Fingerprint analysis of FTIR spectra of polymers containing vinyl acetate

The analysis of materials using Fourier transform infrared (FTIR) spectroscopy has a unique area called the fingerprint region for each compound. However, this area is almost never discussed because of its complexity due to the large number of signals that appear in it. In this work, the fingerprint region analysis of the ethylene–vinyl acetate copolymer (EVA) with different percentages of vinyl acetate (VA) (18%, 28%, 40%) was performed. In comparison with other instrumental techniques, the crystallinity and structural arrangement of the EVA copolymers were determined simply and economically. The crystallinities for EVA18, EVA28 and EVA40 were 24.39%, 6.95% and1.03%, respectively. In terms of structural ordering, the number of linear chains of EVA copolymer decreases as the concentration of VA increases, which favors the reduction of degrees of freedom and the formation of hydrogen bonds.El análisis de los materiales por espectrometría infrarroja con transformada de Fourier (FTIR) poseen una zona llamada huella dactilar única para cada compuesto, sin embargo, esta zona casi nunca se discute por su complejidad debida al gran número de señales que en ella aparecen. En este trabajo se realizó el análisis de la huella dactilar del copolímero etileno-acetato de vinilo (EVA) con diferentes porcentajes de acetato de vinilo (VA) (18%, 28%, 40%). En comparación con otras técnicas instrumentales, la cristalinidad y el ordenamiento estructural de los copolímeros de EVA fueron determinados de forma sencilla y económica. La cristalinidad para el EVA18, EVA28 y EVA40 fueron 24.39%, 6.95% y 1.03%, respectivamente. En cuanto al ordenamiento estructural, la cantidad de cadenas lineales del copolímero EVA disminuye conforme aumenta la concentración de vinil acetato (VA), lo cual favorece la disminución de los grados de libertad y la formación de puentes de hidrógen

Esterificación del almidón de plátano macho (musa paradisiaca L.)

Hoy en día, el uso de polímeros a base de petróleo ha causado un gran problema de contaminación cuando son desechados al ambiente. Para reducir este problema, se han utilizado polímeros degradables de fuentes renovables como almidón, el cual es el principal carbohidrato de almacenamiento de energía natural. Sin embargo, los materiales a partir de solo almidón no tienen buenas propiedades fisicoquímicas comparadas con los materiales convencionales, debido a esto, el almidón en los últimos años ha sido modificado por diferentes métodos con la finalidad de mejorar sus características físicas y químicas. En este trabajo se realizó la esterificación química del almidón de plátano macho (musa paradisiaca L.) con carbonato de etileno. Esta modificación del almidón se realizó en un vial de vidrio de 10 ml previamente secado, en el cual se colocaron carbonato de etileno (EC, 1.5 g) y almidón (0.25-1.5 g). Posteriormente, el vial se colocó en un baño de aceite de silicón con agitación constante, a una temperatura de 130 °C y un tiempo de 24 h1. La caracterización química del producto obtenido por espectroscopia de infrarrojo demostró que hay una sobreposición de las señales de vibración en el intervalo de 900 a 1000 cm-1, entre el enlace C-O (que corresponde al almidón sin modificar) y C-O (almidón modificado). El análisis por resonancia magnética nuclear (1H, 13C CP/MAS) permitió comprobar la esterificación del almidón, elucidar la estructura del almidón modificado y proponer un posible mecanismo de reacción2. Además, por esta técnica se observo que la esterificación del almidón se realizó en el C6 obteniendo dos tipos de cadenas. Por lo tanto, se concluye que se realizó la esterificación del almidón con carbonato de etileno. El cual tendría un alto potencial de aplicación como material de retención de metales pesados (filtro)

Modified starch with bis(2-hydroxyethyl) terephthalate: synthesis, characterization and elaboration of films

Banana starch was modified with B bis(2-hydroxyethyl) terephthalate and its instrumental characterization allowed to propose a chemical structure. In the carbon 6 (C6) of the starch the modification reactionwas carried out. The morphology of starch changes due to its chemical modification. The modified starch showed a lower crystallinity and thermal stability, compared to the native starch favoring its film formation. The electrical conductivity of the modified starch films was 2.7 times higher than that for the native starch film. The aqueous hydrolysis of the modified starch films was carried out obtaining a degradation of 77% in a determined time. Modified starch films present different mechanical properties compared to native starch film. These results have high application potential to be used in PET degradation products.We are grateful to Concejo Nacional de Ciencia yTecnología (Conacyt), Instituto de Ciencia y Tecnología de Polímeros(ICTP), Universidad del Papaloapan campus Tuxtepec, MartínezOlguiín Aldo de Jesús, Martha Ferrer Guadalupe and Martha RocioValencia Estacio for their assistance on this article

Modification of banana starch (Musa paradisiaca L.) with polyethylene terephthalate: Virgin and bottle waste

Chemical modification of banana starch (Musa paradisiaca L.) with the degradation products of virgin and bottle waste of polyethylene terephthalate was carried out in situ. The modified starch was characterized by FTIR and NMR, which allowed proposing three chemical structures. SEM micrographs showed that the morphology of the modified starch granule is directly related with mass ratio of Starch/PET and type of PET used in the reaction. The crystallinity of the modified starch decreased up to 92.6% and 62.5% using bottle waste and virgin PET, respectively, according to XRD diffractograms. TGA analysis showed that the starch degradation temperature decreased by 12 ¿C. Modified starch films were elaborate and its electrical conductivity was found to be 2.9 times compared to that of native starch. The starch/PET film presented the highest value in the mechanical property of elongation at break compared to the starch-only film. The modified starch film was degraded above 80% by aqueous hydrolysis.We are grateful to Concejo Nacional de Ciencia y Tecnología (Con-acyt), Instituto de Ciencia y Tecnología de Polímeros (ICTP), Universidad del Papaloapan campus Tuxtepec, Martínez Olguin Aldo de Jesús, Martha Ferrer Guadalupe and Martha Rocio Valencia Estacio for their assistance on this article

Characterization of Starch from Jinicuil (<i>Inga jinicuil</i>) Seeds and Its Evaluation as Wall Material in Spray Drying

Jinicuil seed starch (JSS) was partially characterized and then evaluated as wall material. JSS showed higher content of proteins, lipids, and resistant starch than commercial corn starch (CCS). JSS granules presented both oval-spherical shapes and heterogeneous sizes (~1–40 µm) and exhibited a crystallinity lower than CCS with an A-type X-ray diffraction pattern. Both gelatinization peak and final viscosity values in the pasting profile were higher in JSS than in CCS. At 90 °C, the water solubility was 22% and the swelling power was 17 g g−1. Under refrigeration and freeze-thaw, the JSS gel showed high stability. JSS showed a significant presence of protein and small particles; therefore, it was evaluated as wall material in spray drying. The results showed the formation of spherical aggregates and encapsulation efficiencies of L-ascorbic acid of 14.97–81.84%, with process yields of 19.96–27.64%, under the conditions evaluated. JSS has a potential application in the food industry but also as wall material for microencapsulation by spray drying

Effect of oxidation and crosslinking on functional, rheological and thermal properties of oat and apple starches

Oat (Oa) and apple (Ap) starches were isolated and chemically modified by oxidation with 10% NaOCl to obtain oxidized starches (OOa and OAp), followed by cross-linking with a mixture of 5.6 g of sodium tripolyphosphate and 11 g of sodium trimetaphosphate to obtain doubly modified starches (OCOa and OCAp). In the native and modified starches, the functional properties (swelling power and solubility, and freeze-thaw stability) and thermal and rheological properties (steady-state flow curves and paste formation profile) were evaluated. The swelling power of native and double modified starches varied from 57 to 86 g/g and the solubility from 0.8 to 6.0 g/100 g, these variables increased as the study temperature increased; the increment in these properties was greater in Oa compared to Ap. Oxidation followed by crosslinking increased the freeze-thaw stability in Oa and Ap starches at 30, 60, 75, and 90 °C. It also increased the Tg of OCAp and OCOa ≈ 9% compared to the native samples, respectively; while an inverse pattern was observed in apparent viscosity were this value decreased ≈ 0.8 Pa × s for Oa and ≈ 0.5 Pa × s for Ap compared to the double modified samples. All samples presented a thinning cut-type behavior (pseudoplastic), indicating structural differences. Cross-linking in oxidized starches produced a reinforcing matrix that was determined in the paste formation profile. Dual modification (oxidation-cross-linking) could be an alternative for using starches from underused botanical sources, such as apples and oats, with different functional properties and feasible applications in food systems