg. When the DMF concentration was increased to 40.23 ppm, the catalyst activity decreased to 43 TM/Kg, and with 75.32 ppm, it dropped even further to 39 TM/Kg. The highest concentration of DMF evaluated, 89.92 ppm, resulted in a catalyst productivity of 36.5 TM/Kg and lost productivity of 22%. In addition, significant changes in the polymer’s melt flow index (MFI) were noted as the DMF concentration increased. When 89.92 ppm of DMF was added, the MFI loss was 75%, indicating a higher flowability of the poly mer. In this study, it was found that dimethylformamide (DMF) exhibits a strong affinity for the titanium center of a Ziegler–Natta (ZN) catalyst, with an adsorption energy (Ead) of approximately −46.157 kcal/mol, indicating a robust interaction. This affinity is significantly higher compared to propylene, which has an Ead of approximately −5.2 kcal/mol. The study also revealed that the energy gap between the highest occupied molecular orbital (HOMO) of DMF and the lowest unoccupied molecular orbital (SOMO) of the Ziegler–Natta (ZN) catalyst is energetically favorable, with a value of approximately 0.311 eV.Universidad Tecnológica de Bolivar, Universidad de Cartagena, Universidad de la Cost

Parts per Million of Propanol and Arsine as Responsible for the Poisoning of the Propylene Polymerization Reactio

Polypropylene synthesis is a critical process in the plastics industry, where control of catalytic activity is essential to ensure the quality and performance of the final product. In this study, the effect of two inhibitors, propanol and arsine, on the properties of synthesized polypropylene was investigated. Experiments were conducted using a conventional catalyst to polymerize propylene, and different concentrations of propanol and arsine were incorporated into the process. The results revealed that the addition of propanol led to a significant decrease in the Melt Flow Index (MFI) of the resulting polypropylene. The reduction in the MFI was most notable at a concentration of 62.33 ppm propanol, suggesting that propanol acts as an effective inhibitor by slowing down the polymerization rate and thus reducing the fluidity of the molten polypropylene. On the other hand, introducing arsine as an inhibitor increased the MFI of polypropylene. The maximum increase in the MFI was observed at a concentration of 0.035 ppm arsine. This suggests that small amounts of arsine affect the MFI and Mw of the produced PP. Regarding the catalyst productivity, it was found that as the concentration of propanol in the sample increased (approximately seven ppm), there was a decrease in productivity from 45 TM/kg to 44 TM/kg. Starting from 10 ppm, productivity continued to decline, reaching its lowest point at 52 ppm, with only 35 MT/kg. In the case of arsine, changes in catalyst productivity were observed at lower concentrations than with propanol. Starting from about 0.006 ppm, productivity decreased, reaching 39 MT/kg at a concentration of 0.024 ppm and further decreasing to 36 TM/kg with 0.0036 ppm. Computational analysis supported the experimental findings, indicating that arsine adsorbs more stably to the catalyst with an energy of −60.8 Kcal/mol, compared to propanol (−46.17 Kcal/mol) and isobutyl (−33.13 Kcal/mol). Analyses of HOMO and LUMO orbitals, as well as reactivity descriptors, such as electronegativity, chemical potential, and nucleophilicity, shed light on the potential interactions and chemical reactions involving inhibitors. Generated maps of molecular electrostatic potential (MEP) illustrated the charge distribution within the studied molecules, further contributing to the understanding of their reactivity. The computational results supported the experimental findings and provided additional information on the molecular interactions between the inhibitors and the catalyst, shedding light on the possible modes of inhibition. Solubles in xylene values indicate that both propanol and arsine affect the polymer’s morphology, which may have significant implications for its properties and final applications

Determinación de parámetros cinéticos en la biosorción de Cromo (VI) en solución acuosa

The contamination of aquatic bodies by heavy metals is a growing environmental problem, making more critical the study and development of new technologies and materials that can be used for the removal of this type of pollutants. Thus, adsorption arises using residual materials as a sustainable alternative for the solution to this problem. In the present study, the use of plantain peels in the adsorption of Cr (VI) in a batchsystem is proposed, establishing the kinetics of the process at different temperature conditions, particle size and amount of adsorbent. The fit of the data was done using the theoretical models of pseudo-first-order,pseudo-second-order and Elovich. From the data, it is established that the pseudo-second-order and Elovich models show a better adjustment, so that the adsorption in the material occurs on two adsorption sites and that such process is related to chemical adsorption. The maximum adsorption capacity of Cr (VI) was found at a condition of 0.0306 g, 0.6775 mm and 55°C at a time of 420 min establishing the efficient use of plantain peels for the removal of the ion metallic in the studio.La contaminación de cuerpos acuáticos por metales pesados es un problema ambiental creciente haciendo cada vez más importante el estudio y desarrollo de nuevas tecnologías y materiales que puedan ser usados para la remoción de este tipo de contaminantes. Así surge la adsorción usando materiales residuales como una alternativa sostenible para la solución de esta problemática. En el presente estudio se propone el uso de las cáscaras de plátano en la adsorción de Cr (VI) en un sistema por lotes estableciendo la cinética del proceso a diferentes condiciones de temperatura, tamaño de partícula y cantidad de adsorbente. El ajuste de los datos fue hecho usando los modelos teóricos de pseudo-primer orden, pseudo-segundo orden y Elovich. De los datos se establece que son los modelos de pesudo-segundo orden y Elovich los que muestran un mejor ajuste determinado así que la adsorción en el material se da sobre dos sitios de adsorción y que tal proceso está relacionado con una adsorción química. La máxima capacidad de adsorción de Cr (VI) fue encontrada a una condición de 0.0306 g, 0.6775 mm y 55°C a un tiempo de 420 min estableciendo el uso eficiente de cáscaras de plátano para la remoción del ion metálico en estudio

Applying a Green Solvent with Microwave, Ultrasound, and Soxhlet Extraction Techniques to Quantify the Slip Additive Cis-1,3-docosenamide and Nine Oxidative Degradation Byproducts in Polypropylene Samples

Erucamide is used as an important slip agent for polymers. However, erucamide can degrade during processing and long-term storage, forming various oxidation products. These degra dation products can affect the recovery rates of erucamide. In this study, investigated different solid–liquid extraction methods (Soxhlet, microwave, and ultrasound) and used gas chromatography with mass spectrometry (GC-MS) to quantify erucamide and its degradation byproducts in polypropy lene (PP). A multivariable experiment was designed, and a mixed-effect approach was used to analyze the results. Various extraction variables were examined, such as temperature, time, solvents, and PP pretreatments. Using a mixed-effect model with a Kenward–Roger approximation, an R2 of the model of 97% and p values of 0.168, 0.000, and 0.000 were obtained for the technical, solvent, and type of PP pretreatment variables, respectively. The highest average recoveries of erucamide were found with the microwave technique and were 96.4% using dichloromethane, 94.57% using cyclohexane, and 93.05% using limonene. With ultrasound, recoveries ranged between 85 and 92% for dichloromethane and limonene. In addition, it was observed that the extraction method had better recovery results in ground PP than in films and in pellets. Nine oxidative degradation byproducts of erucamide were identified and semi-quantified by GC-MS. The reaction mechanisms for forming each byproduct were proposed. The byproducts that experienced a higher rate of degradation of erucamide were erucamide with a hydroxyl group at position one and 12-amino-6-12-oxo-dodecanoic acid, showing more prominent peaks using the Soxhlet method with cyclohexane and dichloromethane as solvents and polypropylene (PP) films as the type of material used.Universidad Tecnológica de Bolivar, Universidad de Cartagena, Universidad de la Cost

Active bilayer films of thermoplastic starch and polycaprolactone obtained by compression molding

Chapter 7 of the DOCTORAL THESIS "Development and characterization of corn starch films by blending with more hydrophobic compounds" by Rodrigo Ortega Toro https://riunet.upv.es/handle/10251/52521[EN] Bilayer films consisting of one layer of PCL with either one of thermoplastic starch (S) or one of thermo-plastic starch with 5% PCL (S95) were obtained by compression molding. Before compression, aqueoussolutions of ascorbic acid or potassium sorbate were sprayed onto the S or S95 layers in order to plas-ticize them and favor layer adhesion. S95 films formed bilayers with PCL with very good adhesion andgood mechanical performance, especially when potassium sorbate was added at the interface. All bilayersenhanced their barrier properties to water vapour (up to 96% compared to net starch films) and oxygen(up to 99% compared to PCL pure). Bilayers consisting of PCL and starch containing 5% PCL, with potas-sium sorbate at the interface, showed the best mechanical and barrier properties and interfacial adhesionwhile having active properties, associated with the antimicrobial action of potassium sorbate.The authors acknowledge the financial support from the Spanish Ministerio de Educacion y Ciencia throughout the project AGL2013-42989-R. Rodrigo Ortega-Toro thanks the Conselleria de Educacio de la Comunitat Valenciana for the Santiago Grisolia grant (GROSO-LIA 2012/001). Authors also thank to Electron Microscopy Service of the UPV for their technical assistance.Ortega-Toro, R.; Morey, I.; Talens Oliag, P.; Chiralt, A. (2015). Active bilayer films of thermoplastic starch and polycaprolactone obtained by compression molding. Carbohydrate Polymers. 127:282-290. https://doi.org/10.1016/j.carbpol.2015.03.080S28229012

Influence of citric acid on the properties and stability of starch-polycaprolactone based films

[EN] The influence of citric acid (CA) on structural and physicochemical properties of blend films based on corn starch and polycaprolactone (PCL) was studied. Films were obtained by melt blending of starch and PCL and compression molding. Phase separation of polymers observed by scanning electron microscope and atomic force microscope was reduced by CA incorporation. CA affected both starch and PCL crystallization as deduced from the X-ray diffraction patterns and values of melting enthalpy. Glass transition of starch was reduced by PCL incorporation, while this occurred to a greater extent in films containing CA. Obtained results point to enhanced interactions between PCL and starch chains in films with CA, although this only quantitatively benefits the film properties at a low PCL ratio. Compounding starch with small amounts of PCL, using glycerol and CA, can supply films with better functional properties than net starch films.The authors acknowledge the financial support from the Spanish Ministerio de Educacion y Ciencia throughout the projects AGL2010-20694 and AGL2013-42989-R. Rodrigo Ortega-Toro thanks the Conselleria de Educacio de la Comunitat Valenciana for the Santiago Grisolia grant. Authors also thank the Electron Microscopy Service of the UPV for their technical assistance.Ortega Toro, R.; Collazo-Bigliardi, S.; Talens Oliag, P.; Chiralt, A. (2015). Influence of citric acid on the properties and stability of starch-polycaprolactone based films. Journal of Applied Polymer Science. 133(2):1-16. doi:10.1002/app.42220S1161332Flieger, M., Kantorová, M., Prell, A., Řezanka, T., & Votruba, J. (2003). Biodegradable plastics from renewable sources. Folia Microbiologica, 48(1), 27-44. doi:10.1007/bf02931273GARCIA, M., PINOTTI, A., MARTINO, M., & ZARITZKY, N. (2004). 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