Properties and Biodegradability of Thermoplastic Starch Obtained from Granular Starches Grafted with Polycaprolactone

Granular starches grafted with polycaprolactone (St-g-PCL) were obtained using N-methylimidazole (NMI) as a catalyst. The effect of the starch/monomer ratio and catalyst content was studied to obtain different levels of grafted PCL. The highest grafting percentage (76%) and addition (43%) were achieved for reactions with a starch/monomer ratio of 50/50 and 25% catalyst. The grafting of PCL on the starch granule was verified by the emergence of the carbonyl group in the FTIR spectra and the increased diameter of the grafted starch granule. Thermoplastic starch from ungrafted starch (TPS) and grafted starch (TPGS) was obtained by mixing ungrafted or grafted starch granules with water, glycerol, or sorbitol in a mixer. TPS and TPGS behave as plastic materials, and their mechanical properties depend on the type of plasticizer used. Materials with glycerol as the plasticizer exhibited less rigidity. The presence of starch-g-PCL results in a dramatic increase in the elongation of the thermoplastic material. The starch present in the TPS or TPGS was completely biodegraded while the grafted PCL was partially biodegraded after the enzymatic degradation of the materials

Obtención de Celulosa a Partir de los Desechos Agrícolas del Banano

En este trabajo, se presenta un estudio sobre la factibilidad de obtención de celulosa a partir de residuos agrícolas del banano (pseudotallo y pinzote), usando un procedimiento desarrollado en el Centro de Investigación Científica de Yucatán-México. El proceso consiste en cuatro etapas: hidrólisis ácida, cloración, extracción alcalina y blanqueo. La celulosa se caracterizó mediante termogravimetría, espectroscopía de FTIR y determinación de peso molecular. Se obtuvieron mejores rendimientos con las fibras de pinzote. La celulosa obtenida del pseudotallo presentó aglomeración de fibras debido a residuos de lignina y hemicelulosa. La etapa de cloración afecta el peso molecular de la celulosa obtenida de las fibras de pinzote, obteniéndose pesos moleculares de 90.000 y de 49.000 cuando se usó un pH de 9.2 y 8.4 en la etapa de cloración, respectivamente. Se obtuvieron espectros de FTIR característicos de celulosa, con lo que se comprobó la factibilidad de usar este proceso para eliminar el material no-celulósic

Thermo-mechanical properties of epoxidized hemp oil-based bioresins and biocomposites

Novel epoxidized hemp oil-based biocomposites containing jute fibre reinforcement were produced at the Centre of Excellence in Engineered Fibre Composites (CEEFC) owing to the need to develop new types of biobased materials. Mechanical properties (tensile, flexural, Charpy impact and interlaminar shear), thermo-mechanical properties (glass transition temperature, storage modulus and crosslink density) and moisture-absorption properties (saturation moisture level and diffusion coefficient) were investigated and compared with samples containing commercially produced epoxidized soybean oil and a synthetic bisphenol A diglycidyl ether-based epoxy control, R246TX cured with a blend of triethylenetetramine and isophorone diamine. Scanning electron microscopy was also performed to investigate the fibre-matrix interface. Epoxidized hemp oil-based samples were found to have marginally superior mechanical, dynamic mechanical and similar water-absorption properties in comparison to samples made with epoxidized soybean oil bioresin; however, both sample types were limited to bioresin concentrations below 30%. Synthetic epoxy-based samples exhibited the highest mechanical, dynamic mechanical and lowest water-absorption properties of all investigated samples. This study has also determined that epoxidized hemp oil-based bioresins when applied to jute fibre-reinforced biocomposites can compete with commercially produced epoxidized soybean oil in biocomposite applications